The type species and circumscription of the species-rich Afrotropical snail genus Gulella L. Pfeiffer 1856, based on anatomical and mtDNA data (Mollusca: Eupulmonata: Streptaxidae)
Rowson, Ben; Herbert, David G.
The megadiverse genus Gulella L. Pfeiffer 1856 is currently the most species-rich genus of Afrotropical land snails. Although currently polyphyletic, and treated partly as a “wastebasket taxon”, the genus is likely to remain large even when this is resolved by revision. As a step towards this, the first data are provided on the anatomy of the type species, the South African G. menkeana (L. Pfeiffer 1853). Potentially diagnostic anatomical features, and the shell and radula of the genus Gulella sensu lato are discussed. COI mtDNA sequence data are provided from the neotype population of G. menkeana and from 24 other South African streptaxid species and populations. A strongly supported clade is recognised as the genus Gulella s. l. Lack of resolution still hampers the definition of the type subgenus, Gulella sensu stricto, but other subgenera within Gulella s. l. can be recognised. One South African clade of large species differs from G. menkeana in the radula. The name G. (Zulugulella) n. subgen. is introduced for this group, with G. (Z.) albersi (L. Pfeiffer 1855) (a species previously misidentified as G. menkeana) as type species. The Mauritian type species of Maurennea Schileyko 2000 and the Asian type species of Huttonella L. Pfeiffer 1856 clearly belong in Gulella s. l. on molecular and morphological grounds, and so these taxa may prove to be useful subgenera of Gulella. The Comoros taxon Pseudelma Kobelt 1904 shares the anatomical features of Gulella s. l. and may also be related. The type species of Aenigmigulella Pilsbry & Cockerell 1933 and Primigulella Pilsbry 1919 are shown to belong outside the genus Gulella s. l. and so are raised to generic rank. The analysis also shows three South African “Gulella” species in fact belong to other streptaxid genera with their centres of diversity elsewhere.