D e s c r i p t i o n (figs, 1, A; 2, E; table 2).
General. Small acanthocephalans, males and females similar in size and shape, females slightly larger. Trunk 3,800 –6,240 × 933–1,600. Trunk anterior part widened in the form of ellipsoidal swelling, with small spines extended ventrally more than dorsally. Length of spines increasing from apical (32–38) to median (44–61) and decreasing posteriorly (25–36). Trunk posterior part narrowest at middle, slightly dilated at posterior end. Genital spines present or absent. Proboscis 450–620 × 260–290, almost cylindrical, with widening in its posterior third. Proboscis with 17–19 longitudinal rows of 10–11 hooks each. First 6–7 hooks large, with simple roots directed posteriorly. Next 1–2 hooks transitional, with small roots in the shape of an inverted Y (fig. 2, E). Proximal 3–4 hooks spiniform, with simple roots directed anteriorly. Largest hooks are 6th or 7th. Proboscis receptacle double-walled. Lemnisci broad, leaf-shaped, shorter than proboscis receptacle. Neck truncated cone, 211–620 long, often retracted into foretrunk. Reproductive system in narrow posterior part of trunk.
Remarks. Corynosoma strumosum was initially described by Rudolphi (1802) from harbor seal (Phoca vitulina Linnaeus). This species was also reported in various marine mammals, terrestrial carnivores and aquatic birds throughout the Arctic, Pacific and Atlantic Oceans, and in the Caspian Sea (Delyamure, 1955; Dailey & Brownell, 1972; Shults, 1982; Yurakhno, 1998; Nickol et al., 2002; Ionita et al., 2008; Amin et al., 2011). Morphologically, our specimens of C. strumosum are consistent with the original description of the species. Amphipods are known to be intermediate hosts for C. strumosum (Petrochenko, 1958; Atrashkevich, 2008); more than 30 species of fishes and a few reptiles, and experimentally infected amphibians and reptiles have been reported as paratenic hosts (Dubinin, 1949; Moles, 1982; Skorobrechova et al., 2012).