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).