PSEUDORHABDOSYNOCHUS-YUCATANENSIS SP. N. (MONOGENEA, DIPLECTANIDAE) FROM THE GILLS OF THE RED GROUPER EPINEPHELUS-MORIO (PISCES, SERRANIDAE) OF THE YUCATAN PENINSULA, MEXICO

Pseudorhabdosynochus yucatanensis sp. n. (Diplectanidae) is described from the gills of the red grouper, Epinephelus morio (Valenciennes, 18 24) (Serranidae), from the coast of the Yucatan Peninsula, Mexico. Thi s new species is characterized by having both the ventral and the dors al squamodiscs composed of 10-12 rows of rods, with 0-1 innermost tow forming a closed circle, Furthermore, the vagina of P. yucatanensis ha s a non-sclerotized ampulla with a fine, sclerotized duct leading to a sclerotized seminal receptacle. Prevalence (percentage of infected fi sh) and abundance (mean number of worms per examined fish) were estima ted for P. yucatanensis from 8 localities along the coast of Yucatan. Prevalence varies from 38% to 100%, while abundance was between 1.2 +/ - 0.6 and 43.2 +/- 17.8 worms per fish. The lack of linear relationshi p between the host length and the number of monogeneans per fish (regr ession F-1.188 = 0.56, p = 0.45) was probably due to the fact that the sample was restricted to juvenile hosts.