Afrorhytida knysnaensis ( Pfeiffer, 1846 )

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 : 81-88

Afrorhytida knysnaensis ( Pfeiffer, 1846)

Figs 6A , 7B , 9B , 11B , 53 , 54A, B , 55A–C , 56–60

Helix knysnaensis: Pfeiffer 1846 a (dated 1845): 131; 1846 b: 439; 1848: 84; 1853 in 1853–60: 343, No 858, pl. 133, figs 5, 6; Philippi 1847: (37) 85, pl. 7, fig. 5; Krauss 1848: 76; Reeve 1852 in 1851–54: sp. 403. Type loc.: ‘Knysna, Cape of Good Hope’ [Cuming coll’n] – erroneous and here emended to Fort Beaufort, E. Cape, South Africa.

Helix (Pella) knysnaensis: Pfeiffer 1879 in 1878–81: 102; Tryon 1887: 106, pl. 20, fig. 75.

Aerope knysnaensis: Pilsbry 1889: 277 , pl. 9, figs A–G, J.

Natalina knysnaensis: Pilsbry 1893 in 1892–93: 135; 1908 in 1907–08: xi, pl. 52, fig. 4 (lung) [not 1 as stated]; Melvill & Ponsonby 1898: 170; Sturany 1898: 31; Connolly 1912: 94; 1939: 111 [not text-fig. 9 = Afrorhytida kraussi ].

Natalina coerneyensis Melvill & Ponsonby, 1894: 91 , pl. 1, fig. 2; 1898: 170; Moss 1894: 25, pl. 2, fig. 2; Sturany 1898: 31; Connolly 1912: 92; 1939: 112. Type loc.: Coerney, north of Port Elizabeth, E. Cape. Syn. n.

Rhytida (Afrorhytida) knysnaensis: Möllendorff 1903: 61 , pl. 11, figs 1, 2.

Rhytida (Afrorhytida) coerneyensis: Möllendorff 1903: 64 , pl. 11, fig. 8.

Natalina insignis Melvill & Ponsonby, 1907: 98 , pl. 6, fig. 9; Connolly 1912: 94; 1939: 113. Type loc.: Teafontein farm, between Riebeek East and Grahamstown, E. Cape [Dr Schönland, per Farquhar]. Syn. n.

Natalina (Afrorhytida) knysnaensis: Schileyko 2000 : fig. 970.

Etymology: Named after the purported, but evidently erroneous, type locality, Knysna, W. Cape, South Africa.

Identification: A variable species in terms of shell proportions and body coloration. Elevated, subglobose specimens closely resemble Afrorhytida burseyae sp. n., but attain a slightly larger size and have a somewhat wider umbilicus. Depressed specimens may closely resemble A. kraussi kraussi and A. trimeni , but in both of these the shell is of a richer brown hue when fresh and lacks a yellowish or greenish tint. A. kraussi kraussi also has a pinkish lilac blush inside the aperture of fresh shells and A. trimeni has axial sculpture which remains strong on the last adult whorl. The most distinctive features of A. knysnaensis concern its radula which differs from that of all other Afrorhytida species in that the outermost lateral tooth rather than the penultimate one is the largest. Furthermore, it generally has fewer lateral teeth (<10 per half row) and more numerous marginal teeth (>16 per half row), such that the lateral:marginal ratio is 0.50 or less (compared to 1.0 or more in the other species). The outward reduction in size of the marginal teeth is also noticeably more gradual. Juvenile specimens of Natalina cafra cafra may co-occur with A. knysnaensis and be of similar size, but these have a much larger protoconch, less deeply penetrating umbilicus and fewer whorls for their size.

Description ( Figs 56 , 57 ): Shell proportions very variable, ranging from subglobose (H:D=0.75–0.86, Figs 57A–E ) to lenticular (H:D=0.55–0.65, Figs 57J–L ); adult shell comprising 4–5 whorls, the last usually descending somewhat prior to aperture, sometimes conspicuously so; base glossy, apical surface less so, but still retaining some lustre when fresh. Protoconch 3.7–5.2 mm in diameter, apical portion more or less smooth, axial riblets developing only toward end of final whorl and protoconch relatively weakly sculptured compared to other species; protoconch/teleoconch junction usually poorly defined.Apical surface of teleoconch sculptured by close-set axial riblets, these becoming weaker and less well defined toward end of last adult whorl and on base; base also with traces of spiral liration; aperture subcircular to roundly-ovate and somewhat obliquely descending; outer lip slightly thickened and occasionally weakly reflected in adult specimens, sometimes weakly thickened internally in senescent individuals; upper part of outer lip frequently somewhat flattened in depressed specimens; umbilicus of moderate but variable width, wider in depressed specimens than in subglobose ones in which it is partially obscured by reflected upper portion of columella lip.

Periostracum of fresh specimens usually a shade of yellowish brown with a slight greenish tinge; for the most part relatively uniform, but sometimes with faint axial variation in intensity. Underlying shell and interior of aperture milky-white (no trace of pinkish or lilac hue, cf. Afrorythida kraussi ); apical periostracum frequently eroded, even in living specimens.

Dimensions: Largest specimen (BMNH 1563, Grahamstown), diameter 31.0 mm, height 21.1 mm, but few specimens exceeding diameter 25 mm and height 19 mm. H:D of adults 0.55–0.86 (N=42).

Living animal ( Figs 55A–C ): Coloration very variable, ranging from more or less uniformly pale apricot-orange to dark maroon-black; other specimens more contrastingly coloured with sides of foot pale flesh and dorsal neck region darker grey-black with a paler, dorsolateral, longitudinal stripe on each side extending backward from optic tentacle; tentacles usually darker grey, particularly the optic ones; pedal margin occasionally, but rather rarely, more brightly coloured; tip of tail also often somewhat more intensely pigmented; mantle edge coloration similar to body colour; pigmentation of lung wall variable, usually limited and seldom heavy.

Radula ( Fig. 58 ): Formula 1+(7–10) 1 +(17–24) (N=8); length up to 19 mm, with 60– 80 V-shaped rows of teeth, 3.6–4.4 rows/mm in adult; lateral and marginal series clearly differentiated. Rachidian short, its cusp and base-plate more or less equal in length;

1 Pilsbry (1889) illustrated a radula with 12 lateral teeth under the name Aerope knysnaensis , but the geographical origin of the specimen was not stated (see notes below).

inner lateral teeth more or less parallel-sided, tapering to a point at tip, increasing slightly in size from first to fifth or sixth; outer 2 or 3 laterals considerably larger, with a strong quadrate base-plate and well-developed curved cusp (length of cusp variable between individuals, frequently relatively stout); outer lateral tooth the largest. Marginal teeth slender and more delicate with a much reduced base-plate, innermost one 0.50–0.66 length of outer lateral, remainder decreasing gradually in size, in decreasing increments, toward radula margin, only those at the extreme edge truly vestigial.

Distal genitalia ( Figs 9B , 53 , 54A, B ): See generic description. Epiphallus 75 % or more of penis length, but variable in proportions and curvature, sometimes with distinct greyish pigmentation; distal half broader, progressively narrowing toward vas deferens; mid region of lumen with a transverse ring of four to five short, swollen, longitudinally orientated, white, digit-like pilasters, each narrowly attached to lumen wall; smooth,

low ridges extend from these toward vas deferens, often greyish in colour; lumen wall anterior to pilasters with indistinct ridges between each of which lies a longitudinal row of punctations marking the openings of minute diverticulae in lumen wall, these extending to penial end of epiphallus and visible as striae in cut wall. Papillae lining penis lumen loosely arranged in longitudinal rows.

No spermatophores have been found, but the morphology of the epiphallus suggests that the tail region of the spermatophore may bear weak, longitudinal ridges and the anterior half will possess four to five rows of spinose projections.

Type material ( Fig. 56 ): Lectotype of Helix knysnaensis Pfeiffer, 1846 in BMNH (20080612) (designated Connolly 1912: 94), diameter 24.2 mm ( Figs 56A–C ), plus two paralectotypes (20080613). Holotype of Natalina coerneyensis Melvill & Ponsonby, 1894 in BMNH (1911.8.8.4), diameter 22.5 mm (23.3 mm fide Connolly 1939) ( Figs 56D–F ). Holotype of Natalina insignis Melvill & Ponsonby, 1907 in BMNH (1902.6.26.12) [Dr Schönland], diameter 29.4 mm ( Figs 56G, H ).

Additional material examined (all NMSA unless otherwise indicated): SOUTH AFRICA: North-western E. Cape (west of Great Fish R.): Nieu Bethesda area, Kompasberg slopes (31.79092°S: 24.55475°E), 1600 m, water course krantz in rocky grassland, beneath bushes and grass clumps, Herbert, Davis & Cole, 15/iii/2008, (W6097); Cradock (32.16220°S: 25.60580°E), 921 m, succulent karoo, at the base of Acacia, M. Cunningham , viii/2003 (W4248); Cradock (32.183°S: 25.617°E) (B0028, V5276, V6635, BMNH 1937.12.30.1376–7); Cradock (32.183°S: 25.617°E), ix/1897 (E7914); Cradock (32.183°S: 25.617°E), amongst loose boulders (1496); Graaff-Reinet (32.25°S: 24.55°E) (W1374); Graaff-Reinet, Camdeboo Nat. Park, Valley of Desolation view site (32.26585°S: 24.49203°E), 1350 m, in deep shaded gully between dolerite cliffs, D. Herbert, L. Davis & M. Cole, 14/iii/2008 (W6093); Mountain Zebra Nat. Park (32.24683°S: 25.43352°E), 1450 m, rocky outcrop on hilltop ridge, amongst rocks and under small bushes, Herbert, Davis & Cole, 17/iii/2008 (W6118); Witmoss, N of Cookhouse (32.533°S: 25.733°E), A. Reeve, ex J. Farquhar (B0046, BMNH 1937.12.30.1378–9); Somerset East, Glen Avon Nat.Res. (32.67436°S: 25.64463°E), 978 m, valley thicket/indigenous forest,A. Moussalli & D. Stuart-Fox, 24/xii/2005 (W4847); ditto, ‘Craigie Burn’ (32.6850°S: 25.6783°E) (B0025); ditto, Bosberg (32.70°S: 25.55°E) (3054, B0030, V6845); ditto, slopes of Bosberg (32.70257°S: 25.57605°E), indigenous woodland, in leaf-litter, D. Herbert, M. Bursey & G. Redman, 22/i/2002 (V9790); ditto, Bosberg Nat. Res. (32.70734°S: 25.55959°E), 777 m, indigenous forest, under rocks, A. Moussalli & D. Stuart-Fox, 24/xii/2005 (W4643); ditto, vicinity of camping grounds (32.70734°S: 25.55959°E), 771 m, indigenous forest, in leaf-litter, A. Moussalli & D. Stuart-Fox, 16/iii/2005 (W4846); Somerset East (32.717°S: 25.583°E), ex Mrs Howard and Dr Becker (B0027, B0026, V6841); Jansenville, Meerlust Suid farm (32.87148°S: 24.64085°E), rocky area with dense aloes and bush clumps, under dead aloes, D. Herbert, L. Davis & M. Cole, 12/iii/2008 (W6068); ditto (32.86520°S:24.67360], 450 m, rocky N facing hillside with aloes, noors and bush clumps, under dead aloes, D. Herbert, L. Davis & M. Cole, 11/iii/2008 (W6053); ditto, Fontein Camp (32.85977°S: 24.63966°E), 450 m, rocky area with aloes, noors and bush clumps, under dead aloes, D. Herbert, L. Davis & M. Cole, 11/iii/2008 (W6060); Jansenville, Alwynsfontein farm (32.87949°S: 24.60543°E), 500 m, valley floor with aloes, noors and bush clumps, under dead aloes, D. Herbert, L. Davis & M. Cole, 11/ iii/2008 (W6067); Koedoeskop farm SE of Somerset East (32.9753°S: 25.1717°E), 498 m, on stony ridge, specimen found trying to reach dead mouse in mammal trap, O. Bourquin, 06/xi/1998 (V6774). Southern E. Cape (south of Great Fish R.): Port Elizabeth (33.917°S: 25.600°E), F. Cruden, ii/1922 (1498, E7903); ditto, A.J. Peile (NMH 2242); ditto, MacAndrew coll’n, 05/i/1909 (BMNH un-numbered); Addo area, 6 km SW (33.593664°S: 25.648581°E), 30 m, aloes and other succulents, leg. B. Muller & M. Mostovski, 12/vii/2009 (W6930); Coerney (holotype of Natalina coerneyensis ) (33.4500°S: 25.7333°E) (BMNH 1911.8.8.4); Grahamstown, Teafontein farm (holotype of Natalina insignis ) (33.23300°S: 26.25417°E), Dr Schönland via J. Farquhar (BMNH 1902.6.26.12); Grahamstown, ‘St J. M.’, 31/iii/1909 (BMNH MacAndrew coll’n 1563); Port Alfred (33.6°S: 26.9°E) (W1395). Central E. Cape (north-east of Great Fish R.): Baviaans Valley between Bedford and Tarkastad, Wapadskloof, Huntley Glen farm (32.40945°S: 26.11472°E), under fallen stems of Aloe ferox and under stones, M. Bursey, 31/xii/2006 (W5255); Bedford (32.683°S: 26.083°E), J. Farquhar (B0015); Alice (32.783°S: 26.833°E) (V6839); Alice area, Breakfast Vlei (33.0833°S: 26.9500°E) (BMNH un-numbered); Fort Beaufort (32.783°S: 26.633°E), J.S. Taylor, x/ 1945 (V7729); Fort Beaufort, agricultural college farm (32.80544°S: 26.63381°E), valley thicket with aloes and euphorbs, in leaf-litter under fallen aloes, D. Herbert, L. Davis & M. Bursey, 07/iii/2007 (W5211); ~ 13 km N of Double Drift Game Res. (32.86658°S: 26.81436°E), 573 m, valley thicket, under dead aloes, A. Moussalli & D. Stuart-Fox, 2/xii/2005 (W4749, W5164).

Additional literature records (Connolly 1939; material not seen): SOUTH AFRICA: E. Cape: Enon, north of Port Elizabeth (33.40°S: 25.55°E), Hartwig; Sandflats Station [nr Paterson] (33.43°S: 26.95°E), J. Crawford .

Distribution ( Fig. 59 ): Endemic to E. Cape; occurs in the catchments of the Sundays and Great Fish rivers, from low altitudes near the coast to 1600 m in the Sneeuberge. The original type locality (Knysna) is evidently erroneous (see notes below for emendation).

Habitat: Found largely in the Albany Thicket biome ( Mucina & Rutherford 2006), and in isolated mist-belt forest patches within this, but also extending into the south-eastern Nama Karoo. Evidently catholic in its habitat requirements, but favouring patches of relatively dense vegetation. These, however, vary greatly in plant composition from forest to mixed woody thicket, spekboom thicket ( Portulacaria afra Jacq. ), Aloe – Euphorbia dominated scrub and, at higher altitudes, shrubby rock outcrops in more open Karoo escarpment grassland. Lives buried in leaf-litter beneath shrubs and bush clumps, under logs and fallen aloes, and amongst rocks; evidently not rare, but population densities generally low.

Notes: The material here treated as Afrorhytida knysnaensis exhibits considerable variation in shell proportions ( Fig. 57 ).This notwithstanding, the sculpture and coloration of the teleoconch is relatively consistent, as is the weak axial sculpture on the protoconch and the morphology of the radula, in which the outermost lateral tooth is the largest and there are many marginal teeth of intermediate size. The material thus identified forms a well-supported monophyletic clade in analyses of molecular data ( Moussalli et al. 2009), corroborating the morphological evidence. There is, however, considerable genetic diversity within this clade ( Fig. 1 ), indeed the highest level exhibited of the all the species examined here (e.g., mean uncorrected P-distances of 0.49 for the protein coding mitochondrial gene COI). Thus, there exists the possibility that this taxon constitutes more than one cryptic species.

H:D measurements indicate a north-west to south-east trend in shell proportions, with shells from the north-west being consistently less globose than those from the south-east ( Fig. 60 ). The dotted line in this figure, separating subglobose and lenticular populations, when redrawn on the distribution map to separate the same individuals ( Fig. 59 ), runs approximately south-west to north-east (St Francis Bay to Molteno), dividing the relatively elevated, subglobose south-eastern specimens from the more depressed, lenticular north-western individuals.Additionally, within the south-eastern region, shells from the Port Elizabeth area are noticeably smaller (adult diameter approx. 20 mm). There is, however, no clear disjunction evident within this north-west vs south-east trend in shell proportions ( Fig. 60 ). The line has been positioned for illustrative purposes, and in reality the variation is evidently more clinal than categorical. Some specimens are thus of intermediate proportions, but this notwithstanding, the trend is clear.

Somewhat similar geographic structuring is evident in DNA sequence data ( Moussalli et al. 2009), with analyses of such data identifying strongly supported clades from the Somerset East-Cradock area and from the eastern part of the Fish River valley (Fort Beaufort and Greater Fish River Conservancy). However, individuals from other localities do not cluster in a N–W to S–E pattern consistent with this. At present sequence data are available for too few specimens to determine the degree of concordance between phylogeographic structure and the geographic variation evident in shell proportions. Alternatively variation in shell proportions may not be genetically correlated, but may instead be determined by N–W to S–E variation in environmental parameters such as temperature and/or rainfall.

The small, subglobose individuals from the Port Elizabeth area are currently known from shells alone, there is thus no anatomical or molecular data to confirm that we are correct in referring them to A. knysnaensis . In addition to being small and relatively globose, they have a more elevated spire and a more acute apex ( Fig. 57B ). In this respect it is noteworthy that Pilsbry (1889) illustrated a radula under the name Aerope knysnaensis (locality unspecified) with 12 lateral teeth per half row. This figure is higher than any of the material examined herein, but an old radula slide in the Natal Museum labelled ‘ Natalina knysnaensis, Port Elizabeth’ (not associated with a shell) likewise has 12 lateral teeth per half row. Since Pilsbry’s material (sent by J. Ponsonby) may well have originated in the Port Elizabeth area, there is a possibility that this conchologically divergent population may in addition possess a somewhat distinct radula and perhaps represent a separate and undescribed species. Attempts to collect additional material in the Port Elizabeth area, so that this possibility could be explored further, have been unsuccessful.

The locality given in the original description is evidently erroneous, as is commonly the case with material from the Hugh Cuming collection ( Dance 1986). Knysna lies some 200 km west of the westernmost known records for this species. In accordance with recommendation 76A.2 of the Code ( ICZN 1999 ), we here emend the type locality to be Fort Beaufort. Specimens closely resembling the type series have been found recently in the vicinity of this town. The fort was constructed as a military frontier defence in 1822 and became established as a town in 1837. It is thus possible that material from this locality could have come into the possession of early 19 th century British collectors such as Cuming, well before its description in 1846 .

Synonymy: Connolly (1939) maintained ‘ Natalina ’ knysnaensis and ‘ N. ’ coerneyensis as distinct species, but stated that he would have placed coerneyensis ‘without hesitation in the synonymy of knysnaensis ’, were it not for differences in the radula. His assessment of the radula of ‘ N. ’ knysnaensis was based on a radula slide identified under that name in the Gwatkin collection (present in BMNH) with the locality “ Cape ”. This he compared with another radula slide in the same collection identified as ‘ N. ’ coerneyensis and the figure of the radula of ‘ N. ’ coerneyensis (from Coerney) published by Moss (1894). Re-evaluation of Connolly’s illustration of the ‘ N. ’ knysnaensis radula (Connolly 1939, text-fig. 9) and the slide still present in the BMNH, in the light of the data now available, indicates it was from an incorrectly identified specimen. The outer lateral teeth are relatively slender and the largest is clearly the penultimate one rather than the outermost one. This combined with the relatively large number of marginal teeth (16 per half row) indicates that the radula was in all probability from a specimen of A. kraussi . Since subglobose specimens typical of A. knysnaensis have a radula indistinguishable from that of topotypic specimens of ‘ N. ’ coerneyensis , we conclude that Natalina coerneyensis Melvill & Ponsonby, 1894 is a junior synonym of A. knysnaensis .Although the type material of A. knysnaensis is incorrectly localised, it is clearly subglobose and H:D ratios indicate that both names are likely to apply to the south-eastern population discussed above.

Natalina insignis Melvill & Ponsonby, 1907 is anatomically unknown. Attempts to find living material at the type locality were unsuccessful. Although large, the holotype falls within the range of variability exhibited by A. knysnaensis and a specimen of very similar shape (NMSA V6774 from Koedoeskop farm, SE of Somerset East ( Fig. 57F ), ca 120 km west of the type locality of N. insignis ) has a radula typical of A. knysnaensis and groups within this clade in molecular analyses ( Moussalli et al. 2009). We therefore consider this name to be a further synonym of A. knysnaensis . In terms of the H:D ratio these specimens are of somewhat intermediate shell proportions.

Figures

Fig. 6. Mantle edge anatomy of Afrorhytida, Capitina and Natalina, showing variation in left body lobe structure (all NMSA): (A) Afrorhytida knysnaensis (W5211); (B) Capitina calcicola sp. n. (W3201); (C) Natalina (Natalina) cafra natalensis subsp. n. (V8415); (D) Natalina (Tongalina) wesseliana (V7668).Abbreviations: lbl – left body lobe of mantle, pn – pneumostome, rbl – right body lobe of mantle.

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. 53. Afrorhytida knysnaensis (Pfeiffer, 1846), reproductive tract (NMSA W4643), scale bar = 5.0 mm. Abbreviations: ag – albumen gland, bc – bursa copulatrix, bd – bursa copulatrix duct, ep – epiphallus, ga – genital atrium, hd – hermaphrodite duct, od – oviduct, ot – ovotestis, p – penis, pr – prostate gland, pr – penial retractor muscle, v – vagina, vd – vas deferens.

Fig. 54. Penis and epiphallus of Afrorhytida species, cut open longitudinally to show internal structure (all NMSA): (A) A. knysnaensis, penis (W4248, Cradock); (B) A. knysnaensis, epiphallus (W4643, Somerset East); (C) A. trimeni, epiphallus (W4206, Kap R.); (D) A. burseyae sp. n., epiphallus (paratype, W5231/T2260); (E) A. kraussi kraussi, epiphallus (V6578, Wilderness). Abbreviations: d – diverticulae in epiphallus wall, dp – digit-like pilaster at end of ridge, ep – epiphallus, er – internal epiphallic ridge, ga – genital atrium, lg – longitudinal groove between well-developed folds on inner side of epiphallus, p – penis, pl – penis lumen with papillate lining, pr – penial retractor muscle, v – vagina, vd – vas deferens.

Fig. 55. Afrorhytida species, living animals (all NMSA): (A) A. knysnaensis, Fort Beaufort (W5211), shell diameter 19.0 mm; (B) A. knysnaensis, Cradock (W4248), shell diameter 22.0 mm; (C) A. knysnaensis, Kompasberg, Nieu Bethesda (W6097), shell diameter 20.4 mm; (D) A. kraussi kraussi, Featherbed Nat. Res., Knysna (W4671), shell diameter 16.8 mm; (E) A. k. kraussi, Grootvadersbosch (W5803), shell diameter 23.8 mm; (F) A. kraussi oraria subsp. n., De Hoop Nat. Res. (paratype, W3292/T2363), shell diameter 13.4 mm; (G) A. burseyae sp. n., Wedgeley farm, Kei River Valley (paratype, W5229/T2258), shell diameter 19.3 mm; (H) A. trimeni, Kap River (W4206), shell diameter 24.5 mm.

Fig. 56. Afrorhytida knysnaensis (Pfeiffer, 184), type material: (A–C) lectotype of Helix knysnaensis Pfeiffer, 1846 (designated Connolly 1912: 94) (BMNH 20080612), diameter 24.2 mm; (D–F) holotype of Natalina coerneyensis Melvill & Ponsonby, 1894 (BMNH 1911.8.8.4), diameter 22.5 mm; (G–I) holotype of Natalina insignis Melvill & Ponsonby, 1907 (BMNH 1902.6.26.12), diameter 29.4 mm.

Fig. 57. Afrorhytida knysnaensis (Pfeiffer, 1846) (all NMSA): (A) Fort Beaufort (W5211), diameter 25.6 mm; (B) Port Elizabeth (1498), diameter 19.3 mm; (C) Fort Beaufort (V7729), diameter 23.9 mm; (D) Bedford (B0015), diameter 23.4 mm; (E) Port Alfred (W1395), diameter 24.2 mm; (F) Koedoeskop, SE of Somerset East (V6774), diameter 23.3 mm; (G) Jansenville (W6060), diameter 23.5 mm; (H) Graaff-Reinet (W6093), diameter 19.6 mm; (I) Cradock (W4248), diameter 21.8 mm; J. Somerset East (V6845), diameter 21.2 mm; (K) Cradock (1496), diameter 22.4 mm; (L) Kompasberg, Nieu Bethesda (W6097), diameter 20.4 mm. (A–E) globose specimens, (F–I) intermediate specimens, (J–L) lenticular specimens.

Fig. 58. Afrorhytida knysnaensis (Pfeiffer, 1846), radula: (A–C) Fort Beaufort (NMSA W5211): (A) entire width of radula, scale bar = 0.5 mm; (B) rachidian and inner lateral teeth, scale bar = 150 µm; (C) outer lateral and marginal teeth, scale bar = 250 µm; (D) Cradock (NMSA W4248), outer lateral and marginal teeth, scale bar = 250 µm.

Fig. 59. Distribution of Afrorhytida knysnaensis (Pfeiffer, 1846). Triangles with a white centre indicate localities for specimens used in DNA analyses (Moussalli et al. 2009); contours at 1000 m and 1500 m. The dashed line between St Francis Bay and Molteno corresponds to the similar line drawn in Fig. 60, separating populations with more lenticular shells (north-west) from those with subglobose shells (south-east).

Fig. 60. Afrorhytida knysnaensis (Pfeiffer, 1846), plot of height/diameter measurements, showing differing shell proportions in different populations.The diagonal dashed line corresponds to the line drawn between St Francis Bay and Molteno in the distribution map (Fig. 59).

Fig. 1. All compatible Bayesian consensus tree based on mixed model partitioned analysis of the combined nucleotide dataset (16S and COI = GTR + IΓ, ITS2 = GTR+I). Asterisk indicates nodal support>95 % posterior probability (PP); PP below 95 % are not shown. (From Moussalli et al. 2009)