Aspidosiphon (Akrikos) mexicanus (Murina, 1967)

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

Aspidosiphon (Akrikos) mexicanus (Murina, 1967)

Description: Body wall thin, light yellowish. Trunk in largest specimen 9.6 mm long, 2.7 mm wide; that in smallest specimen 1.7 mm long, 0.7 mm wide. Anal shield weakly developed. Caudal shield not clear. Tail-like structure on posterior part of trunk 7.5 µm and 12.5 µm in diameter. Introvert at a typical angle (45–50) with main trunk axis. Unidentate hooks on distal part of introvert; 25–37.5 µm long, 20–27.5 µm thick at base. Intestinal spiral (13–26 coils) attached to the posterior part of trunk by spindle muscle ( Fig. 4 F). Distance between posterior end of trunk and base of retractors 0.5 mm and 1.5 mm. Retractors originating from 15.6% and 29.4% of distance to end of trunk. Nephridiopores posterior to anus. Nephridia in largest specimen 6.2 mm height, 0.3 mm wide; those in smallest specimen 0.5 mm height, 0.13 mm wide. Trunk 1.5 and 3.4 times nephridia length.

Ecology. In the study area, this species was found on sandy-mud biotope at 73 m depth.

Distribution. Mediterranean, western Atlantic and Indian Oceans (Pancucci-Papadopoulou et al. 1999).

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.