Eight new species of Gulella Pfeiffer, 1856 from the south-east coast of South Africa (Gastropoda: Streptaxidae)

. Eight new species of Gulella Pfeiffer, 1856 are described from south-eastern South Africa, occurring over a linear distance of 550 km within the Maputaland-Pondoland-Albany biodiversity hotspot. Seven species are narrow-range endemics, while Gulella kenbrowni sp. nov. occurs somewhat patchily over most of this distance. The very similar G. fordycei sp. nov. is recorded from only one small nature reserve in medium-altitude mistbelt forest. Six species, G. crookesi sp. nov., G. maraisi sp. nov., G. mkombeni sp. nov., G. abbotti sp. nov., G. donaikeni sp. nov. and G. calcicola sp. nov. each occur at one or a few isolated localities along a narrow strip of 140 km at or near the coast. The latter two are found only in the Marble Delta region, where mining has badly degraded and continues to threaten their habitat, and appear to meet the criteria for Red-Listing as Critically Endangered. Six species occur in nature reserves, highlighting the importance of small pockets of protected habitat for the conservation of terrestrial snails.


Introduction
Gulella Pfeiffer, 1856 is the most common and diverse genus of Streptaxidae in South Africa (Herbert & Kilburn 2004) and the majority are ground-dwelling, occurring in leaf-litter and under logs or rocks. Well over one hundred species have been described from the region, fi fteen in the past 20 years (Herbert 2002(Herbert , 2006(Herbert , 2016Bursey & Herbert 2004;Bruggen 2004Bruggen , 2006Cole & Herbert 2009), while a host of potentially new species have been earmarked for description. These recently described and potentially new species were probably overlooked in the past due to their rarity and very limited geographic ranges; the majority are also very small. Eight species are treated herein as part of an ongoing effort to describe this undocumented diversity.
Most eastern South African Gulella species are referable to Gulel la s. lat. ( sensu Rowson & Herbert 2016), but this represents a conchologically diverse assemblage of species which, apart from a small number of lineage clusters ( Huttonella , Maurennea and Zulugulella ), shows little coherent substructure based on the limited molecular data available (Rowson & Herbert 2016). Several of the species described in this paper resemble each other in terms of their columella lamella morphology and complex, inrunning labral plate, and may genuinely be related (e.g. G. donaikeni , G. fordycei , G. kenbrowni and G. mkombeni ). However, although used in a recent synthesis of the Streptaxoidea (Brown 2021), we refrain from assigning our new species to subgenera. We consider it unlikely that the simplistic criteria upon which subgenera such as Molarella Connolly, 1922 andPlicigulella Pilsbry, 1919 are based (respectively a duplex and triplex columella lamella) will prove to refl ect true phylogenetic relationships. Such decisions must await the availability of further molecular data. This paper focuses on species with minute, smooth or weakly ribbed shells occurring primarily in the coastal hinterland of south-eastern South Africa, within the Maputaland-Pondoland-Albany biodiversity hotspot (Steenkamp et al . 2004). The majority, fi ve species, have only been collected at isolated localities along a narrow strip of approx. 80 km, spanning the north-eastern limit of the Eastern Cape province and the southern section of KwaZulu-Natal province. This is a focal area of high diversity and narrowrange endemism in terrestrial molluscs (Herbert 2002;Bursey & Herbert 2004;Herbert & Kilburn 2004;Cole 2019;Perera et al . 2021), but contains few formally protected reserves. By describing this undocumented diversity we hope to raise awareness of the importance of these habitats as priority areas for conservation. After formal description, these taxa will be assessed according to the IUCN Red List to evaluate whether they qualify for threatened status. Six species occur in small nature reserves, while three of these are each known exclusively from only one nature reserve, highlighting the importance of small protected areas in safeguarding the habitats of terrestrial invertebrates with limited capacity for dispersal.

Material and methods
The material studied was derived primarily from the collection at the KwaZulu-Natal Museum and the East London Museum. This was accumulated over many years, but has been signifi cantly augmented in the last two decades through a programme of fi eld work targeting poorly-surveyed regions of South Africa. Live-collected samples were dried or obtained in a dry state from leaf-litter samples. In some instances whole specimens were preserved in 99% ethanol as tissue samples for on-going molecular studies, and are housed in the KwaZulu-Natal Museum tissue collection.
Shells were photographed using a Zeiss Axio Zoom V16 dissecting microscope with an Axiocam 506 digital camera or a Zeiss Discovery V12 dissecting microscope with an Axiocam 305 digital camera. Stacked images were then combined using Helicon Focus Pro (Helicon Soft Ltd) to provide extended depth of fi eld.
Shell length and width measurements were made with the shell held in apertural view and the long axis horizontal. Holotypes were measured with the Line function of the Graphics menu available in the ZEN ver. 2.3 pro Hardware used with the Zeiss Discovery V12 dissecting microscope and rounded off to two decimal places. Other specimens were measured using an eyepiece graticule. Shell length:width ratios were calculated and the number of protoconch and teleoconch whorls were counted. The sizing guide of Herbert & Kilburn (2004) was followed.
Live-taken specimens and shells of dead specimens still in good condition were assigned as paratypes and distributed among fi ve museums, two in South Africa and three in Europe. Shells in poor condition are listed under 'Other material' except in the case of Gulella maraisi sp. nov. where some fresh specimens were not included in the type material due to minor differences. A catalogue number preceded by "prev." indicates that the specimen(s) was initially recorded in that museum and was transferred to the museum where it is currently housed.

Diagnosis
Shell minute, cylindrical; smooth and glossy; aperture sub-quadrate; apertural dentition seven-fold, including a parietal lamella, a large labral complex extending deeply into aperture with ridge-like upper and lower margins and hollow in centre, a low, inset transverse basal tooth to right of centre, a stronger inset basal tooth to left of centre and a large tricuspid columella lamella with two strong ridge-like teeth, and a smaller tooth below these; umbilicus widely open.

Etymology
Named for Kenneth Brown, long-standing member of the Conchological Society of South Africa, and with a particular interest in Streptaxoidea. Description SHELL (Fig. 1). Shell minute, cylindrical, length 1.9-2.4 mm, width 0.8-1.0 mm, L:W 2.0-2.5 (n = 25); smooth and glossy but with indistinct, microscopic growth lines. Protoconch approx. 0.8 mm in diameter, comprising approx. 2.25 whorls, smooth; junction between protoconch and teleoconch not distinct. Teleoconch comprising approx. 3.5 whorls; fi rst two whorls roundly convex, subsequent ones more weakly convex (Fig. 1A-B). Aperture sub-quadrate, rounded at base, markedly constricted by teeth; peristome thickened and refl ected, broadly interrupted in parietal region; dentition seven-fold ( Fig.  1C): 1) a strong parietal lamella, outer portion oblique and then curving inward so that the remainder runs into aperture more or less at right angles; outer portion fuses smoothly with outer lip; 2) a large labral slab extending deeply into aperture, with a sharp upper margin beginning with a cusp near lip edge defi ning lower part of labral sinus and running into aperture more or less parallel to parietal lamella, and a blunt ridge on its lower margin not reaching lip edge; 3) a low, deeply inset transverse basal tooth just to right of centre; 4) a less deeply inset, stronger, in-running, somewhat ridge-like, basal tooth to left of centre; 5-7) a large columella lamella with three teeth, middle and upper ones strong, with a shorter tooth below these at its base; middle tooth largest and ridge-like often curving downwards as it runs into aperture and appearing concave on its lower surface. Labral slab corresponds with a fairly shallow indentation behind outer lip (Fig. 1B). Umbilicus widely open, elongate-oval, with a deep indentation underlying columella lamella; umbilical margin with axial pleats, often irregular and rather indistinct (Fig. 1D). Shell almost transparent when fresh, orange-red or yellowish coloration of dried tissue of animal visible internally. Distribution (Fig. 2) Recorded on the coast of the Eastern Cape from East London northwards and in southern KwaZulu-Natal, where it is also recorded inland in the Kokstad area (1350 m a.s.l.). The latter locality is somewhat unexpected since the species is usually collected in close proximity to the coast.

Remarks
Gulella kenbrowni sp. nov. has been treated as G. sylvia (Melvill & Ponsonby, 1903) (Herbert & Kilburn 2004), although it was noted that Transkei and southern KwaZulu-Natal material might turn out to be a separate, unnamed species upon further study. Gulella kenbrowni sp. nov. resembles G. bomvana Cole & Herbert, 2009, which occupies a small area within the range of G. kenbrowni sp. nov., but the latter is larger, its basal tooth is further to the left of centre, and its umbilicus is widely open. Gulella kenbrowni sp. nov. also closely resembles G. fordycei sp. nov. described below; differences are discussed thereunder. The labral slab resembles that of Gulella tietzae Cole & Herbert, 2009, but it is smaller than that of both G. bomvana and G. tietzae .

Conservation
Gulella kenbrowni sp. nov. occurs over a relatively wider range than the other species described in this paper and many other South African Streptaxidae (Herbert & Kilburn 2004;Bursey & Herbert 2004;Cole & Herbert 2009). There are several small nature reserves within its range, but uncontrolled human access and trampling by cattle are commonplace. Forests in this region remain habitats of conservation concern.
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.   Description SHELL (Fig. 3). Shell minute, cylindrical, length 2.2-2.5 mm, width 1.0-1.1 mm, L:W 2.1-2.3 (n = 6). Protoconch approx. 1 mm in diameter, comprising approx. 2.25 whorls, smooth and glossy; junction between protoconch and teleoconch evident. Teleoconch comprising approx. 3.5-4 whorls; fi rst 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 refl ected, 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 profi le 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 (

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 2.3 mm and 2.1 mm, 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 andG. 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).

Diagnosis
Shell minute, cylindrical; smooth and glossy; apertural dentition seven-fold, including a parietal lamella with a notch in its lower margin, a large labral complex extending deeply into aperture with ridge-like upper and lower margins bounding a broad sunken mid region, a low, inset transverse basal tooth to right of centre, an inset oblique ridge-like basal tooth to left of centre and a columella lamella set with two ridge-like teeth, the lower stronger and extending to near lip edge; umbilicus widely open with distinct peri-umbilical pleats.

Etymology
Xhosa for 'place of the ikomba palm', or Pondo palm ( Jubaeopsis caffra Becc.), another of the several species narrowly endemic to the Mkambati Nature Reserve and immediate vicinity. Description SHELL (Fig. 4). Shell minute, cylindrical, length 2.3-2.7 mm, width 1.0-1.3 mm, L:W 2.0-2.4 (n = 16); smooth and glossy with microscopic growth lines. Protoconch approx. 0.7 mm in diameter, comprising approx. 2.25 whorls, smooth; junction between protoconch and teleoconch not distinct. Teleoconch comprising approx. 4 whorls; fi rst two whorls roundly convex, subsequent ones weakly convex (Fig.  4A, B). Aperture sub-quadrate, rounded at base, markedly constricted by teeth; peristome thickened and refl ected; dentition seven-fold ( Fig. 4C): 1) an oblique parietal lamella usually with a notch in its lower margin; 2-3) a large labral complex extending deeply into aperture; a ridge on lip edge more or less in centre of labral complex curves upwards and outwards and continues inwards as a sharp upper margin, a small cusp near lip edge defi nes lower part of labral sinus; lower margin of labral complex more rounded and does not reach lip edge, becoming narrower further into aperture; upper and lower ridges do not quite meet at inner end of labral slab; between ridges is a wide, sunken area; 4) a low, deeply inset transverse basal tooth to right of centre; 5) an inset oblique ridge-like basal tooth to left of centre which runs inwards and upwards beneath columella lamella; 6-7) a large columella lamella set with two ridgelike teeth, the lower one larger, almost reaching lip edge. Labral complex corresponds with a shallow indentation behind outer lip (Fig. 4B); basal tooth to left of centre corresponds with an external furrow (Fig. 4D). Umbilicus widely open with a deep indentation underlying columella lamella, peri-umbilical region with distinct axial pleats (Fig. 4D). Shell almost transparent when fresh, orange-red coloration of dried tissue of animal visible internally. Distribution (Fig. 2) Recorded only from the Mkambati Nature Reserve in Pondoland on the north-eastern coast of the Eastern Cape.

Remarks
Gulella mkombeni sp. nov. closely resembles G. kenbrowni sp. nov. which occurs to the north and south of the Mkambati Nature Reserve, but has not been recorded in the reserve itself. Gulella mkombeni sp. nov. is distinguished by the ridge-like lower tooth on the columella lamella which extends much closer to the lip edge. Other differences are that it is larger, the upper and lower margins of the labral complex do not meet within the aperture, the parietal lamella usually has a notch in its lower margin, and the peri-umbilical region is more strongly pleated. Additionally, the basal tooth to the left of centre is longer, extending beneath the columella lamella. The columella lamella is also reminiscent of that of G. tietzae, G. ndibo and G. aprosdoketa, in which the columella lamella extends to the lip edge, but in these three species it is tricuspid.

Conservation
Gulella mkombeni sp. nov. is to date known only from the Mkambati Nature Reserve, despite reasonable collecting efforts along the coast of the Eastern Cape and KwaZulu-Natal. Other taxa also occur only in Mkambati, e.g., G. newmani Bursey & Herbert, 2004. This region, known as Pondoland, has been shown to be an important centre of cladogenic events in rhytidid molluscs (Herbert & Moussalli 2010;Moussalli et al . 2009

Diagnosis
Shell minute, cylindrical; smooth and glossy; apertural dentition seven-fold, including a parietal lamella with outer portion oblique and then curving inward, the labral lip is thickened with a cusp at upper and lower ends and a large scoop-shaped plate extending deeply into aperture, a low, inset transverse basal tooth to right of centre, an inset basal tooth to left of centre and a large columella lamella with two rounded teeth, the lower large and broad and the upper relatively small; umbilicus widely open.

Etymology
Named for Don W. Aiken (1930Aiken ( -1988, an enthusiastic collector of South African land snails and author of two important publications dealing with South African Streptaxidae (Aiken 1981(Aiken , 1995. Description SHELL (Fig. 5). Shell minute, cylindrical, length 1.8-2.3 mm, width 0.8-0.9 mm, L:W 2.2-2.6 (n = 16); smooth and glossy with microscopic growth lines. Protoconch approx. 0.7 mm in diameter, comprising approx. 2.5 whorls, smooth; junction between protoconch and teleoconch not distinct. Teleoconch comprising approx. 3.5 whorls; whorls relatively fl at-sided ( Fig. 5A-B). Aperture sub-quadrate, rounded at base, markedly constricted by teeth; peristome thickened and refl ected, broadly interrupted in parietal region; dentition seven-fold (Fig. 5C): 1) a parietal lamella, outer portion strongly oblique (almost transverse) and then curving inward; 2-3) labral lip thickened, forming a vertical ridge which bears a cusp at its upper and lower ends, each inside aperture edge, the upper cusp defi nes lower part of labral sinus; beginning just behind thickened labral lip a large, shallow scoop-shaped plate with a sharp ridge around its border extends deeply into aperture beyond level of columella lamella in aperture view; 4) a low, deeply inset transverse basal tooth to right of centre; 5) an inset oblique basal tooth to left of centre; 6-7) a large columella lamella with two well-spaced rounded teeth, the lower one large, broad and sloping outward toward outer lip, the upper one smaller and more deep-set. Labral tooth corresponds with a shallow indentation behind outer lip (Fig. 5B); basal tooth to left of centre corresponds with a narrow external furrow (Fig. 5D). Umbilicus open, relatively wide and deep with a conspicuous pit underlying columella lamella, approx. 0.2 mm across, peri-umbilical region with distinct axial pleats (Fig. 5D). Shell almost transparent when fresh, orange-red coloration of dried tissue of animal visible internally.
Distribution (Fig. 6) Known only from an area approx. 16 km NW of Port Shepstone in southern KwaZulu-Natal, mainly from the Marble Delta, and the neighbouring Four Man's Hill and Hlokohloko Valley. G. donaikeni sp. nov. has only been recorded south of the Mzimkulu River and G. calcicola sp. nov. (see below) only north of the river.

Habitat
Patches of dense valley thicket (Low & Rebelo 1996), also referred to as Eastern Valley Bushveld (Rutherford et al . 2006) and KwaZulu-Natal Scarp forest (Mucina et al . 2018b); in leaf-litter and under logs. The indigenous vegetation has been heavily invaded by alien plants, notably Chromolaena odorata (L.) R.M.King (Asteraceae), and Lantana camara L. (Verbenaceae), both from South and Central America.

Remarks
In terms of its minute size, smooth glossy shell and dentition, Gulella donaikeni sp. nov. resembles G. tietzae , G. kenbrowni sp. nov. and G. mkombeni sp. nov. It is distinguished from G. tietzae by the large rounded lower tooth on the columella lamella and the presence of a low inset basal tooth to the right of centre. The labral complex extends further into the aperture than that of G. kenbrowni sp. nov., and G. mkombeni sp. nov. and the lower columella tooth is rounded and not ridge-like.

Conservation
Gulella donaikeni sp. nov. has been found in a very small, degraded area and its habitat continues to be threatened by mining. The lower portion of the Hlokohloko Valley has been sacrifi ced to provide a waste rock dump for the quarry. The species evidently meets the criteria for red-listing as Critically Endangered. Conservation remarks pertaining to Gulella calcicola sp. nov. (see below) also apply to G. donaikeni .

Diagnosis
Shell minute, sub-cylindrical; smooth and glossy; aperture markedly constricted by teeth and narrower towards base; apertural dentition nine-fold, including an oblique parietal lamella with a notch in its lower margin, a large triangular labral tooth, its upper margin sinuous, and with a denticle near lip edge and another further into aperture, three inset basal teeth in close apposition, a low, broad rounded denticle on columella lip and a large inset tricuspid columella lamella; umbilicus widely open and with distinct peri-umbilical pleats.

Etymology
Named for the type locality, the Vernon Crookes Nature Reserve, KwaZulu-Natal.

Paratypes
SOUTH AFRICA -KwaZulu-Natal • 1 spec.; same collection data as for holotype; NMSA P1617/ T4499, prev. ELMD 16438 • 4 specs.; same collection data as for holotype; ELMD 16438/T 230 • 2 specs.; same collection data as for holotype; NHMUK 20210071, prev. ELMD 16438 • 2 specs.; same collection data as for holotype; NMW.Z.2021.011.00003, prev. ELMD 16438 • 1 spec.; same collection data as for holotype; RMNH.MOL.452590, prev. ELMD 16438 • 1 spec.; same locality as for holotype, Station 11-14; 15 April 2011; D. Herbert, L, Davis, M. Cole and R. Daniels leg.; NMSA W8095/T4484. Description SHELL (Fig. 7). Shell minute, sub-cylindrical to squat, length 2.4-2.6 mm, width 1.1-1.2 mm, L:W 2.0-2.2 (n = 7). Protoconch approx. 0.9 mm in diameter, comprising approx. 2.5 whorls, smooth; junction between protoconch and teleoconch not distinct. Teleoconch comprising approx. 4 whorls; whorls weakly convex; smooth and glossy but with fi ne growth lines (Fig. 7A, B), surface often eroded and pitted even in live-collected shells; axial pleats on lower half of last whorl and around umbilicus (Fig. 7D), extending to adapical suture just prior to outer lip (Fig. 7B). Aperture narrower towards base on right hand side (in aperture view); peristome thickened and refl ected; aperture markedly constricted by teeth, dentition nine-fold (Fig. 7C): 1) a parietal lamella, with outer portion markedly oblique and then curving inward so that remainder runs into aperture, and with a notch in its lower margin; 2) a large triangular labral tooth, its upper margin sinuous and with a denticle near lip edge and another further into aperture; 3, 4 and 5) two deeply inset ridge-like basal teeth in close apposition plus one behind labral tooth, visible through translucent shell, 6) a low, broad rounded denticle at base of somewhat thickened columella lip, and in some specimens, an even less prominent one at top of columella lip; 7-9) a large inset tricuspid columella lamella, the upper and middle teeth large and rounded (particularly the middle one), the lower one smaller, often little more than a bump. Labral tooth corresponds with a deep pit behind outer lip (Fig. 7B). Umbilicus widely open, elongate-oval, approx. 0.2 mm in length (Fig. 7D). Shell almost transparent when fresh, orange-red coloration of dried tissue of animal visible internally. Distribution (Fig. 2) Known only from Vernon Crookes Nature Reserve, in southern KwaZulu-Natal; at approx. 400 m above sea level.

Habitat
Patches of KwaZulu-Natal Scarp forest (Mucina et al. 2018b); in leaf-litter and under logs.

Remarks
The two closely adpressed, ridge-like basal teeth are unusual; in taxa with a basal tooth to the right of centre, it is usually low and transverse, not in-running. The tricuspid columella lamella of Gulella crookesi sp. nov. resembles that of G. fordycei sp. nov. and several species from the Eastern Cape coast, particularly G. bomvana and G. kenbrowni sp. nov. The latter two taxa are also smooth and glossy. The labral tooth of G. crookesi sp. nov. is relatively larger than that of G. fordycei sp. nov., obstructing the aperture to a larger degree and obscuring the details of the columella lamella. The labral tooth of G. bomvana is also very large, but it extends behind the columella lamella.

Conservation
Gulella crookesi sp. nov. has been found only at Vernon Crookes Nature Reserve, a protected area under the jurisdiction of Ezemvelo-KZN Wildlife. The south coast of KwaZulu-Natal and hinterland have been extensively modifi ed by sugarcane farming and development. Vernon Crookes Nature Reserve, although small, is a very important haven for biodiversity in the region. Twenty-nine species of terrestrial Mollusca have been recorded, including Chlamydephorus dimidius (Watson, 1915), listed as Vulnerable and several other narrow-range species. It is the type and only known locality of two species of microchaetid earthworm, and the major locality for a third species which has also been recorded just outside the reserve (Plisko 1998). The reserve is surrounded by sugarcane farms and rural villages, and portions of the fence are missing, enabling cattle to enter, which poses a threat to the integrity of the indigenous forest patches and the well-being of their litter-dwelling invertebrates.

Diagnosis
Shell minute, sub-cylindrical; smooth and glossy; aperture markedly constricted by teeth, slightly defl ected to left in apertural view, peristome thickened and refl ected. Apertural dentition four-fold including a parietal lamella, with outer portion oblique and then curving inward, a large, square labral tooth, its upper margin sinuous and with a small denticle near lip edge and another further into aperture, Description SHELL (Fig. 8). Shell minute, sub-cylindrical, length 1.9-2.2 mm, width 0.8-1.0 mm, L:W 2.1-2.5 (n = 13). Protoconch approx. 0.7 mm in diameter, comprising approx. 2.5 whorls, smooth; junction between protoconch and teleoconch not distinct. Teleoconch comprising approx. 3.5 whorls; convex; smooth and glossy but with weak axial pleats around umbilicus (Fig. 8A-B, D). Aperture markedly constricted by teeth, slightly defl ected towards left in apertural view; peristome thickened and refl ected (Fig. 8A, C). Apertural dentition four-fold (Fig. 8C): 1) a parietal lamella, with outer portion oblique and then curving inward so that remainder runs into aperture, lower margin sometimes weakly notched; 2) a large square labral tooth, its upper margin sinuous and with a small denticle near lip edge and another further into aperture; 3) a deeply inset peg-like basal tooth; 4) a very large, even more deeply inset rounded, scoop-shaped columella lamella, largely obscured by labral tooth. Labral tooth corresponds with a deep pit behind outer lip (Fig. 8B). Apertural tube behind columella lip somewhat infl ated and collar-like; umbilicus very small and comma-shaped (Fig. 8D). Shell almost transparent when fresh, orange-red coloration of dried tissue of animal visible internally. Distribution (Fig. 6) Known only from the Marble Delta, an area of ca 40 km 2 at the junction of the Mzimkulu and Mzimkulwana Rivers, inland of Port Shepstone in southern KwaZulu-Natal. Based on existing records, it occurs only on the portion of the limestone deposit that lies to the north-east of the Mzimkulu River.

Habitat
Patches of valley thicket (Low & Rebelo 1996), also referred to as Eastern Valley Bushveld (Rutherford et al . 2006) and KwaZulu-Natal Scarp forest (Mucina et al. 2018b); in leaf-litter and under logs. The indigenous vegetation has been heavily invaded by alien plants, notably Chromolaena odorata (L.) R M.King (Asteraceae), and Lantana camara L. (Verbenaceae), both from South and Central America.

Remarks
The labral complex of Gulella calcicola sp. nov. resembles that of G. crookesi sp. nov., particularly due to the upper margin with a denticle near the lip edge and another further into the aperture. However, the portion furthest into the aperture is square in G. calcicola while that of G. crookesi sp. nov. is triangular. The other apertural teeth all differ between these two species. Gulella farquhari is also somewhat similar, but possesses axial sculpture (if only subsutural riblets) and its labral tooth is proportionally smaller and does not obscure the columella lamella to such an extent.

Conservation
Gulella calcicola sp. nov. has been found only at the Marble Delta, which stands out as the largest and most important limestone outcrop in the province, with a calcium concentration of ca 4000 mg/l (Herbert 2002). Like G. salpinx Herbert, 2002, it appears to be a holoendemic taxon (sensu Richardson 1978; Van Wyk & Smith 2001) that has evolved in response to the environmental conditions prevailing in the Marble Delta, perhaps chiefl y those associated with soil chemistry. Much of the Marble Delta is now badly degraded as a result of mining operations and the invasion of alien plants. Mining continues in the area and the habitat of the species must thus be considered threatened. The species meets the criteria for red listing as Critically Endangered. A recommendation made by Herbert (2002) is echoed here, namely that mining operations not be conducted on a section of the northern bank of the Mzimkulu River, in an attempt to preserve the habitat as much as possible (acknowledging that alien plants will already have altered this to some extent). Some local indigenous habitat is formally preserved at Oribi Gorge Nature Reserve, upstream on the Mzimkulwana River, but this does not lie within in the Marble Delta area and its soils, derived from decomposed granite and sandstone, have a much lower calcium content (Herbert 2002). No specimens of Gulella calcicola sp. nov., G. salpinx or G. donaikeni sp. nov. have been found in the Oribi Gorge reserve despite its malacofauna being relatively well-known.
Gulella abbotti sp. nov. urn:lsid:zoobank.org:act:374C7E0D-187B-4EEE-A8C8-AE04AC64118B Figs 9 A-D, 10 Diagnosis Shell minute, cylindrical; spire whorls with weak subsutural riblets developing into stronger axial riblets on fi nal half whorl; aperture sub-quadrate, little obstructed by teeth; dentition fi ve-fold, including a parietal lamella, a simple trigonal labral tooth extending from lip edge, a small basal tooth well to left of centre, a broad, low swelling in middle of columella lip and a round columella lamella; umbilicus closed.

Etymology
Named for the late Tony Abbott ( Description SHELL (Fig. 9). Shell minute, elongated and cylindrical, length 2.3-2.7 mm, width 0.8-1.0 mm, L:W 2.6-3.1 (n = 6). Protoconch approx. 0.8 mm in diameter, comprising approx. 2.5 whorls, smooth; junction between protoconch and teleoconch not distinct. Teleoconch comprising approx. 4.25 whorls; fi rst whorl convex, others weakly so, suture not strongly indented; mostly smooth and glossy, but with weak subsutural axial riblets, these stronger on last whorl and extending from suture to suture, some specimens more or less smooth with only periodic growth lines (Fig. 9A, B); axial riblets prominent and pleat-like in umbilical region. Peristome fused with base of penultimate whorl in parietal region; peristome thickened ( Fig. 9C). Aperture sub-quadrate, not extensively obstructed by teeth; apertural dentition fi ve-fold (Fig. 9C): 1) an oblique parietal lamella which curves and runs into aperture; 2) a simple, roundly trigonal labral tooth beginning at lip edge; 3) a small, rounded basal tooth well to left of centre; 4) a broad, low swelling on columella lip; 5) an evenly rounded columella lamella. Labral tooth corresponds with a pit behind outer lip (Fig. 9B). Columella corresponds with a pit behind columella lip, but umbilicus closed (Fig. 9D). Shell translucent, uniformly milky-white when fresh. Distribution (Fig. 10) Endemic to a narrow range in southern KwaZulu-Natal, from the coast up to approx. 130 m above sea level.

Remarks
Gulella abbotti sp. nov. resembles three other Gulella species occurring in KwaZulu-Natal. G. bushmanensis Burnup, 1926 from inland regions in the north of the province, although also elongate and cylindrical, lacks axial sculpture, has two fused labral teeth, a roundly quadrate and almost mammillate columella lamella, and lacks a low swelling on the columella lip. The widespread G. pentheri (Sturany, 1898), again elongate and cylindrical, is smooth and it has only three apertural teeth of much smaller size. Gulella appletoni van Bruggen, 1975, from coastal localities in northern Zululand, has similar fi vefold apertural dentition, but it is smooth, less elongate and smaller (length <2.0 mm), and it has a larger tooth on the columella lip and a strong quadrate columella lamella.

Conservation
Gulella abbotti sp. nov. appears to be a very rare species, with few records despite the streptaxid fauna of the KwaZulu-Natal south coast being relatively well known (see Discussion). The only formally conserved area in which it has been found is the Mtamvuna Gorge Nature Reserve. Aside from specimens collected in beach drift, it has been collected at two localities approx. 40 km apart, but not in the Oribi Gorge Nature Reserve which lies immediately west of the type locality. It also does not appear to extend into coastal forest of the relatively recent Indian Ocean Coastal Belt (von Maltitz et al. 2003).

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. 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.

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. superfi cially 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 sacrifi ced 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.

Discussion
The streptaxid fauna of the KwaZulu-Natal south coast is relatively well known, having been sampled extensively during the fi rst half of the twentieth century by Henry Burnup and a number of other local streptaxid enthusiasts (Herbert 2002). The discovery of seven undescribed species in the area, six described herein plus the enigmatic " Gulella" salpinx Herbert, 2002, is thus surprising. ( Gulella salpinx does not belong in Gulella s. lat. (Rowson & Herbert 2016).) The Marble Delta and its immediate vicinity is confi rmed to be a hotspot of narrow-range endemism in molluscs. Two of the species described herein, G. calcicola sp. nov. and G. donaikeni sp. nov. are evidently restricted to this area and are of genuinely very limited range. There appears to be a defi nite segregation between populations of these two species, with G. calcicola restricted to the limestone deposits of the Marble Delta north of the Mzimkulu River and G. donaikeni found south of the Mzimkulu River in limestone and peripheral soils. These species are not known from any formally protected area, and their habitat continues to be threatened by mining. The Marble Delta and vicinity are also among the very few localities where G. abbotti sp. nov. and G. maraisi sp. nov. occur.
The Vernon Crookes Nature Reserve is about the same distance from the coast as the Marble Delta, approx. 15 km, and is the only locality where G. crookesi sp. nov. has been recorded, in addition to several point-endemic earthworms (Plisko 1998). This and the four species discussed above all occur in scarp forest and have not been found in coastal forest. Scarp forest is a forest type occurring on south-and east-facing slopes and gorges of the fi rst plateau escarpment inland of the eastern seaboard (300-1100 m) . Scarp forests support a high diversity of fauna and fl ora, including more ancient Afrotemperate and more recent Indian Ocean Coastal Belt elements, and a large number of endemics (Mucina et al . , 2007Lawes et al . 2007). An isolated population of the tree Colubrina nicholsonii (Rhamnaceae), considered to be an ancient relict and otherwise endemic to the Pondoland Centre of botanical endemism, occurs at Vernon Crookes Nature Reserve (Van Wyk & Smith 2001). In contrast, Gulella kenbrowni sp. nov. does occur in coastal forest of the south coast of KwaZulu-Natal, but has not been found at any of the localities where the fi ve new Gulella species discussed above were recorded. It is the only relatively widespread species described in this paper, recorded in coastal, scarp and mist-belt forest over a linear distance of 450 km. However, it does not occur throughout this range, but is concentrated in the northern and southern parts, with an intervening gap apparent in the northeastern Eastern Cape province traditionally known as Pondoland.
Another very narrow-range endemic, G. mkombeni sp. nov., has been recorded only in the Mkambati Nature Reserve in Pondoland. The south coast of KwaZulu-Natal and adjacent Pondoland have been shown to be a focus of endemism in Mollusca (Herbert & Kilburn 2004), with at least eleven species endemic to the region (excluding the species described herein) (Herbert & Kilburn 2004;Bursey & Herbert 2004;Herbert 2017;Cole 2019) and several other near-endvemic species, the core distribution of which lies in this region. It is a well-known centre of botanical endemism with a large proportion of palaeoendemics and neoendemics, as well as a number of undescribed plant species, concentrated in scarp forests in deep gorges (van Wyk & Smith 2001;Mucina et al . 2018a).
Gulella fordycei sp. nov. is also known from a single nature reserve, Fort Fordyce, an outlier of the Amathole Mountains supporting several taxa not recorded elsewhere (Herbert 2020;Daniels et al . 2017). These observations suggest that historic contractions and expansions of forests in this region have had a signifi cant and complex impact on the phylogeography of low-vagility organisms (Daniels et al. 2017).
Seven of the eight species described here are narrow-range endemics. Two are not found in formally protected areas, and their conservation merits urgent attention. Mechanisms for the protection of small parcels of land targeted at the conservation of narrowly endemic and less vagile invertebrates need to be included in conservation planning (Perera et al . 2021). Six species described here are found in small nature reserves highlighting the importance of even small formally protected areas for the conservation of terrestrial molluscs and other moisture-dependent taxa with limited capabilities of dispersal.