Interstitial fauna of the Galapagos: Typhlopolycystidinae (PlatyhelminthesPolycystididae)

Three new species belonging to two new genera of Typhlopolycystidinae Evdon in 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 i s 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 e ach other in the shape and dimensions of the stylet; S. axi has a plate-lik e 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 trans ferred to the genus Myobulla: as M. swedmarki ki (Karling 1978) n. comb. Th e name Lagenopolycystis n. nom. is proposed to replace Lagenorhynchus Brune t 1965, a junior synonym of Lagenorhynchus Gray 1846.