Gulella mcmasteri sp. nov.

urn:lsid:zoobank.org:act: 68B280AF-D687-44B4-B708-BA778EB82F08

Figs 3, 7

Diagnosis

Shell very small to minute, cylindrical; sculptured with well-developed, but not strong axial ribs; edge of labrum projecting outward in side-view; dentition eight-fold, including a strong parietal lamella, three labral teeth, one at lip edge and two within aperture, the lower stronger, a low, inset transverse basal tooth to right of centre, a basal tooth to left of centre, a tooth on mid-upper columella lip, a very large, deep-set rounded columella lamella; umbilicus closed.

Etymology

Named for the late Cameron McMaster who had a keen interest in natural history and whose brother, Nigel, farms at the type locality.

Type material

Holotype SOUTH AFRICA – Eastern Cape • Cathcart Nature Reserve, Windvogelberg Hiking Trail, south-facing slope of watercourse; 32.2851° S, 27.1347° E; 1266 m a.s.l.; 6 Mar. 2007; D. Herbert, L. Davis and M. Bursey leg.; riverine forest, alive in leaf-litter; NMSA-Mol 0P2359/T4608 ex ELMD 15178.

Paratypes (listed north to south) SOUTH AFRICA – Eastern Cape • 7 specs; Middledrift Farm, southern end of Windvogelberg, 6 km SW of Cathcart; 32.3290° S, 27.0883° E; 1500 m a.s.l.; 6 Mar. 2007; D. Herbert, L. Davis and M. Bursey leg.; grassy slope with rocks and scrubby forest, in leaf-litter and under rocks; NMSA W5291 / T4599 • 1 spec.; same collection data as for preceding; RMNH.MOL.346280, ex NMSA W5291 • 5 specs; same collection data as for preceding; ELMD 15170/T240 • 1 spec.; same collection data as for preceding; NHMUK 20230169, ex ELMD 15170 • 1 spec.; same collection data as for preceding; NMW.Z.2023.001.00003, ex ELMD 15170 • 5 specs; Patchwood Farm, forest north of homestead; 32.3875° S, 27.4501° E; 1196 m a.s.l.; 18 Dec. 2012; M. Cole leg.; ELMD 17105/T236 • 4 specs; Patchwood Farm, forest at source of Quanti River; 32.3824° S, 27.4470° E; 1238 m a.s.l.; 18 Dec. 2012; M. Cole leg.; ELMD 17102/T237 • 3 specs; same collection data as for preceding; NMSA-Mol 0P2360/ T4609, ex ELMD 17102 • 1 spec.; same collection data as for preceding; NHMUK 20230170, ex ELMD 17102 • 1 spec.; same collection data as for preceding; NMW.Z.2023.001.00004, ex ELMD 17102 • 1 spec.; same collection data as for preceding; RMNH.MOL.346281, ex ELMD 17102 • 1 spec.; same locality data as for preceding; 6 Apr. 2016; M. Cole leg.; ELMD 18145/T238 • 2 specs; Qacu Forest Nature Reserve, NNE of Stutterheim; 32.4031° S, 27.4486° E; 1273 m a.s.l.; 6 Apr. 2016; M. Cole leg.; ELMD 18136/T239 .

Other material examined

SOUTH AFRICA – Eastern Cape • 5 specs (3 adult, 1 immature, 1 juvenile); Middledrift farm, southern end of Windvogelberg, 6 km SW of Cathcart; 32.3290° S, 27.0883° E; 6 Mar. 2007; D. Herbert, L. Davis and M. Bursey leg.; grassy slope with rocks and scrubby forest, in leaf-litter and under rocks; NMSA-Mol 0P2351 • 2 specs; same collection data as for preceding; ELMD 19088 (was 15170) .

Description

SHELL (Fig. 7). Shell very small to minute, elongate-cylindrical, length 2.4 –2.7 mm, width 1.0– 1.2 mm, L:W 2.07–2.42 (n = 12). Protoconch approx. 0. 8 mm in diameter, comprising approx. 2.25–2.5 whorls, smooth (Fig. 7A–B); junction with teleoconch not distinct. Teleoconch comprising approx. 3.75 whorls; the first convex, but subsequent ones more flat-sided; sculptured by well-developed, but not strong axial ribs, extending from suture to suture (approx. 42 on penultimate whorl), weak on early part of first whorl; rib intervals lacking obvious microsculpture (Fig. 7A–B). Aperture somewhat asymmetrical due to narrowing from labral tooth towards base, rounded at base; peristome broadly interrupted in parietal region, middle region of labrum projecting outward in side-view (Fig. 7B). Dentition eight-fold (Fig. 7C): 1) a strong parietal lamella, outer portion oblique and projecting beyond aperture in side-view, extending to level of upper labral tooth, curves and runs into aperture so that side facing labral sinus is concave; 2–4) a strong mid-labral base beginning at lip edge with three labral teeth, one on lip edge (a low bulge), and two further into aperture, lower one stronger; 5) a very low, inset transverse basal tooth to right of centre; 6) a basal tooth to left of centre usually near lip edge; 7) a low, broad tooth on mid to upper columellar lip; 8) a very large, deep-set, rounded columella lamella with thickened distal rim. Labral tooth corresponds with a pit behind outer lip (Fig. 7B). Umbilicus closed (Fig. 7D). Shell almost transparent when fresh, reddish-orange dried tissue of animal visible internally.

Distribution (Fig. 3)

Recorded from isolated forest patches on the Windvogelberg south of Cathcart, and the Qacu forests north-east of Stutterheim, Eastern Cape; at altitudes between 1200 m and 1500 m above sea level. These forests lie between the Amatholes and the Kei River valley and are disjunct from the large forest blocks of the Amathole Mountains.

Habitat

Southern Mistbelt Forest (Mucina & Geldenhuys 2006); in leaf-litter and under rocks.

Remarks

Amongst other Eastern Cape species of Gulella, the apertural dentition of G. mcmasteri sp. nov. resembles that of G. ponsonbyi (Burnup, 1914), G. caryatis (Melvill & Ponsonby, 1898) and G. phragma (Melvill & Ponsonby, 1907), but G. mcmasteri has three labral teeth, its basal tooth to the left of centre is close to the lip edge and its columella lamella is differently shaped, resulting in a closed umbilicus. The aperture rim is less thickened than that of G. ponsonbyi, the parietal lamella is smaller and the columella lamella is not mammillate as in G. ponsonbyi, but is concave with a raised edge. Gulella caryatis is more elongate and its axial ribs are weaker, extending only half-way down each whorl and the aperture of G. mcmasteri is markedly more obstructed by teeth. Gulella phragma is a poorly known species also recorded from the Cathcart area, but it is larger (length 4.3 mm) and has a prominent superficial tooth on the columella lip mirrored by the underlying columella lamella, and joined to it by a ridge.

Conservation

Gulella mcmasteri sp. nov. is found in relict forest patches including two formally protected areas, Cathcart Nature Reserve and Qacu Forest Nature Reserve, although this status does not always guarantee protection due to lack of compliance. Cathcart Nature Reserve is on the outskirts of the town with uncontrolled access to people and cattle. Qacu is probably relatively undisturbed due to its isolation. The present landowners of the two private farms on which the species has been recorded are both conservationists and its forest habitats at these localities are therefore safe at present.