Gulella hlathikhulu, 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 : 16-19

Gulella hlathikhulu sp. nov.

urn:lsid:zoobank.org:act:C7827C2A-D171-46BD-8A7F-842D0C4D07E7

Figs 8–9

Diagnosis

Shell minute, cylindrical; smooth and glossy; aperture quadrate, base truncate; dentition five-fold, including a large parietal lamella, a simple in-running, ridge-like labral tooth extending from lip edge, a short, broad basal tooth slightly to left of centre beginning very near lip edge, a prominent swelling in middle of columella lip and a large, convex columella lamella; peristome protruding at position of labral and superficial columella teeth; umbilicus closed.

Etymology

Named for the Hlathikhulu [Gwaliweni] Forest Reserve, translated from isiZulu as ‘Big Bush’ or ‘Big Forest’.

Type material

Holotype SOUTH AFRICA – KwaZulu-Natal • Lebombo Mountains, Gwaliweni Forest , site 2, mesic scarp forest ; 27.3242° S, 31.9966° E, 563 m a.s.l.; Feb. 2008; N. Crouch and T. Edwards leg.; NMSA W6129 / T4598.

Paratypes SOUTH AFRICA – KwaZulu-Natal • 2 specs; Lebombo Mountains, Hlathikhulu Forest Nature Reserve , scarp forest ; 27.3247° S, 31.990° E; 647 m a.s.l.; 29 Dec. 2006; A. Moussalli and D. Stuart-Fox leg.; NMSA W5730 /T4597 • 1 spec.; same collection data as for preceding; RMNH.MOL.346282, ex NMSA W5730 • 1 spec.; Lebombo Mountains, Hlathikhulu Forest Nature Reserve , scarp forest; 27.3243° S, 31.9906° E; 640 m a.s.l.; 15 Aug. 2015; T. Nxele leg.; NMSA P0363 /T4596 • 3 specs; Lebombo Mountains, eastern side, Hlathikhulu Forest Nature Reserve , 70 km from coast; 27.3244° S, 31.9910° E; 643 m a.s.l.; 18 Jan. 2010; M. and K. Cole leg.; ELMD 16339/T241 • 1 spec.; same collection data as for preceding; ELMW 3395/T242 • 1 spec.; same collection data as for preceding; NHMUK 20230171 , ex ELMD 16339 • 1 spec.; same collection data as for preceding; NMW.Z.2023.001.00005, ex ELMD 16339 .

Other material examined

SOUTH AFRICA – KwaZulu-Natal • 3 specs; Lebombo Mountains, eastern side, Hlathikhulu Forest Nature Reserve , 70 km from coast; 27.3244° S, 31.9910° E; 643 m a.s.l.; 18 Jan. 2010; M. and K. Cole leg.; ELMD 18893, ex ELMD 16339 .

Description

SHELL ( Fig. 8 ). Shell minute, cylindrical, length 2.7–3.3 mm, width 1.2–1.4 mm, L:W 2.03–2.36 (n = 7). Protoconch approx. 1.0 mm in diameter, comprising approx. 2.5 whorls, smooth ( Fig. 8A–B ); junction between protoconch and teleoconch not distinct. Teleoconch comprising approx. 4.25 whorls; first whorl convex, others weakly so, suture not strongly indented; smooth and glossy with a few axial pleats behind labrum and around base ( Fig. 8A–B ). Peristome little thickened, interrupted in parietal region. Aperture quadrate, base flattened rather than rounded; apertural dentition five-fold ( Fig. 8C ): 1) a large parietal lamella which curves and runs into aperture; side facing labral sinus concave; 2) a simple labral tooth in the form of an in-running ridge beginning at lip edge; 3) a low, broad, somewhat oblique basal tooth slightly to left of centre beginning very near lip edge; 4) a prominent swelling on columella lip; 5) a large, convex columella lamella with no bulb or swelling. Labral tooth corresponds with a very shallow pit behind outer lip. When viewed from laterally, profile of aperture juts out in position of teeth on labral and columella lips, which lie opposite each other ( Fig. 8B ). Umbilicus closed ( Fig. 8D ). Shell translucent when fresh, orange coloration of dried tissue of animal visible internally.

Distribution ( Fig. 9 )

Evidently endemic to the Hlathikhulu Forest near the southern limit of the Lebombo Mountains in northeastern KwaZulu-Natal, between 550 m and 650 m above sea level.

Habitat

Northern Scarp forest of the Lebombo Scarp subtype ( Mucina et al. 2018); in leaf-litter and under logs.

Remarks

Gulella hlathikhulu sp. nov. resembles two species occurring in the adjacent coastal regions of Zululand, Gulella appletoni van Bruggen, 1975 and Gulella perspicuaeformis (Sturany, 1898) . Gulella hlathikhulu is larger than G. appletoni (length <2.0 mm), and its labral tooth is a simple, in-running ridge rather than a bicuspid trigonal tooth, and the basal tooth is more robust, beginning very near the lip edge. In addition, the mid-region of the columella does not protrude in G. appletoni . The aperture of G. perspicuaeformis is noticeably less obstructed by teeth than that of G. hlathikhulu ; it lacks a basal and superficial columella tooth, and the columella lamella, parietal and labral teeth are all relatively small ( Herbert 2006).

Conservation

Gulella hlathikhulu sp. nov. appears to be a very rare species, with few records. The Hlathikhulu Forest Reserve (also known as the Gwaliweni Forest) is a formally protected area under the jurisdiction of Ezemvelo-KZN Wildlife, the provincial conservation authority for KwaZulu-Natal, although lack of compliance may limit the effectiveness of protected status. The forest habitat crosses the Eswatini [ Swaziland] border and probably also occurs further north along the Lebombo Mountains, straddling this international boundary, especially in the surrounds of the Ingwavuma Gorge ( Mucina et al. 2018). It is thus possible that G. hlathikhulu occurs at additional, as yet unsampled, sites along this ridge of mountains.

Figures

Fig. 8. Gulella hlathikhulu sp. nov., holotype (NMSA W6129/T4598), length 3.2 mm, width 1.5 mm. A. Aperture view. B. Side view. C. Detail of aperture. D. Oblique view of base showing umbilicus.

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.