TREMATODOS DE LAS RANAS DE LA CIENAGA DE LERMA, MEX. I.

Resumen

In this first part of the study of the Trematoda from the frogs of the marshes of Lerma, Mexico, some species already known are redescribed, because it is the first time they have been found in our country. The description is given also of two new species belonging to the genera Halipegus and Haematoloechus, respectively.
Halipegus lermensis n . sp. is similar to H. occidualis Stafford, 1905, and H. eccentricus Thomas, 1939, but differs from them because of the absence of oesophagus, the extensión up to the posterior border of the body of the intestinal caeca which are wide, sinuous and coiled; because the testicles are not extracaecal and because the acetabulum, pharynx and eggs are larger in size.
There is a greater similarity between our species and H. mehransis Srivastava, 1933, although it also differs from it in the size of the body and, therefore, in the size of the oral sucker, acetabulum and pharynx; the testicles are not extracaecal in H. lerrnensis and the sexual pores open on the side near the pharynx.
In the description of H. varioplexus by Cort, the eggs measure from 0.034 mm. to 0.040 mm. in lenght by 0.017 mm. to 0.021 mm. in width , while in ours we have found 0.029 mm. by 0.012; however, all the other observations are concordant. In the redescription of this same parasite by Freitas & and Lent we find also some differences in the size of the eggs and in the location of the groups of vitellaria. May be the difference which we observed in the size of the eggs was due to our preparations being mounted in balsam, which retracts the structures.
Haematoloechus macrorchis n. sp. is very similar to H. longiplexus from which it differs in the extension of the longitudinal extracaecal coils which reach as far as the ovary or a little more, but never to the pharynx as Stafford (1902) and Cort (1915) observed, nor to the middle distance between the pharynx and the ovary as stated by Manter (1938). Other differences are the size of the testicles, the distribution of the vitellaria, the development of the intestinal caeca, the size of the eggs and the ascending and descending distribution of the uterus.
There are less similarities between this species and H. breviplexus; the fundamental differences with this Canadian species are the
existence in ours of a cuticle with minute spines, the length of the longitudinal extracaecal coils, the form of the testicles and ovary, the location of the vitellaria and the distribution of the uterus.
Our observations were made on a great number of specimens, alive and fixed, these last, pressed and unprepared; and we did not
find in any case the longitudinal extracaecal coils of the uterus extending beyond the ovary nor to the testicles.