Gulella hadroglossa, Herbert, 2016

Herbert, David G., 2016, New narrow-range endemic land snails from the sky islands of northern South Africa (Gastropoda: Streptaxidae and Urocyclidae), European Journal of Taxonomy 236, pp. 1-29 : 7-9

Gulella hadroglossa sp. nov.

urn:lsid:zoobank.org:act:B0429B6A-4C92-40BB-B2E7-A707A32ADE96

Fig. 3

Etymology

From hadros (Gr.) ‘well-developed, great, strong’, and glossa (Gr.) ‘tongue’; referring to the large, tongue-like parietal lamella.

Material examined

Holotype

SOUTH AFRICA: Mpumalanga, Mariepskop Forest Reserve, Picnic Trail , 24.56847° S, 30.85920° E, 1545 m, northern mist-belt forest, in leaf-litter, D. Herbert, L. Davis & M. Cole, stn 14-27, 4 Dec. 2014, height 3.0 mm, diameter 1.5 mm ( NMSA P0230/T4084 , dry specimen).

Paratypes

SOUTH AFRICA: Mpumalanga, same data as holotype ( NMSA P 0417/T4085 , five dry specimens; NHMUK 20160038 , one dry specimen ; RMNH. 5004142 , one dry specimen) ; Mariepskop Forest Reserve, 24.55117° S, 30.89395° E, 1460 m, indigenous Afromontane forest, in leaf-litter on forest floor, J.L. Horn, 23 Apr. 2005 ( NMSA W3500/T4081 , four dry specimens) ; Mariepskop Forest Reserve, Bushpig Trail , 24.56795° S, 30.86138° E, 1520 m, northern mist-belt forest, in leaf-litter, D. Herbert, L. Davis & M. Cole, stn 14-22a, 3 Dec. 2014 ( NMSA P0263/T4082 , one dry specimen) ; Mariepskop Forest Reserve, east facing slope, 24.57108° S, 30.86014° E, 1519 m, leg. M. Cole, 18 Oct. 2010 ( ELM D16635/T033 , three dry specimens) ; Mariepskop Forest Reserve, in forest beside road at 1520–1700 m, leg. M. Cole, 3–4 Dec. 2014 ( ELM D18019/T034 , six dry specimens).

Type locality

SOUTH AFRICA: Mpumalanga, Mariepskop Forest Reserve, Picnic Trail, 24.56847° S, 30.85920° E, 1545 m.

Identification

A small species of Gulella with a smooth, glossy, pupiform shell and 3-fold apertural dentition including a very large, oblique, tongue-like parietal lamella projecting far beyond the peristome; a mid-labral plate, the upper edge of which forms a narrow ridge-like tooth that runs obliquely inward and downward; a horizontal in-running tooth at columella base.

Description

SHELL ( Fig. 3 ). Small, pupiform; adult height 3.0– 3.1 mm, diameter 1.45–1.55 mm; H:D 1.96–2.09, with up to 7.25 whorls. Protoconch diameter ~ 0.7 mm, comprising 1.5–1.75 whorls beyond nucleus, smooth and glossy when fresh; junction with teleoconch indistinct. Teleoconch comprising 5.0–5.5 whorls; whorls weakly convex, lacking a shoulder and suture weakly indented (may appear somewhat channelled in eroded specimens); smooth and glossy, sculptured only by occasional weak growthlines, some specimens with faint traces of subsutural pliculae (not evident in holotype); growth-lines stronger and more close-set on apertural tube behind peristome. Aperture ovate, but truncated where peristome interrupted in parietal region; aperture rim flaring and strongly recurved, forming a nearly closed channel behind lip; apertural dentition 3-fold ( Fig. 3 C–D): 1) a very large parietal lamella with a tongue-like anterior element that curves outward and to the right, well beyond plane of aperture and then backward towards outer lip; interval between lamella and outer lip partially filled with an overarching shelf, leaving a U-shaped notch behind lamella; 2) a mid-labral plate running inward from a low thickening of outer lip, its upper margin raised to form a narrow ridge that runs obliquely inward and downward (hidden by parietal lamella in frontal view), basal margin usually ill-defined; 3) a narrow in-running tooth near base of columella; a columella lamella is not evident, though in some specimens a very deep-set vertical ledge may be discerned where apertural tube kinks around to join rounded portion of last whorl. A juvenile specimen of ~2.25 teleoconch whorls possessed 4-fold apertural dentition ( Fig. 3 F–G) comprising: two well-developed, flattened, semi-circular teeth set transversely at left and right of basal lip, that on the right more deep-set; a curved parietal tooth just beyond limit of aperture, behind and to the right of which arises a fourth, more rounded tooth; a second, identical set of teeth visible by transparency one half-whorl behind aperture. Umbilicus closed, base grooved beneath basal columella tooth ( Fig. 3E ). Empty shells translucent greyish-white when fresh; yellow colour of dried body showing through in live-collected material.

LIVING ANIMAL. No preserved specimens available.

Distribution

A narrow-range endemic, currently recorded only from Mariepskop Forest Reserve on the edge of the Drakensberg Escarpment in northern Mpumalanga, South Africa; at altitudes from 1460 to 1545 m.

Habitat

Northern mist-belt forest ( Mucina & Rutherford 2006), in leaf-litter.

Remarks

Gulella hadroglossa sp. nov. is rendered distinctive amongst small, smooth-shelled Gulella species on account of its large recurved parietal lamella. It is comparable in size (slightly smaller) and superficially similar to G. verdcourti Bruggen, 1966 , from the neighbouring Wolkberg massif, but that species has a distinct subsutural shoulder resulting in an incised suture, and its apertural dentition is also different, the parietal lamella not projecting as far and the mid-labral tooth being stronger.

Figures

Fig. 3. Gulella hadroglossa sp. nov. A–E. Holotype, height 3.0 mm, diameter 1.5 mm (NMSA P0230/ T4084). F–G. Juvenile specimen showing apertural dentition, diameter 1.5 mm (paratype, NMSA P0417/T4085).