Natalina cafra amathole, 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 : 36-38

Natalina cafra amathole subsp. n.

Figs 14A , 15C , 16 , 21–23

Natalina compacta Connolly, 1939: 108 [in part, but not holotype].

Etymology: A toponym reflecting the geographical distribution of the taxon in the Amathole Mts, E. Cape, South Africa.

Identification ( Fig. 21 ): For general description see Natalina c. cafra above. Closely resembles the other subspecies of N. cafra , from which it cannot be reliably distinguished using shell characters alone. N. c. amathole , however, seems not to attain such a large size, and shows much less variation in shape than N. c. cafra , all specimens being consistently globose but still falling within the H:D range exhibited by the nominotypical subspecies. Umbilicus perhaps generally slightly broader than in N. c. cafra , but this is difficult to quantify, as there is no clear limit to the umbilical rim. Most similar to N. c. eumacta , particularly in terms of its globose proportions, relatively weak axial ribbing and the somewhat more broadly patent umbilicus. That subspecies, however, is more variable in periostracum colour (some individuals distinctly brown). Radula with six pairs of lateral teeth in each transverse row, compared to five in N. c. cafra and eight in N. c. eumacta .

Periostracum coloration similar to N. cafra cafra , usually of an olive-green or olive-brown hue when fresh, but evidently not as brown as some populations of N. cafra eumacta .

Dimensions: Holotype, diameter 40.5 mm; largest specimen (NMSA V8092, Katberg), diameter 50.4 mm; H:D of adults 0.78–0.90 (N=8).

Living animal ( Fig. 15C ): Limited data available. Head-foot fawn-brown to pale grey-brown with a diffuse pale stripe running backwards along neck from base of each optic tentacle; tentacles grey; pedal margin tinged yellow or orange.

Radula ( Fig. 22 ): Formula 1+6+~25 (N=3); length in adult 32–40 mm, with 50–60 rows of teeth. The radula is essentially the same as that of the nominotypical subspecies except that the lateral teeth in N. c. amathole consistently number six pairs per transverse row, compared to five in N. c. cafra . These figures, however, are based on a relatively small sample.

Distal genitalia: As in Natalina c. cafra , but no bulla evident on epiphallus.

Spermatophore ( Fig. 14A ): A well preserved allospermatophore has been found in one specimen, collected in early December (NMSA W4193). Spermatophore relatively slender, straightened length approx. 21 mm; anterior 2/3 tapering gently toward head, with 6–8 primary longitudinal ridges; ridges cease well before recurved tail and posterior third largely smooth. Very similar to that of N. c. eumacta and N. beyrichi but more slender and without a subterminal process at base of tail. The spermatophore of N. c. natalensis is proportionately broader and the longitudinal ridges continue almost to the tail tip.

Holotype ( Figs 21A–C ): SOUTH AFRICA: E. Cape: Hogsback , env. of Madonna & Child waterfall (32.60703°S: 26.96268°E), 1075 m, indigenous forest, in leaf-litter, D. Herbert, M. Bursey & G. Redman, 25/i/2002 ( NMSA V9792 /T2308).

Paratypes: SOUTH AFRICA: E. Cape: same data as holotype ( BMNH 20100123 , 1 specimen; NMSA W6371 /T2309, 7 specimens) ; Hogsback (32.600°S: 26.933°E), J. Hewitt ( NMSA E7864 /T2311, 1 specimen) ; Hogsback (32.600°S: 26.933°E), Dr Rattray,1919 ( NMSA V2012 /T2312, 1 specimen) ; Hogsback (32.59766°S: 26.95865°E), indigenous forest, in leaf-litter, A. Moussalli, D. Stuart-Fox & M. Bursey, 1/xii/2005 ( NMSA W4193 /T2313, 1 specimen) ; Hogsback environs (32.58935°S: 26.93563°E), indigenous forest, A. Moussalli & D. Stuart-Fox, 21/i/2005 ( NMSA W4829 /T2310, 1 specimen) ; Hogsback, Madonna and Child forest (32.5670°S: 26.9167°E), M. Bursey, 25/i/2002 ( ELM D13624 , 1 specimen) .

Additional material examined (all NMSA unless otherwise indicated): SOUTH AFRICA: E. Cape: Katberg, north of Fort Beaufort (32.533°S: 26.683°E), V. Fitzsimons, 1947 (V8092); Hogsback , Madonna and Child forest (32.5670°S: 26.9167°E), M. Bursey, 25/i/2002 ( ELM D13624 ) ; Hogsback , env. of Madonna & Child waterfall (32.60703°S: 26.96268°E), indigenous forest, in leaf-litter, A. Moussalli, D. Stuart-Fox & M. Bursey, 1/xii/2005 (W4196); Hogsback, Dr Rattray, i/1918 ( NMSA V6840 ) ; Hogsback, J. Hewitt, xii/1933 ( NMSA W6001 ) ; Mount Kempt (32.7000°S: 27.2667°E), Bigalke, 15/vi/1986 ( ELM D11299 ) ; Stutterheim, Kologha Forest (32.533°S: 27.367°E), C. Vernon, 25/x/1992 ( ELM D13139 ) .

Additional literature records probably referable to this subspecies (material not seen): SOUTH AFRICA: E. Cape: Pirie Mountain (32.767°S: 27.350°E), Godfrey ( Connolly 1912) .

Distribution ( Fig. 23 ):A narrow-range E. Cape endemic, known only from the Amathole Mts ; occurs at altitudes of 1100–1400 m.

Habitat: Little habitat data available, but appears primarily to inhabit southern mist-belt forest; in leaf-litter and under logs. Moderately common in forests in the Hogsback area.

Notes: This taxon is erected primarily on the basis of DNA data, which indicate that material of Natalina cafra from the Amathole region forms a distinct genetic lineage ( Moussalli et al. 2009). At present, such information is only available for specimens from the Hogsback area and individuals from other localities in the Amathole mountains have been identified with this material only on the basis of similarity in shell form and the number of lateral teeth in the radula. Additional molecular sequence data will be needed before their identity can be confirmed.

Connolly (1939) identified this Hogsback material with his new taxon Natalina compacta , but DNA sequence data for topotypic N. compacta material show it to belong within the N. c. cafra lineage (see above).

Conservation: Natalina c. amathole is evidently a narrow-range taxon, but the precise extent of its distribution is uncertain and requires further study. From the limited data available it is clear that the indigenous forests of the Amathole Mountains , particularly in the Hogsback area, are likely to be important for the conservation of this taxon.

Figures

Fig. 14. Natalina s.s. spermatophores (all NMSA): (A) N.cafra amathole subsp. n. (W4193), length 21 mm; (B) N. cafra natalensis subsp. n. (W7136), length 18.3 mm; (C) N. cafra eumacta (W4055, Manubi Forest), distorted spermatophore with finger-like process on tail region, length 12 mm; (D) N. c. eumacta (W4160, Manubi Forest), well preserved spermatophore lacking finger-like process on tail region, length 18.5 mm; (E) N. beyrichi (W4123), length 25.8 mm; (F) N. quekettiana lucaris subsp. n. (paratype, W3305/T2559), length 26.5 mm. The lengths given are for the spermatophore as if straightened out.

Fig. 15. Natalina s.s., living animals of larger species (all NMSA): (A) N. beyrichi, Hluleka (W2895), shell diameter 41.5 mm; (B) N. cafra cafra, Mountain Drive, Grahamstown (W5212), shell diameter 30.0 mm; (C) N. cafra amathole subsp. n., Hogsback (paratype, W6371/T2309), shell diameter 39.0 mm; (D) N. cafra natalensis subsp. n., Pietermaritzburg (specimen not collected), shell diameter approx. 58 mm; (E) N. c. natalensis subsp. n., Mtamvuna (paratype, W0308/T2370), shell diameter 40.3 mm; (F) N. cafra eumacta, Mazeppa Bay (W4044), shell diameter 40.4 mm; (G) N. c. eumacta, Dwesa (V7868), shell diameter 48.3 mm; (H) N. c. eumacta, egg, Manubi Forest (W4067), scale in millimetres.

Fig. 16. Distribution of Natalina cafra subspecies: N. c. cafra (triangles), N. c. amathole subsp. n. (stars), N. c. natalensis subsp. n. (circles), N. c. eumacta (squares).

Fig. 21. Natalina cafra amathole subsp. n., Hogsback, E. Cape: (A–C) holotype (NMSA V9792/T2308), diameter 40.5 mm; (D) paratype (NMSA E7864/T2311), diameter 49.0 mm.

Fig. 22. Natalina cafra amathole subsp. n., radula, Hogsback (NMSA W4193/T2313): (A) rachidian and lateral teeth, scale bar = 1.0 mm; (B) vestigial marginal teeth, scale bar = 250 µm.

Fig. 23. Distribution of Natalina cafra amathole subsp. n. Triangles with a white centre indicate localities for specimens used in DNA analyses (Moussalli et al. 2009); contours at 1000 m and 1500 m.