Two new species of the genus Duplacrorhynchus Schockaert & Karling, 1970, with remarks on relationships within the genus and on the Duplacrorhynchinae (Platyhelminthes, Polycustididae)

Abstract

Two new species of Polycystididae are described: Duplacrorhynchus megalophallus sp. nov. from the bay of Marseille (France) and D. heyleni sp. nov. from Zanzibar (Tanzania). The female system of both is characterized by the presence of a muscular bulb at the proximal end of the bursal stalk, with three strong teeth in D. megalophallus, and in D. heyleni ri the muscle bulb is highly asymmetric. In D. megalophallus the copulatory bulb is divided by a septum, and the cirrus has small spines and a proximal umbrella-like expansion. In D. heyleni only the cirrus, which has strong teeth, is enclosed in the cirrus sack: the seminal and prostate vesicles are not. Relationships with the two known species of the genus (D. minor Schockaert & Karling, 1970 and D. major Schockaert & Karling, 1970) are discussed. The subfamily Duplacrorhynchinae Schockaert & Karling, 1970 may constitue a monophyletic taxon, characterised by the 3+2 configuration of the proboscis retractor system. Dupracrorhynchinae contains all genera of Polycystididae with an interposed prostate vesicle. The taxon Duplacrorhynchus may be the sister taxon of all these genera.