Neogyptis hongkongensis, Pleijel & Rouse & Sundkvist & Nygren, 2012

Pleijel, Fredrik, Rouse, Greg W., Sundkvist, Tobias & Nygren, Arne, 2012, A partial revision of Gyptis (Gyptini, Ophiodrominae, Hesionidae, Aciculata, Annelida), with descriptions of a new tribe, a new genus and five new species, Zoological Journal of the Linnean Society (Zool. J. Linn. Soc.) 165 (3), pp. 471-494 : 486-489

NEOGYPTIS HONGKONGENSIS SP. NOV. ( FIG. 11 )

Gyptis sp. A , Pleijel (1998), figure 22A–F.

Type material: Holotype ( SIO-BIC A2496 ) and 21 paratypes ( SIO-BIC A2497 ).

Type locality: Hong Kong, Cape D’Aquilar , Lobster Bay, 22°12.4′N, 114°15.5′E, 1 m.

Etymology: Named after Hong Kong, the type locality.

Material examined: Holotype ( SIO-BIC A2496 , fixed in formaldehyde), Hong Kong, Cape d’Aquilar , Lobster Bay, 22°12.4′N, 114°15.5′E, coarse sand, 1 m, 10–15.vii.1995; 21 paratypes ( SIO-BIC A2497 ; fixed in formaldehyde), same collection data as holotype; ten spms ( FP collection; fixed in osmium and mounted on stubs for SEM), same locality and date.

Description: Length up to 2.6 mm for 25 segments. Body outline cylindrical with tapering posterior end. Live animals transparent; eyes brown-black. Prostomium rounded quadrangular, as wide as long ( Fig. 11A ). Palpophores cylindrical, palpostyles tapering to rounded tips; palpostyles longer than palpophores. Paired antennae as long as palps but thinner, with tapering distal part ( Fig. 11B ). Median antenna much shorter than paired antennae, inserted on anterior third of prostomium, weakly club-shaped. Eyes medium-sized, anterior pair twice as large as posterior and situated anterolaterally to posterior pair. Nuchal organs ciliated bands along lateral sides of prostomium ( Fig. 11A, D ). Distinct lip pads present ( Fig. 11C ). Proboscis with smooth distal and terminal rings, opening with terminal ring of ten small papillae. Non-everted proboscis reaching segment 7–8. Segment 1 dorsally reduced, segment 2 fully developed. Dorsal cirri and cirrophores segment 1–5 longer and stouter than following ones, distinctly annulated. Ventral cirri segment 1–4 with well-delineated cirrophores and longer and stouter cirri than on following segments. Segment 5 with neuropodial lobes, neurochaetae and ventral cirri similar to following segments, segment 6 with notopodial lobes and notochaetae. Elevated and slightly stouter dorsal cirri on segment 8, 12, 15, 17, 19, 21, 23, and 25. Transverse dorsal ridges absent. Dorsal cirri short, not reaching beyond notochaetae. Transverse ridges absent ( Fig. 11E ). Notopodial aciculary lobes conical. Notochaetae of two kinds; single or several dorsally bent aciculary chaetae inserted near tip of notoaciculae, and c. ten capillary chaetae with two alternating rows of teeth. Prechaetal neuropodial lobes conical. About 15 neurochaetae, all compound and unidentate, with dorsal and median blades up to four times longer than ventral. Single noto- and neuroaciculae. Ventral cirri tapering to fine points ( Fig. 11F ). Pygidial cirri much longer than dorsal cirri; pygidial papilla absent.

Habitat: Coarse sand at 1 m depth.

Distribution: Only known from the type locality. Remarks: Neogyptis hongkongensis sp. nov., shares brown-black eye colour with N. rosea comb. nov., N. fauchaldi sp. nov., and N. vostokensis comb. nov. It differs from N. rosea comb. nov. in having ten, rather than 35–80, papillae terminally on the proboscis, from N. fauchaldi sp. nov. in lacking curved notochaetae with conical side subdistally serrated, and from N. vostokensis comb. nov. in having slimmer ventral cirri with well-demarcated tips. Furthermore, it differs from all Amphidurini in having lip pads, a feature that otherwise is present in Gyptis . The species is referred to Neogyptis based on the presence of distally inserted ventral cirri. However, at least one of these features must be homoplastic, and the preference of Neogyptis , rather than Gyptis , is somewhat arbitrary. Unfortunately no specimens were available for molecular study.

This is the smallest known member of Neogyptis and, as no mature specimens were observed and all were collected within a limited time period, we cannot exclude the possibility that they may attain a larger size. However, the absence of notochaetae on segment 1–5 and neurochaetae on segment 1–4, together with the development of the dorsal and ventral cirri on segment 1–5 and 1–3, respectively, indicate that they indeed are adults (see e.g. Pleijel, 1998, on the development of hesionids).

Figures

Figure 11. Neogyptis hongkongensis sp. nov., scanning electron microscopy photographs of specimens from the type locality. A, anterior end, dorsal view. B, anterior end, ventral view. C, lip pads. D, anterior end, right side. E, median segments, dorsal view. F, median parapodia, anteroventral view, right side. Scale bars: A, B, D, E = 100 Mm, C = 25 Mm, F = 50 Mm.