Gemmula Weinkauff, 1875

Kilburn, Richard N., 2005, New species of Drilliidae and Turridae from southern Africa (Mollusca: Gastropoda: Conoidea), African Invertebrates 46, pp. 85-92 : 87-88

Gemmula Weinkauff, 1875

Gemmula Weinkauff, 1875: 287 . Type species (s.d. Cossmann, 1896): Pleurotoma gemmata Reeve, 1843

(non Conrad, 1835) [= Gemmula hindsiana Berry, 1958 ].

? Unedogemmula MacNeil, 1960: 101 . Type species (o.d.): Turris [= Pleurotoma ] unedo Kiener, 1840 .

Remarks: The new species described here shows closest resemblance to the type species of the taxon Unedogemmula MacNeil, 1860 , namely Pleurotoma unedo Kiener, 1840 . Powell (1964: 269, 1966: 48) treated Unedogemmula as a subgenus of Gemmula Weinkauff, 1875 , but acknowledged equal similarity to Lophiotoma Casey, 1904 . Medinskaya (2002) described the radula and foregut anatomy of the type species of Lophiotoma and several species of Gemmula , and evidently found no major differences. In Unedogemmula , peripheral gemmules are typically present only on the early whorls, but in Gemmula alwyni , which otherwise closely resembles G. unedo —it was misidentified as that by Medinskaya (2002) —they continue onto the later teleoconch whorls. Obsolescence of gemmules with growth would appear to be the end of a transformation sequence, and cannot be usefully utilised to qualify taxa or subtaxa. The presence of gemmules is in itself not a valid synapomorphy, as this characterises not only Gemmula , but a range of turrine and crassispirine genera.Although the type species of Unedogemmula shows a form typical of Lophiotoma , namely fusiform with a long siphonal canal and strongly shouldered or angular whorls, apparent intermediate states occur within Gemmula . On the other hand, in Turris invicta Melvill, 1910 , the juvenile gemmules may be so weak that the species could more appropriately be referred to Lophiotoma than to Gemmula . Radula characters (Powell 1966; Kilburn 1963;

Medinskaya 2002) in Gemmula , Unedogemmula , and Lophiotoma do not provide significant systematic data. Consequently, Unedogemmula is here tentatively synonymised with Gemmula .

The following couplets may be inserted into the dichotomous key to South African Gemmula species given by Kilburn (1983: 566):

1. Subsutural cord subequal in width to shoulder sulcus or wider than it; peripheral cord normally marked with brown or yellow ....................................................... 2 – Subsutural cord distinctly narrower than shoulder sulcus; peripheral cord occasionally patterned ............................................................. 3a (after couplet 3)

3a. Peripheral cord markedly angular, strongly spotted with brown ....... alwyni sp. n. – Peripheral cord neither strongly angular nor spotted with brown ........................ 4