Discussion of taxonomic characters and classification of Ampharetidae (Polychaeta)

Abstract

The morphology of about half of the valid ampharetid species (25% including types) was examined. The usefulness of morphological characters, including traditional ones and newly proposed ones, for generic diagnoses are discussed in detail. If possible, intraspecific and interspecific variation in external morphological characters, both traditional and newly proposed were examined. Some of the characters that have traditionally been used for generic identification are considered useful at a specific level. This results in a fundamental change of generic diagnoses and a considerable reduction of the number of genera from 90 described to 24 (some genera have uncertain taxonomical status). New diagnoses for all valid genera, a list of genera, a synopsis of proposed generic synonymies and an identification key for genera are provided.

Keywords:

• Ampharetidae
• taxonomic characters
• identification key

Introduction

Ampharetids have a worldwide marine distribution from the intertidal to 8292 m deep (personal observation). A few (two or three) species are restricted to freshwater systems. Almost 100 genera of Ampharetidae have been described for less than 300 species, although the overview by Reuscher et al. (2009) regarded only about 70 valid. Of the genera described to date, 37 genera are monotypic (Holthe 2002), suggesting that ampharetid generic diagnoses are very narrow. Traditionally, since Malmgren (1866) ampharetid taxonomy has been based on meristic and qualitative characters including the number of thoracic segments, the number of branchiae and the presence/absence of paleae. The present classification with its multitude of monotypic genera does not represent a natural system. I aim to re-define generic diagnoses and modify the ampharetid classification so that it reflects the phylogenetic relationships more realistically.

Material and methods

For the present study almost half of the known ampharetid species and more than 20 species yet to be described have been examined from the following collections:

•	Department of Hydrobiology, Moscow State University, Russia;
•	Forschungsinstitut Senckenberg, Abteilung Deutsches Zentrum für Marine Biodiversitätsforschung, Germany;
•	Marine Ecological Survey Ltd, Bath, UK;
•	N.N. Severtsov Institute of Ecology and Evolution of the Russian Academy of Sciences, Russia;
•	Natural History Museum, London, UK;
•	P.P. Shirshov Institute of Oceanology of the Russian Academy of Sciences, Russia;
•	Thomson Unicomarine Ltd, UK;
•	Zoological Institute of Russian Academy of Sciences, St. Petersburg, Russia;
•	Zoological Museum of Moscow State University, Russia; and
•	Zoologisches Institut und Zoologisches Museum, Universität Hamburg, Germany.

The total number of specimens examined is in the tens of thousands. The total number of investigated species is about 150 (73 of these were type material), 129 are listed in Table II; here I only mention new species that are described in papers that are already or almost in press. If possible, intraspecific and interspecific variation in external morphological characters, traditional and newly proposed morphological characters were examined.

Specimens were studied with a stereomicroscope, generally stained with methylene blue in water, which helps observation of certain morphological characters and enabled one to find some previously unrecognized characters. The precise concentration does not matter; it should colour the specimen blue (not too dark!) in a few seconds. After staining, specimens were rinsed in order to remove excess dye. Investigation was made in water as alcohol immediately dissolves the staining pattern. A few days after returning the specimens to alcohol the methyl blue dissolves, leaving the specimens in their initial condition. The chaetae of 46 species were examined using scannning electron microscopy (SEM).

The following abbreviations are used:

•	AU, abdominal unciniger;
•	TC, thoracic chaetiger;
•	TU, thoracic unciniger.

Abbreviations with a number refer to an actual segment, i. e. AU2 means the second abdominal segment.

Characters of Ampharetidae and their value for taxonomy

I have previously reviewed the taxonomic value of some characters for the classification of Ampharetidae (Jirkov 2001, 2009). Additional examination has revealed new insights into previously discussed characters and new characters of taxonomic interest.

Prostomium

The most common types of prostomium were described earlier (Jirkov 2001, 2009). Additional types can be distinguished (Figure 1).

Figure 1. Main types of prostomia.

Noanelia-type (Figures 1e, 2). The tentacle membrane of this genus is unable retract into the mouth cavity, as with Terebellidae (Figure 2a). The anterior prostomium has a transverse ridge caused by the attachment of tentacles. Such a ridge has not been described in any other ampharetid including specimens with extended tentacles. The prostomium is not separated into parts. A pair of straight or slightly arched anteriorly wide low ridges is present. They range from the median prostomium to the lateral margins without medial gap between them. There are yellow (in fixed specimens) nuchal (?) organs along anterior margins of these ridges. This type of prostomium is known from Noanelia only (see also remarks for the generic diagnosis).

Figure 2. Noanelia hartmanae. a, Lateral view; b, entire prostomium, dorsal view; c, posterior thorax and abdomen, lateral view. Scales: a, 0.5 mm; b, 0.25 mm; c, 1 mm.

Three more types of prostomium can be distinguished: a Neosabellides-type, a Phyllocomus-type, and a Glyphanostomum-type (Figure 1). For their descriptions, see generic diagnosis below.

Segmentation

Most likely, the uncini of Ampharetidae start on the same segment throughout the family. Some authors argue that the paleae are located in the second segment and uncini start in the sixth segment (Orrhage 2001; Reuscher et al. 2009), while others suggest third and seventh segment, respectively (Malmgren, 1865; Fauvel, 1927). However, for the delimitation of genera, the number of the first uncinigerous segment does not matter if a clear statement is provided to prevent confusion. Herein paleae are considered notochaetae situated in the 2nd segment, irrespective of size.

Recently, Reuscher et al. (2009) suggest counting thoracic chaetigers including the paleal chaetiger (in Terebellomorpha the most commonly accepted definition of thoracic segments is any segments with notochaetae). Some species have one or two achetous segment next to the paleal segment, so it is not possible to count them as chaetigers or even as thoracic segments. In my opinion, the paleal segment and segments with notochaetae need to be counted separately in order to avoid confusion.

Buccal tentacles

The diagnosis of Ampharetidae includes the statement that buccal tentacles are attached inside the mouth (Hilbig 2000; Jirkov 2001). However, in Noanelia hartmanae and Noanelia sp. nov., the buccal tentacles are attached outside the mouth (Figure 2a). Probably the same situation is in Andamanella Holthe, 2002, but the nature of the last taxon is not clear from the original description. Examined types of Glyphanostomum holthei have a ring of papillae in addition to normal buccal tentacles. The variation of the tentacles in Polycirrinae is high; in different species they are attached differently, sometimes they are distinctly different in size, some have a groove, other have not. I suggest that the papillae and tentacles of G. holthei as well as tentacles of Terebellidae are probably homologous.

Jaws

Jaws have been described for three ampharetid species: Gnathampharete paradoxa Desbruyeres, 1978; Adercodon pleijeli Mackie, 1994, and Ampharete sp. B Uebelacker, 1984. All known species share other characters (Ampharete-type prostomium; neuropodia of the first two abdominal chaetigers are of thoracic type, a pair of nephridial papillae behind the branchiae). These characters they share with species of Ampharete sensu lato, so the presence of jaws can be treated as synapomorphy and new species with jaws can be found within previously described species of Ampharete sensu lato. The presence of jaws might be a valuable character for generic diagnoses. However, jaws can be observed only after dissection, so for most species we do not know if they have jaws.

Lower lip

The lower lip of Ampharetidae is usually similar. However, in Lysippe, Samytha, Pterolysippe and Lysippides it is enlarged with numerous longitudinal grooves and extends laterally.

‘Horns’

Here the first segment (the segment preceding the paleal segment) has large (of notopodium size) papillae, the methylene blue staining pattern is dark blue, much darker than the surrounding body. This structure is only known from a recently found undescribed genus.

Modified notopodia

Two new types of modification can be added to previously described types.

A Noanelia-type (Figure 2c), where there are large papillae between the notopodia and the neuropodia of last two TU in small (5–6 mm long) specimens. These papillae are similar in size to the notopodia. In larger specimens papillae are fused to the notopodia, so these notopodia become larger than others. In all specimens notopodia of last TU are shifted, especially on the 2nd from last TU. However, there are no other differences between the two last TU and other segments (dorsal ridges, bands, etc.). The last two pairs of notopodia are slightly enlarged, but do not differ in shape.

An Auchenoplax-type, where the thorax is sharply subdivided into two regions: (1) anterior 9–10 TS short with well-developed ventral glandular pads, occupying all of the ventral surface between the notopodia of anterior TS; (2) last 5 TU very long, glandular pads not developed. There are no transitional segments. Notopodia of the anterior region are cylindrical, those of the posterior slightly flattened. Notopodia of the posterior part of the thorax are connected by a more or less developed dorsal ridge. Sometimes ridges are developed near the notopodia only.

Modified neuropodia

The size of neuropodia can vary greatly, even between congeners. The neuropodia of TU1 are often the most developed; they gradually decrease in size posteriorly, and their position does not change. Only Auchenoplax shows a remarkable difference. Usually in this genus the neuropodia of TU2 and/or TU1 can be moved ventrally and the rows of their uncini are several times longer than those of the rest TU (Figure 3).

Figure 3. Neuropodial modification in Auchenoplax. a, Holotype of Auchenoplax crinita, ventral view; b,c, ventral view of two undescribed species of Auchenoplax.

Different types of neuropodia

In most Ampharetidae the shape of thoracic and abdominal neuropodia differs. The uncini of thoracic neuropodia are situated in a furrow; the uncini of abdominal neuropodia at the margin. I propose to call them thoracic and abdominal types. The change of types is very sharp, without any transitional segments. However, the change from the thoracic to the abdominal type of neuropodia does not necessarily match up with the transition from thorax to abdomen. Usually, there are two anterior AU with the thoracic type of neuropodia. This is the case for genera with an Ampharete-type prostomium (Ampharete, Anobothrus, Sosane, Gnathampharete, Lysippe, Eclysippe, Melinnampharete and some others) and for Neosabellides. In Grubianella only the first AU has thoracic-type neuropodia, while in Amage, Amphicteis and Amphysamytha all TU have thoracic-type neuropodia and all AU have abdominal-type neuropodia. In Melinna the last two TU have neuropodia of the abdominal type. In several genera the number of TU varies, but the number of two anterior AU with neuropodia of thoracic-type remains constant: Ampharete always has two, while Amage has none: this means that the number of segments with thoracic-type neuropodia and notopodia varies. Contrarily, in the case of Lysippe, the order of the last segments with thoracic-type neuropodia is constant despite variation in TU; this means that only the number of notopodia varies.

Genera with the simplest types of prostomium like Samythella and Phyllocomus have no difference between thoracic and abdominal neuropodia: all neuropodia are the same type throughout, which, in my opinion, represents the plesiomorphic condition in Ampharetidae. The absence of thoracic neuropodia in Andamanella may be an artefact: in some species (in very small specimens, like the only known specimen of Andamanella) I failed to find neuropodia even after staining.

Uncini: changes along the body

Often the shape of uncini varies among different regions of the body. If so, abdominal uncini are smaller, have more rows of teeth and fewer teeth per row. However, there is no consensus on the taxonomic value of the shape of uncini. Investigation of variation shows that difference in number of rows (2 or 3) and a slight change in number of teeth per row has no importance as this variation can be observed within a single neuropodium (Figure 4). On the other hand, in some genera the neuropodial uncini of thoracic and abdominal types (which do no not necessary coincide with thorax/abdomen) differ consistently (Figure 5).

Figure 4. Variation in uncini in a single neuropodium (Lysippe sexcirrata). Scale 10 μm.

Figure 5. Uncini of neuropodia of thoracic and abdominal types of some genera. All scales 10 μm.

Ventral glandulations

All Ampharetidae build tubes. Ventral glands of anterior segments secrete organic mucus as a matrix for tube construction. Methylene blue staining of glandular fields shows a darker blue than surrounding tissue. Usually there are no distinct ventral shields as in most Terebellinae and Polycirrinae; the glandular surface extends as transversal strip from one neuropodium to another of the same segment through the ventrum. The width of these strips gradually decreases caudally. Among the studied ampharetids only Noanelia has well marked ventral shields like most of the Terebellinae. In Auchenoplax and Eclysippe the thorax is sharply subdivided into two regions: (1) anterior 9–10 TS short with well-developed ventral glandular pads; (2) last 5 TU very long, glandular pads not developed. In all other Ampharetidae all thoracic segments remain similar in length, and the size of glandular pads usually reduce gradually.

Dorsal crest in Melinninae

Usually there is a single dentate crest, but in Melinna elisabethae I have seen up to three crests (one per segment), dorsally decreasing in size and dentation.

Dorsal hooks in Melinninae

Some authors (Fauchald 1977; Reuscher et al. 2009) propose that Moyanus Chamberlin, 1919 differs from Melinna Malmgren by the presence of two pairs of dorsal hooks, rather than one pair. However, Chamberlin (1919) did not state the presence of four hooks, he wrote: ‘Two stout spines, but little exposed, caudad of the branchiae on each side’ (p. 452). Moreover, I have seen several Melinna elisabethae and M. palmata with three hooks (two on one side and one on the other).

Table I contains the synopsis of the proposed taxonomical value of morphological characters of Ampharetidae.

Table I. Taxonomical value of morphological characters in Ampharetidae

Character	Plesiomorphic state	Apomorphic state	Taxonomical level
Minute acicular chaetae	absent	present	subfamily
Prostomium	without lobes	trilobed	generic
Prostomial middle lobe	rounded	incised	generic
Prostomial longitudinal ridges	absent	present	generic
Nuchal organs	absent	present	generic
Undulating transversal nuchal organs	absent	present	generic
Lateral glandular fields	present	absent	generic
Buccal tentacles	smooth	pinnate	specific, may vary intraspecifically
Buccal tentacles	smooth	ciliated	specific
Jaws	absent	present	generic
Pairs of branchiae	4	2 or 3	specific
Branchostyles	cirriform	foliaceous	specific
Branchostyles	smooth	pinnate	specific
Branchostyles	smooth	ciliated	specific
Nephridia papillae behind branchiae	invisible	clear	generic
Paleal chaetae	as notochaetae	much bigger or absent	specific
Dorsal crest Anobothrus-type	absent	present	generic
Dorsal crest Melinnampharete-type	absent	present	generic
Dorsal crest Melinna-type	absent	present	generic
Thorax separation Eclysippe-type	absent	present	generic
Postranchial hooks	absent	present	generic
Modified notopodia Anobothrus-type	absent	present	generic
Modified notopodia Sosane-type	absent	present	generic
Modified anterior neuropodia	absent	present	generic
Number of types of neuropodia	one	two	generic
Number of AU (for species)	varies	constant	generic
Neuropodial cirri	absent	present	specific
Abdominal specific modified rudimentary notopodia	absent	present	specific
Thoracic and abdominal uncini	similar	very different	generic

Table II. List of examined species.
Remark. Only species are described in Schüller & Jirkov (in prep.) are mentioned as sp. nov

Species	Type	SEM
Amage adspersa (Grube, 1863)
Amage anops (Johnston, 1901)
Amage asiaticus Uschakov, 1955	1	1
Amage auricula Malmgren, 1866		1
Amage benhami Reuscher et al., 2009	1
Amage gallasii Marion, 1875		1
Amage sculpta Ehlers, 1908
Amage sibogae Caullery, 1944		1
Amage sp. nov.	1	1
Ampharete acutifrons Grube, 1860
Ampharete baltica Eliason, 1955
Ampharete borealis (Sars, 1856)		1
Ampharete brevibranchiata Treadwell, 1926
Ampharete crassiseta Annenkova, 1929	1
Ampharete eupalea Chamberlin, 1920
Ampharete falcata Eliason, 1955		1
Ampharete finmarchica Sars, 1865		1
Ampharete goeesi Malmgren, 1866		1
Ampharete goeesi brazhnikovi Annenkova, 1929	1
Ampharete grubei Malmgren, 1866
Ampharete kerguelensis McIntosh, 1885	1
Ampharete kerguelensis auct non McIntosh, 1885
Ampharete kudenovi Jirkov, 1994	1
Ampharete lindstroemi Malmgren in Hessle, 1917		1
Ampharete litoralis (Annenkova, 1934)	1
Ampharete longipaleolata Uschakov, 1950	1
Ampharete luederitzi Augener, 1918	1
Ampharete manriquei (Salazar-Vallejo, 1993)	1
Ampharete octocirrata (Sars, 1835)		1
Ampharete petersenae Jirkov, 1997	1
Ampharete safronovae Jirkov, 1994	1
Ampharete seribranchiata Treadwell, 1926
Ampharete sibirica (Wiren, 1883)
Ampharete vega (Wiren, 1883)
Amphicteis bifolium Kucheruk, 1976	1
Amphicteis chilensis Hartmann-Schröder, 1965 in Hartmann-Schröder, Hartmann, 1965	1
Amphicteis dalmatica Hutchings, Rainer, 1979	1
Amphicteis foliata Haswell, 1883
Amphicteis gunneri Sars, 1835		1
Amphicteis gunneri atlantica McIntosh, 1885	1
Amphicteis japonica McIntosh, 1885	1
Amphicteis mederi Annenkova, 1929	1
Amphicteis midas (Gosse, 1855)
Amphicteis ninonae Jirkov, 1985	1	1
Amphicteis papillosa Hutchings, 1977	1
Amphicteis phillippinarum Grube, 1878	1
Amphicteis sarsi McIntosh, 1885	1
Amphicteis scaphobranchiata Moore, 1906
Amphicteis sp. nov. A	1	1
Amphicteis sp. nov. B	1	1
Amphicteis sundevalli Malmgren, 1866
Amphicteis wyvillei McIntosh, 1885	1
Amphisamytha vanuatuensis Reuscher et al., 2009	1
Amythasides macroglossus (Eliason, 1955)
Anobothrus antarctica Monro, 1939		1
Anobothrus apaleatus Reuscher et al., 2009	1
Anobothrus glandularis (Hartmann-Schroder, 1965)	1	1
Anobothrus gracilis (Malmgren, 1866)	1	1
Anobothrus laubieri (Desbruyeres, 1978)		1
Anobothrus mironovi Jirkov, 2009	1	1
Anobothrus nataliae Jirkov, 2009	1	1
Anobothrus patagonicus (Kinberg, 1867)
Anobothrus patersoni Jirkov, 2009	1	1
Anobothrus pseudoampharete Shuller, 2008	1
Anobothrus sp. nov. A	1	1
Anobothrus sp. nov. B	1	1
Anobothrus sp. nov. C	1	1
Auchenoplax crinita Ehlers, 1887	1
Auchenoplax sp. nov.	1	1
Eclysippe affinis Day, 1963
Eclysippe vanelli (Fauvel,1936) sensu Eliason 1955		1
Gen. sp. nov.	1	1
Glyphanostomum pallescens (Theel, 1879)	1	1
‘Glyphanostomum’ holthei Reuscher et al., 2009	1
Gnathampharete pleijeli (Mackie, 1994)	1
Grassleia hydrothermalis Solis-Weiss, 1993	1
Grubianella antarctica McIntosh, 1885	1	1
Grubianella klugei (Pergament et Chlebovitch, 1964)	1	1
Hypania brevispina Grube, 1860
Hypania invalida Grube, 1860		1
Hypania kowalewskii (Grimm, 1877)
Hypania romijni Horst, 1919	1
Jugamphicteis paleata Fauchald, Hancock, 1981		1
Jugamphicteis sargassoensis (Hartman, Fauchald, 1971)		1
Jugamphicteis sibogae (Caullery, 1944)		1
Lysippe bipinnata (Augener, 1918)	1
Lysippe capensis Day, 1961	1
Lysippe gurjanovae Uschakov, 1950	1
Lysippe labiata Malmgren, 1866		1
Lysippe sexcirrata (Sars, 1856)		1
Melinnampharete eoa Annenkova, 1937	1	1
Melinnampharete gracilis (Hartman, 1967)
Melinnampharete septemdentata Levenstein, 1978	1
Neosabellides australiensis Hartmann-Schroder, 1981	1
Neosabellides elongatus (Ehlers, 1913)	1
Neosabellides membranifera (Benham, 1921)	1
Noanelia sp. nov.	1	1
Phyllocomus crocea Grube, 1878
Phyllocomus hiltoni (Chamberlin, 1919)
Phyllocomus sovjeticus (Annenkova, 1937)
Phyllocomus uschakovi (Kuznetsov et Levenstein, 1988)
Samythella elongata Verrill, 1873		1
Samythopsis grubei (McIntosh, 1885)	1
Sosane holthei Jirkov, 1994	1
Sosane kergulensis (Monro, 1939)	1
Sosane sulcata Malmgren, 1866		1
Sosane wahrbergi (Eliason, 1955)
Sosane wireni (Hessle, 1917)		1
Zatsepinia rittichae Jirkov, 1986
Zatsepinia sp. nov.	1	1
Isolda albula Mohammad 1971	1
Isolda pulchella Muller, 1858	1
Isolda sibogae Caullery, 1944	1
Isolda viridis Hartmann-Schroder, 1965	1
Isolda warnbroensis Augener, 1914	1
Melinna albicincta Mackie and Plijel, 1995
Melinna cristata (Sars, 1851)
Melinna cristata australis (Hartmann-Schroder, 1965)	1
Melinna elisabethae (McIntosh, 1922)		1
Melinna ochotica (Uschakov, 1950)	1
Melinnides pacifica (McIntosh, 1885)	1
Melinnides qauterdentata (Kucheruk, 1976)	1
Melinnopsis annenkovae (Uschakov, 1952)	1
Melinnopsis arctica (Annenkova, 1931)	1	1
Melinnopsis atlantica McIntosh, 1885	1
Melinnopsis capensis Day, 1955	1
(Continued)

The following characters are considered to be valuable for specific, rather than generic diagnoses: number of branchiae, TU, presence/absence of paleae. However, the degree of variation of these characters within the newly defined genera differs. The most uniform genus is Amphicteis, whose species all have 4 pairs of branchiae, 14 TU, 17 TC, and usually 15 AU; most species have well-developed paleae. On the other hand, Sosane shows great variation of all these characters: it has 9–13 TU, 3–4 pairs of branchiae, paleae present or absent, even the position of modified thoracic segment varies. Other large genera (Amage, Ampharete, Anobothrus) are intermediate in terms of variation.

The branchial arrangement (not number!) is very characteristic for genera (see Jirkov 2001, 20092009), and may be included in the diagnoses.

Key to genera

The re-evaluation of characters results in emended generic diagnoses and an updated identification key. All previously proposed keys (Malmgren 1866; Chamberlin 1919; Fauvel 1927; Day 1964; Fauchald 1977; Reuscher et al. 2009) have been based on characters such as number of segments, branchiae and presence/absence of paleae, which, in my opinion, are not useful for generic delimitation, as discussed above. This newly proposed key is based only on characters considered valuable on generic level, as discussed above and previously (Jirkov 2001, 2009).

Only genera that I have examined or that have been described in sufficient detail are included in the key. In some cases I was not able to point out a diagnostic character for genera, but for different reasons (explained below in the generic diagnosis) I would not like to treat them as synonyms. Such genera are separated by commas. Synonyms are in round parentheses after = sign.

1.	Three or four anterior segments with vertical rows of minute acicular chaetae. . . . . . . . . . . . . . . Melinninae . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 – Minute acicular chaetae absent. . . . . . . . . . . . . . . Ampharetinae . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
2.	Hooks (usually one pair) and dorsal crest (usually one and dentate) behind the branchiae present . . . . . . . Melinna, Isolda, Irana, Moyanus – Dorsal crest present, hooks absent . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Melinnides (=Melinnantipoda) – Dorsal crest and hooks absent . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Melinnopsis (= Amelinna; Melinnexis, Melinnopsides)
3.	Prostomium Jugamphicteis-type (Figure 1j,k): trilobed, with transversal nuchal organs, middle lobe simple, anteriorly rounded . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Jugamphicteis – Prostomium Amphicteis-type (Figure 1i): trilobed, with prominent transversal nuchal organs, middle lobe with pair longitudinal ridges, anteriorly incised . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Amphicteis (= Crossostoma; Paramphicteis, Phyllamphictes, Pseudoamphicteis) – Prostomium Ampharete or Amage-type (Figure 1f–h): trilobed, without nuchal organs (if present they are not prominent) . . . . . . . . . . 4 – Prostomium Noanelia-type (Figure 1e), buccal tentacles attached outside the mouth, methylene blue staining pattern of ventral glandular shields well marked . . . . . . . . Noanelia – Prostomium without lobes (Figure 1a–d) . . . 15
4.	Thorax sharply subdivided into two regions: (1) anterior 9–10 TS short with entirely glandular ventrum, (2) last 5 TU very long, glandular pads not developed . . . . . . . . . . . . . . . .5 – All thoracic segments remain similar in length; glandular pads may reduce gradually or stop abruptly, but the above characters are not combined . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .6
5.	Neuropodia of TU2 or/and TU1 enlarged and moved ventrally (Figure 3) . . . . . . . Auchenoplax – Anterior neuropodia not enlarged and not moved ventrally . . . . . . . . . . . . . . . . . . . . . Eclysippe
6.	One, usually 5th (4th–6th) from last, pair of posterior notopodia slightly shifted dorsally and connected by low ridge . . . . . . . . . . . . Anobothrus (=Anobothrella, Melythasides, Sosanides) – One pair of posterior notopodia (last, 2nd or 3rd from last) flattened and shifted dorsally . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Sosane (=Mugga; Muggoides; Sosanella; Sosanopsis; Genus A sensu Uebelacker 1984; ?Melinnata) – Posterior notopodia neither flattened nor shifted dorsally, ridges also absent . . . . . . . . . . . 7
7.	– Distinct transversal dorsal ridge between TC3 and TC4 present . . . . . . . Melinnampharete (Eusamytha Hartman, 1967 non McIntosh, 1885; Eusamythella; Neosamytha) – Dorsal ridge absent . . . . . . . . . . . . . . . . . . . . . . . . . 8
8.	Middle lobe of prostomium anteriorly incised or with horns, with or without longitudinal ridges (Figure 1g,h) . . . . . . . . . . . . . . . . . . . . . . . . 9 – Middle lobe of prostomium anteriorly rounded or pointed (Figure 1f) . . . . . . . . . . . . . . . . . . . . . 12
9.	Middle lobe of prostomium with longitudinal ridges (Figure 1h) Hypania (=Alkmaria, . . . . . . . . . . . . . . . . . . . Hypaniola, Microsamytha, Parhypania) – Middle lobe of prostomium without longitudinal ridges (Figure 1g) . . . . . . . . . . . . . . . . . . . . . . 10
10.	Abdominal neuropodia with very long cirri, longer than width of segment . . . . . . . . . . . . . . . . . Samythopsis (= Neopaiwa; Paiwa; Weddelia) – Abdominal neuropodial cirri, if present much shorter than width of segment . . . . . . . . . . . . . 11
11.	AU1 with neuropodia of abdominal type, less than 16 AU . . . . . . . . . . . . . . . . . . . . . . . . . . . Amage (= Egamella; Mexamage; Paramage; Phyllampharete) – AU1 with neuropodia of thoracic type, more than 20 AU . . . . . . . . Grubianella (= Amagopsis)
12.	1st segment with ‘horns’ . . . . . . . . Gen. sp. nov. – 1st segment without ‘horns’ . . . . . . . . . . . . . . . 13
13.	Lower lip enlarged, longitudinally grooved . . . . . . . . . . . . . Lysippe (= Lysippides, Paralysippe, Pseudampharete, Pterolysippe, Samytha) – Lower lip not enlarged . . . . . . . . . . . . . . . . . . . . . 14
14.	Numerous jaws present . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Gnathampharete (= Adercodon) – Jaws absent . . . . . . . . . . . . . . . . . . . . . . . . Ampharete (= Asabellides; Parampharete; Pseudosabellides; Pterampharete; Sabellides, ?Amythasides)
15.	2nd from last notopodia slightly shifted dorsally and connected by low ridge . . . . . . . . Zatsepinia – Dorsally shifted notopodia and dorsal transverse ridges absent . . . . . . . . . . . . . . . . . . . . . . . . . 16
16.	Prostomium with pair of tranversal nuchal organs (Figure 1c) . . . . . . . . . . . . . . . . Phyllocomus (= Shistocomus; Pavelius, ? Amphisamytha) – Prostomium with unpaired transversal groove (nuchal organ?) (Figure 1b) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Neosabellides, Amythas – Prostomium without nuchal organs (Figure 1a,d) .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
17.	Prostomium laterally with glandular fields . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Glyphanostomum – Prostomium without glandular fields . . . . . . . . . . Samythella (= Eusamytha McIntosh, 1885, non Hartman, 1967)

New proposed diagnosis of genera

Ampharetinae

Diagnosis. Minute acicular chaetae in anterior segments absent.

Amage Malmgren, 1866

(= Egamella; Mexamage; Paramage; Phyllampharete)

Diagnosis. Middle lobe of prostomium anteriorly incised or with horns, without longitudinal ridges (Figure 1g). Neuropodia of two types. AU1 with neuropodia of abdominal type, less than 16 AU. Number of AU usually constant for species.

Ampharete Malmgren, 1866

(=Asabellides; Parampharete; Pseudosabellides; Pterampharete; Sabellides, ? Amythasides)

Diagnosis. Prostomium Ampharete-type; middle lobe anteriorly rounded (Figure 1f). Neuropodia of two types, their uncini generally similar. Number of AU usually constant for species (most species have 12 or 13 AU). Number of AU with neuropodia of thoracic type always two, while number of TU can be 11 or 12.

Remark. Amythasides seems very similar to Ampharete. The small size of types (or specimens) does not allow a final descision about its taxonomic status.

Amphicteis Grube, 1850

(= Crossostoma; Paramphicteis, Phyllamphictes, Pseudoamphicteis)

Diagnosis. Prostomium Amphicteis-type (Figure 1i): with transversal prominent nuchal organs and with a pair of longitudinal ridges, anteriorly incised. Neuropodia of two types, no AU with thoracic type neuropodia. Thoracic and abdominal uncini generally similar, usually with one row of teeth.

Remark. Always four pairs of branchiae and usually 15 AU.

Anobothrus Levinsen, 1884

(= Anobothrella, Melythasides, Sosanides)

Diagnosis. Prostomium Ampharete-type. One of posterior notopodia (usually 5th from last) slightly shifted dorsally and connected by low ridge. There is a glandular circular band behind parapodia of 1st, 2nd or 3rd TC. There is a pair of nephridial papillae medially behind the branchiae. Neuropodia of two types, their uncini generally similar. Two anterior AU with neuropodia of thoracic type.

Remark. Number of AU usually constant for species (most species have 12 AU).

Auchenoplax Ehlers, 1887

Diagnosis. Prostomium Ampharete-type. Thorax distinctly subdivided into two regions: anterior segments (up to TC-9) several times shorter than posterior one. Neuropodia of TU-2 and/or TU-1 enlarged and moved ventrally (Figure 3). Notopodia of posterior TU slightly shifted and are connected by more or less developed transversal dorsal ridge. Neuropodia of two types, first two AU with thoracic type ones.

Eclysippe Eliason, 1955

Diagnosis. Prostomium Ampharete-type. Thorax distinctly subdivided into two regions: anterior segments (up to TC-9) several times shorter than posterior one. Anterior neuropodia not enlarged and not moved ventrally. Notopodia of posterior TU slightly shifted and are connected by more or less developed transversal dorsal ridges.

Remark. Genus is very similar to Auchenoplax.

Gen. sp. nov.

Diagnosis. Prostomium Ampharete-type. 1st segment with ‘horns’. No modified noto- and neuropodia. Neuropodia of two types, no AU with thoracic type neuropodia.

Remark. The description of Gen. sp. nov. is currently prepared (Schüller & Jirkov, in prep.).

Glyphanostomum Levinsen, 1884

Diagnosis. Prostomium without lobes, but laterally with glandular fields, often whitish. AU numerous, varying interspecifically. Neuropodia of two types: thoracic (all thoracic and first two abdominal) and abdominal (remaining abdominal). Uncini (Figure 5) of neuropodia of thoracic type with teeth in one row, except lower, paired, uncini of neuropodia of abdominal type with numerous teeth in several rows.

Remark. Lateral prostomial glandular fields are illustrated by Uschakov (1955, figure 138) and Hartman (1969).

Gnathampharete Desbruyères, 1978

(= Adercodon)

Diagnosis. Prostomium Ampharete-type (Figure 1f). Numerous jaws present. Neuropodia of two first abdominal chaetigers of thoracic type, pair of nephridial papillae behind branchiae.

Remarks. Externaly all three species of this genus looks like very small species of Ampharete sensu lato. So examination of the pharyngeal anatomy of Ampharete sensu lato, and especially small species, is needed, as some may belong to Gnathampharete. Examination of the origin of the jaws is warranted.

Grubianella McIntosh, 1885

(= Amagopsis)

Diagnosis. Middle lobe of prostomium anteriorly incised without longitudinal ridges (Figure 1g). AU1 with neuropodia of thoracic type, more than 20 AU.

Remark. Deepwater genus.

Hypania Ostroumow, 1897

(= Alkmaria, Hypaniola, Microsamytha, Parhypania)

Diagnosis. Middle lobe of prostomium anteriorly incised with longitudinal ridges (Figure 1h). Neuropodia and their uncini of two types, uncini of neuropodia of thoracic type with teeth in one row, uncini of neuropodia of abdominal type with numerous teeth in several rows. AU numerous, varying interspecifically.

Remark. Species of this genus occur in fresh or brackish water.

Jugamphicteis Fauchald et Hanckock, 1981

Diagnosis. Prostomium Jugamphicteis-type (Figure 1j,k): trilobed, with transversal prominent nuchal organs, middle lobe simple, anteriorly rounded in small specimens, straight in middle-sized and longitudinally grooved in large. AU1 with enlarged foliaceous rudimental notopodia. Neuropodia and their uncini of two types (Figure 5): uncini of neuropodia of thoracic-type (all thoracic) with teeth in one row, except upper teeth, uncini of neuropodia of abdominal-type (all abdominal) with numerous teeth in several rows.

Remark. Deepwater genus.

Lysippe Malmgren, 1866

(= Lysippides, Paralysippe, Pseudampharete, Pterolysippe, Samytha)

Diagnosis. Prostomium Ampharete-type; middle lobe anteriorly rounded (Figure 1f). Lower lip enlarged, longitudinally grooved. Neuropodia of two types, their uncini generally similar.

Remark. Contrary to Ampharete, number of segments with neuropodia of thoracic type is constant (always 14 uncinigers with neuropodia of thoracic type), while number of TU can be 12–14.

Melinnampharete Annenkova, 1937

(= Eusamytha Hartman, 1967 non McIntosh, 1885; Eusamythella; Neosamytha)

Diagnosis. Prostomium Ampharete-type. There is a distinct transversal dorsal crest between TC3 and TC4. Neuropodia and their uncini (Figure 5) of two types: uncini of neuropodia of thoracic-type (in type species all thoracic and two anterior abdominal) with teeth in one row, uncini of neuropodia of abdominal-type (in type species starting from AU3) with numerous teeth in several rows.

Remark. All known species have small paleae, 12 TU and 15 AU.

Noanelia Desbruyères et Laubier, 1977

Diagnosis. Prostomium Noanelia-type (Figure 1e), buccal tentacles attached outside the mouth, methylene blue staining pattern of ventral glandular shields well marked, while in all other investigated ampharetid species and genera there is no any trace of ventral glandular shields. Neuropodia of two types, thoracic in thorax, AU1 and AU2, remaining AU with neuropodia of abdominal type.

Remarks. The position of this genus within Terebellomorpha remains unresolved. Unlike all other ampharetids, the buccal tentacles are outside the mouth as in Terebellidae. Also, distinct unpaired glandular shields are diagnostic for Terebellinae. On the other hand, moving it to Terebellidae will not clearly resolve the problem. Species of Terebellinae have a double row uncini at least in the posterior thorax, while Noanelia lacks this. Analysis of DNA may help to find the proper position of the genus.

Neosabellides Hessle, 1917

(= ? Amythas Benham, 1921)

Diagnosis. Prostomium without lobes but with transversal groove, sometimes lateral ends of groove with more or less deep depressions (nuchal organ?). Contrary to Ampharete-type, this grove does not completely split the prostomium. Neuropodia of two types: thoracic in thorax, AU1 and AU2; remaining AU with neuropodia of abdominal-type.

Remark. The only investigated specimen of Amythas is a holotype of Amythas membranifera Benham, 1921. It has everted its tentacle membrane, changing the shape of its prostomium, and was incomplete posteriorly. More specimens are needed to clear the taxonomic position of this genus.

Phyllocomus Grube, 1878

(= Shistocomus; Pavelius, ? Amphisamytha)

Diagnosis. Prostomium without lobes but with a pair of transversal nuchal organs. When tentacles are withdrawn and specimens sufficiently well preserved, nuchal organs can be connected by a groove, and this groove can continue laterally up to the prostomium margin. The number of AU is high and varies individually. All neuropodia and their uncini are of the same type (there is no difference between abdominal- and thoracic-type).

Remark. Specimens known from Phyllocomus, Shistocomus, Pavelius have similar prostomia. As for Amphisamytha, A. vanuatuensis Reuscher, Fiege, Wehe, 2009 has similar prostomia as well as identical types of neuropodia throughout the body.

Samythella Verrill, 1873

Diagnosis. Prostomium simple, without lobes and nuchal organs. Number of AU is high and varies individually. All neuropodia and their uncini of the same type, with teeth in a single row.

Samythopsis McIntosh, 1885

(= Neopaiwa; Paiwa; Weddelia)

Diagnosis. Middle lobe of prostomium anteriorly incised without longitudinal ridges (Figure 1g). Neuropodia of two types: thorax with thoracic-type, abdomen with abdominal-type neuropodia only. Abdominal neuropodia with very long cirri, longer then width of segment.

Remark. Deepwater genus.

Sosane Malmgren, 1866

(= Mugga; Muggoides; Sosanella; Sosanopsis; Genus A sensu Uebelacker, 1984; ? Melinnata)

Diagnosis. Prostomium Ampharete-type. One of posterior notopodia (usually last, 2nd or 3rd from last) flattened and shifted dorsally. Thorax and 0–2 anterior AU with thoracic0type neuropodia, remaining AU with abdominal-type neuropodia.

Zatsepinia Jirkov, 1986

Diagnosis. Prostomium without ridges, grooves and nuchal organs. Notopodia of 2nd from last TU slightly shifted dorsally and connected by low transversal ridge. Neuropodia of two types: thoracic in thorax, AU1 and AU2 and abdominal in remaining AU.

Melinninae

Diagnosis. Three or four anterior segments with vertical rows of minute acicular chaetae.

Remark. All Melinninae have varying and comparatively large number of AU.

Melinna Malmgren, 1866, Isolda, Irana, Moyanus

Diagnosis. There are hooks (usually one pair) and dorsal crest (usually one and dentate) behind the branchiae.

Remarks. Here the difference between these four genera is not found to be sound. Since I have not examined type material of all species, additional characters on the generic level may exist. I suppose for the present time it will be better not to change the taxonomy of this group until we have additional information, especially since most species of this group belong to Melinna, the type genus of the subfamily, which would have be treated as junior synonym of Isolda Müller (in Grube) 1858.

Melinnides Wesenberg-Lund, 1950

(= Melinnantipoda)

Diagnosis. There is only dorsal crest behind the branchiae, no hooks.

Melinnopsis McIntosh, 1885

(=Amelinna; Melinnexis, Melinnopsides)

Diagnosis. There are neither hooks nor crest behind the branchiae.

Acknowledgements

I am very much in debt to Dr G. Paterson (Natural History Museum, London), Dr Myriam Shüller (Forschungsinstitut Senckenberg, Abteilung Deutsches Zentrum für Marine Biodiversitätsforschung), Dr T.A. Britaev (N.N. Severtsov Institute of Ecology and Evolution of the Russian Academy of Sciences), Dr N. Budaeva (P.P. Shirshov Institute of Oceanology of the Russian Academy of Sciences), Dr D. Hall and Dr T. Worsfold (Thomson Unicomarine Ltd), Dr G.N. Buzhinskaja and S. Potin (Zoological Institute of Russian Academy of Sciences St. Petersburg), and Dr G. Hartman-Schröder (Zoologisches Institut und Zoologisches Museum, Universität Hamburg) for kindly allowing me to examine their materials for the present study.

The visit to the Zoologisches Institut und Zoologisches Museum, Universität Hamburg was possible due to financial support of the DAAD, visiting Natural History Museum, London due to financial supports of the Linnaean Society and the Thomson Unicomarine Ltd, visiting DZMB Wilhelmshaven for the investigation of Antarctic Polychaeta was supported by the grant from the CeDAMar. Special thanks to Emma Delduca (MES Ltd, UK), who corrected my English. Finally I wish to thank an anonymous referee and the editor who spent a lot of time trying to make my paper better.