Kerkophorus scrobicolus, 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 : 17-22

Kerkophorus scrobicolus sp. nov.

urn:lsid:zoobank.org:act:EB0294D6-0D65-432A-9B63-A72299417580

Figs 11–15

Diagnosis

Characterised by its relatively wide umbilicus, tight coiling, lenticular to globose-lenticular profile, weakly angled periphery, smooth protoconch, somewhat glossy surface and uniform colour (no peripheral brown spiral line).

Etymology

From the Anglo-Saxon ‘ scrob ’ a shrub and the Latin ‘ colus ’, dweller, inhabitant; referring to the climbing habit of the species.

Material examined

Holotype

SOUTH AFRICA: E Cape, Mkambati Nature Reserve , 31.31374° S, 29.96914° E, 71 m, coastal dune forest, on understorey foliage, A. Moussalli and D. Stuart-Fox leg., 1 Nov. 2005 ( NMSA W4109/T4164 , dry shell with body in ethanol).

Paratypes (listed north to south)

SOUTH AFRICA: KwaZulu-Natal: Umtamvuna Nature Reserve, Beacon Hill, 31.001459° S, 30.168292° E, M. Bursey leg., 10 Dec. 2006 ( ELM W3150/T157, two dry shells with bodies in ethanol, three whole juvenile specimens in ethanol); Umtamvuna Nature Reserve, below Clearwater Camp, 31.04361° S, 30.16806° E, 205 m, riverine forest in gorge on E bank of river, under leaves, M. Bursey leg., 9 Dec. 2006 ( NMSA W5258/T4166, two dry shells with bodies in ethanol). — E Cape: Mkambati Nature Reserve, ‘Super Bowl’ forest, 31.297840° S, 29.929333° E, M. Bursey and V. Ndibo leg., 18 Oct. 2005 ( ELM W2870/T156, two dry shells and one juvenile specimen in ethanol); Mkambati Nature Reserve, ‘Super Bowl’ forest at junction of Msikaba and KwaDlambu Rivers, 31.2979° S, 29.9294° E, 200 m, indigenous forest, under leaves of understorey vegetation, D. Herbert leg., 5 Mar. 2001 ( NMSA V8911/T4163, two dry shells with one body in ethanol); Mkambati Nature Reserve, ‘Super Bowl’ forest, 31.29892° S, 29.92872° E, 208 m, coastal indigenous forest, on understorey foliage, A. Moussalli and D. Stuart-Fox leg., 1 Nov. 2005 ( NMSA W4111/T4165, one dry shell with body in ethanol).

Other material

SOUTH AFRICA: E Cape: Mkambati Nature Reserve, Horseshoe Falls on Mkambati River, 31.2673° S, 30.0121° E, 70 m, forest on N bank below falls, in leaf-litter, D. Herbert leg., 6 Mar. 2001 ( NMSA V9006); Mkambati Nature Reserve, 31.29599° S, 29.92570° E, 156 m, forest, Earthwatch ‘Hidden Species’, 31 Jan. 2008 ( NMSA W6342).

Description

SHELL ( Fig. 11 ). Lenticular to globose-lenticular, spire remaining relatively prominent; periphery at midwhorl, weakly angled; H:D 0.66–0.69 (N=4); suture shallowly indented, inserting just above periphery; thin, translucent, uniformly pale buff to pale honey-coloured; surface glossy but with a slight silky sheen. Protoconch diameter 1.80–1.93 mm (N=4); junction with teleoconch weakly marked; essentially smooth with only traces of microspiral sculpture. Teleoconch of up to 4.25 whorls; coiling relatively tight, whorls not expanding rapidly; sculptured by weak growth-lines and exceptionally fine and closeset, microscopic spiral lines. Umbilicus open and relatively wide. Aperture obliquely lunate, upper portion of columella lip reflected and partially obscuring umbilicus. Diameter up to 16.4 mm; holotype, diameter 15.3 mm, height 10.1 mm.

LIVING ANIMAL ( Fig. 12 ). Head-foot fawn-brown, optic tentacles and their retractor muscles slightly darker; body lobes of mantle of similar coloration to body; shell lobes well developed, slender and elongate; caudal appendage dark grey. Lining of pulmonary cavity variously speckled with irregular black and cream pigment spots and blotches; a large, more diffuse dark blotch lies just above and behind pneumostome; mantle margin beneath outer lip of shell bordered by a narrow cream line, broader above pneumostome. Spire viscera darker brown, with scattered irregular cream markings.

RADULA ( Fig. 13 ). Formula R+13+(1–2)+(130–140); rachidian tricuspid, mesocone broad and ectocones relatively small; anterior margin of shaft base not indented in mid-line; 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 teeth of intermediate shape and then a very long series of marginals; marginals stout and strongly curved, terminally bicuspid, with additional irregular serrations on outer edge of shaft; marginals progressively decreasing in size toward edge of radula, but otherwise morphologically similar.

DISTAL GENITALIA ( Fig. 14 A–C). Penis encased in thin sheath and with a distinct S-shaped bend or kink in basal half; retractor muscle attached to penis apex. Interior of penis lacking a distinct verge, but with a constriction at approximately one-third of its length from base; lumen below constriction with low longitudinal folds bearing minute, close-set, transverse wrinkles; lumen above constriction with smooth longitudinal folds ( Fig. 14B ). Epiphallus very short; caecum cylindrical, approximately equal to epiphallus in length, hollow, lined with widely spaced, interrupted longitudinal ridges; caecum arising very close to penis apex and retractor muscle. Flagellum stout and relatively short, comprising 1–2 whorls, f1 with distinct transverse internal structure, broadest in mid-region and tapering distally; f2 slender, straight in some specimens, slightly twisted in others, and with a central tube-like core that extends into (beneath) f1; 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 welldeveloped stimulator projecting into atrial lumen, below opening of vagina ( Fig. 14C ); stimulator rolled to form an open tube; remainder of atrial wall with numerous, close-set, longitudinal folds; vagina relatively short; gametolytic sac almost spherical and thin-walled, its duct of moderate length; base of free oviduct swollen, dark brown to black in fresh material; spermoviduct divided into distinct prostatic and oviductal portions.

SPERMATOPHORE ( Fig. 14D ). Elbowed, with a crescent-shaped capsule and a bifid tail comprising a short, relatively stout and elaborately spinose element of approx. 1.25 whorls and a long, slender, spineless element that splits off the spinose element shortly after is origin from capsule; proximal portion of spinose element with a row of spines on each side, rows converging distally and ending as a single row of progressively smaller, less elaborate spines that continue to tip; larger spines flabellate and very finely divided (plumose), terminal branches deeply V-shaped, with curved, pointed tips. Slender element has a loose coil of approx. one whorl close to its base, but otherwise straight for much of its length. Coiled length of entire spermatophore approx. 9.0 mm.

Distribution ( Fig. 15 )

A narrow-range endemic, known only from the coastal hinterland in the extreme south of KwaZulu- Natal and the north-eastern E Cape (Pondoland); at altitudes between 70 m and 210 m above sea level.

Habitat

Northern Coastal Forest and Scarp Forest ( Mucina & Rutherford 2006); on leaves of understorey vegetation during the wet summer months.

Remarks

Kerkophorus scrobicolus sp. nov. resembles K. puzeyi ( Connolly, 1939) , but lacks the marked peripheral angulation characteristic of that species. Neither does it possess the peripheral brown spiral line usually present in K. puzeyi and in the latter the umbilicus is also narrower and more extensively obscured by the reflected columella lip. In addition, although relatively few specimens of K. scrobicolus sp. nov. are available, it appears that it does not attain as large a size as does K. puzeyi (diameter up to 23 mm).

The anatomy of the distal genitalia of the two species exhibits no obvious differences and, judging by one damaged example, the spermatophore of K. puzeyi also has a bifid tail and is of similar morphology to that of K. scrobicolus sp. nov. This is a feature that I have not observed in other species of Kerkophorus for which spermatophores are available and it may be a synapomorphy indicative of a sister-species relationship. Spermatophores with bifid tails also occur in species of Microkerkus , but in these the spinose limb is much less elaborate, and the morphology of their distal reproductive tract is clearly distinct.

Both K. puzeyi and K. scrobicolus sp. nov. are restricted to forests in close proximity to the coast and, based on existing records, the ranges of the two do not overlap. K. puzeyi occurs to the south of K. scrobicolus sp. nov., ranging from Mbotyi to the Mazeppa Bay area. The interval between the ranges of the two species is only approximately 25 km, but this largely comprises a hinterland of grassland with high coastal cliffs (Waterfall Bluff), which may have limited the potential for genetic exchange, particularly during glacial periods when the extent of coastal forest cover would have been more restricted compared to warmer interglacial periods.

Conservation

Given that the total known range of Kerkophorus scrobicolus sp. nov. extends for a linear distance of only ± 40 km, the species must be considered one of conservation concern. In general, the forests in this region are threatened by a number of activities including on-going coastal development, smallscale agriculture, alien plant invasion, subsistence harvesting of forest products and the incursion of livestock. Those close to the coast are also threatened by dune mining for heavy metals. However, the two localities at which K. scrobicolus sp. nov. has been found are formally conserved areas, namely Umtamvuna and Mkambati nature reserves. Thus, provided that conservation protocols are maintained in these reserves, the populations at these localities will be afforded a degree of protection.

Figures

Fig. 11. Kerkophorus scrobicolus sp. nov. A–C. Holotype, diameter 15.3 mm (NMSA W4109/T4164). D. Umtamvuna, KwaZulu-Natal, diameter 16.4 mm (paratype, NMSA W5258/T4166).

Fig. 12. Kerkophorus scrobicolus sp. nov., living animal, Mkambati Nature Reserve, E Cape, shell diameter 14.1 mm (paratype, NMSA V8911/T4163).

Fig. 13. Kerkophorus scrobicolus sp. nov., holotype, radula (NMSA W4109/T4164). 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 = 100 μm; B–D = 50 μm.

Fig. 14. Kerkophorus scrobicolus sp. nov., genitalia and spermatophore. A–C. Holotype (NMSA W4109/ T4164). A. Distal portion of genital tract. B. Dissection of penis showing difference in structure of lumen wall between apical and basal portions. C. Dissection of genital atrium and penis sheath to show atrial stimulator and kinked penis. D. Spermatophore with bifid tail (paratype, NMSA V8911/T4163).

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.