Aspidosiphon muelleri Diesing, 1851

Adrianov, Andrey V. & Maiorova, Anastassya S., 2012, Peanut worms of the phylum Sipuncula from the Nha Trang Bay (South China Sea) with a key to species, Zootaxa 3166, pp. 41-58 : 53

Aspidosiphon muelleri Diesing, 1851

( Fig. 5 I–J)

Material. NhaTrang Bay: Dung Island, 15 m depth, sand, vacant gastropods shells, 3 specimens; fish trawl, 25 m depth, solitary corals ( Heteropsammia cohlea ), 40 specimens.

Description. Trunk 5–12 mm long, 2–2.5 mm wide; grey, with minute papillae distributed over the entire trunk, larger papillae at anal and caudal shields; introvert 2– 3 X of trunk length. Anal shield yellow-brown, with small units arranged into groups of various size separated by longitudinal furrows dorsally and by transverse furrows laterally; caudal shield yellow-brown, with 15–20 radial grooves. Small unidentate, compressed hooks, 20–30 μm in height, arranged in rings distally; proximal introvert with scattered conical hooks. Continuous longitudinal musculature layer splits in the area of the anal shield; retractor muscles originate 10% of trunk length from the caudal shield. Spindle muscle is attached posteriorly to the body wall. Nephridia are about 70% of trunk length.

Discussion. This species differs from other representatives of the subgenus Aspidosiphon (Aspidosiphon) by the structure of the anal shield with individual units that are arranged into longitudinal ridges above the dorsal region.

Aspidosiphon muelleri , the most widespread representative of the genus Aspidosiphon , is a cosmopolitan species reported from shallow to bathyal depths. In the West Pacific it has been found from Australia to Japan and in the South China Sea from the Vietnam coast, Tonkin Bay and Hainan Island. Generally, it inhabits discarded mollusk shells and dead corals.

Figures

FIGURE 5. A – C. Aspidosiphon elegans. A) lateral view, introvert everted; B) bidentate hook; C) conical hook. D – H. A. gracilis. D) lateral view, introvert half everted; E) anal shield; F) caudal shield (white arrowhead - caudal shield.); G) hooks; H) the base of hooks (black asterisk - bifurcated posterior edge of hooks). I – J. A. muelleri. I) lateral view, introvert everted; J) hooks. K – L. A. laevis. K) lateral view, introvert everted; L) hooks. M-Q. A. steenstrupii. M) lateral view, introvert everted; N) close-up view of the introvert with calcareous anal shield (white arrow, calcareous cap on anal shield); O) bidentate hook; P) bidentate hooks & papillae; Q) pyramidal hooks. R-S. A. tenuis. R) lateral view, introvert everted; S) hook. Scale bars: A, 5 mm; B, 20 µm; C, 50 µm; D, 5 mm; E – F, 1 mm; G – H, 50 µm; I, 5 mm; J, 20 µm; K, 5 mm; L, 20 µm; M – N, 5 mm; O, 50 µm; P, 25 µm; Q, 50 µm; R, 5 mm; S, 50 µm.