Pycnoderma glasbyi, Salazar-Vallejo, Sergio I., 2011

Salazar-Vallejo, Sergio I., 2011, Revision of Piromis Kinberg, 1867 and Pycnoderma Grube, 1877 (Polychaeta: Flabelligeridae), Zootaxa 2819, pp. 1-50 : 39-41

Pycnoderma glasbyi n. sp.

Figure 18

Type material. Eastern Indian Ocean, Timor Sea. Holotype (NTM-18917), Sta. DW197A (12°28.25ʹ S, 130°50.32ʹ E), Darwin Harbor, Australia, 2 m, Mar. Ecol. Unit, coll.

Description. Holotype (NTM-18917), complete, broken into two pieces ( Fig. 18 A), slightly damaged. Body brown-yellowish anteriorly, paler posteriorly, cylindrical, tapering towards both ends, slightly swollen posteriorly; tunic scarcely papillated, with a thick tunic adhering fine sediment particles, especially in anterior body half; papillae arranged in longitudinal rows, four dorsally, two ventrally. Holotype 46 (29+17) mm long, 2.5 mm wide (posterior swollen region 2 mm wide), cephalic cage 2 mm long, 68 (42+26) chaetigers.

Cephalic hood not exposed ( Fig. 18 B); not dissected to avoid further damage. Cephalic cage chaetae shorter than body width. Chaetigers 1–3 involved in the cephalic cage; chaetae arranged in short lateral rows, with 4–5 chaetae per bundle. Anterior dorsal margin of chaetiger 1 papillated. Chaetigers 1–3 becoming slightly longer posteriorly. Chaetal transition from cephalic cage to body chaetae abrupt; aristate neurospines from chaetiger 7. Gonopodial lobes not projected; with transverse depression along neurochaetal lobe.

Parapodia poorly developed; chaetae emerging from the body wall. Parapodia lateral; median neuropodia ventrolateral. Noto- and neuropodia long lobes, each with one suprachaetal, one infrachaetal and another papillae inferior to the latter, especially in anterior chaetigers; posterior chaetal lobes each with a single infrachaetal and one interramal papilla.

Median notochaetae arranged in short transverse row, 5–6 per bundle, about as long as 2/5 body width; all notochaetae multiarticulated capillaries, dark yellow, with short articles basally and medially, medium-sized distally ( Fig. 18 C). Neurochaetae multiarticulated capillaries in chaetigers 1–4 ( Fig. 18 D); aristate neurospines from chaetiger 5, arranged in transverse row, 4–5 per ramus; neurospines become distally foliose, bifid from chaetiger 18 ( Fig. 18 E). Each neurospine dark yellow, with short articles basally and medially, distally yellow, hyaline, aristate, bifurcate.

Posterior end subdistally swollen; pygidium a short cone; anus terminal, no anal cirri.

Etymology. This species is named after my good friend and colleague, Christopher Glasby, who has been working on Australian polychaetes in general, by providing the type specimen, and because he has been extremely helpful with my research activities for many years.

Remarks. Pycnoderma glasbyi n. sp. is unique by having median and posterior neurospines distally foliose and bifid. The species resembles P. gracilis ( Hartman, 1961) n. comb. because both have a sediment cover with small grains. They differ in the relative development of the dorsal lobes and the relative density of adhering sediment grains. In P. glasbyi n. sp. there are no dorsal lobes and the sediment particles are sparse, while in P. gracilis there are dorsal lobes and the sediment particles are densely packed. There is at least another species in Australia having abundant sediment grains on the tunic (ZMUC POL-2110). The only specimen available is a damaged anterior fragment, dredged in 8 m in Eden Bay, NSW. Additional specimens are needed in order to make a full description.

Type locality. Darwin Harbor, Northern Territory, Australia.

Distribution. Only known from the type locality, in shallow water (2 m).

Figures

FIGURE 18. Pycnoderma glasbyi n. sp. Holotype (NTM- 18917): A. Complete, lateral view. B. Same, anterior end, lateral view. C. Notochaetae from chaetiger 10 (insert: basal, median and distal regions). D. Neurochaetae from chaetiger 11. E. Neurospines from chaetiger 41. Scale bars: A: 2.5 mm, B: 1 mm, C: 130 µm, D: 75 µm, E: 60 µm.