Nata caffrula (Melvill & Ponsonby, 1898) Melvill & Ponsonby, 1898

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 : 23-24

Nata caffrula (Melvill & Ponsonby, 1898) comb. nov.

Figure 14

Natalina caffrula Melvill & Ponsonby, 1898a: 24 , pl. 8, fig. 1. Melvill & Ponsonby, 1898b: 170. Möllendorff, 1903 in Möllendorff & Kobelt, 1903 –1905: 23, pl. 4, figs 4, 5. Kobelt, 1909: 53. Connolly, 1912: 91. Connolly, 1925: 122. Connolly, 1939: 110. Richardson, 1986: 48. Type loc.: Knysna, W. Cape.

Not Natalina caffrula — Sturany, 1898: 32. Germain, 1935: 5. Haas, 1936: 18 [= Nata vernicosa and N. erugata sp. nov.].

Etymology. Diminutive of the Latinized form of the Arabic kafir (unbeliever); in reference to its resemblance to Natalina cafra (Férussac, 1821) .

Type material. Holotype ( Fig. 14 A–C) in NHMUK (1911.8.8.10), diameter 11.2 mm [given as 11.5 mm by Melvill & Ponsonby 1898a]; two paratypes in SAMC (2369), one here figured ( Fig. 14 D–F).

Distribution: Connolly (1912) cited Crawford material from Port Elizabeth, but subsequently doubted its provenance ( Connolly 1939). Records from Durban, Zululand and southern Mozambique ( Sturany 1898; Germain 1935; Haas 1936) are erroneous and almost certainly represent misidentified specimens of Nata vernicosa s.l. Thus the only seemingly reliable record is that given as the type locality, but even this is suspect (see Remarks below).

Habitat. Unknown.

Remarks. Despite its small size, Connolly (1939) maintained this species in the genus Natalina , commenting that it resembled a miniature version of Natalina cafra . However, this decision is puzzling since he observed that the apical whorls of the holotype (the only specimen known to him), although defective, were ‘apparently smooth’. In fact the protoconch of the holotype is effectively missing, but Connolly was evidently unaware of the existence of two paratypes in the SAMC. These have intact apices with a protoconch that is both small (diameter 1.5–1.6 mm) and smooth. Such an apex is typical of Nata s.l. rather than Natalina s.l., species of which have a much larger (diameter> 2.5 mm), axially ribbed protoconch ( Herbert & Moussalli 2010). It is thus clear that the taxon should be transferred to the genus Nata . Its relatively small size is also consistent with a position in Nata , species of which are invariably smaller-shelled than any of the genera now recognised within Natalina s.l. ( Herbert & Moussalli 2010).

The type specimens of this species remain the only material available. In terms of size, sculpture and proportions, they exhibit a very close resemblance to larger specimens of Nata dumeticola from the Saldanha Bay area, differing only in colour, having a somewhat more olive-green hue. Connolly (1939) rightly questioned the validity of records of N. caffrula from Mozambique and KwaZulu-Natal, and also doubted Port Elizabeth, evidently believing only the type locality (Knysna) to be reliable. However, no further specimens have come to light from the Knysna area. We strongly suspect that N. caffrula is a synonym of N. dumeticola and, since the latter is known only from the Cape Peninsula and the Atlantic coast of W. Cape, the provenance of the types of N. caffrula must also be considered dubious. The specimens were presented (and almost certainly collected) by W.F. Purcell (L. Hoenson, pers. comm., xi/2012) an employee of SAMC (1896–1905) who is known to have collected primarily in the south-western Cape ( Summers 1975; Glen & Germishuizen 2010). Nevertheless, the Knysna area is not well surveyed and there remains a possibility that further material may be found there.

Figures

FIGURE 14. Nata caffrula (Melvill & Ponsonby, 1898), type material. A – C, holotype of Natalina caffrula Melvill & Ponsonby, 1898, diameter 11.2 mm (NHMUK 1911.8.8.10). D – F, paratype of Natalina caffrula Melvill & Ponsonby, 1898, diameter 12.5 mm (SAMC 2369).