Corynosoma obtuscens Lincicome 1943

Corynosoma obtuscens Lincicome, 1943

D e s c r i p t i o n (figs 1, B; 2, F; table 2).

General. Small acanthocephalans. Trunk with dilatation in its anterior part. Spine field extends to 609–976 dorsally, and to posterior end of trunk ventrally, in males with bare zone between ventral and genital spines. Length of somatic spines increasing from anterior (17–37) to posterior (36–44). Genital spines present, 41–49 long. Proboscis almost cylindrical, with widening in its posterior quarter. Proboscis with 17–19 longitudinal rows of 11–14 hooks each. First 9–11 hooks large, with simple roots directed posteriorly. Next 1–2 hooks transitional with small roots in shape of inverted Y (fig. 2, F). Next 2–3 hooks spiniform, with simple roots directed anteriorly or without roots. Largest hooks 9 th and 10 th. Proboscis receptacle double-walled. Neck 145–261 long. Lemnisci 505–901 long, attached in neck and extending to level of proboscis receptacle bottom or slightly posterior to it. Gonopore subterminal in both sexes.

R e m a r k s. Corynosoma obtuscens is a common parasite of sea lions (Lincicome, 1943; Van Cleave, 1953 a, b). The species was described by Lincicome (1943) from Z. californianus from the San Diego Zoo, California, USA. It was also registered in northern fur seals (Callorhinus ursinus Linnaeus) and South American sea lions (Otaria byronia Péron) from the California coast, in the Gulf of Mexico, off the coast of South America and in Alaska (Van Cleve, 1953 a, b), and from domestic dogs in Peru (Cabrera et al., 1999). Juvenile specimens were also registered in sea otter (Enhydra lutris Linnaeus) (Ward & Winter, 1952). Domestic dogs were successfully infected experimentally with cystacanths collected from fish (Castro & Martínez, 2004). Our material corresponds to the original description provided by Lincicome (1943). Intermediate hosts for C. obtuscens are unknown. Several species of fishes (paratenic hosts) off the Pacific coast of South America were found to be infected with cystacanths of C. obtuscens with prevalence up to 60 % (Tantaleán & Huiza, 1994; Tantaleán et al., 2005; Chero et al., 2014).