Gulella latimerae, Bursey & Herbert, 2004

Bursey, M. L. & Herbert, D. G., 2004, Four new narrow-range endemic species of Gulella from Eastern Cape, South Africa (Mollusca: Pulmonata: Streptaxidae), African Invertebrates 45, pp. 249-262 : 255-257

Gulella latimerae sp. n.

Figs 12–17 , 24

Etymology: Named after Dr Marjorie Courtenay-Latimer, first curator of the East London Museum, well known for her discovery of the first living coelacanth, Latimeria chalumnae .

Diagnosis: Shell small, sub-cylindrical; sculptured with strong axial ribs; peristome entire, disjunct from penultimate whorl in parietal region and forming a short, detached apertural tube, margin strongly flaring; apertural dentition six-fold; umbilicus narrow (approx. 0.8 mm).

Description: Shell small, sub-cylindrical, relatively broad; length 3.98–4.44 mm, width 2.16–2.40 mm; length:width 1.83–1.95. Embryonic shell approx. 1.28 mm in diameter, comprising approx. 2.25 whorls; initially with only an extremely fine, microscopically shagreened sculpture, but with slit-like, axial grooves appearing above abapical suture on second whorl ( Fig. 17 ), these becoming progressively stronger and transforming into fine, close-set axial riblets on final part of embryonic shell; no trace of spiral sculpture; junction between embryonic shell and teleoconch distinct. Teleoconch comprising approx. 5.25 whorls; whorls strongly convex, suture strongly indented; sculptured by well-developed, prosocline axial ribs, extending from suture to suture (47–49 on penultimate whorl); rib intervals lacking obvious microsculpture and with no evidence of spiral threads except for feeble traces just below suture ( Fig. 16 ). Peristome entire; terminal part of last whorl disjunct from preceding whorl and drawn out into a short, detached apertural tube; tube constricted behind basal lip. Apertural dentition six-fold ( Figs 14, 15 ): 1) a well-developed parietal lamella, outer portion strongly oblique, its lower margin weakly sinuous; 2) a compound, broad-based labral tooth, with an in-running, roundly triangular slab at its centre, this with a small pointed denticle at its upper base, defining lower part of labral sinus, lower margin of labral slab buttressed but without a discrete tooth; 3) an oblique in-running basal ridge commencing just to right of centre, but not extending to aperture edge; 4) a broad, low, indistinct ridge to left of centre, at base of columella lip (and mostly obscured by it), running inward parallel to basal ridge (not visible in figures); 5) a bicuspid tooth on upper part of columella, comprising two in-running ridges united at apertural edge; 6) a large, rounded, deep-set columella lamella, excavated in centre. Exterior of apertural tube strongly indented in region of labral, basal and columellar teeth, appearing constricted in lateral view ( Fig. 13 ). Umbilicus relatively narrow (width approx. 0.8 mm), its opening semi-circular to crescentic ( Fig. 15 ). Shell translucent, uniformly milky-white when fresh.

Type material: Holotype: NMSA, W1426 /T1997, length 4.32 mm, width 2.36 mm. South Africa, Eastern Cape, Transkei, Kumqolo Forest (32º09.553'S: 28º59.12'E), 500 m upstream of Xora River mouth, steeply sloping southern side, in leaf-litter, leg. M. Bursey, viii/2001.

Paratype 1: ELM 13663 , South Africa, Eastern Cape, Transkei, Dwesa Nature Reserve , coastal forest along road east of camp (32.28ºS: 28.842ºE), in leaf-litter, leg. M. Bursey, 7/iii/2000 .

Paratype 2: NMSA W1817 /T2012, South Africa, Eastern Cape, Pondoland coast, environs of Mntafufu River mouth, south side of river (31.55021ºS: 29.61777ºE), coastal scarp forest, amongst talus and leaf-litter at base of road cutting, leg. D. Herbert & M. Bursey, 29/iv/2004 .

Paratype 3: ELM 13901 , as paratype 2, but on northern side of Mntafufu River mouth (31.55596ºS: 29.62606ºE) coastal scarp forest, in soil inside dead achatinid snail, leg. M. Bursey & D. Herbert, 29/iv.2004 .

Distribution and habitat ( Fig. 24 ): Known from three localities along the coast of the Transkei region of Eastern Cape, from the mouth of the Mntafufu River in the north to Dwesa Nature Reserve in the south. These localities are separated by a straight line distance of only approx. 110 km.

Found in patches of coastal scarp forest, in leaf-litter. The type locality, Kumqolo Forest, is heavily utilised by local people for structural timber and traditional medicines, and is trampled by cattle and goats.

Remarks: Gulella latimerae resembles G. newmani sp. n. described below, in terms of its disjunct peristome with detached apertural tube, and the form of the major apertural teeth, however, the apertural tube is longer and more strongly descending in G. newmani , and the apertural rim of G. latimerae lacks superficial tubercles (more details given in the remarks pertaining to G. newmani ). At first glance, the apertural dentition of G. latimerae also resembles that of Gulella tharfieldensis (Melvill & Ponsonby, 1893) , and to a lesser extent G. munita (Melvill & Ponsonby, 1893) , both from the Port Alfred- Grahamstown (Albany) area, particularly with regard to the well-developed labral and columellar teeth. However, their shells are narrower, less crisply sculptured and have a clearly interrupted peristome.

Figures

Figs 12–17. Gulella latimerae sp. n., holotype. 12, 13, apertural and lateral views of shell, length = 4.32 mm; 14, enlarged view of the aperture, bar = 0.4 mm; 15, umbilical region, bar = 0.5 mm; 16, detail of sculpture (end of penultimate whorl and start of last whorl), bar = 100 µm; 17, microsculpture on embryonic shell, bar = 50 µm.

Fig. 24. Map of northern Eastern Cape showing distribution of new species.