THE ANATOMY OF CYLINDROTIS QUADRASI FORM OKINAWA ISLAND, JAPAN AND THE SUBFAMILIAL POSITION OF THE GENUS CYLINDROTIS MOLLENDORFF, 1895 (ARCHAEOPULMONATA: ELLOBIIDAE)

Cylindrotis quadrasi Mollendorff, 1895, the type species ofthe ellobiid genus Cylindrotis, was collected from Okinawa Island,southwest Japan. This is the first record of C. quadrasi inJapan and the third in the world. The anatomical charactersof this species, i.e. shell, head-foot, pallial cavity, radula,stomach, reproductive system, and central nervous system, aredescribed in detail for the first time. The significance ofthese observations is discussed and the subfamilial positionof Cylindrotis is reconsidered. Cylindrotis was included inthe Pythiinae, the most primitive group of the Ellobiidae, basedon the conchological characters alone. However, the male andfemale tracts of the reproductive system are entirely separated,and other internal organs exhibit highly derived conditions.Accordingly, Cylindrotis is transferred from the Pythiinae tothe Ellobiinae. Among the genera of the latter subfamily, Cylindrotisseems to be allied to Blauneria Shuttleworth, 1854 and LcucophytiaWinckworth, 1949. (Received 1 February 1993; accepted 7 June 1993)