A. Choudhury et Ta. Dick, SYSTEMATICS OF THE DEROPRISTIIDAE CABLE AND HUNNINEN, 1942 (TREMATODA) AND BIOGEOGRAPHICAL ASSOCIATIONS WITH STURGEONS (OSTEICHTHYES, ACIPENSERIDAE), Systematic parasitology, 41(1), 1998, pp. 21-39
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. Skrjabinopso
lus elongatus (Madhavi, 1974) (= S. indicus Gupta & Ahmad, 1976, S. ku
rotchkini Parukhin, 1976), S. sanyaensis Shen, 1990, Deropristis pauro
soma Wang, 1989 and Cestrahelmins Fischthal, 1957, do not belong to th
e Deropristiidae. The genus Opisthodiplomonorchis Madhavi, 1974 is res
urrected for its type-species, O. elongatus (= S. elongatus), and D. p
aurosoma is also transferred to this genus. Species of Opisthodiplomon
orchis occur in polynemid fishes of the Indo-Pacific. Five nominal spe
cies thus comprise the Deropristiidae, i.e. S. armatus Ivanov in Ivano
v 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 o
f Skrjabinopsolus from acipenserids in North America and Europe reveal
ed variability in morphological characters considered diagnostic in th
e past (body size and position of the ovary and testes). Based on the
morphology and biology, the two species of Skrjabinopsolus can be cons
idered incipient species. A phylogenetic analysis of the redefined Der
opristiidae indicates that Deropristis and Pristicola may form a monop
hyletic group with Skrjabinopsolus as the sister taxon. The biogeograp
hy of the Deropristiidae suggests an origin and distribution associate
d with the formation of the North Atlantic basin. Freshwater and marin
e/estuarine origins for the family are equally parsimonious possibilit
ies. 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 De
ropristiidae is indicated by the biogeography of its sister taxa (outg
roups 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 in
to Atlantic Anguilla spp.