TREMATODOS DE LAS TORTUGAS DE MEXICO

Resumen

In this contribution a study is made of some Trematodes from the fresh-water turtles of Mexico. In accordance with E. W. Price, we consider Polystoma (Polystomoides) oblongum, which we described in 1938, in the genus Polystomoidella. A redescription of Polystomoidella oblongum (Wright, 1879) Price, 1939, first found in Mexico, is made; and two new species are described: Schizamphistomoides resupinatus and Cercorchis membranaceus.
The three species of the genus Schizamphistomoides so far known differ from ours in the position of the testicles, which are slightly pre-equatorial; in the arrangement and extension of the vitellaria and in the position of the excretory vesicle. Because this species was found in the same place as S. tabascensis it was possible to compare young and fully developed specimens, and we found that in S. tabascensis the testicles are always oblique. Eggs were found in S. spinulosum only.
Cercorchis stunkardi is similar to the species we establish in the length of the body and the size of the eggs, but is different in all
measures and anatomical structures. It is similar to C. stenonura in size, diameter of the suckers and the pharynx, but differs in the distribution of the vitellaria and in the size of the eggs. C. cryptobranchi is similar in size of the body and of the testicles and ovary, but different in the distribution of the vitellaria and in the size of the eggs.
C. medius is similar in the size of the ovary and the acetabulum, but díffers in the size of the spines, in the length of the pharynx, the testicles and eggs, and in the distríbution of the vitellaría.