Austrobilharzia variglandis (Miller and Northup, 1926) Penner, 1953, (Trematoda: Schistosomatidae) in Hawaii with Notes on Its Biology

Abstract

In November, 1950, apharyngeal, furcocercous cercariae were recovered from marine snails (Littorina pintado Wood) collected from the rocky shores of two bird islands just off the coast of Oahu in Hawaii. Chu (1952) reported the cercariae and the possibility of their being the etiological agent involved in local cases of swimmers' itch. Subsequently, young noddy and sooty terns (Anous stolidus pileatus Scopoli and Sterna fuscata oahuensis Bloxam), chickens and ducks were experimentally exposed to these cercariae, and, as a result, sexually mature schistosomes were recovered from mesenteric veins in birds of all these species. All stages of the life cycle have been successfully maintained in the laboratory for more than 1 year. In December, 1952, adult worms identical with those raised experimentally were recovered from the mesenteric veins in 4 out of 8 ruddy turnstones, Arenaria interpres interpres (L.), killed on the island of Oahu. A careful comparison of the morphology of the adults and larval stages of the Hawaiian schistosome with that of other species in the subfamily SCHISTOSOMINAE, as far as published data have permitted, shows that the Hawaiian worm most closely resembles Microbilharzia variglandis (Miller and Northup, 1926) Stunkard and Hinchliffe, 1951. However, the Hawaiian schistosome differs from Microbilharzia chapini Price, 1929, which Stunkard and Hinchliffe (1952) reduced to synonymy with M. variglandis. After comparing the description and figures of M. variglandis with the type of M. chapini,l it is hard to reconcile the striking difference between their ceca, which are straight and without diverticula in M. chapini but anastomosing and with numerous diverticula in M. variglandis ( and in the Hawaiian schistosome). The configuration of this organ is so constant in the Hawaiian worms that it appears to rate consideration as a specific character. In addition, a comparison of cecal measurements for the 2 species, based on published descriptions (E. W. Price, 1929; Stunkard and Hinchliffe, 1952), shows that the common cecum of M. chapini is only about one-third the length of that in M. variglandis. Penner (1953) suppressed the genus Microbilharzia and reallocated the species to the genus Austrobilharzia Johnston, 1916. He is probably correct in doing so, but such a change would be more justified had a rather complete morphological study of both the adult and larval stages of Austrobilharzia terrigalensis been made. Since rather complete reviews of the literature on the avian schistosomes have been included in several recent papers, e. g. Stunkard and Hinchliffe (1952), no