Phascolion (Phascolion) strombus subsp. strombus Montuga 1804

Phascolion (Phascolion) strombus strombus (Montuga, 1804)

Description. Body semi-transparent, lightly yellowish. Trunk 2.2 mm long, 1.7 mm wide. Introvert 2.3 mm long, 0.6 mm wide. Papillae distributed over trunk and introvert. Papillae on anterior part of trunk 42.5–90 µm height, 40–45 µm in diameter. Papillae on posterior part of trunk 25–60 µm height, 12.5–57.5 µm in diameter.

Distinct proteinized borders on holdfast papillae (Fig. 4 C); 72.5–120 µm height, 72.5–95 µm in diameter. Hooks on introvert (Fig. 4 D); 45–60 μm long, 20–57.5 µm thick at base. Ventral retractor muscle thinner than dorsal, attached near posterior end of trunk. Intestine in loose loops without spiral. Single nephridium located at right side of ventral nerve cord. Nephridia 0.7 mm height, 0.2 mm wide. Trunk 3.1 times nephridia length. Two black eye spots present.

Ecology. In the study area, this species was found on muddy-sand biotope at 27 m depth. Distribution. North Atlantic, Arctic and Pacific Oceans, Mediterranean Sea, Red Sea (Cutler et al. 2004) and Southwest Indian Ocean (Cutler & Cutler 1996).