Renicola williamsi n. sp. (Trematoda: Digenea: Renicolidae) from the South Polar Skua, Catharacta maccormiki

Abstract

Renicola williamsi n. sp., is described from specimens collected from the South Polar skua Catharacta maccormiki. R. williamsi differs from other renicolids by its short esophagus, linear and mediolateral arrangement of vitelline follicles, linear extent of intestinal caeca, gonadal shape, caecal width, reduced sucker ratio, and disposition of the uterus. Fifteen specimens were compared with existing morphological descriptions of adult Renicola and Nephromonorcha. Renicolid trematodes are parasites in the kidneys of birds (Yamaguti, 1971). Dollfus (1946) revised the Renicolidae (Dollfus, 1939), listing nine flukes from the renal organs of birds together with a taxonomic key for species identification. Since 1946, various authors have attempted to devise new taxonomic keys for Renicolidae (LaRue, 1957; Odening, 1962; Riley & Owen, 1972; Sudarikov & Sten'ko, 1984; Wright, 1954, 1956, 1957). Of the 56 known species of Renicolidae, two were described on the basis of cercariae only (Martin, 1971; Martin & Gregory, 1951). We agree with Sudarikov & Sten'ko (1984) in considering Renicola (Cohn, 1904) and Nephromonorcha (Leonov, 1960) to be the only valid genera. Their mutual exclusion is based on testicular fusion in the latter. Prior to the present study, renicolid trematodes never have been recovered from birds within the Antarctic Circle. Sergeeva (1971) reported Renicola lari (Timon-David, 1933) from the parasitic jaeger, Stercorarius parasiticus (L.) in north-central Siberia. This host is a vagrant of the sub-Antarctic (Watson, 1975). Several species of captive penguins known to inhabit Antarctic or sub-Antarctic regions, were reported to harbor Renicola sloanei Wright, 1954 (see Campbell & Sloan, 1943; Wright, 1956). A total of 37 South Polar Skua, Catharacta maccormiki (Saunders), were collected near McMurdo and Hallett stations, Antarctica. Post-mortem examinations resulted in the recognition of three birds infected with kidney flukes. After preliminary microscopic examination of whole mounts, the trematodes were determined to be renicolids, based on linear distribution of follicular 1 This investigation was supported in part by NSF Grant DPP76-239-79, to the Smithsonian Institution, B. J. Landrum, Principal Investigator, and by grants from the Biology Department and Graduate School, University of North Dakota. Publication costs, in part, are being met by a grant from the Spencer-Tolles Fund of the American Microscopical Society. 2 Present address: Experimental Pathology Program, Department of Pathology and Laboratory Medicine, Medical University of South Carolina, 171 Ashley Avenue, Charleston, South Carolina