Gulella judithmastersae, 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 : 7-10

Gulella judithmastersae sp. nov.

urn:lsid:zoobank.org:act:FBEC0F3F-8E42-4B59-BC2E-5D3FABD34467

Figs 3–5

Diagnosis

Shell very small, sub-cylindrical; sculptured with strong axial ribs; peristome entire and thickened, fused to preceding whorl in parietal region; aperture constricted by teeth; dentition five-fold, including a strong parietal lamella, a large trigonal labral slab running deeply into aperture, a deep-set, oblique in-running ridge-like basal tooth to left of centre, a low, broad, rounded denticle at top of columellar lip and a very large, deep-set columella lamella; apertural tube behind columella lip somewhat expanded and collar-like; umbilicus very small.

Etymology

Named in honour of the late Prof. Judith Masters (1956–2022), University of Fort Hare and formerly Assistant Director of the Natal Museum (1998–2006). Judith, a friend and former colleague of the second author, was a world-renowned primatologist specializing in lemurs, was tragically murdered, together with her partner in life and science, Dr Fabien Génin, in their Hogsback home on October 3, 2022 ( Tattersall & Delpero 2022; Andrews et al. 2023). Having recently retired, Judith was beginning what might have been the most productive period of her scientific career.

Type material

Holotype SOUTH AFRICA – Eastern Cape • Isidenge State Forest, south-east of Mount Kemp, Artillery Forest , south-facing; 32.6954° S, 27.2870° E; 1051 m a.s.l.; 5 Apr. 2016; M. Cole leg.; NMSA-Mol 0P2354/ T4603, ex ELMD 18090.

Paratypes SOUTH AFRICA – Eastern Cape • 2 specs; Isidenge State Forest, south-east of Mount Kemp, Artillery Forest , south-facing; 32.6954° S, 27.2870° E; 1051 m a.s.l.; 4 Feb. 2021; M. Cole leg.; NMSA-Mol 0P2355/T4604 • 2 specs; same collection data as for preceding; ELMD 18885/T232 • 2 specs; same collection data as for preceding; NHMUK 20230168 • 2 specs; same collection data as for preceding; NMW.Z.2023.001.00002 • 2 specs; same collection data as for preceding; RMNH.MOL.346279 • 1 spec.; same collection data as for preceding; 7 Jan. 2022; ELMD 18884/T233 • 1 spec.; Isidenge State Forest, south-east of Mount Kemp, Artillery Forest lower site, south-facing; 32.7013° S, 27.2921° E; 948 m a.s.l.; 7 Jan. 2022; M. Cole leg.; NMSA-Mol 0P2356/T4605 • 1 spec.; same collection data as for preceding; ELMD 18882/T234 .

Other material examined

SOUTH AFRICA – Eastern Cape • 1 spec.; Isidenge State Forest, south-east of Mount Kemp, Artillery Forest, south-facing; 32.6954° S, 27.2870° E; 1051 m a.s.l.; 4 Feb. 2021; M. Cole leg.; ELMD 18886 • 2 specs; same collection data as for preceding; 7 Jan. 2022; ELMD 18883 .

Description

SHELL ( FigS 4–5 ). Shell very small, sub-cylindrical, length 3.0– 3.6 mm, width 1.6–1.7 mm, L:W 1.84– 2.20 (n = 13). Protoconch approx. 0.9 mm in diameter, comprising approx. 2.25 whorls, sculptured with raised microscopic spiral threads, weaker on apical bulb ( Fig. 5 ), last half-whorl also with weak axial riblets; junction between protoconch and teleoconch distinct. Teleoconch comprising approx. 4.25 whorls; whorls moderately convex, suture strongly indented; sculptured by well-developed axial ribs, extending from suture to suture (approx. 47 on penultimate whorl); rib intervals lacking sculpture ( Fig. 4A–B ). Peristome fused with base of penultimate whorl in parietal region; parietal callus well developed, peristome thickened. Aperture markedly constricted by teeth, dentition five-fold ( Fig. 4C ): 1) a strong parietal lamella, outer portion oblique; 2) a large trigonal wedge-like labral slab with a point on its upper margin near lip edge, its upper margin running deeply into aperture, more or less parallel to lower margin of parietal lamella initially, angled progressively more toward columella internally; 3) a deep-set, oblique in-running ridge-like basal tooth to left of centre; 4) a low, broad, rounded denticle at top of columella; 5) a very large, deep-set columella lamella. Labral slab corresponds with a deep pit behind outer lip ( Fig. 4B ); basal ridge corresponds with a shallow indentation behind basal lip ( Fig. 4D ). Apertural tube behind columella lip somewhat inflated and collar-like; umbilicus very small, elongate-ovate ( Fig. 4D ). Shell translucent, uniformly milky-white when fresh.

Distribution ( Fig. 3 )

Endemic to the Isidenge area of the Amathole Mountains ; at altitudes between 950 m and 1050 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 judithmastersae sp. nov. resembles Gulella dejae Bursey & Herbert, 2004 from coastal Eastern Cape and G. viae Burnup, 1925 from Afromontane forests in KwaZulu-Natal and northwards into Mpumalanga and Limpopo provinces. These three species have a very large parietal lamella with oblique outer portion, a trigonal labral tooth running into the aperture, a concave columella lip with a tooth or thickening at the upper and lower ends and an inflated, collar-like apertural tube behind the columella lip. There are differences in the dimensions of the apertural teeth between the three species. The parietal lamella of G. judithmastersae is larger than that of G. dejae ; the outer portion projects outwards, but not as prominently as in G. viae . In side view the outer lip arches forward in the vicinity of the labral tooth in G. judithmastersae and even more strongly in G. viae . The labral slab of G. dejae is largest and hence the aperture is more constricted by teeth. Gulella viae has a more pointed tooth on the upper margin of the labral slab. In G. judithmastersae there is a deep-set, oblique in-running ridge-like basal tooth to left of centre at the base of the columella lip, while G. dejae and G. viae have a tooth at the lower end of columella lip in this position, but it does not run into the aperture. Gulella judithmastersae is similar to G. dejae , G. phyllisae Burnup, 1925 , G. hamerae Bursey & Herbert, 2004 and G. claustralis Connolly, 1939 in the possession of spiral threads on the protoconch, absent in G. viae . Gulella judithmastersae also bears resemblance to G. arnoldi (Sturany, 1898) , but that species also lacks spiral sculpture on the protoconch. Gulella judithmastersae differs from G. phyllisae and G. arnoldi in the large size of the parietal lamella, the position of the basal tooth (to the left not right of centre) and the shape of the columella lamella. Gulella judithmastersae does not resemble G. hamerae or G. claustralis in the shape of the aperture and its dentition. The aperture of the latter two species is y-shaped and the columella lip is indented.

Conservation

Despite fairly extensive collecting efforts throughout the Amathole mountain range , Gulella judithmastersae sp. nov. has been found at only two localities, both in the Isidenge area. It therefore appears to be a very narrow-range endemic. Isidenge is a State Forest protected under the National Forest Act (Act 84 of 1998).

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. 4. Gulella judithmastersae sp. nov., holotype (NMSA-Mol 0P2354/T4603), length 3.4 mm, width 1.6 mm. A. Aperture view. B. Side view. C. Detail of aperture. D. Oblique view of base showing umbilicus.

Fig. 5. Protoconch of Gulella judithmastersae sp. nov., paratype (NMW.Z.2023.001.00002). A. Detail of sculpture of protoconch. B. Close-up of microscopic spiral threads. Scale bars: A = 200 µm; B = 100 µm.