The Occurrence and Distribution of a Syndesmid (Turbellaria: Umagillidae) in Jamaican Sea Urchins

Turbellarians of the genus Syndesmis inhabit the coelom and digestive tract of echinoids. Unfortunately, little is known of the nature of the relations between these endosymbionts and their hosts. Jennings (1971, Adv. Parasit. 9: 1-32) listed 5 species of Syndesmis parasitizing sea urchins (S. echinorum, S. punicea, S. grandulosa, S. antillarum, and S. franciscana), and Komschlies and Vande Vusse (1980, J. Parasit. 66: 659-663, and 66: 664-666) reported 4 additional species (S. alcalai, S. mammilata, S. philippinensis, and S. compacta). The first record of a syndesmid from Caribbean urchins was given by Hyman (1960, Amer. Mus. Novitates 1984: 114), who identified as S. franciscana a umagillid found in Lytechinus variegatus collected at Mayaguez, Puerto Rico. Jennings and Mettrick (1968, Caribb. J. Sci. 8: 57-69) reported finding S. franciscana, later identified by them as S. antillarum (see Mettrick and Jennings, 1969, J. Fish. Res. Bd Can. 26: 2669-2679) in the gut and coelom of L. variegatus collected from shallow water beds of Thalassia testudinum off the southern shore of Jamaica, in the areas of Kingston Harbor and Port Royal. They also examined 4 other species of urchin, Diadema antillarum, Tripneustes ventricosus, Echinometra viridis, and Clypeaster rosaceus, but were unable to find any syndesmids in these organisms. The only other report of a syndesmid parasitizing Caribbean urchins was made by Jones and Canton (1970, Caribb. J. Sci. 10: 71-72), who found what they believed to be S. franciscana in both L. variegatus and T. ventricosus collected from the southern coast of Puerto Rico and Haiti. The parasite was found in both the coelom and gut of the host. This study reports the presence of a syndesmid in shallow water urchins from the northern coast of Jamaica, in the areas of Discovery Bay and Ocho Rios, and from Negril on the western coast. Initially, 8 species of urchin were collected from various locations in the fore-reef, back-reef and shoreline areas of Discovery Bay, and examined for the presence of intestinal parasites. These early studies, which were conducted in June, 1979, 1980, and 1982, showed that 2 species of urchin were parasitized by a syndesmid, L. variegatus (71.6% infection; n = 614) and E. viridis (22.6% infection, n = 292), but it was only those specimens collected from specific areas of the bay that were infected. The other species examined but not found infected with the syndesmid were D. antillarum (n = 261), Echinometra lacunter (n = 340), Eucidaris tribuloides (n = 230), L. williamsi (n = 204) and C. rosaceus (n = 83). Based on the descriptions of Mettrick and Jennings (1969, loc. cit.), the parasite was identified as S. antillarum. The average number of parasites found in L. variegatus was 36 (range 1 to 205), and in E. viridis 2 (ranges 1 to 5). Adult worms and small, immature individuals lacking reproductive structures were found in the gut and coelomic cavity of both hosts. Subsequent studies conducted in June 1983 . ranciscana in both L. variegatus and T. ven-