Gulella nkandla, Cole & Herbert, 2023

Cole, Mary L. & Herbert, David G., 2023, Seven new narrowly endemic species of Gulella Pfeiffer, 1856 from eastern South Africa (Gastropoda, Streptaxidae) and status revision for another, European Journal of Taxonomy 900 (1), pp. 1-31 : 19-21

Gulella nkandla sp. nov.

urn:lsid:zoobank.org:act:A7752B1D-EEB9-474F-B53D-BAA9A42F4AE0

Figs 9–10

Diagnosis

Shell very small, sub-cylindrical; smooth and glossy; aperture markedly constricted by teeth and narrower towards base; apertural dentition four-fold, including an oblique parietal lamella, a large rounded labral tooth, its outer face concave and its upper margin sinuous, bearing a small cusp near lip edge, an inset tooth in centre of base and a large elongate inset columella lamella; apertural tube behind columella lip somewhat expanded and collar-like; umbilicus very small with distinct peri-umbilical pleats.

Etymology

Named for the type locality, the Nkandla Forest Reserve, KwaZulu-Natal.

Type material

Holotype SOUTH AFRICA – KwaZulu-Natal • Nkandla Forest Reserve, 37 km NW of Eshowe, Chibini area ; 28.7233° S, 31.1317° E; ± 1200 m a.s.l.; 14 Jan. 2010; M. Cole leg.; NMSA-Mol 0P2361/T4610, ex

ELMD 16456.

Paratype SOUTH AFRICA – KwaZulu-Natal • 1 spec.; Nkandla Forest Reserve , near picnic site north of main road, mistbelt forest; 28.7347° S, 31.1439° E; ± 1040 m a.s.l.; 9 Apr. 2015; M. and K. Cole leg.; alive in leaf-litter; ELMD 18624/T243 .

Description

SHELL ( Fig. 10 ). Shell very small, sub-cylindrical, length 3.7–4.0 mm, width 1.8–1.9 mm, L:W 2.07– 2.10 (n = 2). Protoconch approx. 1.0 mm in diameter, comprising approx. 2.5 whorls, smooth ( Fig. 10B ); junction between protoconch and teleoconch not distinct. Teleoconch comprising approx. 4.5 whorls; whorls weakly convex; smooth and glossy ( Fig. 10A–B ); axial pleats on last whorl behind labrum and around umbilicus ( Fig. 10B, D ). Aperture narrower towards base on right and slightly pinched in below parietal insertion; peristome thickened and reflected; aperture markedly constricted by teeth, dentition four-fold ( Fig. 10C ): 1) a parietal lamella, with outer portion markedly oblique and then curving inward so that remainder runs into aperture, 2) a large rounded labral tooth with concave outer face and thickened, sinuous upper margin bearing a small cusp near lip edge, 3) an inset tooth in centre of base, 4) a large deeply-inset, elongate columella lamella with a hollow in its centre. Edge of the columella lip slightly thickened. Labral tooth corresponds with a narrow slit behind outer lip ( Fig. 10B ). Apertural tube behind columella lip somewhat expanded and collar-like, bearing axial pleats; umbilicus very small, elongate-oval, approx. 0.12 mm in length and with distinct peri-umbilical pleats ( Fig. 10D ). Shell almost transparent when fresh, orange coloration of dried tissue of animal visible internally.

Distribution ( Fig. 9 )

Known only from Nkandla Forest Reserve, in northern KwaZulu-Natal; between approx. 1000 m and 1200 m above sea level.

Habitat

Patches of KwaZulu-Natal Scarp forest of the KwaZulu-Natal Inland Scarp subtype ( Mucina et al. 2018); in leaf-litter and under logs.

Remarks

Gulella nkandla sp. nov. resembles the variable G. farquhari (Melvill & Ponsonby, 1895) , but the latter has some form of axial sculpture while G. nkandla is smooth and glossy with axial pleats only on the last whorl behind the labrum and around the umbilicus. Furthermore, the labral tooth of G. nkandla has a definite cusp on its upper margin near the lip edge, lacking in G. farquhari and the columella lamella is more elongate. The labral tooth of G. nkandla bears some resemblance to that of G. contraria Connolly, 1932 , in particular the upper denticle, but in the latter species the bulk of the tooth is in the form of an inset ridge that extends inward and basally from the upper denticle, behind the more superficial labral ridge. Gulella contraria also has a very strong, broad, squarish tooth in the middle of the columella lip.

Conservation

Gulella nkandla sp. nov. has been found only at Nkandla Forest Reserve, a protected area under the jurisdiction of the provincial conservation authority, Ezemvelo-KZN Wildlife.

Figures

Fig. 9. Distribution map of Gulella hlathikhulu sp. nov. (green circles), G. nkandla sp. nov. (yellow triangles), G. mystica sp. nov. (red squares) and G. libertas sp. nov. (blue circle) in north-central KwaZulu-Natal. Contours at 1000 m and 2000 m.

Fig. 10. Gulella nkandla sp. nov., holotype (NMSA-Mol 0P2361/T4610), length 3.8 mm, width 1.9 mm. A. Aperture view. B. Side view. C. Detail of aperture. D. Oblique view of base showing umbilicus.