Selatodryas roseosoma, Herbert, 2017

Herbert, David G., 2017, A new genus and eight new species of tail-wagger snails from eastern South Africa, with a key to genera within Sheldonia s. l. (Gastropoda: Urocyclidae), European Journal of Taxonomy 309, pp. 1-50 : 33-37

Selatodryas roseosoma gen. et sp. nov.

urn:lsid:zoobank.org:act:02EF7ACF-2BE4-4435-A973-2FEEDC3BACA3

Figs 15 , 23–26

Diagnosis

Characterised by the low-spired, glossy yellowish-brown shell, non-punctate protoconch and columella that runs into the axis of coiling rather than fusing with the parietal region. Distal genitalia with relatively long flagellum of which f1 comprises approx. three whorls.

Etymology

From the Latin ‘ roseus ’, rose-coloured, and the Greek ‘ soma ’, body; referring to the reddish-pink coloration of the living animal.

Material examined

Holotype

SOUTH AFRICA: E Cape, Maclear district, Redcliffe valley , 31.00750° S, 28.16429° E, 1538 m, patches of montane forest in gullies, M. Bursey leg., 23 Jan. 2007 ( NMSA W5379/T3865 , dry shell with body in ethanol).

Paratypes (listed north to south, all E Cape)

SOUTH AFRICA: same data as holotype, adults under logs, immatures under leaves ( ELM W3162/ T162, two dry shells with bodies in ethanol; NMSA W5257/T3867, one dry shell with one body and one whole specimen in ethanol; NMSA W5380/T3866, eight dry shells); Maclear district, Redcliffe valley, 31.00962° S, 28.16209° E, 1500 m, southern mistbelt forest, in leaf-litter amongst Dietes clumps, D. Herbert, S. Bell-Cross and L. Davis leg., 11 Apr. 2014 ( NHMUK 20160244, two dry shells; RMNH.5004186, two dry shells); Maclear district, Redcliffe valley, 31.01103° S, 28.15975° E, 1500 m, patches of montane forest in gullies, adults under dead logs, immatures under leaves, M. Bursey and S. Bell-Cross leg., 18 Feb. 2003 ( NMSA W5005/T3870, two dry shells with bodies in ethanol; W5381/ T3864, three dry shells; ELM D15747/T163, ten dry shells); Maclear district, Minniehaha, 31.02972° S, 28.17888° E, 1660 m, patches of montane forest in gullies, adults under dead logs, immatures under leaves, M. Bursey, 24 Jan. 2007 ( NMSA W5382/T3869, one dry shell with body in ethanol); Prentjiesberg, 31.04192° S, 28.20285° E, 1386 m, indigenous forest, general searching, M. Hamer et al. leg., MTDP 5389, 9 Feb. 2006 ( NMSA W4462/T3868, two dry shells with body of one in ethanol); Prentjiesberg, 31.06729° S, 28.19450° E, 1416 m, indigenous forest, ground searching, M. Hamer et al. leg., site F61, 8 Feb. 2006 ( NMSA W5063/T3871, two dry shells, with two bodies and one whole specimen in ethanol); Prentjiesberg, 31.15505° S, 28.20529° E, 1534 m, indigenous forest, ground searching, M. Hamer et al. leg., site F65, 7 Feb. 2006 ( NMSA W5073/T3872, three dry shells with three bodies and one whole specimen in ethanol).

Other material (listed north to south, all E Cape, NMSA)

SOUTH AFRICA: Maclear district, Woodcliffe valley, 30.94833° S, 28.17194° E, indigenous forest, under leaves, esp. Rapanea melanophoeos, M. Bursey leg., 17 Feb. 2003 (W9627, W9628, ethanol material only); Maclear district, Woodcliffe valley, 30.98818° S, 28.15246° E, 1415 m, southern mistbelt forest, dead in leaf-litter, D. Herbert and L. Davis leg., st. 14-04, 12 Apr. 2014 (W9724); Maclear district, Redcliffe valley, 31.00962° S, 28.16209° E, 1500 m, southern mistbelt forest, in leaf-litter amongst Dietes clumps, D. Herbert, S. Bell-Cross and L. Davis leg., 11 Apr. 2014 (W9722); Prentjiesberg, 31.06729° S, 28.19450° E, 1416 m, indigenous forest, ground searching, M. Hamer et al. leg., site F61, 8 Feb. 2006 (W9690); Prentjiesberg, 31.06895° S, 28.18844° E, 1447 m, indigenous forest, M. Hamer et al. leg., site F63, 4 Feb. 2006 (W5065); Prentjiesberg, 31.07319° S, 28.17802° E, 1640 m, indigenous forest, ground searching, M. Hamer et al. leg., site F64, 5 Feb. 2006 (W5071).

Description

SHELL ( Fig. 23 ). Lenticular; periphery at mid-whorl, evenly rounded; H:D 0.61–0.69 (N=11); suture rather distinctly indented, inserting just above periphery; very thin and delicate; translucent, more or less uniformly yellowish-brown, some specimens with a greenish tint; apical and basal surfaces both glossy. Protoconch diameter 1.68–1.87 mm (N=10); essentially smooth, but with extremely fine, closeset, microscopic scratch-like spiral lines; no evidence of punctation; junction with teleoconch usually weakly marked. Teleoconch of up to 2.25 whorls; whorls expanding moderately rapidly; spiral sculpture virtually obsolete, later whorls with only the finest traces of microscopic, close-set, wavy, spiral ripples, even weaker on base; teleoconch otherwise only with weak, uneven growth irregularities. Umbilicus absent, edge of columella lip reflected and slightly thickened with a thin, whitish, somewhat pleated callus; columella running into axis of coiling rather than fusing with parietal region; aperture roundly lunate. Diameter up to 15.0 mm; holotype, diameter 14.9 mm, height 9.6 mm.

LIVING ANIMAL ( Fig. 24 ). Head-foot predominantly reddish-pink, coloration due to presence of numerous microscopic pigment granules; tentacles dark grey-black; caudal appendage well developed, dark grey; peripodial groove distinct and skin grooves on tail region well defined. Body lobes of mantle extensive, coloration similar to that of head-foot; shell lobes well developed; mantle edge bordered internally by a thin cream line behind which is a diffuse grey band; a small dark grey spot on mantle edge posterior to pneumostome; lining of pulmonary cavity with little pigmentation save for sparse irregular cream specks, particularly below suture; spire viscera brown with somewhat more conspicuous cream specks; primary ureter delimited by a diffuse grey band, kidney region pale orange-yellow.

RADULA ( Fig. 25 ). Formula R+11+(1–2)+(80–90); rachidian tricuspid, anterior edge of shaft base with V-shaped mid-line notch; laterals essentially bicuspid with a mesocone and strong basal ectocone, but also with a minute endocone on side of mesocone; shaft of laterals rectangular (longer than wide) with mesocone set at a distinct angle to long axis of shaft; laterals followed by 1–2 intermediary teeth and then a long series of marginals; marginals curved, bearing a large terminal cusp with a smaller subterminal cusp on outer (concave) margin, followed by a series of small serrations; marginals progressively decreasing in size toward edge of radula, but otherwise morphologically similar.

DISTAL GENITALIA ( Fig. 26 A–B). Penis long, enveloped in a thin sheath, apical part variously looped within sheath; basal half somewhat broader and with thin, spongy wall, lumen with fine close-set transverse folds throughout; apical half narrower, its wall muscular, lumen with longitudinal folds; retractor muscle attached to penis apex. Epiphallus long, distal portion little differentiated from penis; an elongate caecum arises at approx. one-third length of epiphallus from insertion of vas deferens; caecum curved or sinuous; proximal third of epiphallus wider, its wall less muscular. Flagellum of moderate length, tightly coiled; f1 comprising approx. 3.0 whorls, with distinct transverse internal structure; f2 very short, with tubular core. Base of flagellum and proximal region of epiphallus, close to insertion of vas deferens, with opaque white contents; vas deferens slender. Genital atrium small and simple, lacking any accessory modifications; penis base with a weak flange prior to its junction with atrium; vagina long. Gametolytic sac large, its duct relatively short; sac variable in shape and with thin wall. Base of free oviduct swollen, pale apricot in colour; spermoviduct divided into distinct prostatic and oviductal portions.

SPERMATOPHORE ( Fig. 26C ). Elbowed, with a large capsule and well-developed tail (tail length approx. 5.5 mm); tail coiled into approximately three revolutions with branched spines; spines possessing up to eight T-shaped tips on initial 1.5 whorls, but those on distal whorl un-branched, the tip remaining T-shaped rather than pointed; spineless tip of tail short and slender.

Distribution ( Fig. 15 )

A narrow-range endemic, known only from the edge of the Great Escarpment in the Maclear–Ugie area (Prentjiesberg), E Cape, South Africa; at altitudes between 1385 m and 1660 m above sea level.

Habitat

Patches of Southern Mistbelt Forest ( Mucina & Rutherford 2006) on south-facing slopes below sandstone cliffs of the ‘Little Berg’; under logs, amongst clumps of forest floor plants, e.g., Dietes spp. (mostly adults) and on the leaves of understorey plants (juveniles).

Remarks

Characters separating Selatodryas roseosoma gen. et sp. nov. from S. luteosoma gen. et sp. nov. are given in the remarks for that taxon.

Conservation

The limited range of Selatodryas roseosoma gen. et sp. nov. renders it a species of conservation concern. The forests in which it occurs are located largely on privately owned farmland. On-going maintenance of the current relatively pristine condition of these forests is thus not secure and is dependent on the environmental oversight exercised by the landowners. Commercial forestry plantations exist in the area, but they are mostly situated at a slightly lower altitude, some distance away from the escarpment-edge forests. Potential threats include livestock disturbance of the forest understorey and runaway fires in the surrounding grasslands.

Figures

Fig. 15. Distribution of Kerkophorus scrobicolus sp. nov. (asterisks), Kerkophorus terrestris sp. nov. (circumpuncta), Selatodryas luteosoma gen. et sp. nov. (pentagons), S. roseosoma gen. et sp. nov. (triangles) and Sheldonia fingolandensis sp. nov. (squares). Contours at 1000 and 1500 m.

Fig. 23. Selatodryas roseosoma gen. et sp. nov., holotype, diameter 14.9 mm (NMSA W5379/T3865).

Fig. 24. Selatodryas roseosoma gen. et sp. nov., living animal, Redcliffe, Maclear, E Cape, shell diameter 10.5 mm (NMSA W9722).

Fig. 25. Selatodryas roseosoma gen. et sp. nov., holotype, radula (NMSA W5379/T3865). A. Rachidian and left lateral teeth. B. Rachidian and innermost lateral teeth. C. Inner right marginal teeth. D. Outer left marginal teeth. Scale bars: A = 100 μm; B–C = 50 μm; D = 25 μm.

Fig. 26. Selatodryas roseosoma gen. et sp. nov., genitalia and spermatophore. A. Entire genital tract. B. Flagellum. C. Spermatophore. A–B. Paratype (NMSA W4462/T3868). C. Holotype (NMSA W5379/ T3867).