Aspidosiphon (Aspidosiphon) muelleri Diesing, 1851

Açik, Sermin, 2009, Soft-bottom sipunculans in Izmir Bay (Aegean Sea, eastern Mediterranean), Zootaxa 2136, pp. 40-48 : 45-46

Aspidosiphon (Aspidosiphon) muelleri Diesing, 1851

Description. Body wall thin, semi-transparent. Trunk 2–16.4 mm long, 0.6–1.4 mm wide. Introvert 1.5 times trunk length. Anal and caudal shield black-brown in colour and grooved. Anal shield with 12–15 longitudinal grooves ( Fig. 4 G). Caudal shield with 18–20 radial grooves. Finger-like spines (3–10 spines) on anal shield of 8 individuals, 70–120 µm long. Spine-like papillae scattered on introvert, 12.5–22.5 μm long. 9–12 small tentacles at end of introvert. Hooks arranged in 65–118 rings of hooks. Bidentate hooks on rings located on distal part of introvert; 15–25 µm high, 17.5–32.5 µm thick at base. Unidentate hooks scattered on proximal part of introvert; 17.5–30 µm high, 20–35 µm thick at base. Intestinal spiral with 5–24 coils. Retractor muscles attached at near posterior part of trunk. Anus and nephridiopores placed at same level. Nephridia length (largest individual) 6.3 mm; 0.4 mm wide. Trunk 2.6 times nephridia length. Two black eye spots present. Some specimens with eggs; longer axis 110–150 µm in diameter, smaller axis 80–120 µm in diameter.

Ecology. In the study area, this species was found in sandy, muddy-sand and Posidonia oceanica biotopes at 22–77 m depth. Many specimens were found within the empty shells of gastropods and tubes of the polychaete species Vermiliopsis sp.

Distribution. Indian Ocean ( Saiz Salinas 1993a), Northeastern Atlantic and Eastern Pacific Oceans, Mediterranean and Red Sea ( Cutler 1994).

Figures

FIGURE 4. A, Golfingia (G.) vulgaris vulgaris, introvert hook. B, Thysanocardia procera, tentacles surrounding bilobed nuchal organ. C, D, Phascolion (P.) strombus strombus, holdfast papillae (C) and introvert hook (D). E, Onchnesoma steenstrupii steenstrupii, egg in coelomic cavity. F, Aspidosiphon (A.) mexicanus, intestinal coils and spindle muscle. G, Aspidosiphon (A.) muelleri, anal shield. Scale bars: A, 15 µm; B, 0.3 mm; C, 40 µm; D, 20 µm; E, 20 µm; F, 1 mm; G, 0.5 mm.