TREMATODOS DE LAS TORTUGAS DE MEXlCO. II. DESCRIPCION DE UN NUEVO GENERO DE LA FAMILIA Pronocephalidae Looss, 1902 Y DESCRIPCION DE UNA NUEVA ESPECIE DEL GENERO Octangioides Price, 1937.

Resumen

With a Trematode found in the intestine of a fresh-water turtle Dermatemys mawii from Tlacotalpan, State of Veracruz, Mexico, the author creates a new sub-family Choanophorinae in the family Pronocephalidae Looss, 1902, for the new genus Choanophorus
and species rovirosai n. sp.
The diagnosis of the sub-family and genus are as follows:
Choanophorinae, n. sub-fam.: Body cylindrical and elongated; cephalic collar scarcely developed; truncated posterior end with two finger-like diverticula invaginated; cuticular copulatory pouch present; median pre-equatorial sexual pore; large, median, pre-equatorial cirrus pouch; testicles with entire borders, postovaric, pre-equatorial, intercaecal and located one beside the other; median, intercaecal, post-equotorial ovary; Melhis' gland median, post-ovaric; eggs witn polar filaments.
Choanophorus, n. gen.- Elongated cylindrical body; smooth cuticle; cephalic collar rudimentary; posterior end truncated transversally and with two finger-like invaginations which extend till the viciniey of the posterior extremities of the intestinal
caeca; median, pre-equatorial, cuticular copulatory pouch; sub-terminal oral sucker; digestive tube without pharynx, with oesophagus expanded in its posterior extremity; intestinal caeca extending behind the testicles which are lateral narrow and with
walls that have in their anterior part short side prolongations; cirrus pouch claviform; median and pre-equatorial; receptaculum seminis absent, seminal vesicle convoluted and outside the cirrus pouch; sexual pores at the level of the anterior and median
border of the cirrus pouch; uterus in the median part of the body between the ovary and the cirrus pouch; post-equatorial ovary on the left side, intercaecal; Mehlis'gland post-ovaric and well developed; testicles entire, ovoid, post-ovaric and intercaecal; lateral vitellaria in two groups with 15 and 17 solid follicles, at the level of the ovary, extracaecal and caecal; eggs ovoid, with one side more convex than the other and with polar filaments.
Octangioides tlacotalpensis n. sp. is the second species found of this genus created by E. W. Price, in 1937. It differs from Octangioides skrjabini Price, 1937 in the development and extension of the intestinal caeca; distribution of the vitellaria ; position
of the excretory vesicle; structure of the principal excretory tubes; shape and size of other organs and of the body as a whole.
By the general shape of the body and the development of the iniestinal caeca it comes near Octangium sagitta (Looss, 1899) but differs from this species in the distribution of the vitellaria and, principally, in the position of the genital pores and the structure of the excretory system.