Phylogeny and classification of Hesionidae (Polychaeta)

Abstract

Hesionid interrelationships are assessed in a parsimony analysis of 97 (86 informative) absent/present coded morphological characters of 37 terminal taxa within the group. Character information is based on examination of available types, newly collected topotypes and additional non‐types, with introduction of many not previously recorded characters. Polarity is assessed differently in two separate analyses, one by outgroup comparison with nereids and chrysopetalids, yielding two equally parsimonious trees, and one by observations from juvenile hesionids, yielding 10 equally parsimonious trees. The outgroup rooted trees are selected for a reclassification, and three main groups are recognised: Hesiolyrinae, new subfamily, Hesioninae Grube, 1850, and Ophiodrominae, new subfamily. Hesiolyrinae is monotypic for Hesiolyra, Hesioninae includes Hesionini Grube, 1850 and Psamathini, new tribe, and Ophiodrominae includes Gyptini and Ophiodromini, both new tribes. Sirsoe, new genus and member of Psamathini, is established for Orseis grasslei Blake, 1985 and the yet undescribed Sirsoe A. High degrees of homoplasy are demonstrated for a number of characters traditionally used in hesionid taxonomy, e.g., distribution of anterior, enlarged cirri, and first segment provided with neurochaetae and neuropodial lobes. Diagnoses and descriptions are provided for all supraspecific hesionid taxa and a checklist of hesionids is included. For improved precision in polychaete descriptions it is suggested that the term ‘tentacular cirri’ should be replaced by ‘anteriorly situated cirri’ with specified position and morphology. The following new generic synonyms are introduced: Lamproderma Grube, 1877, objective junior synonym of Leocrates Kinberg, 1866; Neopodarke Hartman, 1965 junior synonym of Nereimyra Blainville, 1828; Orseis Ehlers, 1864, junior synonym of Ophiodromus Sars, 1862; Paragyptis Pocklington, 1984 junior synonym of Gyptis Marion & Bobretzky in Marion, 1874; and Podarke Ehlers, 1864, objective junior synonym of Ophiodromus. Additionally a number of new species group synonyms and new combinations are proposed. Parallel to the Linnaean, type‐based definitions of taxon names, a hesionid classification is introduced with phylogenetic taxon name definitions.

<i>Pleijelius longae</i> n. gen., n. sp., a remarkable deep water polychaete from the Northwestern Atlantic (Polychaeta: Hesionidae)

“…The analysis produced 11 equally parsimonious trees (285 steps long, CI 0.34, RI 0.70), with topologies mostly contrasting with the ones found by Pleijel (1998), and Pleijel and Rouse (2000; 262 steps long, CI 0.34, RI 0.73). Thus, in the one nereidid + two chrysopetalids outgroup, in all trees:…”

“…Considering that a general key to all hesionid genera has not been published since Fauchald (1977), we thought it appropriate to construct one that includes recently described taxa and, at the same time, follows Pleijel (1998). However, it includes some genera that do not belong in the Hesionidae, but since they have been associated with them in the past, they were inserted to make it as comprehensive as possible.…”

“…Regarding the pharynx papillae, after Pleijel (1998), there are at least seven genera provided with 10 distal papillae (Gyptis, Heteropodarke Hartmann-Schröder, 1962, Nereimyra de Blainville, 1828, Ophiodromus Sars, 1862, Podarkeopsis Laubier, 1961, Sirsoe Pleijel, 1998, and Syllidea de Quatrefages, 1866), but none of them has cushionshaped papillae, including the other Gyptini. To date the only two genera to be provided with that type of papillae are Leocrates Kinberg, 1866, and Leocratides Ehlers, 1908, but since they both have 8 pairs of enlarged anterior cirri, they are not so closely related to Pleijelius.…”

“…Hesionids have been reviewed extensively and in detail by Pleijel (1998); members of the family have cylindrical bodies and cephalisation of the anterior end (Wilson, 2000); they have a variable number of enlarged anterior cirri, and lateral parapodia with notopodia variously developed, provided with simple chaetae, while neuropodia are better developed and provided with compound chaetae. The family includes about 20 genera which are separated using the number of anterior enlarged cirri, the presence and type of palps, the presence and position of a median antenna, the development of nuchal organs, the notopodia and chaetae, the presence of jaws and marginal papillae in the pharynx, and the presence of penises.…”

Worms by number

“…Alternation patterns were scored for seven families-Acoetidae, Aphroditidae, Chrysopetalidae, Hesionidae (see also Pleijel 1998;Ruta & Pleijel 2006), Polynoidae, Sigalionidae and Syllidae-from segments 1 to 39 as long (L), short (S) or elytra (E). Elytrae were assumed to be homologous with long DC (i.e.…”