Proctocaecum blairi sp. nov. (Digenea, Cryptogonimidae) from the freshwater crocodile, Crocodylus johnstoni, in Northern Territory, Australia

Abstract

AbstractProctocaecum blairi sp. nov. is described from specimens found in the intestine of an Australian freshwater crocodile, Crocodylus johnstoni, from Northern Territory, Australia. The most important diagnostic features of the new species are the body proportions and size, the position of the pharynx (relative length of the prepharynx and oesophagus), the relative length and position of the vitelline fields, and the number, shape and size of the circumoral spines. The new species is morphologically most similar to Proctocaecum atae, P. elongatum, P. crocodili, P. gairhei and Acanthostomum slusarskii. It differs from all of these species in having a much longer prepharynx, and differs from both P. atae and P. crocodili in having a much longer body and posteriorly situated vitelline fields. Proctocaecum blairi sp. nov. differs from P. elongatum in having a shorter body, a greater forebody to hindbody ratio, a much smaller ventral sucker, and a higher number of circumoral spines (23 vs 21 in P. elongatum). The new species differs from P. gairhei in possessing a much larger body length:width ratio and an ovary separated from the anterior testis by a seminal receptacle. Acanthostomum slusarskii lacks a gonotyl and has fewer circumoral spines than the new species. Proctocaecum blairi sp. nov. is the third species of Proctocaecum and the fourth cryptogonimid species known from crocodiles in Australia.