A new genus and species of the Didymozoidae (Digenea) from the skipjack tuna Katsuwonus pelamis (L.) (Scombridae).

Abstract

A new genus and species of didymozoid digenean is described from the skipjack tuna Katsuwonus pelamis (Linnaeus) in the Southwest Atlantic Ocean off Brazil. Pozdnyakovia gibsoni n. g., n. sp. is placed in the Gonapodasmiinae Ishii, 1935. The new genus differs from other genera in the morphology of the posterior regions of the fused pair; this consists of an unlobed, rounded mass fused only dorsally and with a large, elliptical ventral aperture opening into a longitudinal deep cavity from which emerge the two elongate anterior regions. It also differs in the form of the testes, which form two sets of three to four branches in each partner.