The 2011 edition of “The Freshwater Algal Flora of the British Isles”: additions, corrections, nomenclatural and taxonomic changes

ABSTRACT

Taxonomic, nomenclatural and distributional changes since the publication of the 2011 edition (reprinted 2021) of The Freshwater Algal Flora of the British Isles (“Flora”) are reviewed together with some changes overlooked earlier. Many of the more recent changes are a result of studies combining an analysis of morphological and DNA sequence data. Of the 473 changes reported most concern the Chlorophyta (131) and the Charophyta (156) followed by the Cyanobacteria (101), with most of the alterations to the Charophyta involving the desmids (136). Also included are 83 new additions to the British and Irish freshwater algal floras, including 20 overlooked in the Flora. Most of these additions are new records: four are newly described desmids and Synura hibernica (Ochrophyta, Chrysophyceae, Synurales) and Chlorococcum turfosum (Chlorophyta, Chlorophyceae, Chlamydomonadales) are also new. The new additions to Flora include information on locality, collector and publication source. Reference is made to discussions in the Flora giving reasons why some genera and species combinations were not accepted, particularly concerning the Cyanobacteria for which a relatively conservative approach had been adopted in the previous edition of the Flora.

KEYWORDS:

• Algae
• Britain
• freshwater
• Ireland
• new combinations
• new records
• nomenclature
• revision
• taxonomy

Introduction

The second edition of the “Freshwater Algal Flora of the British Isles” (John, Whitton, & Brook, 2011; hereafter the “Flora”) is a much expanded and updated version of the original edition first published in 2002. The second edition of the Flora (reprinted in 2021) remains the only comprehensive account and identification guide to the freshwater and terrestrial algae (excluding diatoms) of Britain and Ireland. It includes information on their ecology, worldwide distribution, identification keys and many line drawings of species. The second edition is accompanied by a DVD containing a photographic catalogue of 680 images, some highly illustrated articles and video clips. The 2021 reprint is not accompanied by the DVD, however its contents are available for download from the Cambridge University Press (CUP) website. Since publication of the last edition, there have been major advances in our understanding of algal diversity and phylogenetic relationships, often due to molecular investigations involving the analysis of DNA sequence data and reassessment of the characters used to define genera and species.

Reviewed here are all taxonomic and/or nomenclatural changes (up to June 2021) since publication of the second edition of the Flora, including all new additions. The conservative approach adopted for the Cyanobacteria has meant that some of the changes predate publication of this edition. Over the past decade, taxonomic studies have focussed on some groups more than others and this is reflected in the number of changes. For example, there is a disproportionately large number of changes in the desmids (Charophyta, Desmidiales) due in large part to a revision of the genera Staurastrum & Staurodesmus based on morphology by Coesel & Meesters (2013). Many of the new desmid records are thanks to David Williamson who has also described a number of new taxa from these islands. Since of the second edition of the Flora the number of images has increased to over 2,300 due largely to new photographs contributed by Chris Carter. The original and new images are searchable on the AlgaeVision website (Carter, John, & Wilbraham, 2016; http://algaevision.myspecies.info) hosted by the Natural History Museum, London, developed by Joanna Wilbraham. The original photo catalogue is now available on the CUP website (under “Resources”) and many of the images are also available on the AlgaeBase website (Guiry & Guiry, 2021). The text accompanying each image entry on AlgaeVision gives the page number of the description/illustration(s) in the Flora and provides a weblink to the entry in AlgaeBase.

Worldwide sales of the Flora volumes (almost 2,700 copies) reflect the requirement for a user-friendly guide to enable the identification of frequently very widely distributed freshwater algae. The need for accurate species level identification using morphological characters and, in future, species-specific DNA sequences (“barcodes”), is increasingly important as the health of our freshwater environment continues to decline due to anthropogenic impact and climate change. Undesirable changes to freshwater environments worldwide will inevitably cause the disruption of food webs in which often algae play a key role as primary producers. It is predicted that “lake heatwaves” will in the future threaten biodiversity by changing the composition of aquatic communities, with algae, together with entire lake ecosystems, being driven to the very limits of their resilience (e.g., Woolway et al., 2021). Interest in freshwater algae continues unabated as these algae are increasingly used as indicators of the ecological and conservation status of aquatic habitats (see John & Williamson, 2007; Stewart, 2004), as sources of useful chemicals, producers of toxins and as nuisance organisms, and potential sequestrators or capturers of carbon and therefore used to combat or mitigate against some of the worst impacts of climate change.

Methodology

The current status of the taxonomic entries in the Flora was determined using AlgaeBase (Guiry & Guiry, 2021), employed worldwide as a reliable source of such information. The website, however, cautions that some of the species names it as current are “ … a compromise of taxonomic opinions that may or may not reflect your conclusions”. AlgaeBase was also used as a source of information the literature for most of the taxonomic and nomenclatural changes listed here.

Many of the important references, new records, errors and taxonomic and/or nomenclatural changes mentioned here are in the web-based version of the Coded List of British and Irish Freshwater Algae (Whitton & John, 2014) and published as corrections or updates in a series of articles (John & Whitton, 2012, 2013, 2014, 2015, 2017, John, Williamson, & van Weston, 2018, 2019).

Some of the changes and new additions include taxa overlooked previously, ones newly described, and many discovered in Britain and Ireland over the past decade. Also noted are a few taxa erroneously recorded from Britain and Ireland.

If the names of the taxa listed have changed more than once since publication of the Flora then the synonym(s) is in parentheses under the currently accepted name. The consensus classification published by Ruggiero et al. (2014) is generally adopted here (as in AlgaeBase), with some phyla in the Flora now classes under the Phylum Ochrophyta.

A double asterisk (**) before a binomial indicates the correction of an error in the Flora. Nomenclatural authorities with more than four authors have been reduced to the first author and “et”. As far as possible names of authorities comply with The International Plant Names Index (https://ipni.org). In accordance with best practice, a double bar “ = ” indicates a heterotypic synonym whilst a triple bar “≡” indicates a homotypic synonym. “ICN Art”. Refers to an Article of the International Code of Nomenclature (Wiersema et al., 2018). Invalid designations (“names”) are in double quotes.

Cyanobacteria Stanier ex Cavalier-Smith

In a series of monographs and papers Anagnostidis, Komárek and colleagues have proposed extensive rearrangements and splitting of cyanobacterial genera. Many of the changes were not adopted in the second edition of the Flora and some of the reasons given for not these new taxa were because “… culture and molecular studies are still insufficient in most cases to establish sound generic limits, which can be applied to both field identifications and laboratory research” (John et al., 2011: p. 36). The following genera were not recognized: Blennothrix, Leibleinia, Planktolyngbya, Limnococcus, Leptolyngbya, Dolichospermum, Phormidesmis, Pseudophormidium, Jaaginema, Tapinothrix, Trichormus and Jaaginema. The following new genera were in the Flora for “practical reasons” (see discussion in John et al., 2011: p. 34–38), or considered to be supported by particularly convincing evidence: Planktothrix, Tychonema, Sphaerospermum, Cuspidothrix and Heteroleibleinia. Since publication of the second edition there have been some combined morphological and molecular phylogenetic studies that have resulted in the creation of the following new genera: Anagnostidinema, Chrysosporum, Kamptonema, Potamolinea, Anathece, Desmonostoc, Johanseninema and Drouetiella. Names accepted in AlgaeBase and mentioned here are recommended in the Handbook of Cyanobacterial Monitoring and Cyanotoxin Analysis (Santos et al., 2017) for use by water managers dealing with cyanobacterial blooms and toxigenic species.

Note: Species are listed in orders in accordance with their present ordinal attribution.

Class Cyanophyceae Schaffner Order Chroococcales Schaffner

Gloeocapsa magma (Brébisson) Kützing is now Gloeocapsopsis magma (Brébisson) Komárek & Anagnostidis ex Komárek. In the Flora the author of the cyanobacteria considered Gloeocapsopsis magma to be a homotypic synonym of Gloeocapsa magma, commenting (p. 60) that “it seems unlikely that most users will be confident in separating the two” when referring to the difficulty of separating the genera on the characters mentioned by Komárek and Anagnostidis (1999).

** “Microcystis wesenbergii” (Komárek) Komárek, nom. inval. now Microcystis wesenbergii (Komárek) Komárek ex Komárek. The name was first validated in Joosten (2006, p. 209) when he cited the basionym and gave the name as “Microcystis wesenbergii (Komárek) Komárek ex Komárek” which meets the requirements of the ICN for validation of a name.

Order Oscillatoriales Schaffner

For practical difficulties associated with distinguishing genera of the Oscillatoriales, including the distinction between Pseudanabaena and Limnothrix, see discussion in the Flora (John et al., 2011: pp. 78–80). Also discussed (John et al., 2011: p. 83) is the reason for not recognizing some of the new genera (including Leptolyngbya, Leibleinia, Planktolyngbya) created by the splitting and rearrangement of species of Lyngbya sensu lato, with these changes by Komárek and Anagnostidis (2005).

Homoeothrix balearica (Bornet & Flahault ex Forti) Lemmermann now Phormidiochaete balearica (Bornet & Flahault ex Forti) Komárek.

Homoeothrix caespitosa Kirchner, nom. illeg. now Phormidiochaete nordstedtii (Bornet & Flahault) Komárek. The supposed basionym, “Calothrix caespitosa” Rabenhorst, is invalid (pre-starting- point name). Homoeothrix caespitosa Kirchner could be treated as a new name but is illegitimate as included in the synonymy of Dichothrix nordstedtii Bornet & Flahault [erroneously given as “Diplothrix nordstedtii”], a valid and legitimate name and transferred to Phormidiochaete by Komárek in Anagnostidis (2001).

Hydrocoleum heterotrichum Gomont ex Gomont now Blennothrix heterotricha (Gomont ex Gomont) Anagnostidis & Komárek. This species and H. lyngbyaceum (below) are treated as basionyms of Blennothrix species by Anagnostidis & Komárek (1988).

Hydrocoleum lyngbyaceum Kützing ex Gomont now Blennothrix lyngbyacea (Kützing ex Gomont) Komárek & Anagnostidis.

Lyngbya aerugineo-caerulea Gomont (≡ Phormidium aeruginosa-caeruleum (Gomont) Komárek & Anagnostidis) now Potamolinea aerugineocaerulea (Gomont) M.D.Martins & L.H.Z.Branco. Basionym and homotypic synonym of this Potamolinea species are based upon a phylogenetic study by Martins and Branco (2016). Hyphen removed in accordance with ICN art. 60.12.

Lyngbya diguetii Gomont now Phormidium diguetii (Gomont) Anagnostidis & Komárek. This

Lyngbya and some of those mentioned below are now considered to be species of Phormidium.

Lyngbya lutescens Hansgirg now Phormidium lutescens (Meneghini) Anagnostidis & Komárek. Homotypic synonym of this Phormidium species.

Oscillatoria amphibia C.Agardh ex Gomont [≡ Geitlerinema amphibium (C.Agardh ex Gomont) Anagnostidis] now Anagnostidinema amphibium (C.Agardh ex Gomont) Strunecký, Bohunick, J.R.Johansen & Komárek. Basionym of this species of the genus Anagnostidinema created by Strunecký et al. (2017). This species was initially transferred to Geitlerinema, one of several genera not treated in the Flora (John et al., 2011: p. 95). Geitlerinema amphibium is a homotypic synonym of Anagnostidinema amphibium.

Oscillatoria brevis Kützing ex Gomont now Phormidium breve (Kützing ex Gomont) Anagnostidis & Komárek. Basionym and homotypic synonym of this Phormidium species. One of several Oscillatoria species mentioned below that Anagnostidis & Komárek (1988) transferred to the genus Phormidium.

Oscillatoria chalybea Mertens ex Gomont now Phormidium chalybeum (Mertens ex Gomont) Anagnostidis & Komárek.

Oscillatoria cortiana Meneghini ex Gomont now Kamptonema cortianum (Meneghini ex Gomont) Strunecký, Komárek & J.Smarda. One of the Oscillatoria species mentioned below is a basionym of a Kamptonema species (Strunecký, Komárek, & Smarda, 2014).

Oscillatoria formosa Bory ex Gomont now Kamptonema formosum (Bory ex Gomont) Strunecký, Komárek & J.Smarda.

Oscillatoria granulata N.L.Gardner now Phormidium granulatum (N.L.Gardner) Anagnostidis

Oscillatoria hamelii Frémy now Phormidium hamelii (Frémy) Anagnostidis & Komárek.

Oscillatoria irrigua Kützing ex Gomont now Phormidium irriguum (Kützing ex Gomont) Anagnostidis & Komárek.

Oscillatoria nigra Vaucher ex Gomont now Phormidium nigrum (Vaucher ex Gomont) Anagnostidis & Komárek.

Oscillatoria nigro-viridis Thwaites ex Gomont now Phormidium nigroviride (Thwaites ex Gomont) Anagnostidis & Komárek. Hyphen removed in accordance with ICN art. 60.12.

Oscillatoria okenii C.Agardh ex Gomont now Kamptonema okenii (C.Agardh ex Gomont) Strunecký, Komárek & J.Smarda.

Oscillatoria prolifica Gomont now Planktothrix prolifica (Gomont) Anagnostidis & Komárek. Basionym and homotypic synonym of this Planktothrix species (Anagnostidis & Komárek, 1988).

Oscillatoria splendida Greville ex Gomont now Geitlerinema splendidum (Greville ex Gomont) Anagnostidis. Basionym of this Geitlerinema species (Anagnostidis, 1989).

Oscillatoria subtilissima Kützing ex Forti now Jaaginema subtilissimum (Kützing ex Forti) Anagnostidis & Komárek. Basionym of this Jaaginema species (Anagnostidis & Komárek, 1988).

Oscillatoria terebriformis C.Agardh ex Gomont now Phormidium terebriforme (C.Agardh ex Gomont) Anagnostidis & Komárek. Basionym and homotypic synonym of this Phormidium species.

Phormidium acutissimum (Kufferath) Anagnostidis & Komárek now Anagnostidinema acutissimum (Kufferath) Strunecký, Bohunická, J.R.Johansen & Komárek (Strunecký et al., 2017).

“Phormidium amoenum” Kützing, nom. inval. now Microcoleus amoenus (Gomont) Strunecký, Komárek & J.R.Johansen. This and other Phormidium species mentioned below are basionyms and homotypic synonyms of species of Microcoleus (Strunecký, Komárek, Johansen, Lukesová, & Elster, 2013), Drouetiella (Mai, Johansen, Pietrasiak, Bohunická, & Martin, 2018) and Kamptonema (Strunecký et al., 2014).

Phormidium autumnale Gomont now Microcoleus autumnalis (Gomont) Strunecký, Komárek & J.R.Johansen.

Phormidium favosum Gomont now Microcoleus favosus (Gomont) Strunecký, Komárek & J.R.Johansen.

Phormidium laetevirens H.Crouan & P.Crouan ex Gomont now Kamptonema laetevirens (H.Crouan & P.Crouan ex Gomont) Strunecký, Komárek & J.Smarda.

Phormidium luridum Gomont now Drouetiella lurida (Gomont) Mai, J.R.Johansen & Pietrasiak. Basionym of this species of Drouetiella (see Mai et al., 2018).

Phormidium okenii (C.Agardh ex Gomont) Anagnostidis & Komárek now Kamptonema okenii

(C.Agardh ex Gomont) Strunecký, Komárek & J.Smarda.

Phormidium subuliforme (Thwaites ex Gomont) Anagnostidis & Komárek, nom. illeg. now Phormidium thwaitesii I.Umezaki & M.Watanabe. Heterotypic synonym of this species described by Umezaki and Watanabe (1994).

Plectonema tenue Thuret ex Gomont now Pseudophormidium tenue (Thuret ex Gomont) Anagnostidis & Komárek. Basionym and homotypic synonym of this Pseudophormidium species (Anagnostidis & Komárek, 1988).

Schizothrix friesii Gomont now Symplocastrum friesii (Gomont) Kirchner. Basionym and homotypic synonym of this Symplocastrum species.

Order Synechcoccales L.Hoffmann, Komárek & Kastovsky

Aphanothece bachmannii Komárková-Legnerová & G.Cronberg now Anathece bachmannii (Komárková-Legnerová & G.Cronberg) Komárek, Kastovsky & Jezberová. This and other Aphanothece species listed below are now basionyms of the genus Anathece (Komárek, Kastovsky, & Jezberová, 2011).

Aphanothece clathrata West & G.S.West now Anathece clathrata (West & G.S.West) Komárek, Kastovsky & Jezberová.

Aphanothece endophytica (West & G.S.West) Komárková-Legnerová & G.Cronberg now Anathece endophytica (West & G.S.West) Komárek, Kastovsky & Jezberová.

Aphanothece clathrata West & G.S.West now Anathece clathrata (West & G.S.West) Komárek, Kastovsky & Jezberová.

Aphanothece minutissima (West) Komárková-Legnerová & G.Cronberg now Anathece minutissima (West) Komárek, Kastovsky & Jezberová.

Chroococcus limneticus Lemmermann now Limnococcus limneticus (Lemmermann) Komárková, Jezberová, Komárek & Zapomelová. Basionym of the type species of the genus Limnococcus created by Komáreková et al. (2010).

Heteroleibleinia epiphytica Komárek, nom. illeg. now Heteroleibleinia willei Guiry & D.M.John (Guiry & John, 2021).

Homoeothrix crustacea Borzí now Tapinothrix crustacea (Borzí) Bohunická & J.R.Johansen. Many species of Homoeothrix have been transferred by Bohunická, Johansen, & Fucíková (2011) to Tapinothrix based on morphology and 16S–23S ITS sequences (see below).

Homoeothrix fusca Starmach now Tapinothrix fusca (Starmach) Bohunická & J.R.Johansen.

Homoeothrix varians Geitler now Tapinothrix varians (Geitler) Bohunická & J.R.Johansen.

Lyngbya bipunctata Lemmermann now Planktolyngbya bipunctata (Lemmermann) Anagnostidis & Komárek. The Lyngbya species listed below are also basionyms of Planktolyngbya species (see Anagnostidis & Komárek, 1988).

Lyngbya contorta Lemmermann now Planktolyngbya contorta (Lemmermann) Anagnostidis & Komárek.

Lyngbya epiphytica Hieronymus now Leibleinia epiphytica (Hieronymus) Compère. This and the Lyngbya species mentioned below are now considered to be species of Leibleinia.

Lyngbya gracilis Rabenhorst ex Gomont now Leibleinia gracilis (Rabenhorst ex Gomont) Anagnostidis & Komárek.

Lyngbya lagerheimii Gomont now Leptolyngbya lagerheimii (Gomont) Anagnostidis & Komárek.

Lyngbya limnetica Lemmermann now Planktolyngbya limnetica (Lemmermann) Komárková- Legnerová & G.Cronberg.

Lyngbya nordgaardii Wille, nom. illeg. [≡ Leibleinia nordgaardii (Wille) Anagnostidis & Komárek] now Heteroleibleinia willei (Setchell & N.L.Gardner) Guiry & D.M.John. The description of Heteroleibleinia epiphytica Komárek, nom. illeg. is broadened in the Flora (John et al., 2011: p. 82) to include Lyngbya nordgaardii Wille sensu Weldon [≡ Leibleinia nordgaardii (Wille) Anagnostidis & Komárek]. These are very similar species and may represent the same taxon. It was concluded in the Flora (John et al., 2011: p. 92) that the issue can only be “ … resolved clearly when more is known about how the hormogonia first become attached … ”. If the species prove to be conspecific, then Leibleinia nordgaardii will become a synonym of Heteroleibleinia willei (formerly H. epiphytica Wille) as this is the earliest valid name available. See note under Heteroleibleinia epiphytica.

Lyngbya ochracea Thuret ex Gomont now Leptolyngbya ochracea (Thuret ex Gomont) Anagnostidis & Komárek.

Lyngbya rivulariarum Gomont now Leptolyngbya rivulariarum (Gomont) Anagnostidis & Komárek.

Lyngbya vandenberghenii Symoens now Leptolyngbya vandenberghenii (Symoens) Anagnostidis.

Merismopedia punctata Meyen, nom. illeg. now Merismopedia tranquilla (Ehrenberg) Trevisan. Heterotypic synonym of this Merismopedia species. Merismopedia punctata Meyen was superfluous and thus illegitimate when published as it included Gonium tranquillum Ehrenberg, 1834 and Gonium glaucum Ehrenberg, 1838. The name Merismopedia glauca (Ehrenberg) Kützing is available.

Oscillatoria angustissima West & G.S.West now Jaaginema angustissimum (West & G.S.West) Anagnostidis & Komárek (1988).

Oscillatoria subtilissima Kützing ex Forti now Jaaginema subtilissimum (Kützing ex Forti) Anagnostidis & Komárek.

Phormidium angustissimum West et G.S.West now Leptolyngbya angustissima (West & G.S.West) Anagnostidis & Komárek.

Phormidium foveolarum Gomont now Leptolyngbya foveolarum (Gomont) Anagnostidis & Komárek.

Phormidium laminosum Gomont ex Gomont now Leptolyngbya laminosa (Gomont ex Gomont) Anagnostidis & Komárek.

Phormidium molle Gomont now Phormidesmis mollis (Gomont) Turicchia, Ventura, Komárková & Komárek. Homotypic synonym of this species of Phormidesmis, a genus established based on morphology and sequence data (Turicchia, Ventura, Komárková, & Komárek, 2009).

Phormidium tenue Gomont now Leptolyngbya tenuis (Gomont) Anagnostidis & Komárek.

Phormidium valderianum Gomont now Leptolyngbya valderiana (Gomont) Anagnostidis & Komárek.

Plectonema battersii Gomont now Leptolyngbya battersii (Gomont) Anagnostidis & Komárek

Plectonema species listed below are basionyms of Leptolyngbya species.

Plectonema boryanum Gomont now Leptolyngbya boryana (Gomont) Anagnostidis & Komárek.

Plectonema calothrichoides Gomont now Leptolyngbya calothricoides (Gomont) Anagnostidis & Komárek.

Plectonema golenkinianum Gomont now Leptolyngbya golenkinianum (Gomont) Anagnostidis & Komárek.

Plectonema gracillimum Zopi ex Hansgirg now Leptolyngbya gracillima (Zopi ex Hansgirg) Anagnostidis & Komárek.

Plectonema norvegicum Gomont now Leptolyngbya norvegica (Gomont) Anagnostidis & Komárek.

Plectonema nostocorum (Bornet ex Gomont) Gomont now Leptolyngbya nostocorum (Bornet ex Gomont) Anagnostidis & Komárek.

Plectonema notatum Schmidle now Leptolyngbya notata (Schmidle) Anagnostidis & Komárek.

Plectonema terebrans Bornet & Flahault ex Gomont now Leptolyngbya terebrans (Bornet & Flahault ex Gomont) Anagnostidis & Komárek.

“Pseudanabaena redekei” (Goor) B.A.Whitton, nom. inval. now Limnothrix redekei (Goor) M.- E.Meffert. Homotypic synonym of Limnothrix redekei (see Meffert, 1988). Pseudanabaena redekei is an invalid name as a full and direct reference to the page number of the basionym is not given as is required for validity (ICN Art. 41.5 and Note 1).

Schizothrix muelleri Nägeli ex Gomont now Planktolyngbya contorta (Lemmermann) Anagnostidis & Komárek [including now “Stichococcus contortus” (Lemmermann) Hindák, nom. inval. (≡ Lyngbya contorta Lemmermann)]. Stichococcus contortus is invalid as the incorrect basionym is given because of a taxonomic misinterpretation.

Schizothrix perforans Geitler now Leptolyngbya perforans (Geitler) Anagnostidis & Komárek. Basionym and homotypic synonym of this Leptolyngbya species.

Synechococcus bacillaris Butcher now Cyanobium bacillare (Butcher) Komárek, Kopecký & Cepák. Basionym and homotypic synonym of this Cyanobium species.

Order Nostocales Borzì

Anabaena catenula var. affinis Lemmermann now Dolichospermum affine (Lemmermann) P.Wacklin, L.Hoffmann & Komárek. This taxon and planktonic, gas vacuolate Anabaena species listed below are now referred to the genus Dolichospermum (Wacklin, Hoffmann, & Komárek, 2009).

Anabaena circinalis Rabenhorst ex Bornet & Flahault now Dolichospermum circinale (Rabenhorst ex Bornet & Flahault) P.Wacklin, L.Hoffmann & Komárek.“Anabaena compacta” (Nygaard) Hickel, nom. inval. now Dolichospermum compactum (Nygaard) P.Wacklin, L.Hoffmann & Komárek.

Anabaena crassa (Lemmermann) P.Wacklin, L.Hoffmann & Komárek now Dolichospermum crassum (Lemmermann) P.Wacklin, L.Hoffmann & Komárek.

Anabaena delicatula Lemmermann now Dolichospermum delicatulum (Lemmermann) P.Wacklin, L.Hoffmann & Komárek.

Anabaena flos-aquae Brébisson ex Bornet & Flahault now Dolichospermum flosaquae (Brébisson ex Bornet & Flahault) P.Wacklin, L.Hoffmann & Komárek. Hyphen removed in accordance with ICN Art. 60.12.

Anabaena lemmermannii P.G.Richter now Dolichospermum lemmermannii (P.G.Richter) P.Wacklin, L.Hoffmann & Komárek.

Anabaena macrospora Klebahn now Dolichospermum macrosporum (Klebahn) P.Wacklin, L.Hoffmann & Komárek.

Anabaena mendotae Trelease now Dolichospermum mendotae (Trelease) P.Wacklin, L.Hoffmann & Komárek.

Anabaena planctonica Brunnthaler now Dolichospermum planctonicum (Brunnthaler) P.Wacklin, L.Hoffmann & Komárek.

Anabaena solitaria Klebahn now Dolichospermum solitarium (Klebahn) P.Wacklin, L.Hoffmann & Komárek.

Anabaena spiroides Klebahn now Dolichospermum spiroides (Klebahn) P.Wacklin, L.Hoffmann & Komárek.

Anabaena variabilis Kützing ex Bornet & Flahault now Trichormus variabilis (Kützing ex Bornet & Flahault) Komárek & Anagnostidis and is the type species of the genus Trichormus (Komárek & Anagnostidis, 1989).

Anabaena viguieri Denis & Frémy now Dolichospermum viguieri (Denis & Frémy) P.Wacklin, L.Hoffmann & Komárek.

Aphanizomenon ovalisporum Forti now Chrysosporum ovalisporum (Forti) Zapomelová et al. The basionym binomial is not cited and page of publication not given in Zapomelová et al. (2012: 359) and not validly published until the following year (Zapomelová, Skácelová, Pumann, Kopp, & Janacek, 2013: 201).

Hapalosiphon fontinalis Bornet now Hapalosiphon pumilis Kirchner ex Bornet & Flahault. Heterotypic synonym of this Hapalosiphon species.

Nostoc commune var. flagelliforme Bornet & Flahault now Nostoc flagelliforme Harvey ex Molinari, Calvo-Pérez & Guiry. Homotypic synonym of this Nostoc species. The change in authorship of Nostoc flagelliforme Bornet & Flahault to Nostoc flagelliforme Harvey ex Molinari-Novoa, Calvo-Pérez & Guiry was proposed by Molinari-Novoa et al. (2016) and was necessary to meet both nomenclatural and taxonomic requirements.

Nostoc muscorum C.Agardh ex Bornet & Flahault now Desmonostoc muscorum (C.Agardh ex Bornet & Flahault) Hrouzek & Ventura. Basionym of this type species of the genus Desmonostoc was established based largely upon a 16S rRNA gene sequence study by Hrouzek, Lukešová, Mareš, & Ventura (2013).

Scytonema alatum Borzì ex Bornet & Flahault now Petalonema alatum (Borzì ex Bornet & Flahault) Correns, the type species of the genus Petalonema (see Mares et al., 2015).

Scytonema crispum Bornet ex De Toni now Heteroscytonema crispum (Bornet ex De Toni) G.B.McGregor & Sendall. Basionym of the type species of the genus Heteroscytonema (Sendall & McGregor, 2018).

Scytonema crustaceum Thuret ex Bornet & Flahault now Scytonematopsis crustacea (Thuret ex Bornet & Flahault) Kováčik & Komárek. Basionym of this Scytonematopsis species (Kováčik & Komárek, 1988).

Tolypothrix byssoidea Kirchner now Hassallia byssoidea Hassall ex Bornet & Flahault. Homotypic synonym of this Hassallia species.

Tolypothrix distorta var. penicillata (C.Agardh) Lemmermann now Tolypothrix penicillata Thuret ex Bornet & Flahault. Technically a heterotypic synonym of this Tolypothrix species.

“Tolypothrix tenuis var. calcarata” (Schmidle) B.A.Whitton, nom. inval. now Tolypothrix calcarata Schmidle. Heterotypic synonym of this Tolypothrix species. Tolypothrix tenuis var. calcarata is invalid as a full and direct reference to the supposed basionym was not given.

Order Pleurocapsales Geitler

Xenococcus kerneri Hansgirg now Xenotholos kerneri (Hansgirg) Gold-Morgan, Montejano & J.Komárek. Basionym and homotypic synonym of this Xenococcus species.

Rhodophyta Wettstein

Class Florideophyceae Cronquist

Order Batrachospermales Pueschel & K.M.Cole

Batrachospermum arcuatum Kylin now Sheathia arcuata (Kylin) Salomaki & M.L.Vis.

This species and others listed below are basionyms and homotypic synonyms of Sheathia, a genus created by Salomaki et al. (2014) based upon morphological and sequencing data.

Batrachospermum atrum (Hudson) Harvey now Torularia atra (Hudson) M.J.Wynne [≡ Atrophycus ater (Hudson) Necchi & Rossignolo]. Basionym and homotypic synonym of this species of Torularia, a genus reinstated for Atrophycus (Wynne, 2019).

Batrachospermum boryanum Sirodot now Sheathia boryana (Sirodot) Salomaki & M.L.Vis.

Batrachospermum confusum (Bory) Hassall now Sheathia confusa (Bory) Salomaki & M.L.Vis.

Batrachospermum helminthosum Bory now Virescentia helminthosa (Bory) Necchi, D.C.Agostinho & M.L.Vis. Basionym and homotypic synonym of this the type species of Virescentia, a genus established by Necchi, Agostinho, & Vis (2018).

Batrachospermum turfosum Bory now Paludicola turfosa (Bory) M.L.Vis & Necchi. Basionym and homotypic synonym of this the type species of the genus Paludicola (Vis et al., 2020).

Euglenozoa Cavalier-Smith [EUGLENOPHYTA]

Note: included in the Flora as the Euglenophyta. The phylum Euglenozoa, as currently conceived (Cavalier-Smith, 2016), includes 8 classes, including the Euglenophyceae, which is ancestrally largely photoautotrophic. The other classes are mostly treated under the International Code for Zoological Nomenclature (ICZN). It is clear now that the Euglenophyceae show [/CSF];… evolved by the symbiogenetic merger of two fundamentally different lineages” (Ruggiero et al., 2014: 4).

Class Euglenophyceae Schoenichen

Order Euglenales F.Stein [also known as the Euglenida]

Astasia longa E.G. Pringsheim now Euglena longa (E.G. Pringsheim) Marin & Melkonian. Basionym and homotypic synonym of this species of Euglena (Marin 2003).

Colacium vesiculosum f. cyclopicola (Gicklhorn) T.G.Popova ex Wołowski now Colacium cyclopicola (Gicklhorn) Woronichin & T.G.Popova. Homotypic synonym of this Colacium species.

Euglena anabaena Mainx now Euglenaria anabaena (Mainx) Karnkowska-Ishikawa & E.W.Linton. Basionym and homotypic synonym of this Euglenaria species. Several species of Euglena (see below) are basionyms and homotypic synonyms of species belonging to the genus Euglenaria (Linton et al., 2010).

Euglena caudata E.F.W.Hübner now Euglenaria caudata (E.F.W.Hübner) Karnkowska-Ishikawa, E.W.Linton & Kwiatkowski.

Euglena clavata Skuja now Euglenaria clavata (Skuja) Karnowski & E.W.Linton

Euglena communis Gojdics now Euglena granulata (G.A.Klebs) F.Schmitz. Heterotypic synonym of this Euglena species.

Euglena deses var. intermedia G.A.Klebs now Euglena deses Ehrenberg. Heterotypic synonym of this Euglena species.

Euglena deses f. klebsii (Lemmermann) T.G.Popova now Euglena deses Ehrenberg. Heterotypic synonym of this Euglena species.

Euglena limnophila Lemmermann now Phacus limnophila (Lemmermann) E.W.Linton & Karnkowska-Ishikawa. Basionym and homotypic synonym of this species of Phacus (Linton et al., 2010).

Euglena magnifica E.G. Pringsheim now Euglena sanguinea Ehrenberg. Heterotypic synonym of this Euglena species.

Euglena obtusa Goor, nom. illeg. [priority for E. obtusa F.Schmitz, 1884] now Euglena van-goori Deflandre. Heterotypic synonym of this Euglena species.

Euglena polymorpha P.A.Dangeard now Euglena granulata (G.A.Klebs) F.Schmitz. Heterotypic synonym of this Euglena species.

Euglena proxima P.A.Dangeard now Euglenaformis proxima (P.A.Dangeard) M.S.Bennett & Triemer. Basionym and homotypic synonym of this the type species of the genus Euglenaformis (Bennett, Wiegert, & Triemer, 2014).

Euglena spathirhyncha Skuja now Discoplastis spathirhyncha (Skuja) Triemer. Basionym and homotypic synonym of this the type species of the genus Discoplastis (Triemer et al., 2006).

Lepocinclis playfairiana (Deflandre) Deflandre now Lepocinclis caudata (A.M.Cunha) Pascher. Heterotypic synonym of this species of Lepocinclis (see Łukomska-Kowalczyk et al., 2019).

Lepocinclis salina F.E.Fritsch now Phacus salina (F.E.Fritsch) E.E.Linton & Karnkowska. Basionym and homotypic synonym of this Phacus species.

Lepocinclis steinii var. suecica Lemmermann now Lepocinclis steinii (Lemmermann) Lemmermann. Heterotypic synonym of this species of Lepocinclis.

Lepocinclis texta (Dujardin) Lemmermann now Euglena texta (Dujardin) Hübner. Homotypic synonym of this Euglena species.

Peranema trichophorum (Ehrenberg) F.Stein [≡ Peranemopsis trichophora (Ehrenberg) Péterfi] now Pseudoperanema trichophorum (Ehrenberg) J.Larsen. Homotypic synonym of this Pseudoperanema species. Doubt attaches to the authorship of the new combination since Larsen (1987) and Compère (1987) independently proposed the name in studies published in December 1987, but priority is yet to be determined.

**Phacus alatus G.A.Klebs. Mistakenly placed in the synonymy of Phacus pusillus Lemmermann in the Flora (John et al., 2011: p. 212).

Phacus hispidulus (Eichwald) Klebs now Lepocinclis hispidula (Eichwald) Daday. Homotypic synonym of this Lepocinclis species.

Phacus triqueter (Ehrenberg) Dujardin [not Phacus triquetra (Ehrenberg) Dujardin] now Phacus alatus G.A.Klebs. Heterotypic synonym of this species of Phacus (see Łukomska-Kowalczyk, Fells, Chaber, Milanowski, & Zakrys, 2020: p. 1143).

Trachelomonas bernardinensis Vischer now Trachelomonas caudata (Ehrenberg) F.Stein. Heterotypic synonym of this Trachelomonas species.

Trachelomonas oblonga var. truncata Lemmermann now Trachelomonas truncata (Lemmermann) Skvortsov. Basionym and heterotypic synonym of this Trachelomonas species.

Trachelomonas rugulosa var. meandrina (Conrad) Conrad now Trachelomonas stokesiana f. meandrina (Conrad) T.G.Popova. Homotypic synonym of this form of Trachelomonas.

Trachelomonas scabra Playfair now “Strombomonas scabra” (Playfair) Tell & Conforti, nom. inval. Basionym and homotypic synonym of this Strombomonas species. Place of publication of the basionym not fully cited.

Class Peranemea Cavalier-Smith

Order Acroglissida Cavalier-Smith

Heteronema scaphurum Skuja now Teloprocta scaphurum (Skuja) Cavalier-Smith (Teloproctidae). Basionym and homotypic synonym of this species of Teloprocta (Cavalier-Smith, Chao, & Vickerman, 2016: p. 163).

Order Natomonadida Cavalier-Smith

Rhabdomonas spiralis E.G. Pringsheim now Rhabdospira spiralis (E.G. Pringsheim) E.G. Pringsheim.

Class Stavomonadea Cavalier-Smith

Order Petalomonadida Cavalier-Smith

Petalomonas mediocanellata F.Stein now Notosolenus mediocanellatus (Klebs) Schroeckh, W.J.Lee & D.J.Patterson.

Cryptophyta Cavalier-Smith

Order Cryptomonadales E.G. Pringsheim

Chilomonas paramaecium Ehrenberg now Cryptomonas paramaecium (Ehrenberg) Hoef-Emden & Melkonian. Basionym and homotypic synonym of this species of Cryptomonas (Hoef-Emden & Melkonian, 2003).

Chroomonas acuta Utermöhl now Komma caudata (Geitler) D.R.A.Hill. Heterotypic synonym of this Komma species (Hill, 1991).

Chroomonas rosenbergii Huber-Pestalozzi now Chroomonas coerulea (Geitler) Skuja. Heterotypic synonym of this Chroomonas species.

Cryptomonas stigmatica Wislouch now Rhodomonas stigmatica (Wislouch) D.R.A.Hill. Basionym and homotypic synonym of this Rhodomonas species. Recorded with doubt in the Flora (John et al., 2011: p. 247).

DINOZOA Cavalier-Smith [as DINOPHYTA Dillon]

Notes: The phylum Dinozoa includes a number of classes that are generally treated under the ICZN (see Ruggiero et al., 2014). Over the past two decades many studies on phylogenetic relationships have resulted in a revision of generic boundaries, the recognition of several new genera and a number of species reassignments (Craveiro, Calado, Daugbjerg, Hansen, & Moestrup, 2011; Moestrup & Calado, 2018), and the description of several new orders.

Order Amphidiniales Moestrup & Calado

Amphidinium amphidinioides (Geitler) J.Schiller now Nusuttodinium amphidinioides (Geitler) Y.Takano & T.Horiguchi in Y.Tanako et al. Homotypic synonym of this Nusuttodinium species (see Takano, Yamaguchi, Inouye, Moestrup, & Horiguchi, 2014).

Order Peridiniales Haeckel

Glenodinium cinctum Ehrenberg now Glenodiniopsis steinii Wołoszyńska. Heterotypic synonym of this Glenodiniopsis species; not Glenodiniopsis steinii (Lemmermann) Wołoszyńska 1917 (see comments in AlgaeBase).

Glenodinium inaequale Chodat now “Peridiniopsis inaequalis” (Chodat) J. Stein & Borden, nom. inval. Basionym and homotypic synonym of this Peridiniopsis species. Invalidly published for lack of a reference to place of publication of the basionym. Recorded as doubtful in the Flora (John et al., 2011: p. 264).

Peridiniopsis elpatiewskyi (Ostenfeld) Bourrelly now Parvodinium elpatiewskyi (Ostenfeld) Kretschmann, Zerdoner & Gottschling. Heteromorphic synonym of this Parvodinium species (see Kretschmann, Zerdoner Calasan, Meyer, & Gottschling, 2019).

Peridiniopsis oculata (F.Stein) Bourrelly now Durinskia oculata (F.Stein) Gert Hansen & Flaim. Basionym and homotypic synonym of this species of Durinskia (Hansen & Flaim, 2007).

Peridiniopsis polonica (Wołoszyńska) Bourrelly now Naiadinium polonicum (Wołoszyńska) Carty. Homotypic synonym of this species of Naiadinium (Carty, 2014). Recorded as doubtful in the Flora (John et al., 2011: pp. 273–274) where mentioned as found in four Irish loughs.

Peridinium anglicum G.S.West (= Peridinium palatinum Lauterborn) now Palatinus apiculatus (Ehrenberg) Craveiro, A.J.Calado, N.Daugbjerg & Moestrup. Described and illustrated separately in the Flora (John et al., 2011: p. 271) from Palatinus apiculatus but now considered a heterotypic synonym.

Peridinium lomnickii var. wierzejskii (Wołoszyńska) Er.Lindemann now Chimonodinium lomnickii var. wierzejskii (Wołoszyńska) S.C.Craveiro, A.J.Calado, Daugbjerg, Gert Hansen & Moestrup, Homotypic synonym of this Chimonodinium species.

Peridinium umbonatum var. inaequale Lemmermann now Parvodinium umbonatum (F.Stein) Carty. Heterotypic synonym of this Parvodinium species.

Order Gymnodiniales Apstein

Amphidinium aeschrum T.M.Harris now Gymnodinium aeschrum (T.H.Harris) Moestrup (in Moestrup & Calado, 2018). Mentioned in the Flora (John et al., 2011: p. 260) as doubtful since the original determination was based upon misshapen cells. So far only recorded from the type locality, Mapledurham Lock, Oxfordshire on the River Thames, England.

Gymnodinium aeruginosum F.Stein now Nusuttodinium aeruginosum (F.Stein) Y.Takano & T.Horiguchi. Homotypic synonym of this Nusuttodinium species (Takano et al., 2014).

Katodinium hyperxanthum (T.M.Harris) A.R.Loeblich III now Gymnodinium hyperxanthum (T.M.Harris) Moestrup. Homotypic synonym of this Gymnodinium species (Moestrup & Calado, 2018).

Woloszynskia tylota (Maplesoft, H.Montgomery, J.Waters & P.Wells) B.T.Bibby & J.D.Dodge now Gymnodinium tylotum H.Mapletoft, M.Montgomery, J.Waters & P.Wells. Homotypic synonym of this Gymnodinium species. This species was described from two localities in Berkshire. A type was not designated, and we here designate as lectotype fig. 1 A-I in Maplesoft et al. (1966).

Order Gonyaulacales F.J.R.Taylor

Katodinium campylops (T.M.Harris) A.R.Loeblich III now Opisthoaulax campylops (T.M.Harris) A.J.Calado. This species and the other Katodinium species listed below are basionyms and homotypic synonyms of Opisthoaulax (Calado, 2011).

Katodinium tetragonops (T.M.Harris) A.R.Loeblich III now Opisthoaulax tetragonops (T.M.Harris) A.J.Calado.

Katodinium vorticellum (F.Stein) A.R.Loeblich III now Opisthoaulax vorticella (F.Stein) A.J.Calado.

Woloszynskia neglecta A.J.Schilling now Jadwigia neglecta (A.J.Schilling) Moestrup. Basionym and homotypic synonym of this Jadwigia species (see Moestrup & Calado, 2018).

Order Thoracosphaerales Tangen

Katodinium fungiforme (Anisimova) A.R.Loeblich III now Speroidium fungiforme (Anisimova) Moestrup & Calado. Homotypic synonym of this species of Speroidium (Moestrup & Calado, 2018).

Katodinium molopicum (T.M.Harris) A.R.Loeblich, III now Gyrodinium molopicum (T.M.Harris) Moestrup & Calado. Homotypic synonym of this species of Gyrodinium (Moestrup & Calado, 2018).

Peridiniopsis penardii (Lemmermann) Bourrelly, Moestrup & A.J.Calado now Unruhdinium penardii (Lemmermann) Gottschling. Homotypic synonym of this species of Unruhdinium (see Gottschling, Calasan, Kretschmann, & Gu, 2017). Misspelt “penardiforme” in the Flora (John et al., 2011: p. 272).

Peridinium aciculiferum Lemmermann now Apocalathium aciculiferum (Lemmermann) Craveiro, N.Daugbjerg, Moestrup & A.J.Calado. Basionym and homotypic synonym of the type species of the genus Apocalathium (Craveiro et al., 2016).

Peridinium lomnickii Wołoszyńska now Chimonodinium lomnickii (Wołoszyńska) Craveiro et al. Basionym and homotypic synonym of this Chimonodinium species (Craveiro et al., 2011).

Peridinium lomnickii Wołoszyńska var. wierzejskii (Wołoszyńska) Lindemann now Chimonodinium lomnickii var. wierzejskii (Wołoszyńska) Craveiro et al. Homotypic synonym of this variety of this Chimonodinium species (Craveiro et al., 2011).

Haptophyta Cavalier-Smith

Order Isochrysidales Bourrelly

Chrysotila lamellosa P.L.Anand Ruttnera lamellosa (P.L.Anand) R.A.Andersen, J.I.Kim, Tittley & H.S.Yoon. Basionym and homotypic synonym of type species of the genus Ruttnera (Andersen, Kim, Tittley, & Yoon, 2014).

Ochrophyta Cavalier-Smith

Class Chrysophyceae Pascher [CHRYSOPHYTA]

Order Chromulinales Pascher

Chrysocapsella paludosa (West & G.S.West) Bourrelly now Chrysocapsa wetherbeei R.A. Andersen. Heterotypic synonym of this Chrysocapsa species (see Andersen, Kim, Tittley, & Yoon, 2015).

Chrysocapsella planctonica (West & G.S.West) Bourrelly now Chlamydocapsa planctonica (West & G.S.West) Fott. Homotypic synonym of this Chrysocapsella species.

Chrysococcus rufescens f. triporus J.W.G.Lund now Chrysococcus rufescens Klebs. Heterotypic synonym of this Chrysococcus species.

Chrysolykos skujae (Nauwerck) Bourrelly now Chrysoikos skujae (Nauwerck) Willén. Homotypic synonym of this species of Chrysoikos (Willén, 1967).

Dinobryon sociale var. stipitatum (F.Stein) Lemmermann now Dinobryon stipitatum F.Stein. Basionym and homotypic synonym of this variety of a Dinobryon species.

Gloeochrysis turfosa (Pascher) Bourrelly now Goeochrysis turfosa Pascher. Homotypic synonym of this Goeochrysis species.

Stylochrysalis aurea (Chodat) Bachmann now Epipyxis aurea (Chodat) D.K.Hilliard. Homotypic synonym of this Epipyxis species (Hilliard, 1971).

Uroglena eustylis Skuja now Uroglenopsis eustylis (Skuja) R.H.Thompson & Wujek. Basionym and homotypic synonym of this Uroglenopsis species (Wujek & Thompson, 2002).

Uroglenopsis europaea Pascher now Uroglena europaea (Pascher) Skuja. Basionym and homotypic synonym of this Uroglena species.

Order Ochromonadales Pascher

**Poterioochromonas malhamensis (Pringsheim) L.S.Péterfi. See note in AlgaeBase for various opinions regarding the correct authority for this name.

“Spumella elongata” (A.Stokes) J.H.Belcher & Swale, nom. inval. now “Pedospumella elongata” (A.Stokes) Boenigk & Grossmann, nom. inval. Homotypic synonym of this Pedospumella species.

Order Paraphysomonadales Cavalier-Smith

Spiniferomonas serrata K.H.Nicholls now Chromophysomonas serrata (K.H.Nicholls) Preisig & D.J.Hibberd. This species and the following are homotypic synonyms of Chromophysomonas species (see Preisig & Hibberd, 1982) and are referred to the Paraphysomonadaceae (Paraphysomonadales). These Spiniferomonas species are listed in the Flora (John et al., 2011: p. 303) since only possible to identify by SEM examination of their scales.

Spiniferomonas trioralis E.Takahashi now Chromophysomonas trioralis (K.H.Nicholls) Preisig & D.J.Hibberd.

Order Synurales R.A.Andersen

**Mallomonas acaroides Perty now Mallomonas ploesslii Perty. Mallomonas acaroides Perty as listed in the Flora (John et al., 2011: p. 313) is an invalid name, as it was only incidentally mentioned “Früher M. acaroides” and the latter name was not published earlier; no description was provided by Perty (1852: p. 171).

Mallomonas pumilio var. silvicola K.Harris & D.E.Bradley now Mallomonas silvicola (K.Harris & D.E.Bradley) Nemková (Nemková, Kreidlov, Pusztai, & Neustupa, 2013).

Class Xanthophyceae P.Allorge ex F.E.Fritsch [XANTHOPYTA]

Order Mischococcales F.E.Fritsch

Characiopsis cylindrica (F.D.Lambert) Lemmermann now Heterococcus unguis Pitschmann. Heterotypic synonym of this Heterococcus species. A doubtful record mentioned in the Flora (John et al., 2011: p. 326) as growing on Daphnia and other planktonic animals.

Goniochloris fallax Fott now Pseudogoniochloris tripus (Pascher) Krienitz, E.Hegewald, Reymond & Peschke. Heterotypic synonym of this Pseudogoniochloris species.

Goniochloris smithii (Bourrelly) Fott now Pseudogoniochloris tripus (Pascher) Krienitz, E.Hegewald, Reymond & Peschke. Heterotypic synonym of this Pseudogoniochloris species.

Order Vaucheriales Bohlin

Vaucheria clavata (Vaucher) De Candolle now Vaucheria bursata (O.F.Müller) C.Agardh. This species and the next are heterotypic synonyms of Vaucheria bursata.

Vaucheria sessilis (Vaucher) De Candolle now Vaucheria bursata (O.F.Müller) C.Agardh.

Class Eustigmatophyceae D.J.Hibberd & Leedale [EUSTIGMATOPHYTA]

Order Eustigmatales D.J.Hibberd

Characiopsis cylindrica (F.D.Lambert) Lemmermann now Heterococcus unguis Pitschmann. Heterotypic synonym of this Heterococcus species. A doubtful record mentioned in the Flora (John et al., 2011: p. 326) as growing on Daphnia and other planktonic animals. This genus has been transferred from the Xanthophyceae to the Eustigmatophyceae by Amaral, Ševčíková, Eliáš, & Santos (2021).

Monodus subterranea J.B.Petersen now Monodopsis subterranea (J.B.Petersen) D.J.Hibberd.

Basionym and homotypic synonym of this Monodopsis species (Hibberd, 1981).

Polyedriella helvetica Vischer & Pascher now Vischeria helvetica (Vischer & Pascher) D.J.Hibberd. Basionym and homotypic synonym of this Vischeria species which has been subject to a study using ITS2 sequence data (Kryvenda, Rybalka, Wolf, & Friedl, 2018).

Pseudocharaciopsis ovalis (Chodat) Hibberd now Neomonodus ovalis (Chodat) R.Amaral et al. Homotypic synonym of this Neomonodus species (Amaral et al., 2020).

Order Goniochloridales K.P.Fawley, M.Eliás & M.W.Fawley

Tetraëdron regulare Kützing pro parte now Tetraedriella regularis (Kützing) Fott. Basionym and homotypic synonym of this Tetraedriella species. Placed in the Flora within the phylum Xanthophyta (now Ochrophyta, Xanthophyceae).

Chlorophyta Reichenbach

Class Chlorophyceae Wille

Order Chlamydomonadales F.E.Fritsch

Asterococcus terrestris Vischer now Macrochloris dissecta Korshikov. Heterotypic synonym of this Macrochloris species.

Carteria globosa Korshikov, nom. illeg. now Carteria pseudoglobosa Ettl. Heterotypic synonym of this Carteria species.

Carteria micronucleolata Korshikov now Pseudagloë micronucleolata (Korshikov) K.I.Meyer. Basionym and homotypic synonym of this Pseudagloë species.

Carteria ovata H.C.Jacobsen now Provasoliella ovata (H.C.Jacobsen) A.R.Loeblich III. Basionym and homotypic synonym of this the type species of the genus Provasoliella.

Characium ornithocephalum var. pringsheimii (A.Braun) Komárek now Characium pringsheimii A.Braun. Homotypic synonym of this Characium species.

Characium sieboldii A.Braun now Chlamydopodium sieboldii (A.Braun) Tsarenko. Basionym and homotypic synonym of this Chlamydopodium species.

Chlamydocapsa ampla (Kützing) Fott now Sphaerellocystis ampla (Kützing) Nováková. Homotypic synonym of this Sphaerellocystis species.

Chlamydomonas braunii Goroschankin now Microglena braunii (Goroschankin) Demchenko, Mikhailyuk & Pröschold. Basionym and homotypic synonym of this Microglena species (Demchenko et al., 2014).

Chlamydomonas britannica J.W.G.Lund now Chlamydomonas eustigma Ettl. Heterotypic synonym of this Chlamydomonas species.

Chlamydomonas clathrata Pascher now Chloromonas reticulata (Goroschankin) Gobi. Heterotypic synonym of this Chloromonas species.

Chlamydomonas coccifera Goroschankin now Microglena coccifera (Goroschankin) Demchenko, Mikhailyuk & Pröschold. Basionym and homotypic synonym of this Microglena species (Demchenko et al., 2014). Chlamydomonas debaryana Goroschankin now Edaphochlamys debaryana (Goroschankin) Pröschold & Darienko. Basionym and homotypic synonym of the type species of the genus Edaphochlamys (Pröschold, Darienko, Krienitz, & Coleman, 2018).

Chlamydomonas depauperata Pascher now Chloromonas depauperata (Pascher) Gerloff & Ettl. Basionym and homotypic synonym of this species of Chloromonas.

Chlamydomonas gigantea O.Dill now Oogamochlamys gigantea (O.Dill) Pröschold, B.Marin, U.W.Schlösser & Melkonian. Basionym and homotypic synonym of this type species of Oogamochlamys (Pröschold, Marin, Schlösser, & Melkonian, 2001).

Chlamydomonas grovei G.S.West now Chloromonas grovei (G.S.West) Gerloff & Ettl. Basionym and homotypic synonym of this Chloromonas species.

Chlamydomonas korschikoffii Pascher now Chloromonas korschikoffii (Pascher) P.C.Silva.

Basionym and homotypic synonym of this Chloromonas species.

Chlamydomonas media Klebs now Microglena media (Klebs) Nakada. Basionym and homotypic synonym of this Microglena species (Nakada & Tomita, 2014).

Chlamydomonas mexicana R.A.Lewin now Chlamydomonas oblonga Pringsheim. Heterotypic synonym of this Chlamydomonas species. Chlamydomonas mirabilis Pascher now Chloromonas mirabilis (Pascher) Korshikov ex Ettl. Basionym and homotypic synonym of this Chloromonas species.

Chlamydomonas monadina (Ehrenberg) F.Stein now Microglena monadina Ehrenberg. Homotypic synonym of this the type species of the genus Microglena (Nakada & Tomita, 2014).

Chlamydomonas oxyphila A.Pentecost, nom. illeg. now Chlamydomonas nygaardii Fott. Heterotypic synonym of this Chlamydomonas species.

Chlamydomonas pertyi Goroschankin now Chlorogonium pertyi (Goroschankin) Ettl. Homotypic synonym of this Chlorogonium species.

Chlamydomonas pseudogloeogama F.E.Fritsch & R.P.John, nom. illeg. now Chlamydomonas gloeogama Korshikov. Heterotypic synonym of this latter Chlamydomonas species.

“Chlamydomonas pseudomacrostigma” Péterfi, nom. inval. now Microglena opisthopyren (Skuja) Demchenko, Mikhailyuk & Pröschold. Heterotypic synonym of this Microglena species (Demchenko, Mikhailyuk, Coleman, & Pröschold, 2012).

Chlamydomonas pseudopertusa H.Ettl now Dangeardinia pseudopertusa (H.Ettl) Nakada. Basionym and homotypic synonym of the type species of the reinstated genus Dangeardinia (Nakada, Tomita, Wu, & Nozaki, 2016).

Chlamydomonas rapida Brabez now Chloromonas rapida (Brabez) Gerloff & Ettl. Basionym and homotypic synonym of this Chloromonas species.

Chlamydomonas reticulata Goroschankin now Chloromonas reticulata (Goroschankin) Gobi. Basionym and homotypic basionym of the type species of the genus Chloromonas.

Chlamydomonas similis Korshikov now Rhysamphichloris similis (Korshikov) Nakada. Basionym and homotypic basionym of the type species of the genus Rhysamphichloris (Nakada et al., 2016).

Chlamydomonas similis var. curta J.H.Belcher now Rhysamphichloris curta (J.H.Belcher) Nakada. Type species of the genus Rhysamphichloris (Nakada et al., 2016).

Chlamydomonas variabilis Dangeard now Chloromonas variabilis (Dangeard) Wille. Basionym and homotypic synonym of this Chloromonas species.

Chlamydomonas vulgaris Anakhin now Chloromonas vulgaris (Anakhin) Gerloff & Ettl. Basionym and homotypic synonym of this Chloromonas species.

Chlamydomonas westiana Pascher now Chloromonas westiana (Pascher) Gerloff & Ettl. Basionym and homotypic synonym of this Chloromonas species.

Chlorella ellipsoidea Gerneck now Chloroidium ellipsoideum (Gerneck) Darienko & al. Basionym and homotypic synonym of this Chloroidium species.

Chlorella emersonii Shihira & R.W.Krauss now Graesiella emersonii (Shihara & R.W. Krauss) H.Nozaki & al. Basionym and homotypic synonym of this Graesiella species (Nozaki, Katagiri, Nakagawa, Aizawa, & Watanabe, 1995).

Chlorella minutissima Fott & Nováková now Mychonastes homosphaera (Skuja) Kalina & Puncochárová. Heterotypic synonym of this Mychonastes species (see Kalina & Puncochárová, 1987.

Chlorogonium fusiforme Marvienko now Rusalka fusiformis (Matvienko) T.Nakada. Basionym and homotypic synonym of the type species of the genus Rusalka (Nakada et al., 2008).

Chlorogonium tetragamum (Bohlin) Wille now Chlamydomonas tetragama Bohlin. Homotypic synonym of this Chlamydomonas species.Chloromonas cryophila Hoham & Mullet now Chloromonas nivalis (Chodat) Hoham & Mullet. Heterotypic synonym of this Chloromonas species.

Haematococcus droebakensis Wollenweber now Balticola droebakensis (Wollenweber) Droop. Basionym and homotypic synonym of the type species of the genus Balticola (Buchheim, Sutherland, Buchheim, & Wolf, 2013).

Gonium sociale (Dujardin) Warming now Tetrabaena socialis H.Nozaki & M.Itoh. Homotypic synonym of Tetrabaena species (Nozaki & Ito, 1994).

Neglectella asterifera (Skuja) B.Fott now Skujaster asteriferus (B.Fott) Vodenicarov. Basionym and homotypic synonym of this Skujaster species (see Vodenicarov, 1989).

Pandorina charkowiensis Korshikov now Colemanosphaera charkowiensis (Korshikov) H.Nozaki et al. Basionym and homotypic synonym of this Colemanosphaera species (see Nozaki, Yamada, Takahashi, Matsuzaki, & Nakada, 2014).

Radiosphaera dissecta (Korshikov) Starr now Macrochloris dissecta Korshikov. Homotypic synonym of this Macrochloris species.

Sphaerellopsis fluviatilis (Stein) Pascher now Vitreochlamys fluviatilis (Stein) Batko. This Sphaerellopsis species and the following are basionyms and homotypic synonyms of Vitreochlamys species (Nakazawa, Krienitz, & Nozaki, 2001).

Sphaerellopsis gloeocystiformis (O.Dill) Gerloff now Vitreochlamys gloeocystiformis (O.Dill) A.Nakazawa.

Sphaerellopsis lefevrei Bourrelly now Vitreochlamys lefevrei (Bourrelly) Menezes & C.E.M.Bicudo.

Sphaerellopsis spiralis J.H.Belcher & Swale now Vitreochlamys spiralis (J.H.Belcher & Swale) Alp (in Graf, Yang, Boo, Andersen, & Yoon, 2019).

Sphaerellopsis velata (Korshikov) Gerloff now Vitreochlamys velata (Korshikov) H.Ettl.

Order Sphaeropleales Luerssen

Acutodesmus acuminatus (Lagerheim) Tsarenko now Tetradesmus lagerheimii (Lagerheim) M.J.Wynne & Guiry (priority for Tetradesmus acuminatus C.-C.Jao & Z.-Y.Hu). This and some of the following species are homotypic synonyms of Tetradesmus species (Wynne & Hallan, 2016). Reinstatement of the genus Tetradesmus has meant the transfer to it of Acutodesmus lagerheimii and replacement of Tetradesmus acuminatus (Wynne & Guiry, 2016).

Acutodesmus dimorphus (Turpin) Tsarenko now Tetradesmus dimorphus (Turpin) M.J.Wynne

Acutodesmus obliquus (Turpin) Tsarenko now Tetradesmus obliquus (Turpin) M.J.Wynne.

Acutodesmus pectinatus (Meyen) Tsarenko now Pectinodesmus pectinatus (Meyen) E.Hegewald, M.Wolf, A.Keller, Friedl & Krienitz. Homotypic synonym of this Pectinodesmus species (Hegewald, Wolf, Keller, Friedl, & Krienitz, 2010).

Acutodesmus pectinatus var. bernardii (G.M.Smith) Tsarenko now Tetradesmus bernardii (G.M.Smith) M.J.Wynne.

Acutodesmus wisconsinensis (G.M.Smith) Tsarenko now Tetradesmus wisconsinensis G.M.Smith.

Ankistrodesmus nannoselene Skuja now Drepanochloris nannoselene (Skuja) Marvan, Komárek & Comas. Basionym and homotypic synonym of this Drepanochloris species (Marvan, Komárek, & Comas, 1984). Recorded as a doubtful in the Flora (John et al., 2011: p. 424) since only known from a strain in the Culture Collection of Algae and Protozoa (CCAP Culture No. 202/6B) isolated in England by E.A.George.

Chlorella minutissima Fott & Nováková now Mychonastes homosphaera (Skuja) Kalina & Puncochárová. Heterotypic synonym of this Mychonastes species (Kalina & Puncochárová, 1987).

Coelastrum verrucosum (Reinsch) Reinsch now Coelastrum sphaericum Nägeli. Heterotypic synonym of this Coelastrum species.

Coenococcus polycoccus (Korshikov) Hindák now Radiococcus polycoccus (Korshikov) I.Kostikov, T.Darienko, A.Lukesová & L.Hoffmann. Homotypic synonym of this Radiococcus species (see Kostikov, Darienko, Lukesová, & Hoffmann, 2002).

Coenocystis obtusa Korshikov now Pseudoquadrigula obtusa (Korshikov) Tsarenko. Basionym and homotypic synonym of this species of Pseudoquadrigula (see Tsarenko, 2011).

Gloeocystis polydermatica (Kützing) Hindák now Sporotetras polydermatica (Kützing) I.Kostikov, T.Darienko, A.Lukesová & L.Hoffmann. Homotypic synonym of this Sporotetras species (Kostikov et al., 2002).

Gloeocystis rupestris (Lyngbye) Rabenhorst now Gloeothece rupestris (Lyngbye) Bornet. Homotypic synonym of this Gloeothece species. Doubtful record (see comments in the Flora, John et al., 2011: p. 480).

Kirchneriella contorta (Schmidle) Bohlin now Raphidocelis danubiana (Hindák) Marvan, Komárek & Comas. Several Kirchneriella species lacking pyrenoids have been transferred by Marvan et al. (1984) to Raphidocelis on the basis that the presence or absence of pyrenoids is an important character for separating the genera.

Kirchneriella danubiana Hindák now Raphidocelis danubiana (Hindák) Marvan, Komárek & Comas.

Kirchneriella rotunda (Korshikov) Hindák now Raphidocelis rotunda (Korshikov) Marvan, Komárek & Comas.

Kirchneriella subcapitata Korshikov now Raphidocelis subcapitata (Korshikov) Nygaard, Komárek, J.Kristiansen & O.M.Skulberg.

Monoraphidium arcuatum (Korshikov) Hindák now Ankistrodesmus arcuatus Korshikov. Homotypic synonym of this Ankistrodesmus species.

Nephrodiella lunaris Pascher now Monoraphidium nanum (Pascher) Hindák. Homotypic synonym of this Monoraphidium species (see Hindák, 1980).

Pediastrum biradiatum Meyen now Parapediastrum biradiatum (Meyen) E.Hegewald. This species of Pediastrum and some listed below are homotypic synonyms of Parapediastrum species (Buchheim et al., 2005).

Pediastrum boryanum (Turpin) Meneghini now Pseudopediastrum boryanum (Turpin) E.Hegewald.

Pediastrum boryanum var. longicorne (Reinsch) Hansgirg now Pseudopediastrum boryanum var. longicorne (Reinsch) Tsarenko.

Pediastrum duplex var. gracillimum West & G.S.West now Lacunastrum gracillimum (West & G.S.West) H.McManus. Basionym and homotypic synonym of this species, the type species of the genus Lacunastrum (McManus, Lewis, & Schultz, 2011).

Pediastrum duplex var. subgranulatum Raciborski now Pseudopediastrum subgranulatum (Raciborski) Lenarczyk. Basionym and homotypic synonym of this Pseudopediastrum species (see Lenarczyk, Saluga, & Piatek, 2020).

Pediastrum kawraiskyi Schmidle now Pseudopediastrum kawraiskyi (Schmidle) E.Hegewald. Basionym and homotypic synonym of this Pseudopediastrum species.

Pediastrum privum (Printz) E.Hegewald now Stauridium privum (Printz) E.Hegewald. This species and others below are homotypic synonyms of Stauridium species (Buchheim et al., 2005).

Pediastrum simplex Meyen, now Monactinus simplex (Meyen) Corda. Basionym and homotypic synonym of this Monactinus species (Buchheim et al., 2005). Pediastrum tetras (Ehrenberg) Ralfs now Stauridium tetras (Ehrenberg) E.Hegewald.

Pseudodictyosphaerium scoticum Hindák now Mychonastes scoticus (Hindák) Krienitz, C.Bock, Dadheech & Pröschold. Basionym and homotypic synonym of this Mychonastes species (Krienitz, Bock, Dadheech, & Proschold, 2011).

Scenedesmus arcuatus var. platydiscus G.M.Smith now Comasiella arcuata var. platydisca (G.M.Smith) E.Hegewald & M.Wolf. Basionym and homotypic synonym of this species, the type species of the genus Comasiella (Hegewald et al., 2010).

Selenastrum gracile Reinsch now Messastrum gracile T.Garcia in Kusber, Da Silva, Bock, Krienitz, and Guiry (2021). Basionym and homotypic synonym of this the type species of the genus Messastrum T. Garcia in Garcia da Silva et al., 2015). It was pointed by Kusber et al. (2021) that the combination Messastrum gracile (Reinsch) T.Garcia was not validly published since there was no full and direct citation of the basionym and therefore a lectotype was chosen from amongst Reinsch’s images.

Schroederia robusta Korshikov now Pseudoschroederia robusta (Korshikov) E.Hegewald & Schnepf. Basionym and homotypic synonym of this the type species of Pseudoschroederia (Hegewald & Schnepf, 1986). Tetraedron incus (Teiling) G.M.Smith now Chlorotetraedron incus (Teiling) Komárek & Kovácik.

Homotypic synonym of this Chlorotetraedron species (Komárek & Kovácik, 1985).

Order Oedogoniales Heering

Oedogonium platygynum Wittrock now Oedogonium itzigsohnii De Bary ex Hirn. Heterotypic synonym of this Oedogonium species.

“Oedogonium undulatum var. moebiusii” Schmidle, nom. inval. now Oedogonium moebiusii Skinner & Entwisle. Heterotypic synonym of this Oedogonium species. “Oedogonium undulatum var. moebiusii Schmidle” is an invalid designation (pre-starting-point name for the group).

Class Trebouxiophyceae Friedl Trebouxiophyceae ordo incertae sedis

Chlorella ellipsoidea Gerneck now Chloroidium ellipsoideum (Gerneck) Darienko et al. This species and the next are basionyms and homotypic synonyms of Chloroidium species (Darienko et al., 2010).

Chlorella saccharophila (W.Krüger) Migula now Chloroidium saccharophilum (W.Krüger) Darienko et al.

Choricystis minor (Skuja) Fott now Choricystis parasitica (K.Brandt) Pröschold & Darienko Heterotypic synonym of this Choricystis species (Pröschold, Darienko, Silva, Reisser, & Krienitz, 2011). Reported as doubtful in the Flora (John et al., 2011: p. 500) and were from Scottish lochs.

Crucigenia tetrapedia (Kirchner) Kuntze now Lemmermannia tetrapedia (Kirchner) Lemmermann. Homotypic synonym of this Lemmermannia species.

Pseudotetrastrum punctatum (Schmidle) Hindák now Lemmermannia punctata (Schmidle) C.Bock & Krienitz. Homotypic synonym of this Lemmermannia species.

Tetrastrum komarekii Hindák now Lemmermannia komarekii (Hindák) C.Bock & Krienitz. Basionym and homotypic synonym of this and the following Lemmermannia species (see Boch et al., 2013).

Tetrastrum triangulare (Chodat) Komárek now Lemmermannia triangularis (Chodat) C.Bock & Krienitz.

Order Chlorellales Bold & M.J.Wynne ex Guiry

Acanthococcus aciculiferus Lagerheim now Glochiococcus aciculiferus (Lagerheim) P.C.Silva. Basionym and homotypic synonym of this Glochiococcus species (Silva, 1996).

Actinastrum hantzschii var. fluviatile J.B.L.Schröder now Actinastrum fluviatile (J.B.L.Schröder) Fott. Homotypic synonym of this Actinastrum species (Fott, 1977).

Crucigeniella apiculata (Lemmermann) Komárek now Willea apiculata (Lemmermann) D.M.John, M.J.Wynne & Tsarenko. Homotypic synonym of this Willea species. The illegitimate genus Crucigeniella has been replaced by the reinstatement of Willea (John et al., 2014) hence the recombinations listed below.

Crucigeniella crucifera (Wolle) Komárek now Willea cruciferum (Lemmermann) D.M.John, M.J.Wynne & Tsarenko.

Crucigeniella irregularis (Wille) Tsarenko & D.M.John now Willea irregularis (Wille) D.M.John, M.J.Wynne & Tsarenko.

Crucigeniella rectangularis (Nägeli) Komárek now Willea rectangularis (Nägeli) D.M.John, M.J.Wynne & Tsarenko.

Crucigeniella truncata (G.M.Smith) Komárek now Willea truncata (G.M.Smith) D.M.John, M.J.Wynne & Tsarenko.

Crucigeniella vilhelmii (Fott) D.M.John & Tsarenko now Willea vilhelmii (Fott) Komárek.

Dictyosphaerium chlorelloides (Nauman) Komárek now Chlorella chlorelloides (Naumann) C.Brock, L.Krienitz & Pröschold. Homotypic synonym of this Chlorella species.

Dictyosphaerium pulchellum H.C.Wood now Mucidosphaerium pulchellum (H.C.Wood) C.Bock, Pröschold & Krienitz. Basionym and homotypic synonym of this species of Mucidosphaerium, a genus based upon morphological and molecular data (Bock et al., 2011).

Dictyosphaerium tetrachotomum Printz now Hindakia tetrachotoma (Printz) C.Bock, Pröschold & Krienitz. Basionym and homotypic synonym of the type species of Hindakia, a genus based upon morphological and molecular data (Boch et al., 2010)

Golenkiniopsis parvula (Woronichin) Korshikov now Hegewaldia parvula (Woronichin) Pröschold, C.Bock, W.Luo & Krienitz. Basionym and homotypic synonym of the type species of the genus Hegewaldia (Pröschold, Bock, Luo, & Krienitz, 2010).

Lobocystis planctonica (Tiffany & Ahlstrom) Fott now Dictyosphaerium planctonicum Tiffany & Ahlstrom.

Neglectella asterifera Fott now Skujaster asteriferus (Fott) Vodenicarov. Basionym and homotypic synonym of this Skujaster species.

Oocystella solitaria (Wittrock) Hindák now Neglectella solitaria (Wittrock) Stenclová & Kastovsky. Basionym and homotypic synonym of this Neglectella genus created based upon combined phylogenetic, ultrastructural, and morphological analyses (Stenclová, Fucíková, Kastovsky, & Pazoutová, 2017).

Podohedra falcata Düringer now Podohedriella falcata (Düringer) Hindák. Basionym and homotypic synonym of the type species of the genus Podohedriella. The presence or absence of pyrenoids was considered by Hindák (1988) to be a taxonomically significant character and he therefore transferred Podohedra species lacking visible pyrenoids to a new genus Podohedriella Hindák. We here adopt Podohedriella with caution although in the Flora (John et al., 2011: p. 496) the name Podohedra falcata was used because of doubt associated with the presence or absence of a visible pyrenoid as a reliable character. See comments under Kirchneriella contorta.

Schizochlamydella delicatula (West) Korshikov now Phaeoschizochlamys delicatula (W.West) R.A.Andersen.

Order Chaetophorales Wille

Chaetophora elegans (Roth) C.Agardh now Chaetophoropsis elegans (Roth) B.Wen Liu, Qian Xiong, X.Dong Liu, Z.Yu Hu & G.Xiang Liu. Homotypic synonym of this Chaetophoropsis species (see Liu, Xiong, Liu, Liu, & Hu, 2018).

Chaetophora incrassata Hazen now Chaetophora lobata Schrank. Heterotypic synonym of the type species of Chaetophora.

Chaetophora pisiformis (Roth) C.Agardh now Chaetophoropsis pisiformis (Roth) B.Wen Liu, Qian Xiong, X.Dong Liu, Z.Yu Hu & G.Xiang Liu. Heterotypic synonym of this Chaetophoropsis species (see Liu et al., 2018).

Draparnaldia glomerata (Vaucher) C.Agardh now Draparnaldia mutabilis (Roth) Bory. Heterotypic synonym of this Draparnaldia species.

Gongrosira sclerococcus Kützing, nom. illeg. now Gongrosira viridis (Kützing) De Toni. Heterotypic synonym of this Gongrosira species.

Gongrosira sclerococcus Kützing is an illegitimate name as it included in its synonymy was the earlier valid and legitimate name Stereococcus viridis Kützing.

Pithophora oedogonia (Montagne) Wittrock now Pithophora roettleri (Roth) Wittrock. Heterotypic synonym of this Pithophora species. Recorded as doubtful (see Flora, John et al., 2011: p. 564).

Stigeoclonium longipilum Kützing now Chaetophora draparnaldioides Kützing. Heterotypic synonym of this Chaetophora species.

Class Ulvophyceae K.R.Mattox & K.D.Stewart

Order Scotinosphaerales Škaloud et al.

Chlorochytrium bristoliae (G.M.Smith) D.M.John & Tsarenko now Scotinosphaera paradoxa Klebs. Heterotrophic synonym of this Scotinosphaera species. All Chlorochytrium species are now considered representatives of the genus Scotinosphaera (Wujek & Thompson, 2005).

Chlorochytrium facciolae (Borzì) Bristol now Scotinosphaera paradoxa Klebs.

Chlorochytrium grande Bristol now Scotinosphaera grandis (Bristol) Wujek & R.H.Thompson.

Order Ulvales Blackman & Tansley

Dilabifilum arthropyreniae (Vischer & Klement) Tschermak-Woess now Pseudendoclonium arthropyreniae (Vischer & Klement) Darienko & Pröschold. Basionym and homotypic synonym of this Pseudendoclonium species (Darienko & Pröschold, 2017).

Dilabifilum printzii (Vischer) Tschermak-Woess [≡ Ctenocladus printzii (Vischer) Darienko & Pröschold] now Pseudopleurococcus printzii Vischer. Heterotypic synonym of this Pseudopleurococcus species. According to Škaloud et al. (1917: p. 77) “ … phylogenetic analysis […] indicates that Ctenocladus and Pseudopleurococcus form two distinct clades … . This evidence, together with morphological distinctiveness of both genera, led us not to follow the transfer of P. printzii into the genus Ctenocladus”.

Entocladia cladophorae (Hornby) Starmach now Ulvella cladophorae (Hornby) Mathieson & Dawes. Basionym and homotypic synonym of this Ulvella species (Mathieson & Dawes, 2017). Entocladia cladophorae (Hornby) Starmach (Starmach, 1972) is illegitimate since Entocladia cladophorae Noda (Noda, 1968) has priority.

Entocladia endophytica (K.Möbius) D.M.John now Phaeophila endophyta (M.Möbius) R.Nielsen. Homotypic synonym of this Phaeophila species. “Entocladia endophytica” was an incorrect rendering of the species epithet but is correctable to “Entocladia endophyta (M.Möbius) D.M.John” as the place of publication of the basionym was correctly cited.

Gongrosira fluminensis F.E.Fritsch now Lithotrichon fluminensis (F.E.Fritsch) B.W.Liu et al. Basionym and homotypic synonym of this Lithotrichon species established by Liu et al. (2019) based upon a morphological and phylogenetic investigation.

Order Ulotrichales Borzì

Fernandinella alpina var. semiglobosa F.E.Fritsch & R.P.John now Fernandinella semiglobosa (F.E.Fritsch & R.P.John) Škaloud & Leliaert. Heterotypic synonym of this Fernandinella species. See Škaloud, Rindi, Boedeker, & Leliaert (2018) for discussion of the change of status.

Klebsormidium crenulatum (Kützing) Lokhorst now Hormidiopsis crenulata (Kützing) Heering. Homotypic synonym of this Hormidiopsis species.

Monostroma oxyspermum (Kützing) Doty now Gayralia oxysperma (Kützing) K.L.Vinogradova ex Scagel et al. Homotypic synonym of this Gayralia species.

Planctonema lauterbornii Schmidle now Binuclearia lauterbornii (Schmidle) Proschkina-Lavrenko. Basionym and homotypic synonym of this Binuclearia species.

Pseudendoclonium basiliense Vischer [≡ Chamaetrichon basiliense (Vischer) Darienko & Pröschold] now Hazenia basiliensis (Vischer) Škaloud, Nedbalová, Elster & Komárek. Basionym and homotypic synonym of this Pseudendoclonium species. An isolate from Northamptonshire, Pitsford Water in England, reported in the Flora (John et al., 2011: p. 538) as corresponding closely to Helicodictyon planctonicum and was later identified as Chamaetrichon basiliensis by Darienko & Pröschold (2017). The latter authors intended transferring it to Hazenia but incorrectly believed that this genus had not been validly published. Škaloud & Leliaert (2017) have clarified the nomenclature of the genus Hazenia and demonstrated the combination Hazenia basiliensis to be valid.

Pseudendoclonium basiliense var. brandii Vischer. Some uncertainty surrounds the identity of this variety with Vischer’s original description emended by Tupa (1974). Material Vischer deposited under this name in UTEX (culture 1913) is the holotype of Vischerioclonium submersum Darienko & Pröschold (see Darienko & Pröschold, 2017).

Pseudendoclonium prostratum Tupa now Hazenia prostrata (Tupa) Škaloud & Leliaert. Basionym and homotypic synonym of this Hazenia species (Škaloud et al., 2018).

Ulothrix moniliformis (Kützing) Kützing now Ulothrix albicans Kützing. Heterotypic synonym of this Ulothrix species.

Ulothrix pseudoflacca var. salina V.J.Chapman now Ulothrix palusalsa Lokhorst. Heterotypic synonym of this Ulothrix species. Ulothrix palusalsa was introduced by Lokhorst (1978: 220) as a new name (“nom. nov”.) for Ulothrix pseudoflacca var. salina V.J.Chapman (Chapman, 1946), a valid name (type locality: Malpas Brine Pits, Cheshire, England). Lokhorst’s name is valid despite the lack of a Latin description in his publication as the requirement for Latin for algae was from 1 January 1958 (Art. 44.1).

CHAROPHYTA Migula

The Flora included the Charophyta in the Chlorophyta.

Class Zygnematophyceae Round ex Guiry Order Chaetosphaeridiales Marin & Melkonian

Polychaetophora lamellosa West & G.S.West now Chaetopeltis orbicularis Berthold. Heterotypic synonym of this Chaetopeltis species.

Order Klebsormidiales K.D.Stewart & K.R.Mattox

Spirotaenia parvula W.Archer now Elakatothrix parvula (W.Archer) Hindák. Basionym and homotypic synonym of this Elakatothrix species. Listed under Spirotaenia in the Flora (John et al., 2011: p. 615) since overlooked that Hindák (1962) had earlier transferred it to Elakatothrix.

Order Desmidiales C.E.Bessey

Note: Changes proposed by Coesel & Meesters (2013) are indicated by a single asterisk (*). The majority are the result of new combinations, with a few forms and varieties not considered to be worthy of recognition by them.

Closterium ehrenbergii var. malinvernianum (De Notaris) Rabenhorst now Closterium submoniliferum var. malinvernianum (De Notaris) Coesel. According to Coesel & Meesters (2007), a homotypic synonym of this Closterium species.

Cosmarium arctoum var. tatricum Raciborski now Cosmarium bicuneatum (F.Gay) Nordstedt. Considered to be a heterotypic synonym of this Cosmarium species. Kouwets (1999: p. 28) comments, “Krieger & Gerloff (1969) considers this taxon synonymous with C. bicuneatum (Gay) Nordstedt; the apical view given by Allorge & Manguin (1941), however, argues for C. arctoum”.

Cosmarium bipunctatum Børgesen now Cosmarium vogesiacum var. bipunctatum (Børgesen) Kurt.

Cosmarium botrytis var. depressum West & G.S.West now Cosmarium botrytis var. hyacinthii (Gutwinski) Petlovany. Heterotypic synonym of this Cosmarium variety (Petlovany & Tsarenko, 2014).

Cosmarium candianum Delponte now Cosmarium circulare Reinsch. Heterotypic synonym of this

Cosmarium species (see Palamar-Mordvintseva, 1986).

Cosmarium corribense West & G.S.West now Cosmarium asphaerosporum var. corribense (West & G.S.West) Willi Krieger & Gerloff. Basionym and homotypic synonym of this Cosmarium variety.

Cosmarium crenulatum Nägeli now Cosmarium impressulum var. crenulatum (Nägeli) Willi Krieger & Gerloff. Basionym and homotypic synonym of this Cosmarium variety.

Cosmarium depressum var. achondrum (Boldt) West & G.S.West now Cosmarium neodepressum var. achondrum (Boldt) G.J.P.Ramos & C.W.N.Moura. Homotypic synonym of this variety of Cosmarium neodepressum.

Cosmarium depressum var. planctonicum Reverdin now Cosmarium neodepressum var. planctonicum (Reverdin) G.J.P.Ramos & C.W.N.Moura. Basionym and homotypic synonym of this variety of Cosmarium neodepressum.

Cosmarium depressum var. reniforme West & G.S.West now Cosmarium neodepressum var. reniforme (West et G.S.West) G.J.P.Ramos & C.W.N.Moura. Basionym and homotypic synonym of this variety of Cosmarium neodepressum.

Cosmarium isthmium var. horizontale Schmidle now Cosmarium horizontale (Schmidle) Kouwets. Basionym and homotypic synonym of this Cosmarium species (Kouwets, 1997).

Cosmarium klebsii Gutwinski now Cosmarium subtumidum var. klebsii (Gutwinski) West & G.S.West. Basionym and homotypic synonym of this Cosmarium variety (see Kouwets, 1999).

Cosmarium laeve var. cymatium West & G.S.West now Cosmarium cymatium (West & G.S.West) Willi Krieger & Gerloff. Basionym and homotypic synonym of this Cosmarium species (Krieger & Gerloff, 1962).

Cosmarium meneghinii var. nanum Wille now Cosmarium perpusillum var. nanum (Wille) Willi Krieger et Gerloff. Basionym and homotypic synonym of this variety of Cosmarium (Krieger & Gerloff, 1962).

Cosmarium plicatum var. hibernicum West now Cosmarium holmiense var. hibernicum (West) Schmidle. Basionym and homotypic synonym of this Cosmarium variety (Schmidle, 1894).

Cosmarium punctulatum var. granulusculum (Roy & Bisset) West & G.S.West now Cosmarium punctulatum Brébisson. Heterotypic synonym of this Cosmarium species.

Cosmarium quadrifarium var. hexastichum (P.Lundell) Kurt Förster now Cosmarium hexastichum P.Lundell. Basionym and homotypic synonym of this Cosmarium species.

Cosmarium regnesi var. montanum Schmidle now Cosmarium regnesi var. polonicum (Eichler & Gutwinski) Compère. Heterotypic synonym of this Cosmarium variety (Compère, 1976).

Cosmarium subnotabile Wille now Cosmarium notabile var. subnotabile (Wille) Coesel. Basionym and homotypic synonym of this Cosmarium variety (Coesel & Meesters, 2007).

Cosmarium tetragonum var. heterocrenatum West & G.S.West now Cosmarium levinotabile var. heterocrenatum (West & G.S.West) Croasdale. Basionym and homotypic synonym of this Cosmarium variety. See note under Cosmarium notabile var. heterocrenatum in AlgaeBase concerning the renaming by Croasdale (in Prescott et al., 1981) of Cosmarium notabile de Bary as C. levinotabile Croasdale to avoid confusion with C. notabile Brébisson and transfer of many varieties, including C. notabile var. heterocrenatum (West & G.S.West) Krieger & Gerloff. Many authors, particularly Coesel & Meesters (2009), have continued to C. notabile and its varieties.

Cosmarium variolatum var. cataractarum Raciborski now Cosmarium cataractarum (Raciborski) Eichler. Basionym and homotypic synonym of this Cosmarium variety.

Cosmarium variolatum var. skujae Croasdale now Cosmarium hostensiense Štastný & Kouwets. Heterotypic synonym of this species of Cosmarium described by Štastný and Kouwets (2012). According to Štastný & Kouwets (2012: p. 309), the var. skujae is invalid since not accompanied by a Latin diagnosis and no type was designated; however, the name was validated by Croasdale in Croasdale et al. (1994: p. 206). Material examined from France using the LM and SEM closely corresponded with this variety and was mentioned as common and often dominant in acidic and oligotrophic habitats in the west of Ireland.

Cosmarium venustum var. majus Wittrock now Cosmarium trilobulatum Reinsch var. maius (Wille) Willi Krieger & Gerloff. Heterotypic synonym of this variety of Cosmarium (Krieger & Gerloff, 1962).

Euastrum crassum var. taturnii West & G.S.West now Euastrum crassum Ralfs. Heterotypic synonym of this Euastrum species.

Euastrum crispulum (Nordstedt) West & G.S.West now Euastrum elobatum (Lundell) J.Roy & Bisset. Heterotypic synonym of this Euastrum species.

Euastrum denticulatum F.Gay now Euastrum amoenum F.Gay. Homotypic synonym of this Euastrum species. See note under Euastrum denticulatum in AlgaeBase (searched June 2021, March) concerning the relationship of this species to the earlier use of the name “amoenum”.

Euastrum elegans var. pseudelegans (W.B.Turner) West & G.S.West now Euastrum pseudelegans W.B.Turner. Homotypic synonym of this Euastrum species.

Euastrum elobatum var. subelobatum (West) Kossinskaja now Euastrum elobatum (Lundell) J.Roy & Bisset. Heterotypic synonym of this Euastrum species.

Euastrum groenbladii (Messikommer) Coesel, nom. illeg. now Euastrum coeselii Kouwets. Heterotypic synonym of this Euastrum. Euastrum groenbladii (Messikommer) Coesel (Coesel 1984) is an illegitimate name; priority for Euastrum groenbladii A.M.Scott & Croasdale (see Grönblad & Croasdale, 1971).

Euastrum verrucosum var. alatum Wolle now Cosmarium verrucosum var. alatum (Wolle) J.D.Hall & K.Karol. Basionym and homotypic synonym of this Cosmarium variety.

Genicularia elegans West et G.S.West now Genicularina elegans (West & G.S.West) Molinari- Nova & Guiry. Replacement of the illegitimate name Genicularia by Genicularina has led Molinari-Nova & Guiry (2021) to propose this and the following combination.

Genicularia spirotaenia (De Bary) De Bary now Genicularina spirotaenia (De Bary) Molinari-Nova & Guiry.

Micrasterias fimbriata Ralfs pro parte now M. compereana Neustupa, Štastný & Škaloud. A genomic investigation of M. fimbriata by Neustupa, Happy, & Škaloud (2014) led to the recognition of two monophyletic clades and the creation of this new taxon. Britain and Ireland are mentioned as the only region in which M. compereana and M. fimbriata sensu stricto occur together, with the latter known from its type locality near Dolgellau, Gwynedd, north-west Wales.

Micrasterias truncata f. neodamensis (Braun) J.Dick now Micrasterias truncata Brébisson ex Ralfs. Heterotypic synonym of this Micrasterias species.

Onychonema laeve Nordstedt now Sphaerozosma laeve (Nordstedt) Thomasson. Basionym and homotypic synonym of this Sphaerozosma species.

Onychonema laeve var. latum West & G.S.West now Sphaerozosma laeve var. latum (West & G.S.West) Kurt Förster. Basionym and homotypic synonym of this Sphaerozosma variety.

Penium spirostriolatum var. amplificatum M.Schmidt now Penium amplificatum (M.Schmidt) Van Westen & Coesel. Basionym and homotypic synonym of this Penium species (Van Westen & Coesel, 2012).

Pleurotaenium hutchinsonii (W.B.Turner) West & G.S.West now Pleurotaenium trabecula var. hutchinsonii (W.B.Turner) Croasdale. Homotypic synonym of this Pleurotaenium variety.

Pleurotaenium truncatum var. granulatum West & G.S.West now Pleurotaenium truncatum (Brébisson ex Ralfs) Nägeli. Heterotypic synonym of this Pleurotaenium species.

*“Staurastrum anatinum var. aculeatum” (Meneghini ex Ralfs) A.J.Brook, nom. inval. now Staurastrum aculeatum Meneghini ex Ralfs. This variety name is invalid as Brook (1959) did not provide a full and direct reference to the basionym.

*Staurastrum anatinum subsp. biradiatum West, Staurastrum anatinum var. grande West & G.S. West and Staurastrum anatinum var. truncatum West are all reduced to synonymy under Staurastrum anatinum Cooke & Wills.

**Staurastrum anatinum f. paradoxum A.J.Brook. Mistakenly listed as a “variety” in the Flora (John et al., 2011: p. 719). Status of this form remains uncertain.

*Staurastrum anatinum var. controversum (Brébisson ex Ralfs) A.J.Brook now Staurastrum controversum Brébisson ex Ralfs.

*Staurastrum anatinum f. vestitum (Ralfs) A.J.Brook now Staurastrum vestitum Ralfs.

*Staurastrum arachne var. arachnoides West & G.S.West now Staurastrum arachne Ralfs.

*Staurastrum arcuatum var. guitanense West now Staurastrum arcuatum Nordstedt.

*Staurastrum bieneanum var. ellipticum Wille [≡ Staurastrum lapponicum var. ellipticum (Wille) Grönblad] now Staurastrum lapponicum (Schmidle) Grönblad, Heterotypic synonym of this Staurastrum species.

*Staurastrum brachiatum f. minus (“minor”) Lütkemüller now Staurastrum brachiatum Ralfs.

*Staurastrum brachycerum Brébisson now Staurastrum cyrtocerum var. brachycerum (Brébisson) Coesel & Meesters.

*Staurastrum brasiliense var. lundellii West & G.S.West now Staurastrum brasiliense Nordstedt.

*Staurastrum capitulum var. dimidio-minus Croasdale & Grönblad now Staurastrum capitulum

Ralfs. *Staurastrum capitulum var. spetsbergense (Nordstedt) Cooke (≡ Staurastrum capitulum Brébisson [var. amoenum] f. spetsbergensis Nordstedt) now Staurastrum spetsbergense (Nordstedt) Coesel & Meesters.

*Staurastrum cerastes var. triradiatum G.M. Smith now Staurastrum cerastes P.Lundell.

*Staurastrum cingulum var. affine (West & G.S.West) A.J.Brook now Staurastrum cingulum var.

obesum G.M.Smith. *Staurastrum clepsydra var. undulatum D.B.Williamson & D.M.John now Staurastrum subpygmaeum var. undulatum (D.B.Williamson & D.M.John) Coesel & Meesters.

*Staurastrum cyrtocerum var. compactum W. & G.S.West now Staurastrum cyrtocerum Ralfs.

*Staurastrum dilatatum var. hibernicum (West & G.S.West) West & G.S.West now Staurastrum dilatatum Ralfs.

*Staurastrum disputatum West & G.S.West now Staurastrum sinense var. insigne (Raciborski) Compère. Heterotypic synonym of this variety of Staurastrum sinense. The type of Staurastrum disputatum is from Ireland, but Coesel & Meesters (2013) suggest that it is probably a non- European variety with the nominate variety the only reliable European record.

*Staurastrum erasum Brébisson now Staurastrum brebissonii var. ordinatum Schmidle.

*Staurastrum furcatum var. subsenarium West & G.S.West now Staurastrum forficulatum var.

subsenarium (West & G.S.West) Coesel & Meesters.

*Staurastrum eustephanum Ralfs, and Staurastrum furcigerum var. reductum West & G.S.West now

Staurastrum furcigerum (Brébisson) W.Archer.

*Staurastrum gladiosum W.B.Turner now Staurastrum teliferum var. gladiosum (W.B.Turner) Coesel & Meesters.

*Staurastrum gladiosum var. delicatulum West & G.S.West now Staurastrum teliferum var. gladiosum (W.B.Turner) Coesel & Meesters.

Staurastrum gracile var. nanum Wille now Staurastrum asteroideum var. nanum (Wille) Grönblad. Basionym and homotypic synonym of this Staurastrum variety.

*Staurastrum hexacerum var. semicirculare Wittrock now Staurastrum dispar Brébisson. .

*Staurastrum inconspicuum var. crassum Gay and var . planctonicum G.M.Smith now Staurastrum inconspicuum Nordstedt.

*Staurastrum inflatum West & G.S.West, nom. illeg. now Staurastrum punctulatoides Coesel & Meesters. Staurastrum inflatum West & G.S.West (West & West, 1912) is illegitimate: priority for Staurastrum inflatum C.J. Bernard (Bernard, 1908).

*Staurastrum inflexum Brébisson now Staurastrum cyrtocerum var. inflexum (Brébisson) Coesel & Meesters.

*Staurastrum inflexum var. brachycerum Brébisson now Staurastrum cyrtocerum Ralfs var. brachycerum (Brébisson) Coesel & Meesters.

*Staurastrum kaiseri Růžička, nom. illeg (not Staurastrum kaiseri Pevalek) now Staurastrum crassangulatum Coesel.

*Staurastrum longispinum var. bidentatum (Wittrock) J.A.Cushman now Staurastrum longispinum (Bailey) W.Archer. Considered a heterotypic synonym of this species by Coesel & Meesters (2013). Mentioned as a “doubtfully [taxonomically] valid” variety in the Flora (John et al., 2011: p. 712) and the authorities for the variety incorrectly cited as “(Wittrock) West”.

*Staurastrum lunatum Ralfs now Staurastrum avicula var. lunatum (Ralfs) Coesel & Meesters.

*Staurastrum lunatum var. planctonicum West & G.S.West now Staurastrum avicula var. planctonicum (West & G.S.West) Coesel & Meesters.

*Staurastrum margaritaceum var. coronulatum West and Staurastrum margaritaceum var. subcontortum West & G.S. West now Staurastrum margaritaceum Ralfs.

*Staurastrum monticulosum var. groenlandicum Grönblad now Staurastrum monticulosum Ralfs

*Staurastrum muticum var. depressum Nordstedt now Staurastrum muticum Ralfs.

*Staurastrum oligacanthum Brébisson ex W.Archer now Staurastrum cristatum (Nägeli) var. oligacanthum (Brébisson ex W.Archer) Coesel & Meesters.

Staurastrum ophiura var. cambricum West & G.S. West now Staurastrum ophiura P.Lundell.

*Staurastrum orbiculare var. depressum J. Roy & Bisset now Staurastrum ralfsii var. depressum (J. Roy & Bisset) Coesel & Meesters.

*Staurastrum orbiculare var. extensum Nordstedt now Staurastrum extensum (Nordstedt) Coesel & Meesters.

*Staurastrum orbiculare var. hibernicum (West) West & G.S.West now Staurastrum hibernicum

West. *Staurastrum orbiculare var. ralfsii West & G.S.West now Staurastrum ralfsii (West & G.S.West) Coesel & Meesters.

*Staurastrum pendulum var. pinguiforme Croasdale now Staurastrum saltator var. pendulum

(Nygaard) Coesel & Meesters.

*Staurastrum pileolatum var. cristatum Lütkemüller now Staurastrum pileolatum Ralfs.

*Staurastrum planctonicum Teiling now Staurastrum pingue var. planctonicum (Teiling) Coesel & Meesters.

*Staurastrum polymorphum var. pygmaeum Grönblad now Staurastrum polymorphum Ralfs.

*Staurastrum productum (West & G.S.West) Coesel now Staurastrum manfeldtii var. productum

(West & G.S.West) Coesel & Meesters.

*Staurastrum pseudosebaldi Wille now Staurastrum manfeldtii var. pseudosebaldi (Wille) Coesel & Meesters.

*Staurastrum pseudosebaldi var. simplicius West now Staurastrum manfeldtii var. pseudosebaldi

(Wille) Coesel & Meesters.

*Staurastrum punctulatum var. striatum West & G.S.West now Staurastrum striatum (West & G.S.West) Růžička.

*Staurastrum punctulatum var. kjellmanii Wille, Staurastrum punctulatum var. pygmaeum (Ralfs) West & G.S.West and Staurastrum punctulatum var. subproductum West & G.S.West now considered to be included in Staurastrum punctulatum Ralfs.

*Staurastrum pygmaeum Brébisson ex Ralfs now Staurastrum punctulatum Brébisson.

*Staurastrum retusum var. boreale West & G.S.West now Staurastrum retusum W.B.Turner.

*Staurastrum sebaldi var. ornatum Nordstedt now Staurastrum manfeldtii Delponte.

*Staurastrum sebaldi var. productum West & G.S.West [≡ Staurastrum productum (West & G.S.West) Coesel] now Staurastrum manfeldtii var. productum (West & G.S.West) Coesel & Meesters.

*”Staurastrum sexcostatum var. productum West” [actually Staurastrum sexcostatum subsp. productum West] now included in Staurastrum sexcostatum Ralfs by Coesel & Meesters (2013).

*Staurastrum spongiosum var. griffithsianum (Nägeli) Lagerheim, and Staurastrum spongiosum var. perbifidum West now Staurastrum spongiosum Ralfs.

*Staurastrum subavicula (West) West & G.S.West now Staurastrum arcuatum var. subavicula (West) Coesel & Meesters.

*Staurastrum subscabrum Nordstedt now Staurastrum scabrum Brébisson. According to Coesel & Meesters (2007), a heterotypic synonym of this Staurastrum species with no mention of Staurastrum subscabrum f. scabior West so the taxonomic validity of the forma is uncertain.

**Staurastrum uhtense Grönblad, misspelt should read Staurastrum uhtuense Grönblad.

*Staurastrum tetracerum var. evolutum West & G.S.West now Staurastrum tetracerum Ralfs ex Ralfs.

*Staurastrum tohopekaligense var. trifurcatum West & G.S.West now Staurastrum tohopekaligense

Wolle.

*Staurastrum vestitum var. subanatinum West & G.S.West now Staurastrum anatinum var.

subanatinum (West & G.S.West) Coesel & Meesters.

*Staurodesmus angulatus (West) Teiling now Staurastrum angulatum West.

*Staurodesmus angulatus var. planctonicus (West & G.S.West) Teiling now Staurastrum angulatum

var. planctonicum West & G.S.West.

*Staurodesmus aversus (P.Lundell) S.Lillieroth now Staurastrum aversum P.Lundell.

*Staurodesmus brevispina (Brébisson) Croasdale now Staurastrum brevispina Brébisson.

*Staurodesmus brevispina var. altus (West & G.S.West) Teiling and Staurodesmus brevispina var. retusus (Borge) A.J.Brook now Staurastrum brevispina var. boldtii Lagerheim.

*Staurodesmus brevispina var. obversus (West & G.S.West) Croasdale now Staurastrum brevispina var. obversum West & G.S.West.

“Staurodesmus brevispina var. retusum” (O.Borge) A.J.Brook & D.B.Williamson, nom. inval. now Staurastrum brevispina var. boldtii Lagerheim. This variety name is invalid because Brook and Williamson (1991) do not provide a full and direct reference to the place of publication of the basionym.

*Staurodesmus bulnheimii var. subincus (West & G.S.West) Thomasson now Staurodesmus validus var. subincus (West & G.S.West) Coesel & Meesters

*Staurodesmus conspicuus (West & G.S.West) Teiling now Staurastrum conspicuum West & G.S.West.

*Staurodesmus convergens var. laportei Teiling, Staurodesmus convergens var. pumilus (Nordstedt) Teiling, and Staurodesmus convergens var. ralfsii Teiling now Staurodesmus convergens (Ehrenberg ex Ralfs) S.Lillieroth

*Staurodesmus crassus (West & G.S.West) M. Florin now Staurodesmus controversus var. crassus (West & G.S.West) Coesel & Meesters.

*Staurodesmus cuspidatus var. canadensis G.M. Smith now Staurodesmus cuspidatus (Brébisson ex Ralfs) Teiling.

*Staurodesmus cuspidatus var. curvatus (G.S.West) Teiling now Staurodesmus cuspidicurvatus

Coesel & Meesters.

*Staurodesmus extensus var. longispinus (West & G.S.West) Teiling now Staurodesmus longispinus

(West & G.S.West) Coesel & Meesters.*Staurodesmus grandis var. parvus (West & G.S.West) Teiling (≡ Staurastrum grande var. parvum West & G.S.West) now Staurastrum grande Bulnheim.

*Staurodesmus incus var. ralfsii (West) Teiling now Staurodesmus ralfsii (West) Tomaszewicz.

*Staurodesmus indentatus (West & G.S.West) Teiling now Staurodesmus incus var. indentatus (West & G.S.West) Coesel.

*Staurodesmus inelegans (West & G.S.West) Teiling now Staurastrum inelegans West & G.S.West.

*Staurodesmus jaculiferus (West) Teiling now Staurodesmus incus var. jaculiferus (West) Coesel & Meesters.

*Staurodesmus lanceolatus (W.Archer) Croasdale now Staurastrum lanceolatum W.Archer.

*Staurodesmus lanceolatus var. compressus (West & G.S.West) Teiling now Staurastrum lanceolatum var. compressum West & G.S.West.

*Staurodesmus minutissimus (Averswald) Teiling now Staurastrum minutissimum Averswald.

*Staurastrum omearae var. minutum (West) Teiling now Staurodesmus omearae (W. Archer) Teiling.

*Staurodesmus pachyrhynchus (Nordstedt) Teiling now Staurastrum pachyrhynchum Nordstedt.

*Staurodesmus phimus var. hebridarus (West & G.S.West) Teiling now Staurodesmus hebridarus (West & G.S.West) Kurt Förster.

*Staurodesmus sibiricus (O.Borge) Croasdale now Staurastrum sibiricum O.Borge.

*Staurodesmus subpygmaeus var. subangulatus (West & G.S.West) Teiling now Staurastrum subpygmaeum var. subangulatum West & G.S.West.

*Staurodesmus triangularis var. subhexagonus (West & G.S.West) Teiling now Staurodesmus subhexagonus (West & G.S.West) Coesel.

Staurodesmus tumidus (Brébisson ex Ralfs) Teiling [≡ Staurastrum tumidum Brébisson ex Ralfs] now Xanthidium tumidum (Brébisson ex Ralfs) Stastny, Škaloud & Neustupa. Homotypic synonym of this Xanthidium species (Štastny et al., 2013).

Xanthidium antilopaeum var. oligocanthum Schmidle now Xanthidium antilopaeum f. oligocanthum (Schmidle) Petlovany. Basionym and homotypic synonym of this form of Xanthidium antilopaeum.

Xanthidium antilopaeum var. polymazum Nordstedt now Xanthidium antilopaeum f. polymazum (Nordstedt) Petlovany. Basionym and homotypic synonym of form of this Xanthidium species (Petlovany & Tsarenko, 2014).

Xanthidium antilopaeum var. triquetrum P.Lundell now Xanthidium antilopaeum Kützing. Heterotypic synonym of this Xanthidium species (see Kouwets, 1999).

Xanthidium cristatum var. uncinatum Ralfs now Xanthidium uncinatum (B.Eichler & Raciborski) Štastný, Škaloud & Neustupa. Basionym and homotypic synonym of this Xanthidium species (Štastný et al., 2013).

Xanthidium octocorne Ehrenberg ex Ralfs now Staurodesmus octocornis (Ehrenberg ex Ralfs) Štastný, Škaloud & Neustupa. Basionym and homotypic synonym of this Staurodesmus species (Štastný et al., 2013). Uncertainty surrounds the status of those varieties of Xanthidium octocorne not currently transferred to Staurodesmus.

Order Zygnematales C.E.Bessey

Debarya glyptosperma (De Bary) Wittrock now Transeauina glyptosperma (De Bary) Guiry. Basionym and homotypic synonym of this Transeauina species. Guiry (2013) found that Debarya Wittrock, 1872 was illegitimate and proposed the substitute name Transeauina.

Netrium digitus var. parvum Borge now Netrium parvum (Borge) Petlovany. Basionym and homotypic synonym of this Netrium species (Petlovany, 2015).

Netrium digitus var. rhomboideum Grönblad now Netrium digitus f. rhomboideum (Grönblad) Kossinskaja. Basionym and homotypic synonym of this form.

Netrium interruptum (Brébisson ex Ralfs) Lütkemüller now Planotaenium interruptum (Brébisson ex Ralfs) Petlovany & Palmar-Mordvintseva. Homotypic synonym of this Planotaenium species (Palamar-Mordvintseva & Petlovany, 2009).

Netrium interruptum var. minus (Borge) Willi Krieger (as “minor”) now Planotaenium interruptum var. minus (Borge) Petlovany & Palamar-Mordvintseva. Homotypic synonym of this variety of Planotaenium (Palamar-Mordvintseva & Petlovany, 2009).

Roya obtusa var. montana West & G.S.West now Roya obtusa (Brébisson) West & G.S.West. Heterotypic synonym of this Roya species

Spirogyra calospora f. gracilior Cleve now Spirogyra protecta H.C.Wood. Heterotypic synonym of this Spirogyra species.

Spirogyra communis (Hassall) Kützing now Spirogyra decimina var. elongata (Vaucher) Petlovany, Heterotypic synonym of this variety of Spirogyra.

Spirogyra elongata (Vaucher) Dumortier now Spirogyra decimina var. elongata (Vaucher) Petlovany. Basionym and homotypic synonym of this variety of the species. Note incorrect rendering of Spirogyra “longata” in the Flora (John et al., 2011: p. 595).

Spirogyra grevilleana (Hassall) Kützing now Spirogyra weberi var. grevilleana (Hassall) O.Kirchner. Homotypic synonym of this variety of the species.

Spirogyra reflexa Transeau now Temnogyra reflexa (Transeau) Yamagishi. Basionym and homotypic synonym of this Temnogyra species (Yamagishi, 1963).

Spirotaenia acuta Hilse now Tortitaenia acuta (Hilse) Palamar-Mordvintseva. Basionym and homotypic synonym of this Tortitaenia species (Palamar-Mordvintseva & Petlovany, 2009).

Spirotaenia kirchneri var. erythropunctata (Lagerheim) Willi Krieger now Spirotaenia kirchneri f. erythropunctata (Lagerheim) Lütkemüller.

Spirotaenia parvula W.Archer now Elakatothrix parvula (W.Archer) Hindák. Homotypic synonym of this Elakatothrix species (Hindák, 1962).

Zygnema gracile Hassall, nom. illeg. now Spirogyra gracilis Kützing. Homotypic synonym of this Spirogyra species. Mentioned as a doubtful report in the Flora (John et al., 2011: p. 607) where it was recorded from rocks dripping with water in southern England. Zygnema gracile Hassall (Hassall, 1845) is illegitimate: priority for Zygnema gracile C.Agardh (Agardh, 1817).

Order Charales Dumontier

Chara curta Nolte ex Kützing now Chara aspera var. nodulifera A.Braun ex Leonhardi. Heterotypic synonym of this Chara species.

Chara intermedia A.Braun ex Lange now Chara papillosa Kützing. Heterotypic synonym of this Chara species.

Chara rudis (A.Braun) Leonhardi, nom. illeg. now Chara subspinosa Ruprecht. Heterotypic synonym of this Chara species. Chara rudis is illegitimate as it included Chara subspinosa Ruprecht (Ruprecht, 1846) in synonymy.

Nitella spanioclema J.Groves & Bullock-Webster ex Bullock-Webster now Nitella flexilis [var. flexilis] f. spanioclema (J.Groves & Bullock-Webster) Raam ex Guiry & D.M.John. Homotypic synonym of this form of Nitella flexilis (see Guiry & John, 2021).

New additions

An asterisk (*) following a name indicates a species/subspecies overlooked in the Flora volumes

Cyanobacteria Stanier ex Cavalier-Smith Class Cyanophyceae Schaffner

Order Chroococcales Schaffner

*Chroococcus westii J.B.Petersen Recorded by West (1892b: as Chroococcus turgida var. violacea West) at foot of Bow Fell, near Angle Tarn in the Cumbrian Lake District, England.

Gloeocapsa bituminosa (Bory) Kützing. Collected by Allan Pentecost in 2009 on limestone at Haverbrack, Cumbrian Lake District, England.

*Gloeocapsa quaternata (Brébisson) Kützing. Recorded by West (West, 1892a) at Bow Fell, near Angle Tarn in the Cumbrian Lake District, England.

Gloeocapsa rupicola Kützing. Collected by Allan Pentecost in 2009 at Beesley Falls, Ingleton, Yorkshire and other sites in England.

Gloeothece abiscoensis (Skuja) Komárek & Anagnostidis. Collected by Allan Pentecost in 2010 from the littoral of Knipe Tarn, Cumbrian Lake District, England.

*Gloeothece violacea Rabenhorst. Recorded by West (West, 1892a) from Stickle Tarn in the Cumbrian Lake District, England.

*Microcystis smithii Komárek & Anagnostidis. Recorded by West (1892a: as Aphanocapsa pulchra (Kützing) Rabenhorst) from Bowness in the Cumbrian Lake District, England

Order Oscillatoriales Schaffner

*Homoeothrix pearsallii Godward. Described by Godward (1937) from the littoral of Windermere in the Cumbrian Lake District, England.

Johanseninema constrictum (Szafer) Hašler, Dvořák & Pouličková. Recorded by Hašler & Pouličková (2010: as Komvophoron constrictum (Szafer) Anagnostidis & Komárek) from Ellesmere Lake, the largest of the Shropshire meres, England.

Komvophoron hindakii Hašler & Pouličková. Recorded by Hašler & Pouličková (2010) from several UK lakes, including Ellesmere Lake (North Shropshire), Malham Tarn (Derbyshire) and Blandford Pond (Dorset) in England and Loch Leven in Scotland.

Phormidium ingrediens Backhaus. Collected in 2012 by Allan Pentecost from Wansfell in the Cumbria Lake District, England.

Order Synechococcales L.Hoffmann, Komárek & Kastovsky

*Aphanocapsa stagnalis (Lemmermann) Belyakova. Recorded from England by West & West (1909: as Microcystis stagnalis (Lemmermann) Lemmermann).

*Chamaesiphon cylindricus var. amplus Godward. Described by Godward (1937) from the littoral of Windermere in the Cumbrian Lake District, England.

Leptolyngbya perelegans (Lemmermann) Anagnostidis & Komárek. Recorded in 2010 by Allan Pentecost from Sprinkling Tarn, Cumbrian Lake District, England and earlier by Godward (1937: as Lyngbya perelegans Lemmermann) from Windermere.

*Leptolyngbya purpurascens (Gomont ex Gomont) Anagnostidis & Komárek. Recorded by Godward (1937: as Lyngbya purpurescens Gomont ex Gomont) from the littoral of Windermere in the Cumbrian Lake District, England.

*Leptolyngbya subtilis (West) Anagnostidis. Described by West (1892a: as Lyngbya subtilis West) from several localities in the Cumbrian Lake District, England.

Snowella atomus Komárek & Hindák. Recorded from Scotland by the Scottish Environmental Protection Agency (SEPA) but requiring further verification (Krokowski et al., 2012).

Snowella septentrionalis Komárek & Hindák. Recorded from Scotland by SEPA and mentioned as requiring further verification (Krokowski et al., 2012).

Woronichinia karelica Komárek & Komárková-Legnerová. Recorded from Scotland by SEPA and mentioned as requiring further verification (Krokowski et al., 2012).

Order Nostocales Borzi

“Anabaena azollae” Strasburger, nom. inval. now “Trichormus azollae” Komárek & Anagnostidis, nom. inval. Only included as the fern Azolla has been reported but not this, its obligate cyanobacterial symbiont. Anabaena azollae Strasburger is a pre-starting-point invalid designation; Trichormus azollae is also invalid as it was not validated by Komárek & Anagnostidis (1989: 303).

Rhodophyta Wettstein

Class Florideophyceae Cronguist

Order Batrachospermales Pueschel & K.M.Cole

Batrachospermum anatinum Sirodot now Sheathia boryana (Sirodot) Salomaki & M.L.Vis. Collected by D.M.John in September 2010 from a stream (GR TL485562) running from a spring known as Giant’s Grave at Cherry Hinton, near Cambridge; identified by Janina Kwandrans.

Paralemanea catenata ((Kützing) M.L.Vis & Sheath. Collected on 13 May 2016 by Richard Lansdown in the River Wye at Symonds Yat, Gloucester, England (Carter et al., 2017). According to Chris Carter (pers. comm.), Johanna Knappe believes the River Wye material to correspond closely to Lemanea nodosa Kützing which she considers a form of Paralemanea catenata although Vis & Sheath (1992) had earlier reduced it to a synonym of this species. “Paralemanea catenata f. nodosa” Knappe & Huth is an invalid designation. It is unclear in the original publication what the authors’ intentions were: if it were to make a new combination for Lemanea nodosa Kützing, then there was no “full and direct” citation (ICN Art. 41.5) of the putative basionym (the authors cite as “syn” [synonyms] “Lemanea nodosa Kütz. 1849” and “Lemanea nodosa Sirodot 1872”); if it were to be described as a new form, no description in Latin or English is provided as required by ICN Art. 39.2 and no type was designated.

Euglenozoa Cavalier-Smith [Euglenophyta]

Note: the Euglenozoa includes the Class Euglenophyceae and a number of phyla now regarded as animal taxa (Ruggiero et al., 2014).

Class Euglenophyceae Schoenichen Order Euglenales Leedale

Phacus obolus Pochmann. Collected in March 2012 by Rachel Carter from Sand Spinney Quarry, near Cranford, Northamptonshire, England; identified by Konrad Wołowski.

Ochrophyta Cavalier-Smith

Note: the classes Chrysophyceae, Xanthophyceae and Eustigmatophyceae are currently included in the Phylum Ochrophyta, the Class Chrysophyceae now includes the Class Synurophyceae.

Class Chrysophyceae Pascher [CHRYSOPHYTA] Order Chromulinales Pascher

Dinobryon faculiferum Willén. Collected from Loch Kinord in Aberdeenshire, Scotland (Lang, 2013; Lang & Krokowski, 2014a).

Dinobryon stokesii var. neustonicum Petersen & Hansen. Collected from Loch Flemington, Nairnshire, Scotland (Lang, Mullen, & Krokowski, 2016a).

Ollicola vangoorii (W.Conrad) Vørs. Collected from Loch Grannoch in Dumfries and Galloway, Scotland (Lang, 2013; Lang & Krokowski, 2014b).

Order Hibberdiales R.A.Andersen

Bitrichia ollula (Fott) Fott. Collected in a plankton sample from East Loch Ollay (Loch Olaidh an Ear) located on the machair plain along the west coast of South Uist in the Outer Hebrides, Scotland (Lang et al., 2016b).

Order Synurales R.A.Andersen

Synura hibernica Škaloud & Škaloudová. Described by Škaloud, Škaloudová, Procházkova, and Nĕmcová (2014) between 2009 and 2011 from standing water in blanket-bogs along the west coast of Ireland; type locality Glanmore Lake on the Beara Peninsula, Co. Kerry.

Class Xanthophyceae P.Allorge ex F.E.Fritsch [XANTHOPHYTA]

Order Botrydiales Schaffner

Asterosiphon dichotomus (Kützing) Reith. Collected in 2011 by Rachel Carter from the muddy drawdown of the reservoir Pitsford Water SSSI in Northamptonshire, England (Carter & John, 2012a, 2012b).

Order Heterogloeales Fott ex P.C.Silva

Gloeochloris smithiana Pascher. Collected by Chris Carter between 2013 and 2015 on the submerged branches of a bramble (Rubus sp.) in a ditch at Yardley Chase, Northamptonshire, England (Carter & John, 2015).

Order Vaucheriales Blackman & Tansley

Vaucheria schleicheri De Wildeman. Collected on 3 July 2018 by Jon Graham in a ditch near Whittlesea, Cambridgeshire, England; determined by Chris Carter and Roy Merritt.

Class Eustigmatophyceae D.J.Hibberd & Leedale [EUSTIGMATOPHYTA] Order Goniochloridales K.P.Fawley, M.Eliás & M.W.Fawley

Pseudostaurastrum limneticum (Borge) Guiry. Collected in the nutrient-enriched Loch Flemington in Nairnshire, Scotland (Lang, 2013; Lang et al., 2014).

Chlorophyta Reichenbach Class Chlorophyceae Wille

Order Chlamydomonadales F.E.Fritsch

*Chlamydomonas epibiotica Ettl. Listed by Stockner & Lund (1970: as C. epiphytica G.M.Smith) as in the plankton of Windermere, in the Cumbrian Lake District, England.

Desmatractum spryii Nicholls. Collected from Loch Mochrum in Dumfries and Galloway, Scotland (Lang, 2013; Lang & Krokowski, 2014c).

Pandorina morum f. major Iyengar. Collected in June 2014 from a quarry at Barton-under- Needwood and determined by Chris Carter, Rodger Flower and D. Ryves.

Parachlorococcum turfosum S.Watanabe & L.A.Lewis now Chlorococcum turfosum (Shin Watanabe & L.A.Lewis) Nakada, Shin Watanabe & L.A.Lewis (see Nakada, Watanabe, Lewis, & Tomita, 2019). Type collected by Ralph Lewin from a peaty ditch near Salen, Isle of Mull, Scotland (see Watanabe & Lewis, 2017).

Provasoliella lobata (Pascher) Ettl. Collected by Allan Pentecost (pers. comm.) in 2011 from Tarn Hows bogs in the Cumbrian Lake District, England.

Vitreochlamys ordinata (Skuja) A.Nakazawa. Collected by Allan Pentecost (pers. comm.) in 2011 from Bryan Tarn in the Cumbrian Lake District, England.

Order Sphaeropleales Luerssen

*Characium heteromorphum (Reinsch) Wolle. Recorded by West (1892b: as Hydrianum heteromorphum Reinsch) from various bogs and tarns in the Cumbrian Lake District, England.

*Coenocystis subcylindrica Korshikov. Listed by Stockner and Lund (1970) as in the plankton of Lake Windermere in the Cumbrian Lake District, England.

Order Oedogoniales Heering

Oedogonium pachydermum Wittrock & P.Lundell ex Hirn. Collected by Howard Matcham on 16 April 2014 from a seasonally flooded depression near Chichester, West Sussex, England.

Class Trebouxiophyceae Friedl

Order Chlorellales Bold & M.J.Wynne ex guiry

Dictyosphaerium subsolitarium Van Goor. Recorded by Belcher, George, & Swale (2008) from two ponds in England at Botton’s Pit, Newnham and Cambridge Science Park in Cambridge, England.

Saturnella saturnus (Steinecke) Fott. Collected from bog pools at the Upper Teesdale National Nature Reserve in the North Pennines, England from March to June 2014 and June 2015 by Jeannie Beadle (Beadle, 2015; Beadle, Brown, Carter, & Holden, 2014; Carter et al., 2015).

Order Prasiolales Schaffner

Koliella tatrae (Kol) Hindák. Recorded by Pentecost (2011) who collected it on 20 August 2010 “from a snow patch on Cairngorm known as Cuidhe Crom on the head wall of Coire Cas [NJ002042] about 250 m NW of Cairngorm summit at an altitude of 1010 m” and mentions that “a few cells were subsequently observed on a winter snow patch on the slopes of High Street in Cumbria in February 2011”. Accompanying this snow alga was a species of Chromulina which apparently resembled C. sphaeridia J.Schiller although having smaller dimensions. Further studies are required.

Class Ulvophyceae K.R.Mattox & K.D.Stewart

Order Scotinosphaerales Škaloud & al

Scotinosphaera lemnae (Puncochárová) Wujek & R.H.Thompson. Known only from cultured material isolated by Richard Starr from dead Lemna sampled from a fishpond near Glasgow, Scotland (type locality). See comments in Škaloud et al. (2018).

Charophyta Migula

Class Charophyceae Rabenhorst

Order Desmidiales Bessey

Actinotaenium trachypolum (West & G.S.West) Teiling. Collected in September 2017 by Marien van Westen in a pond (“lily pond”) on Loughrigg Fell, Cumbrian Lake District, England (John et al., 2018).

Closterium acerosum var. borgei (Borge) Willi Krieger. First collected in September 1993 by David Williamson in Goosey Foot Tarn, Grizedale Forest, Cumbrian Lake District, England (Brook & Williamson, 2010).

Closterium pseudocostatum Štastný & Kouwets. According to Štastný & Kouwets (2012), the illustration of material from the west of Ireland recorded as “Cosmarium costatum var. erectum” by John & Williamson (2009: p. 32, pl. 4a) should be attributed to this species.

Cosmarium blacklochense D.B.Williamson. Collected in June 2018 and February 2019 by Chris Carter from Black Loch, Dumfries and Galloway, Scotland (Williamson, 2018a).

Cosmarium didymochondrum var. compressum D.B.Williamson & C.F.Carter. Collected by Chris Carter on 23 August 2015 from small Sphagnum pools in old semi-permanent vehicle ruts and a bog lying a little north-east of Birkdale Tarn, North Yorkshire, England and later on 18 November 2015 by Ian Evans from a lochan, near Durness, Northern Sutherland, Scotland (Williamson & Carter, 2016a, 2017).

Cosmarium difficiloides Kouwets. Collected in September 2017 by Marien van Westen from Long Moss Tarn, School Knott Tarn and Loughrigg Fell, Cumbrian Lake District, England (John et al., 2018). According to Kouwets (2001), similar to C. difficile but smaller in size and its minute pores are easily overlooked.

Cosmarium discrepans Štastný & Kouwets. According to Štastný and Kouwets (2012), this species has been mistakenly reported as C. punctulatum var. subpunctulatum (Nordstedt) Børgesen in the Shetlands by Williamson (1992: figs 19, 4) and by the Wests (West & West, 1897: pl. 6, fig. 19) in southern England.

Cosmarium distentum (G.S.West) Coesel & Meesters. Collected on 9 March 2014 by Howard Matcham in an animal drinking trough at Boxgrove, near Chichester, West Sussex (see Carter et al., 2015b, as Cosmarium laeve Rabenhorst var. distentum G.S.West).

Cosmarium medioretusum Coesel. Collected in September 2017 by Marien van Westen in Long Moss, Kelly Hall Tarn and School Knott Tarn, Cumbrian Lake District, England (John et al., 2018).

Cosmarium pseudoinsigne Prescott. Collected in July 2018 by John Graham in a disused quarry, near Baston, Lincolnshire; identified by Chris Carter and David Williamson (pers. comm.).

Cosmarium raciborskii (Raciborski) Lagerheim. Collected on 19 November 2011 by Ian Evans from a roadside mire pool near Foindle (NC18784781), Sutherland, Scotland (Williamson, 2012).

Cosmarium subochthodes var. maius Schmidle. Collected in September 2017 from Long Moss Tarn in the Cumbrian Lake District, England (John et al., 2018).

Cosmarium tuddalense Strøm. Collected in March 2018 by Ian Evans and Gwen Richards in a boggy pool and small pond in Little Assynt, Sutherland, Scotland (Williamson, 2018b).

Euastrum luetkemuelleri var. carniolicum (Lütkemüller) Willi Krieger. Variety collected in September 2017 by Marien van Westen from a small stream and a “black mire” pool on Loughrigg Fell (335 m) in the Cumbrian Lake District, England (John et al., 2018).

Euastrum pseudotuddalense Messikommer. Collected in September 2017 by Marien van Westen from a puddle on Loughrigg Fell (335 m) in the Cumbrian Lake District, England (see John et al., 2018); easily overlooked because of its small size according to Marien van Westen (pers. comm.).

Heimansia tumida (L.N.Johnson) Coesel. Collected in October 2009 by David Williamson from Kelly Hall Tarn in the Cumbrian Lake District, England. The “Cosmocladium sp”. on the DVD accompanying the Flora was identified as Heimansia tumida by Peter Coesel (pers. comm. to Chris Carter) and is a new record for Britain.

Micrasterias truncata var. quadrata Bulnheim. Collected in September 2017 by Marien van Westen in a small stream on Loughrigg Fell in the Cumbrian Lake District, England (John et al., 2018).

Spirotaenia beijerinckii Coesel. Collected in September 2017 by Marien van Westen from a small stream on Loughrigg Fell in the Cumbrian Lake District, England (John et al., 2018).

*Staurastrum anatinum var. longibrachiatum West & G.S.West. Reported from various sites in Scotland by West & West (1905: p. 504).

Staurastrum arcuatum var. subavicula (West) Coesel & Meesters. Originally reported by West (1892b: p. 732: as Staurastrum arcuatum subsp. subavicula) from Harrop Tarn in the Cumbrian Lake District, England. More recently collected by Chris Carter on 4 March 2012 from a Sphagnum squeezing collected from near Caldbeck in the Cumbrian Lake District, England (see comments in AlgaeBase, searched February 2021).

*Staurastrum avicula var. lunatum (Ralfs) Coesel & Meesters. Recorded by West & West (1894, p. 10: as Staurastrum lunatum var. subarmatum) from Derryclare Lough, Co. Galway, Ireland.

*Staurastrum bacillare Ralfs var. undulatum West & G.S.West. Described by West, West, and Carter (1923) from Rhiconich, Sutherland, Scotland. According to Coesel & Meesters (2013: p. 69), it is “an anomalous form of some other species”.

Staurastrum brachiatoides Coesel & Van Westen. Collected in September 2017 by Marien van Westen from a puddle and in two “mire pools” on Loughrigg Fell in the Cumbrian Lake District, England (John et al., 2018). According to Marien van Westen (pers. comm.), a very distinctive species that is similar to Staurastrum brachiatum Ralfs but is smaller and has less pronounced ends.

Staurastrum chavesii var. latiusculum (West & G.S.West) Coesel & Meesters. The basionym Staurastrum latiusculum West & West (1902: p. 53) was collected from “near Glenties”, Co. Donegal, Ireland (see John, Williamson, & Guiry, 2012).

*Staurastrum controversum var. semivestitum (West) Coesel. Staurastrum vestitum var. semivestitum West, the basionym, was described Loughrigg Fell in the Cumbrian Lake District, England (West, 1892b: p. 732).

Staurastrum forficulatum var. verrucosum Grönblad. Collected in September 2017 by Marien van Westen from “Lily Tarn” on Loughrigg Fell in the Cumbrian Lake District, England (see John et al., 2018).

*Staurastrum manfeldtii var. productum (West & G.S.West) Coesel & Meesters. Collected in September 2017 from Kelly Hall Tarn in the Cumbrian Lake District, England (John et al., 2018; as Staurastrum productum (West & G.S.West) Coesel). Reported as a new record but see nomenclatural change under Staurastrum sebaldi var. productum. David Williamson (pers. comm.) considers that it is easily mistaken for other morphologically similar taxa but considers this to be the most appropriate name because of its distinctly flattened verrucae.

*Staurastrum punctulatoides (West & G.S.West) Coesel & Meesters. Originally described from northern England by West & West (1896: p. 158: as Staurastrum kjellmanii var. rotundatum West & G.S.West).

Staurastrum simonyi var. semicirculare Coesel. Collected in September 2017 by Marien van Westen from a small stream on Loughrigg Fell in the Cumbrian Lake District, England (John et al., 2018).

Staurastrum spinolobatum C.F.Carter & D.B.Williamson. Collected by Chris Carter on 3 July 2016 amongst Sphagnum floating in a shallow (< 0.5 m deep), permanent peat pool (HU416559) from near the summit of Scrae Field (216 m), near Quarff, Shetland Islands, Scotland (Carter & Williamson, 2017)

*Staurastrum tortum (Lagerheim & Nordstedt) West & G.S.West. Originally reported by West & West (1912: p. 161) from a few sites in the British Isles while West’s form trigona is considered by Coesel & Meesters (2013: p. 160) to be inseparable from the type.

Staurodesmus calyxoides var. minor D.B.Williamson & C.F.Carter. Collected on 22 April 2015 by Chris Carter in a Sphagnum squeezing (NR915487) from Glen Catacol, Isle of Arran, Scotland (Williamson & Carter, 2016b, 2017).

Staurodesmus convergens var. wollei Teiling. Collected in September 2017 from School Knott Tarn, Cumbrian Lake District, England (John et al., 2018).

Staurodesmus extensus var. rectus (B.Eichler & Raciborski) Coesel & Meesters. Collected in September 2017 by Marien van Westen from a small stream on Loughrigg Fell, Cumbrian Lake District, England (John et al., 2018).

*Staurodesmus patens var. inflatus (West) Coesel & Meesters. Reported by West (1892b: p. 170: as Staurastrum dejectum Brébisson ex Ralfs var. inflatum West) from Derryclare Lough, Ballynahinch, Co. Galway, Ireland. In a catalogue of Irish desmids (John et al., 2011: p. 68) this variety is placed in the synonymy of another variety, namely var. maximus Teiling, although Coesel & Meesters (2013: p. 32) state var. maximus to be “cf. Std. patens var. inflatus”.

Staurodesmus subquadratus (West & G.S.West) Coesel & Meesters. First described from Chobham Common in Surrey, England by West & West (1897: p. 496: as Arthrodesmus incus var. subquadratus West & G.S.West).

Xanthidium antilopaeum var. minneapoliense Wolle. Collected in September 2017 by Marien van Westen from a small stream on Loughrigg Fell in the Cumbrian Lake District, England (John et al., 2018).

Order Charales Dumortier

Chara virgata var. barbata (Ganterer) Raam ex Guiry & D.M.John. Collected in August 2015 by Chris Carter from Yardley Chase, Northamptonshire, England; identified by Nick Stewart.

Discussion

Of the 473 taxonomic and nomenclatural changes (Table 1), the vast majority have occurred since publication of the Flora in 2011. The majority involve the green algae (287), comprising the Chlorophyta and Charophyta, followed by the Cyanobacteria (101), the Dinozoa, Dinophyceae (23), Euglenozoa (28) and Ochrophyta, Chrysophyceae (13). Each of the remaining major groups having less than 10 changes. Most of the changes to the Charophyta concern the desmids (136; Desmidiales), with many resulting from the revision by Coesel & Meesters (2013) of the genus Staurastrum and monospinous forms belonging to Staurodesmus. In this revision, a considerable number of intraspecific taxa have been consigned to synonymy under the type variety based on what is often termed “best professional judgement”. All the changes proposed by Coesel and Meesters (2013) are listed here, and most are accepted in AlgaeBase (Guiry & Guiry, 2021). There will undoubtedly be further changes, since DNA sequence studies (e.g., Gontcharov & Melkonian, 2011; Štastný & Kouwets, 2012; Štastný et al., 2013) indicate that many desmid genera are polyphyletic. Future molecular studies will undoubtedly lead to wide-ranging revisions of the group, with many subspecies probably reproductively and phylogenetically distinct so probably representing separate species and, possibly, genera.

Table 1. The number of nomenclatural/taxonomic changes and new additions since publication of the 2nd edition of The Freshwater Algal Flora of the British Isles. The numbers of changes and new records are shown under each of the phyla, with the numbers given under the classes in the Phylum Ochrophyta since each class is recognised as a phylum in the 2^nd ed of the Flora. The total numbers for the Chlorophyta and Charophyta are also broken down to changes and records under classes and orders. The total numbers are based upon the numbers in the shaded blocks.

Many of the changes listed here are based on investigations that increasingly involve the analysis of gene sequences in tandem with morphological data sets. Such polyphasic investigations have resulted in the recognition of at least eight cyanobacterial genera and account for many of the large number of taxonomic and morphological changes in this phylum. A conservative approach was adopted for the Cyanobacteria which resulted in the rejection of a number of genera and new combinations have been 83 new additions to the freshwater algal complement of Britain and Ireland since publication of the second edition of the Flora, including 20 previously overlooked and six species new to science (Table 2). Of the overlooked species, eight are desmids mentioned by William and George West (see West, 1892a, 1892b; West & West, 1896, 1912). Some of the desmids recorded by the Wests have not been rediscovered despite David Williamson (DBW) having examined thousands of British and Irish samples since the 1970s. There are at least a further 40 desmids recorded by DBW and these and others will be reported upon following an analysis of the information transferred to a searchable database from his card index of site-specific records (Wilbraham et al., in preparation). Of the six new species, four are desmid taxa from Britain and Ireland and have been described by DBW (see Table 2) who has contributed very significantly to the new desmid records.

Table 2. New taxa described from Britain and Ireland since publication of the second edition of The Freshwater Algal Flora of the British Isles.

Phylum	Class	Order	Species	Reference
Ochrophyta	Chrysophyceae	Synurales	Synura hibernica Škaloud & Škaloudová	Škaloud & Škaloudová, 2014
Chlorophyta	Chlorophyceae	Chlamydomonadales	Chlorococcum turfosum (Shin Watanabe & L.A.Lewis) Nakada, Shin Watanabe & L.A.Lewis; basionym Parachlorococcum turfosum Shin Watanabe & L.A.Lewis;	Nakada et al., 2019;Shin Watanabe & Lewis, 2017
Chlarophyta	Zygnematophyceae	Desmidiales	Cosmarium blacklochense D.B.Williamson	Williamson, 2018a
Charophyta	Zygnematophyceae	Desmidiales	Cosmarium didymochondrum Nordstedt var. compressum D.B.Williamson & C.F.Carter	Williamson & Carter, 2017
Charophyta	Zygnematophyceae	Desmidiales	Staurastrum spinolobatum C.F.Carter & D.B.Williamson	Carter & Williamson, 2017
Charophyta	Zygnematophyceae	Desmidiales	Staurodesmus calyxoides var. minor D.B.Williamson & C.F.Carter	Williamson & Carter, 2017

Molecular techniques continue to alter radically our understanding of the taxonomy, phylogeny, diversity and species relationships of non-marine algae. Over the past decade the analysis of DNA sequence data has resulted in some of the changes reported here, but molecular studies on freshwater algae remain patchy. In the long term the intention is to make it possible for non-specialists to identify quickly and accurately algal species based upon sequence similarities against a priori-defined species rather than relying on morphological characters, such as used in the Flora and other traditional identification tools. This still remains aspirational rather than an actuality, particularly as barcode sequences are not available for types, even when the types can be found and are amenable to DNA extraction.

Acknowledgments

We are very grateful to all those who contributed new records and information on the literature, including David Williamson, Chris Carter, Marien van Westen, Frans Kouwets, Pauline Lang (SEPA, Scotland), Bryan Kennedy (Environmental Protection Agency, Ireland), the late Erica Swale and Hilary Belcher; Joanna Wilbraham’s contribution to this paper was supported by the Natural History Museum, London. Special thanks go to the British Phycological Society and the Natural History Museum for so generously supporting the Flora project over many years.

Disclosure statement

No potential conflict of interest was reported by the author(s).