Revisionary notes on Negulus O. Boettger, 1889, a genus of minute African land snails (Gastropoda Pulmonata: Vertiginidae)

The genus Negulus is reviewed; only four Recent species, restricted to continental Africa, are recognized. The genus is extinct in Europe, being only recorded from Tertiary deposits. A key to the shells of the Recent species (all figured) is supplied. The anatomy is as yet unknown. A sinistral shell of N. abyssinicus is described from among a series of paralectotypes in the Leiden Museum, the first such abnormality in the genus (figured). A fair amount of shell material has become available (among which some historical specimens) so that metric data may be compared with greater confidence. Recent occurrence is established/confirmed for Eritrea, Ethiopia, Sudan, Kenya, Tanzania, Zaire, Zambia, Malaŵi, and Bioko (Fernando Poo). The small size of the shell necessitates sampling forest leaf litter, a technique that has not been widely applied in Africa; undoubtedly the genus occurs much more widely in the Afrotropical Region. Pupa obliquicostulata from St. Helena Is. is removed from the genus because of the presence of apertural dentition.