Soft-bottom sipunculans in Izmir Bay (Aegean Sea, eastern Mediterranean) Author Açik, Sermin text Zootaxa 2009 2136 40 48 journal article 10.5281/zenodo.188511 0f8c81a5-2f90-47b6-a098-9d0a005457da 1175-5326 188511 Onchnesoma steenstrupii steenstrupii Koren & Danielssen, 1875 Description. Pear-shaped or barrel-shaped trunk various coloured: grey, yellow, orange, rusty red. Trunk 0.75–2.8 mm long, 0.6–1 mm wide. Introvert 5–10 times trunk length. 21–23 radiating keels present at posterior part of trunk. Chitinous plate with keel-like structures 20–35 μm long. Small wart-like papillae on surface of trunk; 15–25 µm long, 17.5–32.5 μm in diameter. Spindle and wing muscle absent. Anus located near mouth. Intestine with several coils. Only one retractor attached at posterior part of body. Nephridia single, elongate. Some specimens with eggs in coelom cavity, elliptical ( Fig. 4 E); longer axis 117.5–167.5 μm in diameter, smaller axis 105–142.5 μm in diameter. Ecology. This species was found on different biotopes between 8–77 m in the area. Distribution. Atlantic, western Pacific and southwest Indian Oceans, Mediterranean Sea ( Cutler 1994 ) and Red Sea (Pancucci-Papadopoulou et al . 1999).