Interstitial fauna of the Galapagos: Typhlopolycystidinae (Platyhelminthes Polycystididae)

Three new species belonging to two new genera of Typhlopolycystidinae Evdonin 1977 from the Galapagos are described: Myobulla myobulla n. gen. n. sp., M. dunata n. sp. and Sabulirhynchus axi n. gen. n. sp. The general anatomy closely resembles that of Limipolycystis Schilke 1970. However, Myobulla is characterised by the presence of a muscular knob with four hard teeth on the bursal stalk, while Sabulirhynchus has a pear-shaped seminal receptacle and lacks an accessory glandular organ. The Myobulla species differ from each other in the shape and dimensions of the stylet; S. axi has a plate-like stylet. An undescribed species of Limipolycystis is mentioned but is not described because we lack good material. The subfamily Typhlopolycystidinae is briefly discussed; diagnoses for the new taxa and an emended diagnosis for the subfamily are given. Limipolycystis swedmarki Karling 1978 is transferred to the genus Myobulla: as M. swedmarki ki (Karling 1978) n. comb. The name Lagenopolycystis n. nom. is proposed to replace Lagenorhynchus Brunet 1965, a junior synonym of Lagenorhynchus Gray 1846.