https://orcid.org/0000-0003-1188-3489
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ABSTRACT
Stauroneis Ehrenberg is a species-rich genus that is common and widespread with some variation in frustule morphology. Recently, studies have explored the molecular diversity of the Stauroneis from the temperate region, but there are no molecular data for tropical species. In the present study, four species of Stauroneis were investigated using morphological and molecular data. Morphological characters were analysed using light microscopy (LM) and scanning electron microscopy (SEM), and the features of each taxon were compared with similar species within the genus. For the molecular analyses, Stauroneis strains were isolated, cultured, DNA was extracted, and sequences from rbcL and 18S genes were analysed to determine phylogenetic relationships. Our analysis describes three new species and records one previously known species. The new species are: (1) Stauroneis lateritica Wadmare, Kociolek & B.Karthick, characterized by small frustules with elliptical lanceolate valves and short subrostrate apices, broad central bow-tie shaped stauros, and few moderate striae centrally becoming strongly radiate towards the poles; (2) Stauroneis sholaii Wadmare, Kociolek & B.Karthick, which has broad lanceolate valves with short rectangular stauros and radiate striae; and (3) Stauroneis bartii Wadmare, Kociolek & B.Karthick, which has large, lanceolate valves with rounded apices, a stauros with 4–7 shortened striae and radiate striae. Ultrastructure and molecular data from India for the previously known, widespread species Stauroneis gracilis Ehrenberg are presented. The combined morphological and molecular approach supports recognition of S. lateritica, S. sholaii and S. bartii as new species. This study is the first-ever attempt at molecular species discovery of diatoms from the Indian subcontinent.
Acknowledgements
We are thankful to the Department of Forest, Environment and Wildlife Management, Government of Sikkim for research permission (F. No. 78/GOS/FEWMD/BDR/PCCF/Secy 131) and Department of Forest of Kerala for research permission (WL10-51713/2017). The authors are grateful to Prof. KN Gandhi, Harvard University Herbaria for his nomenclatural inputs. We are also thankful to Dr Mandar Datar, Dr Sumit Singh Dagar, Dr Aravind Madhyastha, Dr Surajit Roy and Mr Radhakrishnan Cheran for their help during the field collections. We thank Paul Hamilton and an anonymous reviewer for the constructive comments on the previous version of the manuscript.
Disclosure statement
No potential conflict of interest was reported by the authors.
Supplementary information
The following supplementary material is accessible via the Supplementary Content tab on the article’s online page at https://doi.org/10.1080/09670262.2021.1888390
Supplementary data S1. Taxa, strain voucher ID and GenBank accession numbers for strains used in the phylogenetic analysis. Sequences that were not available in GenBank are indicated with N.A.
Supplementary data S2. Distance matrices giving an overview of the p-values of rbcL, 18S for the data sets examined in this study.
Author contributions
N. Wadmare: microscopy observations and producing LM and SEM images, culturing, description of new species, molecular and phylogenetic analyses, preparation, and editing the manuscript. A. Baghela: molecular and phylogenetic analyses, revision, and editing the manuscript. J.P. Kociolek: referring type specimens, critical reading, revision, and editing the manuscript. B. Karthick: original concept, designed research, field sampling, description of new species, revision, and editing the manuscript.