Kerkophorus terrestris, 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 : 23-27

Kerkophorus terrestris sp. nov.

urn:lsid:zoobank.org:act:CE081A36-1D43-4736-8BE3-15D3677FD0D6

Figs 15–19

Diagnosis

Rendered distinctive by the fine but well-defined spiral sculpture on the protoconch, silky texture of the apical surface, lack of a peripheral brown spiral line, and the relatively wide umbilicus.

Etymology

From the Latin ‘ terra ’, earth, and ‘ terrestris ’, of the earth; referring to the ground-dwelling habit of the species.

Material examined

Holotype

SOUTH AFRICA: E Cape, Mbhashe River valley, Collywobbles , beside thatched picnic site, 32.00442° S, 28.58172° E, 510 m, valley thicket, in leaf-litter under bushes and aloes, D. Herbert and L. Davis leg., st. 06-010, 20 Feb. 2006 ( NMSA W3979/T3862 , dry shell with body in ethanol).

Paratypes (listed north to south, all E Cape)

SOUTH AFRICA: Port St Johns area, crater-like travertine deposit on S side of Umzimvubu River valley, 31.52053° S, 29.45662° E, 90 m, valley thicket, in leaf-litter, D. Herbert, L. Davis and M. Bursey leg., 22 Apr. 2005 ( NMSA W2933/T3863, 18 dry shells with three bodies and two whole juveniles in ethanol; RMNH.5004185, one dry shell); Port St Johns, Mt Thesiger, near airstrip (Mpembeni), 31.61° S, 29.52° E, 365 m, M. Hamer leg., 20 Jun. 1998 ( NMSA V6515/T3859, three dry shells with bodies and one whole specimen in ethanol); Port St Johns, vicinity of Mpembeni airstrip, 31.60785° S, 29.51461° E, 364 m, grassland/rocky outcrop, in rock crevice, A. Moussalli and D. Stuart-Fox leg., 12 Nov. 2005 ( NMSA W4134/T3860, two dry shells with bodies in ethanol, plus one whole juvenile in ethanol); Mthatha area, Buntingville, approx. 31.652° S, 28.883°E, approx. 650 m, Miss J.F. Barrett leg., ex Transvaal Museum 1978 ( NMSA W1399/T3861, two dry shells); Mbhashe River valley, Collywobbles, overlooking vulture colony, 32.00396° S, 28.59530° E, 585 m, sparse valley thicket invaded with Lantana , in leaf-litter under aloes and bushes, D. Herbert and L. Davis leg., st. 06-011, 20 Feb. 2006 ( NHMUK 20160242, one dry shell; NMSA W4076/T3390, eight dry shells with one body in ethanol); Kei Pass, 32.49364° S, 27.99175° E, 282 m, valley thicket, under rock, A. Moussalli and D. Stuart-Fox leg., 23 Nov. 2005 ( NMSA W4172/T3391, one dry shell with body in ethanol); Sihota, W bank of Kei River, approx. 2.5 km upstream of Kei Bridge, below Moordenaars Kop, 32.50445° S, 27.94945° E, 200 m, alive in soil under fallen Aloe ferox, M. Cole leg., 9 Jan. 2008 ( ELM D15947/T158, one dry shell; ELM D15815/T159, 65 dry shells; NMSA W6387/T3858, 10 dry shells with two bodies and one whole juvenile in ethanol).

Description

SHELL ( Fig. 16 ). Lenticular, but spire remaining relatively prominent; periphery at mid-whorl, evenly rounded; H:D 0.63–0.73 (N=19); suture shallowly indented, inserting above periphery; thin, translucent, pale brownish-yellow to straw-brown when fresh, colour more or less uniform, peripheral brown spiral line absent; apical surface silky, lustreless, base somewhat more glossy. Protoconch diameter 1.47– 1.67 mm (N=5); junction with teleoconch usually weakly marked; sculpture comprising numerous fine but distinct, close-set microscopic incised spiral striae ( Fig. 16E ); no evidence of punctation. Teleoconch of up to 3.5 whorls; coiling relatively tight, whorls not expanding rapidly; spiral sculpture of protoconch continues on first whorl, becoming progressively finer with growth, but remaining evident on last adult whorl in form of exceptionally fine and close-set, microscopic spiral lines, giving surface its silky sheen; slightly coarser axial lines also evident in places, but mostly inconspicuous; spiral microsculpture obsolete on base and surface more glossy; teleoconch otherwise only with uneven growth irregularities. Umbilicus open and relatively wide. Aperture roundly and obliquely lunate, upper portion of columella lip strongly reflected and partially obscuring umbilicus. Diameter up to 13.7 mm; holotype, diameter 13.1 mm, height 8.3 mm.

LIVING ANIMAL ( Fig. 17 ). Head-foot colour variable, some specimens pale greyish-brown with yellowishorange pigment granules concentrated in skin tubercles and along pedal margin ( Fig. 17A ), others with a distinctly reddish hue ( Fig. 17B ); mantle lobes of similar coloration to body, pigmentation more dense near pneumostome; tentacles and tip of caudal appendage dark grey. Spire viscera and lining of pulmonary cavity with numerous irregular yellowish-white blotches and little dark pigmentation except for a band of dark pigment overlying primary ureter, and a narrow black line on mantle margin beneath outer lip of shell.

RADULA ( Fig. 18 ). Formula R+(9–10)+(1–2)+(60–70); rachidian tricuspid, somewhat asymmetrical; laterals essentially bicuspid with a mesocone and strong basal ectocone, but also with a minute endocone on side of mesocone; 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, indistinct and irregular serrations; marginals progressively decreasing in size toward edge of radula, but otherwise morphologically similar.

DISTAL GENITALIA ( Fig. 19 A–C). Penis with a distinct S-shaped bend or kink in mid-region, dividing it into a relatively slender apical portion and a somewhat broader basal portion, the whole encased in a thin sheath; retractor muscle attached to penis apex. Lumen of basal portion of penis with numerous, fine, close-set papillae and with two thickened pilasters in its lower half that extend from folds in upper part of atrium; lumen of apical portion of penis with slender longitudinal folds; no evidence of a penial verge. Epiphallus very short; caecum well developed, arising close to penis–epiphallus junction, near origin of penial retractor muscle; caecum elongate, longer than epiphallus, its tip somewhat swollen. Flagellum divided into two portions; basal portion (f1) broader and with distinct transverse internal structure; apical portion (f2) longer and more slender, with a tube-like central core. Junction of epiphallus and flagellum, at insertion of vas deferens, with opaque white contents; vas deferens simple and slender. Genital atrium swollen, internal wall with a well-developed stimulator projecting into atrial lumen below opening of vagina; additional folds running from base of stimulator toward penis base; stimulator flaccid rather than muscular, its contracted shape variable between individuals; vagina long; gametolytic sac ovate and thin-walled, its duct relatively short; base of free oviduct swollen, yellowish-brown; spermoviduct divided into distinct prostatic and oviductal portions.

SPERMATOPHORE ( Fig. 19D ). Elbowed, with a slender elongate capsule (length approx. 4.6 mm) and a very long, complexly coiled tail; proximal portion of tail smooth, followed by ± 1.5 coils bearing a single row of approx. 35 rather short and stout, branched spines; proximal 3–4 spines rapidly increasing in size, those in mid-region of more or less uniform size, then decreasing gradually in size toward spineless region; spines flabellate, terminating in shallowly and broadly V-shaped bifurcations, some almost T-shaped; distal half of tail lacking spines, very slender and somewhat randomly looped and entwined upon itself.

Distribution ( Fig. 15 )

A relatively narrow-range endemic, known only from the southern portion of the Transkei region, E Cape, South Africa, specifically the lower catchments of the Umzimvubu, Mbhashe and Kei rivers, and smaller intervening rivers; from 90 m to 650 m above sea level.

Habitat

Found primarily in the Eastern Valley Bushveld ( Mucina & Rutherford 2006); ground-dwelling, living under rocks and fallen aloes, in leaf-litter beneath bushes and in crevices in rock outcrops.

Remarks

Kerkophorus terrestris sp. nov. is a well characterised species that can be confused with few others. The combination of distinct spiral sculpture on the protoconch, lustreless surface and open umbilicus is exhibited by few other southern African urocyclids. Having said this, the species is very similar to Sheldonia crawfordi (Melvill & Ponsonby, 1890) from the southern and eastern Karoo. In that species,

however, the protoconch has the distinctive punctations with both an axial and spiral alignment seen in many species of Sheldonia s.s. It also attains a considerably larger size (diameter up to 21 mm).

The spermatophore of K. terrestris sp. nov. is atypical for the genus in having only a single row of spines, and in these being relatively short and stout, with shallowly bifurcating branch tips. Spines of this form are more typical of Sheldonia s.s., but species of that genus also have a double row of nodules on the distal portion of the spermatophore tail (cf. S. fingolandensis sp. nov., below).

The atypical spermatophore, together with the long vagina and distinct spiral microsculpture on the protoconch, set K. terrestris sp. nov. apart from other members of Kerkophorus , suggesting perhaps that it belongs to a separate lineage.

Conservation

The distribution of Kerkophorus terrestris sp. nov. extends for approximately 180 km along the coastal hinterland of the Transkei region of E Cape. In this region there are few formally protected areas and none of the localities at which this species has been recorded fall within such areas. Conservation of the species will depend upon the preservation of its favoured Eastern Valley Bushveld habitats. Currently such habitats are viewed as ‘least threatened’ ( Mucina & Rutherford 2006), although alien invasive plants are a concern. Though not wide-ranging, where it occurs, K. terrestris sp. nov. is not rare and there is little to suggest that the species is under threat. Nonetheless, its limited range could provide additional motivation for the designation of protected areas in Eastern Valley Bushveld habitats, particularly in the lower reaches of the Umzimvubu, Mbhashe and Kei river valleys. Currently, less than 1% of this vegetation type is formally protected ( Mucina & Rutherford 2006).

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. 16. Kerkophorus terrestris sp. nov. A–D. Holotype, diameter 13.1 mm (NMSA W3979/T3862). E. Close-set microspiral sculpture on protoconch, scale bar = 200 μm (paratype, NMSA W2933/T3863).

Fig. 17. Kerkophorus terrestris sp. nov., living animals. A. Collywobbles, E Cape, shell diameter 13.1 mm (holotype, NMSA W3979/T3862). B. Mount Thesiger, Port St Johns, E Cape, shell diameter 10.7 mm (paratype, NMSA V6515/T3859).

Fig. 18. Kerkophorus terrestris sp. nov., radula (holotype, NMSA W3979/T3862). A. Rachidian and left lateral teeth. B. Rachidian and innermost lateral teeth. C. Inner left marginal teeth. D. Outer left marginal teeth. Scale bars: A, C–D = 50 μm; B = 25 μm.

Fig. 19. Kerkophorus terrestris sp. nov., genitalia and spermatophore. A. Entire genital tract (holotype, NMSA W3979/T3862). B. Basal region of penis opened to show papillate lumen and longitudinal pilasters (paratype, NMSA V6515/T3859). C. Genital atrium dissected to show internal folds and atrial stimulator; in this specimen the male system has not been unravelled and the vas deferens is shown in its normal position (paratype, NMSA W4172/T3391). D. Spermatophore (paratype, NMSA W4172/ T3391).