Natalina inhluzana (Melvill & Ponsonby, 1894)

Herbert, D. G. & Moussalli, A., 2010, Revision of the larger cannibal snails (Natalina s. l.) of southern Africa - Natalina s. s., Afrorhytida and Capitina (Mollusca: Gastropoda: Rhytididae), African Invertebrates 51 (1), pp. 1-1 : 66-67

Natalina inhluzana (Melvill & Ponsonby, 1894)

Figs 38 , 46

Helix (Dorcasia) inhluzana: Melvill & Ponsonby 1894: 91 , pl. 1, fig. 4. Type loc.: Inhluzan(i) Mountain

[Nhlosane], Dargle, KwaZulu-Natal [Mrs Shaw].

Dorcasia inhluzana: Melvill & Ponsonby 1895: 165 , pl. 12, fig. 6; Sturany 1898: 50.

Rhytida (Afrorhytida) inhluziana [sic]: Möllendorff 1903: 64, pl. 11, fig. 7.

Rhytida inhluzana: Melvill & Ponsonby 1907: 99 .

Natalina inhluzana: Connolly 1912: 94 ; 1939: 109; Watson 1934: 158; Herbert & Kilburn 2004: 223.

Etymology: Named after Inhluzan(i) Mountain [Nhlosane], Dargle, KwaZulu-Natal, South Africa.

Identification: Very similar to Natalina q. quekettiana , differs only in being smaller (but has fewer whorls, 4.0–4.5 compared to 4.5–5.0) and in having slightly weaker axial sculpture on the apical surface. Largest specimen (lectotype), diameter 23.0 mm; H:D of adults 0.61–0.64 (N=4).

Radula and soft parts: Unknown.

Type material: Two specimens were mentioned in the original description, one in BMNH (1911.8.8.2) was designated lectotype by Connolly (1912: 94), diameter 23.0 mm, height 15.0 mm ( Fig. 46 ).The paralectotype is in NMSA (2853/T592), diameter 22.4 mm, height 13.9 mm.

Additional material examined: SOUTH AFRICA: KZN: Inhluzana [Nhlosane] Mtn (29.55°S: 29.93°E) ( NMSA A7063 , A7064 , juveniles) ; Fort Nottingham , Tony Ker trail (29.41106°S: 29.91512°E), 1575 m, mist-belt Podocarpus forest, D. Herbert & L. Davis, station 08–064, 18/xii/2008 ( NMSA W6640 ) ; Karkloof, H. Burnup Coll’n ( NMSA B0022 ) .

Distribution ( Fig. 38 ): Known only from the Nhlosane–Fort Nottingham region in the KwaZulu-Natal Midlands, and perhaps also the Karkloof area.

Habitat: Not specifically stated in original description or on specimen labels, but presumably mist-belt forest.

Notes: It seems probable that N. inhluzana is a synonym of N. quekettiana quekettiana . Although the type specimens of N. inhluzana have weaker axial sculpture than is typical of N. q. quekettiana from Pietermaritzburg, in other respects they very much resemble subadult specimens of the latter with 4.0–4.5 rather than 4.5–5.0 whorls. It is puzzling that neither Melvill and Ponsonby (1984) nor Connolly (1939) offered any comparison between N. inhluzan a and N. quekettiana , particularly considering the relative proximity of their type localities (approx. 40 km apart). Fresh material and DNA sequence data are needed before a more conclusive assessment of the validity of this taxon can be made. However, despite repeated attempts to obtain living material from the type locality, none has been found. The remaining forest habitats on the Nhlosane Mountain and its southerly spur are now of very limited extent and considerably degraded as a result of alien plant invasion, trampling by cattle and subsistence harvesting of forest products. It is likely that the species is now extinct at the type locality, but attempts to find it in more well-preserved and more extensive forest fragments in the broader Dargle– Nottingham Road area are on-going.

Somewhat worn shells closely resembling the holotype are present in the Natal Museum, with the locality given simply as ‘Karkloof’. Although the Karkloof area is extensive and the locality data thus imprecise, it suggests that the species may occur more widely in this part of the central KwaZulu-Natal Midlands. Likewise, molecular data from an otherwise indeterminate juvenile from Bulwer ( Moussalli et al. 2009) revealed it to be close to N. quekettiana from the type locality (see above), suggesting that this too is more widely distributed in the central KwaZulu-Natal Midlands than was previously thought. The possibility that there is a single species, varying somewhat in size and strength of sculpture, occurring in the mist-belt and lower altitude montane Podocarpus forests of the central KwaZulu-Natal Midlands seems likely.

Conservation: If genuinely a distinct species, Natalina inhluzana would undoubtedly qualify for ranking as a threatened species. However, since there is insufficient data on the taxonomic validity of the species, an evaluation of its threat status cannot be made at present (but see comments concerning N. q. quekettiana above).

Figures

Fig. 38. Distribution of Natalina quekettiana quekettiana (Melvill & Ponsonby, 1893) (squares), N.q. lucaris subsp. n. (triangles) and Natalina inhluzana (Melvill & Ponsonby, 1894) (circles). Symbols with a white centre indicate localities for specimens used in DNA analyses (Moussalli et al. 2009); contours at 1000 m and 1500 m.

Fig. 46. Natalina inhluzana (Melvill & Ponsonby, 1894), lectotype of Helix (Dorcasia) inhluzana Melvill & Ponsonby, 1894 (BMNH 1911.8.8.2), diameter 23.0 mm.