TREMATODOS DE PECES DE AGUAS MEXICANAS DEL PACIFICO. XVII DOS NUEVOS GENEROS DE MONOGENOIDEA BYCHOWSKY, 1937

Resumen

Two new genera of monogenetic trematodes from the gills of marine fishes in coastal waters of the Mexican Pacific Ocean are described and figured. The first of these belongs to the subfamily Tetraonchinae Monticelli, 1903 and has been named Mexicana bychowskyi gen. nov., sp. nov., with the following characterictics: Prohaptor provided with three pairs of glandular adhesive organs; opisthaptor bilobulate, wider than posterior portion of the body, armed with two pairs of anchors, ventral and dorsal in position, and articulating with their corresponding transverse bars; the smaller and wider ventral transverse bar is butterfly-like in form, with lateroventral wing-like expansions; the dorsal transverse bar, simpler in structure and wider than the ventral one, is nonarticulating; each anchor is further associated with a corresponding sclerosed membrane layer irregularly fenestrated, situated on the sides of the opisthaptor. Six hooklets, radially oriented, are located on the margins of the opisthaptor; muscular fibers extend from this adhesive organ to the posterior extremity of the intestinal ceca. Two pairs of eyespots present at level of the anterior portion of the large and pyriform or ovoid pharynx; esophagus present; intestinal ceca wide and slightly ramified, united posteriorly. Testis postovarian; prostatic organ present; copulatory apparatus sclerosed; genital pore opening on the left side at the level of the pharynx. Ovary branched, uterus present; single vagina opening on the left lateral body margin at a level anterior to the ovary; Mehlis gland present. Vitellaria, extending from the anterior margin of the pharynx to the posterior level of the intestinal ceca. Parasites on fishes of the family Sciaenidae.
The second genus has been named Paracalceostoma calceostomoides gen. nov., sp. nov., belongs in the familiy Calceostomatidae (Parona et Perugia, 1890) Poche, 1926, and has the following characteristics: Prohaptor large and cup-shaped, with lapets, and lacking glands. Opisthaptor small, with two adhesive organs in the form of muscular suckers which occupy the greater part of the opisthaptor; armature sclerosed, rudimentary, formed of very small elements bordering the opisthaptor; a structure similar to the clamps of Polyopisthocotylea, in the form of an anchor, is located on the median posterior margin of the opisthaptor and in contact with the suckers; anchor points associated with a single ventral transversal bar. Six small clamp-like structures are distributed along the free edge of the opisthaptor, each being armed with a small hook at its base. Two pairs of eyespots present, at level of the pharynx. Pharynx ovoid and strongly muscular; esophagus lacking; intestinal ceca with lateral diverticula, posterior extremities free, but joined posterior to the testes by means of a transverse connecting branch. Testis single, postovarian and large; seminal vesicle elongate and fusiform, emptying into a large ampula bearing an accessory sacciform organ; copulatory apparatus sclerosed and very complicated; genital pore intercecal, on the left side at level of the ampula. Ovary large and pretesticular; vagina present, opening ventrally on the left side of the body in the pre-ovarían zone. Vitellaria, extending from level of the posterior portion of the pharynx to considerably posterior to the testis. Parasites on Haemulon scudderi Gill, Piscis Haemulidae.