Capitina schaerfiae (Pfeiffer, 1861)

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 : 113-116

Capitina schaerfiae (Pfeiffer, 1861)

Figs 4C , 7C , 9C , 11A , 73A, B , 77 , 78A , 79 , 81

Helix schärfiae: Pfeiffer 1861: 73 , pl. 2, figs 1–3; 1868: 242; Benson 1864: 494. Type loc.: Bredas Bosch, near Genadendal, W. Cape [Madame Schärf]. [ schärfiae emended to schaerfiae following ICZN (1999), Art. 32.5.2.1]

Macrocyclis schaerfiae: Pfeiffer 1878 in 1878–81: 62.

Helix (Ampelita) schaerfiae: Pfeiffer 1879 in 1878–81: 184.

Helix schaerfiae: Kobelt 1886 in 1877–97: 615, pl. 178, figs 1–6.

Helix (Ampelita) schaerfiae: Pilsbry 1890 in 1890–91: 43, pl. 7, figs 95–97, 1, 2.

Rhytida schaerfiae: Melvill & Ponsonby 1898: 170 .

? Macrocyclis schaerfiae: Sturany 1898: 33 .

Natalina schaerfiae: Connolly 1912: 96 (in part); 1939: 116, pl. 4, figs 6–8, text-fig. 10 (in part); Barnard 1951: 142, pl. xxi, fig. 8.

Tulbaghinia schaerfiae: Connolly 1915: 174 .

Natalina (Capitina) schaerfiae: Watson 1934: 153 , pl. 19, figs 1–4.

Etymology: Named for ‘Madame Sophie Schärf ’, perhaps connected with the Moravian

Mission at Genadendal (Barnard 1965).

Identification: More depressed and thinner-shelled than Capitina calcicola sp. n., and with a larger protoconch; umbilicus not obscured to any appreciable extent by reflected columella lip; periostracum darker and more obvious; spiral colour pattern usually less bold.

Description ( Fig. 77 ): Shell lenticular to discoidal, spire low; comprising up to 4.5 whorls, last adult whorl expanding relatively rapidly and descending noticeably prior to aperture; apical surface lustreless, base glossy. Protoconch diameter 6.0–7.0 mm; sculptured primarily by close-set axial riblets ( Fig. 4C ), strongest adapically, but traces of spiral threads may also be present, particularly near periphery.Teleoconch sculptured initially by close-set axial riblets, these becoming less distinct with growth and tending to anastomose, producing a pitted or wrinkled sculpture; this sculpture evanescing at periphery, base smoother and more glossy with only weak growth-lines and fine spiral lirae.Aperture obliquely ovate-reniform; outer lip weakly, but distinctly thickened, white; basal lip almost straight in basal view; umbilicus of moderate width, not appreciably obscured by reflected upper part of columella lip.

Ground colour yellowish brown to mid brown with darker brown spiral lines, one line just above periphery usually more distinct; lines finer on base and usually absent in peri-umbilical area; periostracum relatively well developed, but not extending beyond aperture lip at maturity, honey-brown in fresh shells, though appearing darker in living specimens.

Dimensions: Largest specimen (NMSA B0031, Oubos), diameter 31.6 mm, H:D of adults 0.48–0.53 (N=6).

Living animal ( Fig. 78A ): Head-foot grey or brown to dark grey-brown, sometimes paler laterally and beneath shell; pedal margin tinged with or distinctly orange, orange colour usually more extensive on tail; tentacles generally greyish; paler longitudinal bands on neck not evident; mantle edge a darker shade of main body colour.

Radula ( Figs 73A, B ): See generic description; formula 1+~30 (N=2).

Type material: Originally in Szczecin (Stettin) Museum [H. Dohrn collection], Poland ( Connolly 1912). Although Dance (1986) stated that the Dohrn collection was totally destroyed in the Second World War, we have established through Furth et al. (1994), that some entomological material from the Stettin Museum was transferred to the Museum and Institute of Zoology, Polish Academy of Sciences, Warsaw. Further enquiries have led to the discovery of a specimen labelled ‘ Helix schärfiae ’ at the latter institution. This almost certainly represents a shell from the original sample and indicates that some Stettin Museum molluscan material was transferred to the Institute of Zoology and is still extant.We designate this specimen as lectotype ( Figs 77A, B ).

Material examined: SOUTH AFRICA: W. Cape: Riviersonderendberge, Oubos (Oudebosch) ( NMSA B0031 ex SAMC, BMNH 1937.12.30.1309–10); ditto (34.07702°S: 19.82884°E), 370 m, Afrotemperate forest , in leaf-litter and under logs, D. Herbert & L. Davis, 11/x/2007 ( NMSA W5672 ) ; ‘ Swellendam’ ex E.L. Layard, purchased from Sowerby & Fulton, 1919 ( NMSA 3125 ) .

Distribution ( Fig. 79 ):A narrow-range W. Cape endemic, known only from the southern slopes of the Riviersonderendberge. We consider records from Swellendam to be highly dubious. They relate to old specimens purchased from Sowerby & Fulton and the provenance given may simply refer to a then more well-known locality in the general area of occurrence.Records from the Bredasdorp area ( Connolly 1912, 1939) refer to the following species.

Habitat: Capitina schaerfiae has been found only in patches of southern Afrotemperate forest in valleys on the south-facing slopes of the Riviersonderendberge. At Oubos [Oudebosch], where the material studied by Connolly and Watson originated, the species remains common, living under logs and forest floor debris (altitude 350–400 m).

Notes: In addition to being thinner-shelled, more depressed and generally less boldly marked than Capitina calcicola sp. n., in the present species the protoconch is larger, the head-foot darker and the radula has more teeth per row. Further comparative details are given under C. calcicola .

Conservation: The available data suggest that the distribution of Capitina schaerfiae is both fragmented and highly restricted. Its range in the Riviersonderendberge is essentially linear, and covers a west-east distance of only approx. 65 km. Even within this it evidently occurs only in forest fragments. The only locality at which it has been recorded within the last 50 years is at Oubos, where, for a moderately large predatory species, it seems to be relatively common. More field surveys are needed in order to clarify the current extent of its range, but it seems probable that other populations remain in forested valleys elsewhere on the southern slopes of these mountains.The area is not well sampled.

Large parts of the Riviersonderendberge fall within conservation areas (Greyton Nat. Res., Riviersonderend Provincial Nat. Res. and Riviersonderend Mountain Catchment Area) and are thus afforded some degree of protection.

Figures

Fig. 4. Protoconchs of Natalina, Afrorhytida, Capitina and Nata (all NMSA): (A) Natalina cafra cafra (W4225), scale bar = 5.0 mm; (B) Afrorhytida trimeni (V7904), scale bar = 2.5 mm; (C) Capitina schaerfiae (W5672), scale bar = 2.5 mm; (D) Nata sp. n. (W6029), scale bar = 0.5 mm; arrows mark protoconch/teleoconch junction.

Fig. 7. Pulmonary anatomy of Natalina, Afrorhytida and Capitina (all NMSA): (A) N. cafra cafra (W4220); (B) A. knysnaensis (W5211); (C) C. schaerfiae (W5672).Abbreviations: au – auricle, kid – kidney, pn – pneumostome, pu – primary ureter, pv – pulmonary vein, rec – rectum, su – secondary ureter, uf – ureteric fold on rectum, up – ureteric pore, uv – ureteric vein, ven – ventricle.

Fig. 9. Distal genitalia of Natalina, Afrorhytida and Capitina (all NMSA): (A) N. cafra natalensis subsp. n. (E7682), (B) A. knysnaensis (W4643), (C) C. schaerfiae (W5672). Abbreviations: bd – bursa copulatrix duct, ep – epiphallus, ga – genital atrium, oc – oviduct caecum, p – penis, pr – penial retractor muscle, sod – spermoviduct, v – vagina, vd – vas deferens.

Fig. 11. Suprapedal glands of Capitina, Afrorhytida and Natalina (all NMSA): (A) C. schaerfiae (W5672), scale bar = 5.0 mm; (B) A. knysnaensis (W3351), scale bar = 5.0 mm; (C, D) N. quekettiana lucaris subsp. n. (W3310): (C) pedal cavity with suprapedal gland in situ, scale bar = 10 mm; (D) dissected gland, scale bar = 5.0 mm; (E, F) N. wesseliana (V7668): (E) entire gland, scale bar = 20 mm; (F) enlargement of distal end showing terminal vesicle, scale bar = 5.0 mm; (G) N. cafra cafra (W4220), scale bar = 10 mm. Abbreviations: asg – aperture of suprapedal gland, pa – pedal artery, v – vesicle at posterior end of suprapedal gland.

Fig. 73. Capitina species, radula: (A, B) Capitina schaerfiae (Pfeiffer, 1861), Oubos (NMSA W5672), scale bars = 300 µm and 100 µm; (C, D) Capitina calcicola sp. n., Cape Agulhas (paratype, NMSA W3360/T2270), scale bars = 200 µm and 100 µm.

Fig.77. Capitina schaerfiae (Pfeiffer, 1861): (A, B) lectotype of Helix schärfiae Pfeiffer, 1861, here designated (Polish Academy of Sciences 4295), diameter 31 mm (photographs courtesy of Dominika Mierzwa); (C–E) Oubos, Riviersonderendberge (NMSA W5672), diameter 29.7 mm.

Fig. 78. Capitina species, living animals: (A) Capitina schaerfiae (Pfeiffer, 1861), Oubos, Riviersonderendberge (NMSA W5672), shell diameter 28.0 mm; (B) Capitina calcicola sp. n., Gansbaai (paratype, NMSA W3201/T2269), shell diameter 22.8 mm.

Fig.79. Distribution of Capitina species:C. schaerfiae (Pfeiffer, 1861) (triangles), C. calcicola sp. n. (squares). Symbols with a white centre indicate localities for specimens used in DNA analyses (Moussalli et al. 2009). Contour at 1000 m.

Fig. 81. Plot of height/diameter measurements of Capitina species, showing differing shell proportions in the two species. The largest specimen of C. schaerfiae (31.6 mm diameter) is missing its apex and cannot be included in this plot. Similarly, the height of the lectotype (31 mm diameter) cannot be measured from the photographs available.