Ptilototheca, Herbert, 2016

Herbert, David G., 2016, New narrow-range endemic land snails from the sky islands of northern South Africa (Gastropoda: Streptaxidae and Urocyclidae), European Journal of Taxonomy 236, pp. 1-29 : 9-10

Ptilototheca gen. nov.

urn:lsid:zoobank.org:act:51C2C9E7-9514-43DF-A09B-3E391D3B61DD

Type species

Ptilototheca soutpansbergensis gen. et sp. nov.

Diagnosis

Shell small, delicate and glossy, periphery below mid-whorl, base narrowly umbilicate; protoconch with close-set spiral lines of small punctations. Epiphallus very short, flagellum squat, vas deferens long, thickened and convoluted, penial verge present; spermatophore tail with well-developed, finely divided, branching spines.

Etymology

From ptilon, ptilotos (Gr.) a ‘feather, feathered’ and theca (L.) a ‘case or container’; referring to the plumose ornamentation of the spermatophore. Gender feminine.

Remarks

Within a southern African context, the spirally punctate protoconch of Ptilototheca gen. nov. might suggest an affinity with Sheldonia s.s., but the distal genitalia of the present species are quite distinct and clearly discount any close relationship between the two. Although few other southern African heliciform urocyclids possess such a protoconch, the character is commonly present in semi-slug genera from further north in Africa ( Van Mol 1970). In terms of its distal genital anatomy, P. soutpansbergensis gen. et sp. nov. is unlike any other southern African heliciform urocyclid species. The extremely short epiphallus, short squat flagellum, ornately bristled spermatophore and long, thick, convoluted vas deferens are distinctive characters not seen in other species from the region. In addition, the presence of a penial verge and a papillate preputial region are also unusual features among local species, but these are also present in S. wolkbergensis sp. nov. (see below). That species, however, lacks a spirally punctate protoconch, possesses an atrial diverticulum, has a short, slender, non-convoluted vas deferens, and an epiphallus and flagellum of more conventional length for Sheldonia s.l. Species of the central African semi-slug genus Angustivestis Pilsbry, 1919 also possess a penial verge and a papillate preputial region, as well as a long, thick, convoluted vas deferens, but again in that genus the protoconch is not spirally punctate, the epiphallus and flagellum not conspicuously shortened and there is usually an atrial diverticulum ( Van Mol 1970). Considered collectively, the conchological and anatomical features exhibited by P. soutpansbergensis gen. et sp. nov. strongly suggest that it is not closely related to other southern African heliciform urocyclids and that it belongs to a distinct lineage that may perhaps have closer affinities with central African genera. Its distribution in the extreme north of South Africa is consistent with this.

Helicarion pumilio Melvill & Ponsonby, 1909 , the type species of Andrarion Godwin-Austen, 1912 , was also described from the Soutpansberg. This remains a poorly known and enigmatic species, but it differs from the present material in having a smaller, more depressed shell with a smooth protoconch and a rapidly expanding last whorl [confirmed by examination of the type material: lectotype (des. Connolly 1912: 101) NHMUK 1910.1.5.12 (maj. diameter 6.8 mm) and three paralectotypes NHMUK 1937.12.30.4113–5]. The original specimens remain the only material available and I strongly suspect that they are simply juveniles of a larger species of Sheldonia (Kerkophorus) , at least one species of which occurs in the Afrotemperate forests of Limpopo. This remains a matter requiring further investigation, but for the present it is sufficient to confirm that the material discussed herein is undoubtedly distinct from H. pumilio .