Bathysabellaria, LECHAPT & GRUET, 1993

Capa, María, Hutchings, Pat & Peart, Rachael, 2012, Systematic revision of Sabellariidae (Polychaeta) and their relationships with other polychaetes using morphological and DNA sequence data, Zoological Journal of the Linnean Society 164 (2), pp. 245-284 : 258-259

BATHYSABELLARIA LECHAPT & GRUET, 1993

Bathysabellaria Lechapt & Gruet, 1993: 243 , figs 1–4; Kirtley, 1994: 185.

Type species: Bathysabellaria neocaledoniensis Lechapt & Gruet, 1993 , by monotypy; collected from deep water off New Caledonia .

Diagnosis: Bathysabellaria is the only group of sabellariid with the opercular lobes completely fused along its length, thoracic branchiae absent, and neuropodia of thoracic segments bearing only capillary chaetae.

Description: Operculum with lobes completely fused and with distal end (disc) flat and perpendicular to longitudinal axis. Opercular papillae numerous and digitiform. Outer paleae numerous, arranged in semicircles; shaft and blade slightly geniculate (forming an angle), blades faintly excavated, with smooth margins, except when distal tips frayed or broken. Inner opercular paleae arranged in semicircles, giving the appearance of one row, straight, slightly excavated, with smooth margins. One pair of nuchal spines, only slightly curved distally. Three or four simple (unbranched) tentacular filaments present; buccal flaps absent. Palps similar in length to operculum. With conspicuous median organ present. Neuropodia of segment 1 with one cirri on each side of building organ and capillary chaetae. Segment 2 with one pair of triangular-shaped lateral lobes. Thoracic branchiae absent. Four parathoracic segments. Parathoracic notochaetae lanceolate and capillaries alternating; neurochaetae only capillaries.

Remarks: Lechapt & Gruet (1993) erected this genus based on differences in the shape of palps and nuchal spines compared with other genera having four parathoracic segments. They also mentioned the presence of only capillaries in the neuropodia of parathoracic segments as a diagnostic feature although it was not further mentioned in redescription of the genus and description of a new species by Lechapt & Kirtley (1998). Note that the presence of capillary chaetae in parathoracic neuropodia is also present in Mariansabellaria ( Kirtley, 1994) and at least some Gesaia species ( Fauvel, 1911) . Thoracic branchiae are absent ( Lechapt & Kirtley, 1998; Figs 7, 8 ) although Kirtley (1994: 185) mentioned their presence and a conspicuous median organ projects from the ventral side of the opercular lobes, although it was reported as absent in the genus ( Kirtley, 1994: 185). The genus contains two species only found in deep water (more than 450 m) off New Caledonia ( Lechapt & Kirtley, 1998).

Figures

Figure 8. Photographs of preserved specimens: A, operculum and anterior segments, lateral view, Sabellaria sp. nov. 2; B, operculum and anterior segments, lateral view, Lygdamis giardi; C, detail of opercular papillae, Lygdamis indicus; D, head and thoracic appendices, Idanthyrsus australiensis; E, head and thoracic appendices, Sabellaria sp. nov. 2; F, operculum and anterior segments, ventral view, Phalacrostemma sp. nov.; G, head and thoracic appendices, L. giardi; H, head and thoracic appendices, L. giardi; I, median organ with lateral ocelli, I. australiensis; J, head and thoracic appendices, Bathysabellaria spinifera; K, operculum and paleae, dorsal view, Tetreres robustus; L, operculum and thoracic segments, lateral view, B. spinifera; M, operculum and anterior segments, lateral view, T. robustus. Abbreviations: b, branchia; b2, branchia segment 2; bo, building organ; cn 1, cirrus neuropodia segment 1; chn1, chaetae neuropodium segment 1; dap, dorsal papilla; es, eyespots; ip; inner paleae; li, lips; mo, mouth; mor; median organ; mr, median ridge; ns, nuchal spines (hooks); op, outer paleae; opa, opercular papillae; p, paleae; pa, palp; pl, oral plates; tf, tentacular filaments.