A New Pronocephalid Monostome from a Freshwater Turtle

Abstract

While making collections of turtle parasites in the summer of 1926, several specimens of a very interesting monostome were collected from the western painted terrapin, Pseudemys elegans. Seven specimens were taken from the intestine on June 26 of that year, the host having been collected the same day from Blue River, near Connorville, Johnston County, Oklahoma. No other collections are recorded, although several other specimens of the host have been autopsied at various times since from the same locality. I have identified the parasites as belonging to the family Pronocephalidae Looss. This family is characteristically marine, with the great majority of the species described parasitic in the several species of marine turtles, and inhabiting various parts of the alimentary canal. So far as I have been able to determine from the literature, no previous records of freshwater species has been made. Anatomically the species presents several features of interest, especially pertaining to the excretory system. These features appear to justify a short description and discussion. Before proceeding further I wish to acknowledge the very helpful criticisms of Dr. Henry B. Ward, under whose direction this study has been made. The following generic diagnosis, which must be considered as tentative since only the single species described in this paper is known, clearly separates the worms from any previously described genus of the family. Indeed, the description is at variance with certain family characteristics as given by Looss; these will be discussed in a later section.