Original paper

Madagascar! Georissa, Cyclotus, Omphalotropis and so-called Chondrocyclus (Gastropoda: Caenogastropoda: Hydrocenidae, Cyclophoridae, Assimineidae)

Emberton, Kenneth C .

Abstract

Based on island-wide collections made in 1992-1996 , Madagascar's known species of the small-to-minute caenogastropod genera Georissa BLANFORD 1864 , Cyclotus SWAINSON 1840 , and Omphalotropis PFEIFFER 1851 now total 33 : Georissa ampla n. sp., Georissa ankaranae n. sp., Georissa aurata (ODHNER 1919 ) , Georissa capdambrae n. sp., Georissa detrita BAVAY & GERMAIN 1920 , Georissa fro Ii FISCHER-PIETTE, BLANC, BLANC & SALVAT 1993 , Georissa krant: FISCHER-PIETTE, BLANC, BLANC & SALVAT 1993 , Georissa GERMAIN 1935 , Georissa saintemariae n. sp., Georissa maraoraoa n. sp., Georissa petiti verreti FISCHER-PIETTE, BLANC, BLANC & SALVAT 1993 , Cyclotus bemarahae n. sp., Cyclotus gallorum n. sp., Cyclotus griffithsi n. sp., Cyclotus mamillaris ODHNER 1919 , Cyclotus micromamillaris n. sp., Cyclotus namorokae n. sp., Cyclotus (Millotorbis) ankaranae n. sp., Cyclotus (M.) milloti FISCHER-PIETTE & BEDOUCHA 1965 , Omphalotropis angulata n. sp., Omphalotropis betamponae n. sp., Omphalotropis bevohimenae n. sp., Omphalotropis capdambrae n. sp., Omphalotropis castelli FISCHER-PIETTE, BLANC, BLANC & SALVAT 1993 , Omphalotropis costulata EMBERTON & PEARCE 1999 , Omphalotropis fortis n. sp., Omphalotropis galokoae n. sp., Omphalotropis griffithsi n. sp., Omphalotropis madagascariensis GERMAIN 1921, Omphalotropis manomhoae n. sp., Omphalotropis tantelia n. sp., and Omphalotropis vohimenae EMBERTON & PEARCE 1999 .A dichotomous key is given for identifying these species. Conchological descriptions are given of all the species. The genus Chondrocyclus ANCEY 1898 is deleted from Madagascar's faunal list, as all three of its reported species must be transferred to other genera. Key words: Gastropoda, land snails, biodiversity, tropical.