Decathelepus wambira, Nogueira, João Miguel De Matos & Hutchings, Pat A., 2007

Nogueira, João Miguel De Matos & Hutchings, Pat A., 2007, New species of terebellid polychaetes (Polychaeta: Terebellidae) from Australia, Zootaxa 1473, pp. 1-24 : 15-18

Decathelepus wambira sp. nov.

( Figs. 7–8 )

Material examined. Type series. Holotype: AM W8742: coll. Belmont Beach, New South Wales, 33° 02' 36" S, 151° 40' 56" E, September 1975; posteriorly incomplete specimen, in good condition, with all notochaetigerous segments plus 3 abdominal segments, measuring 7 mm in length, 1.14 mm maximum width. Paratype: AM W8741: coll. 1 km east of Burwood Beach, New South Wales, 32° 57' 31" S, 151° 44' 43" E, May 1975.

Comparative material examined. Decathelepus ocellatus Hutchings, 1977 : Type material: holotype: AM W6782: 2.4 km south of South West Rocks, Peel Island, Moreton Bay, Queensland, Australia, 27° 25' S, 153° 20' E.

Description. Prostomium at base of upper lip, basal part relatively large, with two discrete patches of dorsolateral eyespots, distal part forming thick shelf-like process of uniform width ( Figs 7 A–E; 8A, C, E), from which buccal tentacles originate. Upper lip narrow and elongate, thick, not convoluted; lower lip large, extending to segment 2 ( Figs 7 A–E, 8A, C, E). Segments 1–3 with thickened anterior margins dorsally and laterally, forming raised crests, those on segment 1 dorsally crenulated ( Figs 7 A–D, 8A, C, E). Segment 1 dorsally long, ending laterally to lower lip ( Figs 7 A–E, 8A, C, E). Segment 2 dorsally short, ventrally oblique around and below lower lip ( Figs 7 A–E, 8A, C, E). Segments 3–5 progressively longer; from segment 3, segments strongly glandular, medially swollen all around ( Fig. 7 A–E), forming rings. Ventral shields absent, but entire ventral surface glandular.

Two pairs of branchiae on segments 2–3, each pair with simple filaments, progressively tapering to tips, originating from raised crests on anterior border of segments; at least on segment 3 filaments originating in continuous row across dorsum, without medial gap ( Figs 7 A–D, 8A, C, E).

Notopodia beginning on segment 3 and extending for 15 segments; notopodia short, cylindrical, first pair about same size as following pairs and dorsally aligned to them ( Figs 7 A–C, 8A, C, E). Notochaetae on anterior tier with thick shaft and basally with bulbous limbation, narrower than width of shaft ( Figs 7 G–H, 8F); chaetae on posterior tier with slightly geniculate basally limbation, beginning from middle third of chaetae ( Figs 7 H, 8D).

Neuropodia beginning from segment 12, as low ridges throughout, slightly elevated on abdomen ( Fig. 7 F), internal supporting rods present ( Fig. 7 I). Uncini taller than long, with short triangular heel, developed prow, dorsal button closer to tip of prow than base of main fang and main fang surmounted by 2 rows of secondary teeth ( Fig. 7 I–L, 8B).

Nephridial papillae not visible. Pygidium unknown.

Remarks. Decathelepus wambira sp. nov., differs from D. ocellatus , the only species currently known for this genus, in the structure of the anterior end and the morphology of notochaetae. Both D. ocellatus and D. wambira sp. nov., have elongate upper lip, expanded lower lip, segment 1 ending laterally to lower lip and segment 2 ventrolaterally oblique, around and posteriorly to lower lip. These species differ, as D. ocellatus has a convoluted upper lip, distal part of prostomium forming conspicuous tongue-like process, notochaetae longer, thinner, with limbation not geniculate and, in case of those on posterior tier, starting from close to the point at which chaetae emerge from body wall ( Hutchings 1977 and personal observation), while D. wambira sp. nov., has upper lip thick, not convoluted, lacks tongue-like prostomial process and has notochaetae with geniculate limbation, those on anterior tier shorter and thicker than in D. ocellatus .

Etymology. The specific name “ wambira ” is an Aboriginal word for the coast ( Endacott 1973) and refers to the type locality of the open coast for this species.

Figures

FIGURE 7. Decathelepus wambira sp. nov. A, anterior end, dorsal view; arrow points to basal part of prostomium; B, anterior end, right lateral view; C, anterior end, dorsal view; D, anterior end, left lateral view; E, closer view of anterior end, ventral view; F, abdominal parapodia, G, notochaetae of anterior tier, segment 8 (all notochaetae of posterior tier broken off); H, notochaetae, segment 17; I, uncini, segment 16; J, uncini, segment 19; K – L, closer views of two uncini from segment 19. Photos A – B, D – E from paratype; photos C, F – L from holotype. Numbers refer to segments, ll = lower lip; P (bp) = basal part of prostomium; P (dp) = distal part of prostomium; ul = upper lip. Scale bars: A – D: 250 Μm; E – F: 200 Μm; G: 20 Μm; H: 30 Μm; I – J: 10 Μm; K – L: 5 Μm.

FIGURE 8. Decathelepus wambira sp. nov. A, anterior end, left lateral view; B, uncinus, segment 19; C, anterior end, right lateral view; D, notochaeta from posterior tier, segment 17; E, anterior end, dorsal view; F, notochaeta from anterior tier, segment 8. Figures A and C from paratype, all other figures from holotype. Scale bars: A, C, E: 250 Μm; B: 5 Μm; D: 30 Μm; F: 20 Μm.