The development from metacercaria to adult of Gymnophallus australis Szidat, 1962 (Digenea: Gymnophallidae) from Patagonian coast (Argentina), with an emended diagnosis of the genus Gymnophallus Odhner, 1905

CREMONTE, FLORENCIA; VAZQUEZ, N.N.; ITUARTE, CRISTIÁN F

SYSTEMATIC PARASITOLOGY

SPRINGER

Año: 2008 vol. 69 p. 23 - 31

0165-5752

Parvatrema australis (Szidat, 1962) Szidat, 1965 was described based on larval stages found in specimens of the mussel Mytilus edulis from the Buenos Aires Province (Argentina). Although Szidat later examined hundreds of mussels, this parasite has never been found again until now. In the present study, larval stages including germinal sacs found in mytilids from the Patagonian coast (Argentina) were identified as P. australis. Metacercariae were incubated in vitro at 39ºC in physiological solution for 18-20 hours; after this time, 80% of specimens had eggs. P. australis is redescribed on the basis of infective metacercariae and adults obtained in laboratory, and reassigned to the genus Gymnophallus Odhner, 1900, under which it was originally described. The generic diagnosis of Gymnophallus is here emended to include as diagnostic characters the presence or absence of the lateral lips, form and position of vitellarium (compact or follicular) and the presence of pars prostatica (i.e., prostatic cells are opening into the prostatic duct). The validity of some characters (i.e., the presence of lateral lips of the oral sucker, the form of vitellarium and excretory vesicle, extent of the uterus) as diagnostic at the genus level within the family Gymnophallidae is discussed. It is proposed that the least unambiguous characters that could be used to distinguish gymnophallid genera include the position of the ovary, the presence of a ventral pit, pars prostatica and caecal pockets.