Gulella fordycei Cole & Herbert 2022, sp. nov.

Gulella fordycei sp. nov.

urn:lsid:zoobank.org:act: 8E77FF84-C946-433A-8070-A4CB4036053D

Figs 2, 3A–D

Diagnosis

SHELL minute, cylindrical; smooth and glossy, but with weak axial riblets below suture; apertural dentition seven-fold, including a sinuous parietal lamella, a large labral complex extending deeply into aperture with ridge-like upper and lower margins and a groove in centre, a low, deeply inset transverse basal tooth to right of centre, a ridge-like basal tooth to left of centre beginning close to lip edge and a large inset tricuspid columella lamella; umbilicus widely open.

Etymology

Named after the type locality, Fort Fordyce.

Material examined

Holotype SOUTH AFRICA – Eastern Cape • Fort Fordyce Nature Reserve, kloof with watercourse and sheer krantz; 32.6881°S, 26.5130°E; 915 m a.s.l.; 31 Mar. 2016; M. Cole leg.; NMSA P1679/T4525, prev. ELMD 18109.

Paratypes SOUTH AFRICA – Eastern Cape • 4 specs.; Fort Fordyce Nature Reserve, near Harris Hut; 32.6834° S, 26.4767°E; 1072 m a.s.l.; 5 Oct. 2009; M. Cole leg.; ELMD 16088/T 218 • 2 specs.; Fort Fordyce Nature Reserve, south-facing slope behind lookout; 32.6956°S, 26.4857°E; 1120 m a.s.l.; 3 Jan. 2010; M. Cole leg.; ELMD 16317/T 219 • 2 specs.; same collection data as for preceding; NMSA P1616/ T4498, prev. ELMD 16317 • 2 specs.; same collection data as for preceding; NMW.Z.2021.011.00002, prev. ELMD 16317 • 6 specs.; Fort Fordyce Nature Reserve, kloof with watercourse and sheer krantz; 32.6881°S, 26.5130°E; 915 m a.s.l.; 29 Dec. 2008; M. Cole leg.; ELMD 16377/T 220 • 2 specs.; same collection data as for preceding; RMNH.MOL.452585, prev. ELMD 16377 • 3 specs.; same collection data as for preceding; 6 Oct. 2009; ELMD 16073/T 221 • 1 spec.; same collection data as for preceding; NHMUK 20210067, prev. ELMD 16073 • 3 specs.; same collection data as for preceding; 17 Jan. 2015; ELMD 17842/T 222 • 3 specs.; same collection data as for preceding; NMSA P1615/T4497, prev. ELMD 17842 • 1 spec.; same collection data as for preceding; NHMUK 20210068, prev. ELMD 17842 • 2 specs.; Fort Fordyce Nature Reserve, between Harris Hut and dam; 32.6825°S, 26.4794° E; 1117 m a.s.l.; 18 Jan. 2015; M. Cole leg.; ELMD 17864/T 223.

Other material

SOUTH AFRICA – Eastern Cape • 2 specs.; Fort Fordyce Nature Reserve, kloof with watercourse, east-facing; 32.6704°S, 26.4851°E; 1137 m a.s.l.; 29 Dec. 2008; M. Cole leg.; ELMD 16083 • 2 specs.; Fort Ford yce Nature Reserve, south-facing slope behind lookout; 32.6956° S, 26.4857°E; 1120 m a.s.l.; 30 Dec. 2008; M. Cole leg.; ELMD 16085.

Description

SHELL (Fig. 3). Shell minute, cylindrical, length 2.2–2.5mm, width 1.0– 1.1 mm, L:W 2.1–2.3 (n = 6). Protoconch approx. 1mm in diameter, comprising approx. 2.25 whorls, smooth and glossy; junction between protoconch and teleoconch evident. Teleoconch comprising approx. 3.5–4 whorls; first whorl convex, remaining ones weakly so; weak axial riblets extend more or less half-way down each whorl, stronger immediately below sutures (Fig. 3B). Aperture sub-quadrate, rounded basally, markedly constricted by teeth; peristome thick and reflected, broadly interrupted in parietal region; dentition eightfold (Fig. 3C): 1) a strong parietal lamella with inner portion which runs into aperture somewhat sinuous, outer portion curving to right; parietal lamella projects well beyond profile of aperture in side view; 2) a large labral slab extending into aperture beyond columella lamella (in apertural view), with ridges on its upper and lower margins, bordering a V-shaped central groove, upper ridge sharp with a cusp near lip edge in close proximity to parietal lamella; 3) a low, deeply inset transverse basal tooth to right of centre; 4) an in-running basal ridge to left of centre beginning near lip edge; 5–7) a large columella lamella with three teeth, upper two ridge-like and lowest one small, sometimes little more than a low bulge, middle one largest and extending closer to lip edge. Labral slab corresponds with a deep pit behind outer lip (Fig. 3B); basal ridge with a shallow indentation behind lip. Umbilicus widely open, elongate-oval, with a deep indentation underlying columella lamella, indistinct axial pleats around umbilicus (Fig. 3D). Shell almost transparent when fresh, orange-red coloration of dried tissue of animal visible internally.

Distribution (Fig. 2)

Endemic to the Fort Fordyce Nature Reserve, considered part of the Amathole Mountains; at altitudes between 900m and 1150 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 fordycei sp. nov. is very similar to G. kenbrowni sp. nov. except that it has weak subsutural riblets and is larger (mean length 2.3mm and 2.1mm, respectively). The parietal lamella does not run parallel to the upper ridge of the labral slab, but the lowest point of its edge is in close proximity to the labral slab in the vicinity of the cusp. The labral complex is slightly differently shaped; the ridges of the labral slab have a V-shaped groove between them in G. fordycei sp. nov. The basal ridge to left of centre commences close to the lip edge and causes a shallow external furrow behind the lip, absent in G. kenbrowni sp. nov. In addition, the ridge-like middle tooth of the columella lamella is closer to the columella lip. Compared to other species described herein, the protoconch of G. fordycei sp. nov. is large relative to the size of its shell.

The labral slabs of Gulella fordycei sp. nov. and G. kenbrowni sp. nov. closely resemble those of G. bomvana and G. tietzae from the Eastern Cape coast and several narrow-range species endemic to Zululand, G. genialis (Melvill & Ponsonby, 1903), G. laevorsa Burnup, 1925 and G. vallaris (Melvill & Ponsonby, 1907) (see Gulella Group 9 in Herbert & Kilburn 2004). These Zululand species, however, all possess strong axial riblets running from suture to suture. The tricuspid columella lamella of G. fordycei sp. nov. and G. kenbrowni sp. nov. closely resembles that of G. bomvana and several other smooth-shelled Gulella species from the Eastern Cape coast with a tricuspid columella, Gulella aprosdoketa Connolly, 1939, G. tietzae and G. ndibo Cole & Herbert, 2009, but in the latter three species the columella lamella extends to the lip edge.

Conservation

Gulella fordycei sp. nov. has been found only at Fort Fordyce Nature Reserve, an outlier of the Amathole Mountains, despite extensive collecting efforts throughout the region. It therefore appears to be a very narrow-range endemic. Fort Fordyce is a protected area under the jurisdiction of the Eastern Cape Parks and Tourism Agency. It is known for endemicity of other terrestrial molluscs, viz. Amatholedonta fordycei Herbert, 2020 (Charopidae) and an undescribed species of Fauxulus (Anisoloma) (Fauxulidae). Furthermore, specimens of another litter-dwelling invertebrate, the velvet worm Peripatopsis sedgwicki (Purcell, 1899) from Fort Fordyce were genetically and morphologically distinct, suggesting the presence of a novel lineage at Fort Fordyce (Daniels et al. 2017).