Gulella mystica, 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 : 21-23

Gulella mystica sp. nov.

urn:lsid:zoobank.org:act:6837690E-1542-46A0-BA98-B09F59D56501

Figs 9 , 11

Diagnosis

Shell very small, sub-cylindrical; sculptured with axial ribs extending from suture to suture with spiral microsculpture between them; apertural dentition eight-fold, including a parietal lamella running into the aperture with a sinuous lower margin bearing a notch, a low sinular denticle, a large triangular labral tooth with a peg-like tooth at its upper limit, a low, deeply inset transverse basal tooth to right of centre, a deeply inset trigonal basal tooth to left of centre and a large inset columella lamella consisting of a vertical slab with two ridge-like teeth, pointing obliquely downwards, in its lower half; apertural tube collar-like behind columella lip, umbilicus very small.

Etymology

From the Greek ‘ mystikos ’ (‘ μυσΤΙΚός ’): ‘a mystery, mysterious’; with reference to the environs of Nkandla – long considered a region of mystery in Zulu folklore.

Type material

Holotype SOUTH AFRICA – KwaZulu-Natal • Nkandla Forest Reserve, 38 km NW of Eshowe, Chibini area , mistbelt forest ; 28.7227° S, 31.1283° E; ± 1175 m a.s.l.; 20 Oct. 2003; D. Herbert leg.; under logs and in leaf-litter; NMSA W1181 /T4600.

Paratypes SOUTH AFRICA – KwaZulu-Natal • 1 spec.; Nkandla Forest Reserve, Chibini area , 38 km NW of Eshowe, mistbelt forest ; 28.7227° S, 31.1283° E; ± 1175 m a.s.l.; 9 Apr. 2015; M. and K. Cole leg.; ELMD 18701/T244 • 1 spec.; Nkandla Forest Reserve, 37 km NW of Eshowe, 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.; NMSA-Mol 0P2362/T4611, ex ELMD 18622 .

Other material examined

SOUTH AFRICA – KwaZulu-Natal • 1 spec.; Nkandla Forest Reserve, Mdonini area near eastern boundary, 36 km NW of Eshowe, mistbelt forest; 28.7453° S, 31.1361° E; ± 1050 m a.s.l.; 14 Jan. 2010; M. Cole leg.; ELMD 18888 .

Description

SHELL ( Fig. 11 ). Shell very small, sub-cylindrical to squat, length 3.2–3.3 mm, width 1.7–1.8 mm, L:W 1.88–2.00 (n = 4). Protoconch approx. 0.8 mm in diameter, comprising approx. 2.5 whorls, smooth; junction between protoconch and teleoconch distinct. Teleoconch comprising approx. 5.5 convex whorls; sculptured with well-developed axial ribs, extending from suture to suture, prosocline on spire whorls and almost orthocline on last whorl, rib intervals with spiral microsculpture ( Fig. 11A–B ). Aperture sub-quadrate with rounded base; outer lip shallowly indented, columella straight (in aperture view); peristome thickened and reflected; dentition eight-fold ( Fig. 11C ): 1) an almost vertical parietal lamella, its lower margin sinuous and notched, 2) a minute sinular denticle, 3–4) a large triangular labral tooth extending into aperture, with a small peg-like tooth at its upper limit near lip edge, 5) a deeply inset low, transverse basal tooth to right of centre, 6) a deeply inset pointed trigonal tooth to left of centre, 7–8) a large deeply inset columella lamella consisting of a truncate vertical slab set with two ridge-like downward-pointing teeth in lower half, upper one larger. Aperture indented in region of labral teeth and with a deep pit behind outer lip corresponding to labral tooth base ( Fig. 11B ). Apertural tube behind columella lip collar-like; umbilicus very small, elongate-ovate, approx. 0.08 mm in length ( Fig. 11D ). Shell almost transparent when fresh, yellow-orange coloration of dried tissue of animal visible internally.

Distribution ( Fig. 9 )

Known only from Nkandla Forest Reserve, in northern KwaZulu-Natal; between 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 mystica sp. nov. does not bear close resemblance to any other species. The truncate columella lamella with downward-pointing ridge-like teeth at its lower end is unique. Its apertural dentition bears superficial resemblance to certain features of G. mfongosiensis Burnup, 1925 and G. perissodonta (Sturany, 1898) , namely the large labral tooth with a small tooth on its upper base, basal teeth to right and left of centre and the columella lamella with two ridges. Both G. mfongosiensis and G. perissodonta have an additional parietal denticle and the former also has a denticle in the middle of the columella lip. Gulella mystica occurs in the same broad vicinity as these other two species (inland in northern KwaZulu-Natal), but they occur in drier bushveld habitats while G. mystica occurs in tall, moist forest.

Conservation

Gulella mystica sp. nov. has been found only at Nkandla Forest Reserve, a protected area under the jurisdiction of 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. 11. Gulella mystica sp. nov., holotype (NMSA W1181/T4600), length 3.3 mm, width 1.7 mm. A. Aperture view. B. Side view. C. Oblique view into aperture. D. Oblique view of base showing umbilicus.