Gulella abbotti, Cole & Herbert, 2022

Cole, Mary L. & Herbert, David G., 2022, Eight new species of Gulella Pfeiffer, 1856 from the south-east coast of South Africa (Gastropoda: Streptaxidae), European Journal of Taxonomy 813, pp. 1-32 : 22-25

Gulella abbotti sp. nov.

urn:lsid:zoobank.org:act:374C7E0D-187B-4EEE-A8C8-AE04AC64118B

Figs 9 A–D , 10

Diagnosis

Shell minute, cylindrical; spire whorls with weak subsutural riblets developing into stronger axial riblets on final half whorl; aperture sub-quadrate, little obstructed by teeth; dentition five-fold, including a parietal lamella, a simple trigonal labral tooth extending from lip edge, a small basal tooth well to left of centre, a broad, low swelling in middle of columella lip and a round columella lamella; umbilicus closed.

Etymology

Named for the late Tony Abbott (1936–2013), a respected farmer and conservationist who lived on the border of the Mtamvuna Nature Reserve and possessed considerable expertise in the vegetation of subtropical forests in the deep gorges of Pondoland and the Ugu District of KwaZulu-Natal.

Material examined

Holotype SOUTH AFRICA – KwaZulu-Natal • Port Shepstone area , Four Man’s Hill , S5, scarp forest ; 30.672094°S, 30.334831° E, 127 m a.s.l.; Dec. 2013; D. Herbert leg.; NMSA W9602/T4522 .

Paratypes (listed north to south) SOUTH AFRICA – KwaZulu-Natal • 1 spec.; Port Shepstone area, Four Man’s Hill , S4, scarp forest ; 30.67284°S, 30.335312°E, 112 m a.s.l.; Dec. 2013; D. Herbert leg.; NMSA W9600/T4496 • 1 spec.; Mtamvuna Gorge, Lourie Trail , riverine scarp forest ; 31.056297°S, 30.168879°E, 40 m a.s.l.; 13 Apr 2011; D. Herbert, L. Davis, M. Bursey and R. Daniels leg.; NMSA W7913/T4495 • 1 spec.; same collection data as for preceding; NHMUK 20210076 , prev. NMSA W7913 – Eastern Cape • 1 spec.; Mzamba , beach drift ; 31.100°S, 30.175° E; Oct. 1979; J. P. Marais leg.; NMSA V6350/T4494 .

Other material

SOUTH AFRICA – KwaZulu-Natal • 1 spec.; Mzamba , beach drift ; 31.100°S, 30.175°E; Apr. 1988; J. P. Marais leg.; NMSA V3985 .

Description

SHELL ( Fig. 9 ). Shell minute, elongated and cylindrical, length 2.3–2.7 mm, width 0.8–1.0mm, L:W 2.6–3.1 (n = 6). Protoconch approx. 0.8 mm in diameter, comprising approx. 2.5 whorls, smooth; junction between protoconch and teleoconch not distinct. Teleoconch comprising approx. 4.25 whorls; first whorl convex, others weakly so, suture not strongly indented; mostly smooth and glossy, but with weak subsutural axial riblets, these stronger on last whorl and extending from suture to suture, some specimens more or less smooth with only periodic growth lines ( Fig. 9A, B ); axial riblets prominent and pleat-like in umbilical region. Peristome fused with base of penultimate whorl in parietal region; peristome thickened ( Fig. 9C ). Aperture sub-quadrate, not extensively obstructed by teeth; apertural dentition five-fold ( Fig. 9C ): 1) an oblique parietal lamella which curves and runs into aperture; 2) a simple, roundly trigonal labral tooth beginning at lip edge; 3) a small, rounded basal tooth well to left of centre; 4) a broad, low swelling on columella lip; 5) an evenly rounded columella lamella. Labral tooth corresponds with a pit behind outer lip ( Fig. 9B ). Columella corresponds with a pit behind columella lip, but umbilicus closed ( Fig. 9D ). Shell translucent, uniformly milky-white when fresh.

Distribution ( Fig. 10 )

Endemic to a narrow range in southern KwaZulu-Natal, from the coast up to approx. 130 m above sea level.

Habitat

KwaZulu-Natal Scarp Forest and Pondoland Scarp Forest ( Mucina et al. 2018a,b); in leaf-litter and under logs.

Remarks

Gulella abbotti sp. nov. resembles three other Gulella species occurring in KwaZulu-Natal. G. bushmanensis Burnup, 1926 from inland regions in the north of the province, although also elongate and cylindrical, lacks axial sculpture, has two fused labral teeth, a roundly quadrate and almost mammillate columella lamella, and lacks a low swelling on the columella lip. The widespread G. pentheri (Sturany, 1898) , again elongate and cylindrical, is smooth and it has only three apertural teeth of much smaller size. Gulella appletoni van Bruggen, 1975 , from coastal localities in northern Zululand, has similar fivefold apertural dentition, but it is smooth, less elongate and smaller (length <2.0 mm), and it has a larger tooth on the columella lip and a strong quadrate columella lamella.

Conservation

Gulella abbotti sp. nov. appears to be a very rare species, with few records despite the streptaxid fauna of the KwaZulu-Natal south coast being relatively well known (see Discussion). The only formally conserved area in which it has been found is the Mtamvuna Gorge Nature Reserve.Aside from specimens collected in beach drift, it has been collected at two localities approx. 40 km apart, but not in the Oribi Gorge Nature Reserve which lies immediately west of the type locality. It also does not appear to extend into coastal forest of the relatively recent Indian Ocean Coastal Belt ( von Maltitz et al. 2003).

Figures

Fig. 9. Gulella abbotti sp. nov., holotype (NMSA W9602/T4522), length 2.55 mm, width 0.81 mm. A. Aperture view. B. Side view. C. View into aperture. D. Oblique view of base showing umbilicus. Scale bar = 0.5 mm.

Fig. 10. Distribution map of Gulella abbotti sp. nov. (purple triangles) and G. maraisi sp. nov. (orange circles). Contour at 1000 m.