Systematics of the Deropristiidae Cable & Hunninen, 1942 (Trematoda) and biogeographical associations with sturgeons (Osteichthyes: Acipenseridae)

• Published in: Systematic parasitology 1998-09, Vol.41 (1), p.21-39
• Main Author: Choudhury, Anindo
• Format: Article
• Language: English
• Subjects: Acipenseridae; Biogeography; Brackish; Deropristiidae; Freshwater; Marine
• ISSN: 0165-5752; 1573-5192
• DOI: 10.1023/A:1006084116286

The 11 nominal species of the Deropristiidae, belonging to the genera Deropristis (three species), Pristicola (one species), Skrjabinopsolus (five species) and Cestrahelmins (two species) were re-evaluated for a phylogenetic and biogeographical analysis of the group. Skrjabinopsolus elongatus (Madhavi, 1974) (= S. indicus Gupta & Ahmad, 1976, S. kurotchkini Parukhin, 1976), S. sanyaensis Shen, 1990, Deropristis paurosoma Wang, 1989 and Cestrahelmins Fischthal, 1957, do not belong to the Deropristiidae. The genus Opisthodiplomonorchis Madhavi, 1974 is resurrected for its type-species, O. elongatus (= S. elongatus), and D. paurosoma is also transferred to this genus. Species of Opisthodiplomonorchis occur in polynemid fishes of the Indo-Pacific. Five nominal species thus comprise the Deropristiidae, i.e. S. armatus Ivanov in Ivanov and Mrygin, 1937, S. manteri (Cable, 1952), D. hispida (Abildgaard, 1819), D. inflata (Molin, 1859) and P. sturionis (Little, 1930), which corresponds to the original composition of the family. A comparison of Skrjabinopsolus from acipenserids in North America and Europe revealed variability in morphological characters considered diagnostic in the past (body size and position of the ovary and testes). Based on the morphology and biology, the two species of Skrjabinopsolus can be considered incipient species. A phylogenetic analysis of the redefined Deropristiidae indicates that Deropristis and Pristicola may form a monophyletic group with Skrjabinopsolus as the sister taxon. The biogeography of the Deropristiidae suggests an origin and distribution associated with the formation of the North Atlantic basin. Freshwater and marine/estuarine origins for the family are equally parsimonious possibilities. A freshwater origin can be traced at least to Cretaceous Laurasia followed by a drift-vicariance separation and subsequent association with North Atlantic drainages. Support for a marine ancestry of the Deropristiidae is indicated by the biogeography of its sister taxa (outgroups in this study) and of its hosts, and is also consistent with an Atlantic origin. The deropristiids evidently originated and speciated within the Acipenseridae in the Atlantic region, with a host switch into Atlantic Anguilla spp.[PUBLICATION ABSTRACT]