Nata Watson, 1934

David G. Herbert & Adnan Mousalli, 2016, Revision of the dwarf cannibal snails (Nata s. l.) of southern Africa — Nata s. s. and Natella (Mollusca: Gastropoda: Rhytididae), with description of three new species, Zootaxa 4094 (1), pp. 1-67 : 18

Genus Nata Watson, 1934

Nata Watson, 1934: 158 . Type species (by original designation): Natalina tarachodes Connolly, 1912 .

Diagnosis. Shell small to moderate in size (adult diameter 6–25 mm), thin, subglobose to discoidal, yellowishbrown to honey-brown, frequently with uneven darker axial bands, but lacking spiral colour pattern; apical surface with close-set axial (collabral) riblets or smooth, sculptured only by weak growth-lines, spiral sculpture mostly lacking; usually glossy, occasionally lustreless; base generally smoother and more glossy; peristome interrupted in parietal region; outer lip thin with membranous periostracal fringe, never thickened; umbilicus open, width moderate to wide; protoconch smooth, comprising 1.0–1.25 whorls, diameter 0.7–2.6 mm (rarely more than 2.0 mm).

Radula beloglossan, but tooth morphology variable; labial palps not evident; epiphallus present but usually small, inserting laterally into penis; penis lumen papillate, epiphallus pore may be somewhat raised or surrounded by a flange-like disc, but a verge-like structure is absent; retractor muscle of right optic tentacle passes to left of penis; vas deferens reflexed, passing down penis then back along free oviduct; vagina short or absent; bursa copulatrix duct broader basally; no oviduct caecum present; atrial diverticulum sometimes present; kidney trigonal, primary ureter reflexed around anterior of kidney; suprapedal mucus gland not convoluted, the posterior portion lacking glandular tissue.

Remarks. As indicated in the Introduction, following our previous work ( Moussalli & Herbert 2016), we employ the genus Nata in a restricted sense, and treat Natella as a separate genus. There are significant morphological differences between the two and molecular data demonstrate that Natella constitutes a deeply divergent, basal lineage within the Rhytididae .

Nata is endemic to southern Africa, occurring mostly to the south and east of the Great Escarpment and ranging from the south-western Cape to the Soutpansberg in Limpopo (23°S) and Inhambane in southern Mozambique (24°S). The range of one species also extends into the Highveld of Gauteng, Free State and Lesotho.