Gulella maraisi sp. nov.

urn:lsid:zoobank.org:act: 1D02CEC4-33FC-48DD-86EF-592869390159

Figs 10, 11A–D

Diagnosis

Shell small, cylindrical; sculptured by axial ribs that extend to mid-whorl on spire whorls and from suture to suture on last whorl; aperture little obstructed by teeth; dentition typically three-fold, including

a parietal lamella, a simple labral tooth and a quadrate columella lamella; sometimes with an additional small basal tooth just left of centre; umbilicus small, elongate-ovate.

Etymology

Named for Dr Johan P. Marais, a very productive conchologist who collected much material for the KwaZulu-Natal Museum, including specimens of this species.

Material examined

Holotype SOUTH AFRICA – KwaZulu-Natal • Mtamvuna River mouth beach drift; 31.083°S, 30.197° E; Jun. 1996; leg. J. P. Marais; NMSA P1676/T4520.

Paratypes (listed south to north) SOUTH AFRICA – KwaZulu-Natal • 3specs.; Mtamvuna River mouth beach drift; 31.083°S, 30.197°E; Jun. 1996; J. P. Marais leg.; NMSA V3993/T4485 • 1 spec.; same collection data as for preceding; NHMUK 20210077, prev. NMSA V3993 • 1 spec.; Port Shepstone, Simuma area, Hlokohloko Valley, degraded riverine forest; 30.65898°S, 30.34292° E, ca 130 m a.s.l.; 6 May 2008; D. Herbert and L. Davis leg.; NMSA W6277/T4486 • 1 spec.; Port Shepstone, Simuma area, Hlokohloko Valley, stn 11- 001, riverine forest; 30.66310°S, 30.33685° E, ca 150–200 m a.s.l.; 5 Mar. 2011; D. Herbert and L. Davis leg.; NMSA W7831/T4487 • 1 spec.; Port Shepstone area, Marble Delta, South side of Simuma Hill, woodland/forest, in leaf-litter, stn S1; 30.6683°S, 30.3470° E; 237 m a.s.l.; Feb. 2012; J. Harvey leg.; NMSA W8786/T4483 .

Other material

SOUTH AFRICA – KwaZulu-Natal • 2specs.; Mtamvuna River mouth beach drift; 31.083°S, 30.197°E; Jun. 1996; J. P. Marais leg.; NMSA P1613 prev. NMSA V3993 . Eastern Cape • 1 spec.; Mkambati Nature Reserve, East bank of Mkambati River, between Mkambati and Strandloper waterfalls; 31.2738° S, 30.0236° E; 15 Feb. 2011; M. Cole leg.; ELMD 18754 • 1 spec.; same locality as for preceding; 17 Mar. 2019; M. Cole leg.; ELMD 18475 • 4 specs.; Mkambati Nature Reserve, gorge of Daza River, East side; 31.3000° S, 29.9879°E; 16 Feb. 2011; M. Cole leg.; ELMD 18756 .

Description

SHELL (Fig. 11). Shell small, cylindrical, length 3.5–4.2 mm, width 1.5–1.7 mm, L:W 2.3–2.6 (n = 11). Protoconch 1.1 mm in diameter, comprising approx. 2.5 whorls, smooth; junction between protoconch and teleoconch distinct. Teleoconch comprising approx. 5 whorls; whorls moderately convex; sculptured by subsutural axial riblets extending to mid-whorl on earlier whorls, but strong on last whorl and running from suture to suture (Fig. 11A, B); axial pleats prominent on base, running into umbilicus (Fig. 11D). Peristome thickened, interrupted in parietal region and with a hiatus behind parietal lamella (Fig. 11C). Aperture little obstructed by teeth; apertural dentition three- or four-fold (Fig. 11C, E): 1) an oblique parietal lamella which begins above insertion of labrum and curves and runs into aperture; 2) a simple in-running, ridge-like mid-labral tooth; 3) a small basal tooth just to left of centre near the lip edge in the Eastern Cape population (Fig. 11E); 4) a quadrate columella lamella. Labral tooth corresponds with a shallow pit behind outer lip (Fig. 11B). Umbilicus very small, elongate-ovate (Fig. 11D). Shell translucent, uniformly milky-white when fresh, reddish-pink dried tissue of animal visible internally.

Distribution (Fig. 10)

Recorded at isolated localities in southern KwaZulu-Natal and northeast Eastern Cape provinces, from the coast up to approx. 130 m above sea level.

Habitat

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

Remarks

Specimens collected at Mkambati Nature Reserve are slightly smaller, appear to have one less whorl and have a small basal tooth to the left of centre, absent in all the specimens collected in KwaZulu- Natal. In other respects specimens from both areas appear to be identical. The Eastern Cape population is considered here to be Gulella maraisi sp. nov., but due to the differences mentioned above, these specimens are not included in the type material.

Gulella maraisi sp. nov. superficially resembles G. pentheri, but is larger and has axial sculpture, while G. pentheri is narrower and smooth. The parietal lamella of G. maraisi sp. nov. extends to the edge of the labrum and curves strongly before running into the aperture, a feature not present in G. pentheri . In respect of its apertural dentition and the short axial riblets, G. maraisi sp. nov. resembles G. inhluzaniensis, but in the present species the columella lamella is much larger and the last whorl has much stronger axial ribs. Gulella maraisi sp. nov. also resembles G. abbotti sp. nov., but the latter is smaller, narrower and has a more substantial labral tooth as well as a basal tooth. Species in the Gulella infans group (Herbert & Kilburn 2004) are larger, generally broader, have a less prominent columella lamella and weaker axial sculpture.

Conservation

Gulella maraisi sp. nov. appears to be a very rare species with few records. It has been collected alive at only two localities approx. 75 km apart. One of these is under threat from mining since the lower Hlokohloko Valley is being sacrificed as a waste rock dump. It has not been found in Oribi Gorge Nature Reserve immediately to the west. The other locality is in a protected area, the Mkambati Nature Reserve. It has been collected in beach drift at the mouth of the Mtamvuna River, but as yet not in the Mtamvuna Gorge Nature Reserve upstream.