Gulella kevincolei, 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 : 10-13

Gulella kevincolei sp. nov.

urn:lsid:zoobank.org:act:57C359E6-21D6-4E56-98A5-B56C9FFE3215

Figs 3 , 6

Diagnosis

Shell minute, sub-cylindrical; sculptured by well-developed axial ribs, extending from suture to suture, aperture narrowing towards base on right; apertural dentition four-fold, including an oblique parietal lamella, a large roundly triangular somewhat bicuspid labral slab, a ridge-like basal tooth in centre of base, and a large inset elongate columella lamella; the columella lip is also thickened, and has an indistinct swelling at either end in some specimens; umbilicus widely open.

Etymology

Named for the first author’s husband, Kevin Cole, who was a volunteer at Hobbiton-on-Hogsback helping at 32 two-week camps for disadvantaged children between 1979 and 1986, and subsequently Chairman of its board, and who helped collect specimens of this species.

Type material

Holotype SOUTH AFRICA – Eastern Cape • Hogsback, Auckland Nature Reserve, base of vertical cliff near Madonna and Child waterfall; 32.6063° S, 26.9625° E; 1065 m a.s.l.; 27 Sep. 2021; M. Cole leg.; NMSA-Mol 0P2357/T4506.

Paratypes SOUTH AFRICA – Eastern Cape • 1 spec.; Hogsback Forest, base of vertical cliff near Madonna and Child waterfall; 32.6063° S, 26.9625° E; 1065 m a.s.l.; 27 Sep. 2021; M. Cole leg.; NMSA-Mol 0P2358/ T4607 • 1 spec.; same collection data as for preceding; ELMD18887 /T235 • 1 spec.; same collection data as for preceding; NHMUK 20230167 .

Other material examined

SOUTH AFRICA – Eastern Cape • 1 spec.; Hogsback, Auckland Nature Reserve, Tyume River valley , downstream of Madonna and Child waterfall; 32.6055° S, 26.9603° E; 1030 m a.s.l.; 31 Dec. 2008; M. and K. Cole leg.; NMSA W9361 • 1 spec.; same collection data as for preceding; ELMD 19089 • 1 spec.; Hogsback Forest, base of vertical cliff near Madonna and Child waterfall; 32.6063° S, 26.9625° E; 1065 m a.s.l.; 4 Jan. 2022; M. Cole leg.; ELMD 18880 .

Description

SHELL ( Fig. 6 ). Shell minute, sub-cylindrical, length 2.5–3.0 mm, width 1.2–1.5 mm, L:W 1.98–2.15 (n = 6). Protoconch approx. 0. 9 mm in diameter, comprising approx. 2.5 whorls, smooth; junction with teleoconch distinct. Teleoconch comprising approx. 4.5 whorls; whorls convex; sculptured with well-developed axial ribs from suture to suture (approx. 32 on penultimate whorl; rib intervals lacking sculpture ( Fig. 6A–B ). Aperture narrowing towards base on right (in apertural view); peristome thickened and reflected; base flattened rather than rounded, dentition four-fold ( Fig. 6C ): 1) an almost vertical parietal lamella, concave on side facing labral sinus, 2) a large roundly triangular labral slab, somewhat bicuspid in some specimens, leaving only a narrow slit between it and parietal lamella, 3) a ridge-like basal tooth in centre of base, 4) a large, deep-set, elongate columella lamella; in addition, in some specimens the thickened columella may bear a low, broad denticle near its parietal insertion and another near its base, but in other specimens these are scarcely evident. Labral tooth corresponds with a deep pit behind outer lip ( Fig. 6B ); basal tooth corresponds with a pit behind basal lip. Apertural tube behind columella lip collar-like with fine close-set riblets. Umbilicus widely open, elongate-oval, approx. 0.12 mm in length ( Fig. 6D ). Shell almost transparent when fresh, yellow-orange coloration of dried tissue of animal visible internally.

Distribution ( Fig. 3 )

Known only from Hogsback in the Amathole Mountains ; at altitudes between 1000 m and 1100 m above sea level.

Habitat

Amathole Mistbelt Forest (Southern Mistbelt Forest group) ( von Maltitz et al. 2003); in leaf-litter and under logs.

Remarks

Gulella kevincolei sp. nov. resembles the variable species Gulella farquhari (Melvill & Ponsonby, 1895) but the following differences appear to be consistent. The sculpture of G. kevincolei is much stronger than that of G. farquhari which has variable sculpture, usually in the form of milling just below the suture or weak axial ribbing. Gulella kevincolei has a larger, ridge-like basal tooth which reaches the aperture margin, distinct from the inset basal tooth of G. farquhari . The umbilicus of G. kevincolei is widely open and it has a large, smooth protoconch (0.9 mm in the holotype) clearly distinct from the teleoconch.

Conservation

Gulella kevincolei sp. nov. has been found at only one locality, Hogsback, in the Amathole Mountains , despite fairly extensive collecting efforts throughout the mountain range. It therefore appears to be a very narrow-range endemic, restricted to the main Hogsback forest block.

Figures

Fig. 3. Distribution map of Gulella benthodon van Bruggen, 1980 (blue triangles), G. judithmastersae sp. nov. (green squares), G. kevincolei sp. nov. (yellow circle) and G. mcmasteri sp. nov. (red diamonds) in the Amathole region of the Eastern Cape province. Contours at 1000 m and 2000 m.

Fig. 6. Gulella kevincolei sp. nov., holotype (NMSA-Mol 0P2357/T4506), length 2.9 mm, width 1.5 mm. A. Aperture view. B. Side view. C. Detail of aperture. D. Oblique view of base showing umbilicus.