Natalina quekettiana dracomontana, Herbert & Moussalli, 2010

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 : 61-63

Natalina quekettiana dracomontana subsp. n.

Figs 35C, D , 41–43

Etymology: From Latin draco (a dragon) and mons (a mountain); in reference to the Drakensberg.

Identification ( Fig. 41 ): For general description see Natalina q. quekettiana above. The limited material available indicates this subspecies to vary considerably in shell proportions and colour, but there appear to be no clear-cut morphological characters that serve to reliably distinguish it from other subspecies within the N. quekettiana complex, except N. q. lucaris and N. reenenesis which have fewer pairs of lateral teeth per transverse row in the radula (but see also observations on epiphallus).

Dimensions: Holotype: diameter 27.2 mm, height 19.5 mm; largest specimen (NMSA W4093/T2453, Monks Cowl), diameter 30.2 mm; H:D including some slightly subadult specimens 0.55–0.72 (N=5) (0.55 in single available adult).

Living animal (information available for only two animals) ( Figs 35C, D ): Dorsal region of head-foot dark grey-brown to charcoal-grey, lacking paler longitudinal stripes on neck; tentacles of similar colour; sides of foot paler; mantle edge pale buff-brown or yellow, if yellow then pedal margin also yellow ( Fig. 35D ); lung wall without large black blotches, pigmentation mostly fine and tracking blood vessels, particularly to right of pulmonary vein.

Radula ( Fig. 42 ): Formula 1+(7–8)+(12–19) (N=2); length up to 28.5 mm, with up to 70 V-shaped rows of teeth.

Distal genitalia: Epiphallus like that of N. q. quekettiana , but in both of the two mature specimens available there was a small bulla on the outer side of the epiphallus, just above its junction with the vas deferens. Internally the bulla possessed a short diverticulum of the main epiphallus lumen, suggesting that the spermatophore may possess a thumb-like or finger-like process on the tail region (cf. N. beyrichi and N. cafra eumacta ). Spermatophore: Unknown, but epiphallus structure suggests that as in other subspecies of N. quekettiana , the anterior two-thirds will bear well-developed scale-like spines. The possibility of an additional process on the tail (see previous paragraph), however, is something not so far evident in other subspecies within this complex.

Holotype ( Figs 41A–C ): SOUTH AFRICA: KZN: Injasuthi , central Drakensberg, (29.1417°S: 29.4250°E), 1600 m, montane Podocarpus forest, in leaf-litter, D. Herbert, M. Seddon & P. Tattersfield, 8/xii/1998 ( NMSA V7992 /T2451).

Paratypes: SOUTH AFRICA: KZN: Monk’s Cowl area , forest below Sterkspruit Falls (29.03762°S: 29.40632°E), altitude 1350 m, montane Podocarpus forest, in leaf-litter, D. Herbert, Earthwatch, 15/iii/ 2006 ( NMSA W4093 /T2453, 2 specimens) ; ditto, forest below Sterkspruit Falls (29.03414°S: 29.40685°E), 1420 m, montane Podocarpus forest, in leaf-litter, D. Herbert, Earthwatch, 15/iii/2006 ( NMSA W4101 / T2452, 1 specimen) ; Cathkin Peak area (29.037°S: 29.388°E), Falcon coll’n ( NMSA A7056 /T2454, 3 specimens) .

Other material examined: SOUTH AFRICA: KZN: Monk’s Cowl area (29.03707°S: 29.38753°E), 1650 m, indigenous forest, in leaf-litter, M. Hamer et al., 09/iv/2006 ( NMSA W5097 ) .

Distribution ( Fig. 43 ): Confirmed records only from the Mdedelelo [Cathkin Peak] and Injasuthi areas in the central KwaZulu-Natal Drakensberg; occurs at altitudes of 1350– 1650 m.

Habitat: Afrotemperate forest, in leaf-litter; evidently rare.

Notes: We describe this as a new taxon primarily on the grounds of molecular data ( Moussalli et al. 2009) which indicate it to represent a distinct lineage that is sister to the clade comprising N. q. quekettiana and N. q. lucaris. It shares with these taxa the distinctive bicoloured shell (living and fresh shells only), and in some individuals, the yellow mantle edge and pedal margin. Nearly all the material available is subadult and the aperture thus perhaps less oblique (more circular) than it would be at adulthood. In addition, there is also an indication of a difference in epiphallus structure, namely the presence of an epiphallus bulla, but this observation is based on only two specimens. Given that this character appears variable in N. c. eumacta and N. c. natalensis , its taxonomic significance must be interpreted with caution.

Conservation: The distribution of N. q. dracomontana is evidently somewhat greater than that of N. q. montistempli , but the available records suggest that its range is nonetheless very limited. It occurs in a formally conserved region (the uKhahlamba Drakensberg World Heritage Site ), where disturbance is low and thus its habitat is afforded a high degree of protection. On-going management practices, however, need to ensure that the integrity of forest patches within the broader mosaic of Drakensberg ecosystems is maintained. Uncontrolled fires in the neighbouring grasslands are likely to represent the most significant threat.

Figures

Fig. 35. Natalina quekettiana complex, living animals and eggs (all NMSA):(A) N. q. quekettiana, Ferncliffe, Pietermaritzburg (W6646), shell diameter 31.3 mm; (B) N. q. lucaris subsp. n., Ngome Forest (paratype, V2249/T2563), shell diameter 29.4 mm; (C) N. q. dracomontana subsp. n., Injasuthi (holotype, V7992/T2451), shell diameter 27.2 mm; (D) N. q. dracomontana subsp. n., Monk’s Cowl area (paratype, W4101/T2452), shell diameter 26.4 mm; (E) N. q. montistempli subsp. n., Oqalweni, Cathedral Peak (holotype, W4084/T2422), shell diameter 23.9 mm; (F) N. q. quekettiana, eggs (W6646), scale in millimetres.

Fig. 41. Natalina quekettiana dracomontana subsp. n. (all NMSA): (A–C) holotype, diameter 27.2 mm (V7992/T2451); (D–F) paratype (subadult), recently live-collected, Monk’s Cowl, diameter 26.4 mm (W4101/T2452); (G) depressed specimen, collected as empty shell, Monk’s Cowl, diameter 30.2 mm (W4093/T2453).

Fig. 42.Natalina quekettiana dracomontana subsp. n., radula, holotype (NMSA V7992/T2451): (A) rachidian and lateral teeth, scale bar = 0.5 mm; (B) vestigial marginal teeth, scale bar = 100 µm.

Fig. 43. Distribution of Natalina quekettiana dracomontana subsp. n. (squares), N. q. montistempli subsp. n. (triangles) and N. reenenensis Connolly, 1939 (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.