Hesionidae

Abstract: Hesionids are a very speciose group of polychaetes. In the deep sea, they occur in different environments such as hydrothermal vents, cold seeps, abyssal depths or whale falls. In the present study, a new species of Hesionidae, Hesiospina legendrei sp. nov. has been identified based on morphological and molecular (16S and COI genes) data from hydrothermal vents located in Juan de Fuca Ridge (NE Pacific Ocean). This new species is characterized by trapezoid prostomium; proboscis with high number of distal papillae (20-27), a pair of sac-like structures inserted ventro-laterally in proboscis; notopodia lobe reduced with multiple, slender aciculae on segments 1-5; and neuropodia developed with single, simple chaeta, and numerous, heterogomph falcigers, with 1-2 inferiormost having elongated hood. Hesiospina legendrei sp. nov. is the third described species in the genus. Sequences from the two previously described Hesiospina species are included in the molecular analyses, and although the genes used in this study are not sufficient to resolve the relationships on genus level, the result raises questions about the cosmopolitan aspect of H. vestimentifera.

Abstract: 16 especes appartenant a 8 familles sont signalees, 14 especes et 2 genres sont nouveaux pour la science

Abstract: Cladistic relationships between 7 parts of the hesionid polychaete group Heteropodarke are assessed in a parsimony analysis based on 34 morphological characters. Taxon names are de- fined by apomorphy-based phylogenetic definitions, without reference to Linnean ranks or types. Species entities are omitted and denied any role in taxonomy; taxon names refer to monophyletic groups only. Linnean binomial species names are not employed, and all taxa are assigned uninomi- als. Previously known parts of Heteropodarke (Africana Hartmann-Schroder, 1974; Formalis, Perkins, 1984; Heteromorpha Hartmann-Schroder, 1962; Lyonsi Perkins, 1984; Xiamenensis Ding, Wu, and Wes- theide, 1997) are reexamined, and Bidentata, new taxon, and "Zmyrina" (informal name) are de- scribed from Papua New Guinea and Belize, respectively. The new taxon Crassichaetae is named for a subgroup of Heteropodarke, which is diagnosed by enlarged, anteriorly situated falcigers, and in- cludes Africana, Heteromorpha, Lyonsi, and Xiamenensis . Within this group Africana and Heteromorpha are treated as taxa inquirendae. {Apomorphy-based definitions; Linnean nomenclature; phylogenetic taxonomy; polychaetes; ranks; species concepts; species names; types.}

Abstract: Comparative studies of the genera Hesionides and Microphthalmus have produced a lot of results to anatomy, ecology, life history, locomotion and systematics (3 new species) of polychaetes. The small shape of the body, adhesive anal lobes, neuropods working like legs, aberrant complicated sexual organs, shape of the sperms, formation of spermatophores, development in cocoons, seasonal migrations etc. are considered as adaptations to the extreme environmental factors of sandy biotopes.