Rediscovery of the type species of Euonyma (Subulinidae) and observations on South African species of Gulella (Streptaxidae), with description of two new species (Gastropoda: Eupulmonata)

The rediscovery of the type species of the subulinid genus Euonyma Melvill and Ponsonby, 1896, Euonyma laeocochlis (Melvill and Ponsonby, 1896), is recorded and data regarding its distribution and habitat are provided. No specimens of this species had been collected in the more than 100 years since its original description. The streptaxid Gulella fraudator Connolly, 1939, a taxon previously considered to be of doubtful validity, is shown to be a distinct, narrow‐range endemic and is compared with similar species. Type material and recently collected specimens of both species are illustrated. Two recently discovered species, Gulella deviae sp. n. and G. lindae sp. n., are described.


Introduction
Ongoing field work continues to bring to light new information regarding the terrestrial molluscan fauna of southern Africa. In this paper I record the rediscovery of Euonyma laeocochlis (Melvill and Ponsonby, 1896), type species of the genus Euonyma Melvill and Ponsonby, 1896, and show that Gulella fraudator Connolly, 1939, a taxon previously considered to be of uncertain validity, is indeed a distinct species. In addition, I describe two new species of Gulella from South Africa, G. deviae and G. lindae.

Distribution and habitat
Described from ''Humansdorp'', but currently known only from the Kougaberg, Baviaanskloof Wilderness area, E. Cape, South Africa ( Figure 4); under stones in grassy fynbos at altitudes from 500 to 1000 m.

Remarks
Melvill and Ponsonby's description of this species was based upon two specimens collected in ''Humansdorp, St Francis Bay'', E. Cape, one of which, the lectotype (designated Connolly 1939) (Figure 1), is in the Natural History Museum, London (BMNH 1902.7.30.19). [The location of the other specimen is unknown-it is not present in either the National Museum of Wales or the Manchester Museum (Rowson pers. comm., March 2005), both of which contain other Melvill types.] Although these two specimens were said to have been part of a larger sample, none of this additional material appears to have been deposited in South African museums.
In the more than 100 years since its description, no further specimens of this species have come to light. The absence of additional material, despite an interest in shell collecting at the Albany Museum, Grahamstown, in the first half of the 20th century, suggested that the species was a habitat specialist, which was either now extinct or perhaps confined to habitats of limited extent, the nature of which remained unknown. The type locality, ''Humansdorp, St Francis Bay'', given by Melvill and Ponsonby (1896) almost certainly related to the general area of origin, rather than a precise locality, and is thus of limited value in locating a species of this kind.
Fortuitously, in 1999 some land snail specimens sent to me for identification by Mr Derek Clark, warden of the Baviaanskloof Wilderness Area, E. Cape, proved to be examples of E. laeocochlis. Pursuing this new evidence, I subsequently visited the Baviaanskloof area in 2000 and found the species to be moderately common there, living under stones in grassy fynbos on the summit regions (500-1000 m) of the Kougaberg, in the area between Geelhoutbos and Rooihoek, on the southern side of the valley (Figure 4). The Baviaanskloof lies within the broader Humansdorp District and it possible that this represents the area in which the original specimens were collected. Grassy fynbos is a plant community characteristic of the eastern region of the fynbos biome, occurring both in coastal lowlands and on mountains (Cowling and Richardson 1995). The absence of records from the much more accessible lowland localities suggests that E. laeocochlis is restricted to montane grassy fynbos habitats, which are largely remote and difficult to access. These will be somewhat cooler than coastal localities and benefit from more frequent mist and cloud (mean annual precipitation .800 mm; Schulze 1997). The species was not found at lower altitudes in the Baviaanskloof system where the vegetation changes variously to succulent thicket, Nama Karoo, and savanna, with isolated patches of forest in protected gorges.
The only figure of the species published to date is that of Melvill and Ponsonby (1896) (reproduced by Pilsbry 1906, Plate 10, Figure 68), which is poor and inadequate. I therefore take this opportunity to refigure the BMNH lectotype ( Figure 1) and provide also an illustration of a fresh specimen in good condition ( Figure 2). Connolly (1939) gave the length of the species as 30.4 mm, but the largest specimen in the newly acquired material measures 35.5 mm in length. Connolly (1939) drew attention to the significance of E. laeocochlis as the type species of Euonyma Melvill and Ponsonby, 1896, pointing out that the referral of other large southern African subulinids to this genus may not be justified. Verdcourt (1968) reiterated this more strongly in relation to East African subulinids, stating ''there is no evidence whatever that the larger species are really congeneric with the type of Euonyma…''. Euonyma laeocochlis has a distinctively acute apex (Figure 3), whereas most other supposed Euonyma species, including all those occurring in southern Africa, have a bluntly rounded apex. In this regard E. laeocochlis resembles members of the genus Subuliniscus Pilsbry, 1919, with which Connolly (1939 postulated it might be synonymous, and Oreohomorus Pilsbry, 1919. However, in these taxa the embryonic whorls are reported to have strong spiral sculpture, a feature that is entirely lacking in E. laeocochlis. The embryonic shell in the latter species, after an initially smooth first whorl, bears only axial riblets. Connolly (1939) speculated that the other local subulinids that he placed in Euonyma may need to be referred to a new or alternative genus (genera), but he wisely refrained from pursuing this on account of the lack of anatomical data, not only for E. laeocochlis, but for all local ''Euonyma'' species. The rediscovery of the type species of Euonyma now provides material which can be studied in an attempt to resolve these uncertainties. A number of live-collected specimens were obtained and the soft parts preserved for anatomical examination. Samples were also preserved for molecular study.

Conservation
In the light of this new information, the threat status of the species has been assessed in terms of the current IUCN criteria (IUCN 2001). An application for red-listing as ''Endangered B1'' has been submitted. Fortunately, the Baviaanskloof has been identified as a priority area for conservation (Boshoff et al. 2000).

(Figures 5-12)
Etymology Named for Dr Devi Stuart-Fox, who has collected much valuable terrestrial molluscan material in South Africa, including specimens of this species.

Diagnosis
Shell very small to minute, cylindrical, smooth and glossy; apertural dentition three-fold: a parietal lamella, a protruding labral tooth, a very weak columella lamella; outer lip strongly concave above protruding labral tooth; whorls roundly rebated below suture; last whorl with an internal tubercle situated ca 0.5 whorl behind aperture; terminal part of body whorl lacking axial ribbing; umbilicus closed.

Description
Shell very small to minute, cylindrical, length 2.5-3.1 mm, width 1.20-1.28 mm; length: width 1.96-2.48 (N513). Embryonic shell ca 0.78 mm in diameter, comprising just over two whorls, but junction with teleoconch indistinct; smooth and glossy ( Figure 8). Teleoconch (Figures 5-7) comprising nearly 5.0 whorls; first whorl convex, but subsequent ones rather more flat-sided, as profile becomes cylindrical; suture narrowly indented, upper portion of abapical whorl roundly rebated (excavated); surface smooth and glossy, sculptured only with weak growth-lines. Peristome interrupted extensively in parietal region where base of preceding whorl is covered by a thin inductural layer; elsewhere margin of peristome slightly thickened and reflected to form a narrowly rounded marginal varix. Parietal lip almost horizontal and aperture thus D-shaped, the flat side situated apically. Apertural dentition three-fold ( Figure 5): (1) an obliquely curving parietal lamella which is not fused to the outer lip at its insertion on the base of the penultimate whorl, instead extending well above this, leaving a distinct channel between the parietal lamella and the insertion of outer lip ( Figure 9); (2) a strong, ridge-like, mid-labral tooth which projects strongly outward when viewed from the side (Figures 6,9); (3) a very low columella lamella, often scarcely evident. In addition to the dentition associated with the aperture, there is a distinct tubercle situated inside the body whorl, just above and to the left of the insertion of the columella lip, ca 0.5 whorl behind aperture (Figures 7, 10). This is visible externally only in fresh (non-calcined) shells, appearing as an opaque white blotch in the otherwise translucent shell (Figure 7). It develops only at or near maturity, and is not a feature of juvenile shells. Outer lip strongly concave above labral tooth, but lacking an external pit underlying the tooth (Figure 9). Umbilicus completely closed ( Figure 11) and with no evidence of crenulation or axial ribbing on base or terminal part of last whorl. Shell translucent, uniformly milky-white when fresh; orange-red dried remains of animal visible internally.

Anatomy
Unknown. Although some of the material discussed was live-collected, it was obtained from dried leaf-litter samples. No specimens preserved in ethanol are available.

Distribution and habitat
Northeastern South Africa, from the Soutpansberg (Limpopo) to the environs of Barberton (Mpumalanga) ( Figure 12); in leaf-litter of afromontane forests along the edge of the northern Drakensberg, at altitudes from 750 to 2000 m.

Remarks
The first specimens of this species collected were provisionally identified as Gulella perspicuaeformis (Sturany, 1898), to which it is undoubtedly superficially similar ( Figure 13). That species, however, has a strictly coastal distribution, occurring primarily in dune and coastal lowland forest in southern Mozambique and northern Zululand (Maputaland), at the southern end of the East African coastal plain (Herbert and Kilburn 2004). It has not been found further than 35 km from the coast or at altitudes greater than 250 m. The collection of specimens, perhaps representing G. perspicuaeformis, in afromontane forests far from the coast and at altitudes in excess of 750 m, was thus unexpected. Subsequent study, however, revealed that this afromontane material in fact differs consistently from G. perspicuaeformis in a number of features and represents a distinct, undescribed species, here described as G. deviae. The most obvious feature distinguishing G. deviae from G. perspicuaeformis is the presence of the internal tubercle in the former. This feature had not initially been observed since the first shells collected were calcined and thus no longer translucent. Only when fresh live-collected material became available did this feature become evident. Additional differences include: (1) the greater degree to which the labral tooth projects beyond the outer lip in G. deviae, such that the portion of this lip apical to the tooth is rendered strongly concave; (2) the consistent presence of axial ribbing, albeit weak, on the terminal part of the last whorl, behind the outer lip in G. perspicuaeformis (absent in G. deviae) (compare Figures 9 and 14).
In terms of the Gulella subdivisions proposed by Herbert and Kilburn (2004), G. deviae lies with G. perspicuaeformis in Group 2CB (Group 6(ii) of Connolly 1939). Of other species within this group, G. elliptica (Melvill and Ponsonby, 1898) has superficial denticles on the columella lip, G. inhluzaniensis (Burnup, 1914) has subsutural riblets and G. pentheri (Sturany, 1898) has a more obvious columella lamella and is considerably more elongate. None of these species are known to range north of KwaZulu-Natal. Gulella perspicua  (Melvill and Ponsonby, 1893), with apertural dentition resembling that of G. deviae, occurs like G. deviae in Mpumalanga and Limpopo, and shares with it the unusual, roundly rebated suture, but lacks an internal tubercle. It is also considerably larger (length up to 5 mm), often proportionately broader, sometimes has a basal denticle in the aperture and its outer lip scarcely protrudes in the area of the labral tooth.
The true affinities of G. deviae within the genus Gulella s. l. remain to be established. Although superficially similar to G. perspicuaeformis, the two may not in reality be closely related, having arisen in different faunal assemblages, namely afromontane and tropical/ subtropical coastal belt, respectively. The presence of the internal tubercle inside the last whorl is a feature I have not seen described in other Gulella species, suggesting that G. deviae is rather unusual. Some Gulella species are known to possess internal teeth in juveniles (Herbert and Kilburn 2004), but these are generally situated close to the growing aperture lip and are laid down and resorbed progressively with growth, and ultimately lost once the adult apertural dentition is formed. The species concerned usually have strong axial ribs and often also a spirally lirate embryonic shell. The internal tubercle found in G. deviae is clearly unrelated.

Conservation
Although described for the first time herein, this is probably a result of the small size of the shell, rather than the narrow range of the species. Indeed its distribution is not particularly restricted, spanning more than 300 km of the northern Drakensberg escarpment. However, it is surprising that the species has not been found, despite relatively good sampling, in the forests of the Wolkberg near Tzaneen, suggesting that it occurs only patchily within its total range. Based on the available evidence G. deviae would probably qualify in the ''vulnerable'' category, in terms of the IUCN red-listing criteria (IUCN 2001).

Diagnosis
Shell minute, cylindrical, with short but distinct axial riblets below suture; apertural dentition five-fold: a parietal lamella, two labral teeth, a small basal tooth to left of centre and a strong columella lamella, umbilicus open, its margin crenulate.

Description
Shell minute cylindrical, length 1.77-2.28 mm, width 0.82-0.96 mm, length: width 1.967-2.478 (N550). Embryonic shell domed in specimens from coastal localities (Figures 15-17), flatter in those from localities further inland ( Figure 18); diameter ca 0.58 mm, smooth, comprising approximately two whorls, but its terminal limit frequently not easy to discern ( Figure 21). Teleoconch (Figures 15-18) comprising 4.0-4.5 whorls; first whorl strongly convex, subsequent ones less so; as whorls cease to expand outward, shell profile becomes cylindrical; suture shallowly indented; surface mostly smooth and glossy, but with short, distinct subsutural riblets, giving suture a milled appearance. Peristome interrupted extensively in parietal region where base of preceding whorl is covered by a thin inductural layer; elsewhere margin of peristome thickened and reflected to form a relatively strong marginal varix (Figures 17, 20). Apertural dentition five-fold ( Figure 19): (1) a parietal lamella, the outer part of which curves obliquely to merge smoothly with outer lip at its insertion on base of penultimate whorl; (2-3) two mid-labral teeth, the lower one stronger and ridge-like; (4) a small basal tooth to left of centre, peg-like in some samples, obliquely trigonal in others; (5) a columella lamella with a strong tooth (shape somewhat variable), which extends outward for a short distance as a low ridge, but does not reach aperture edge.
There may in addition be a more deeply set, low collabral thickening between the lower labral and basal teeth ( Figure 19). Labral tooth marked externally by shallow pit behind thickened outer lip; terminal part of last whorl with distinct axial riblets. Umbilicus relatively widely patent (Figure 20), ovoid, with margin crenulated by short axial riblets. Juvenile shells frequently with a small low tubercle inside basal lip, near its junction with columella lip (Figure 22); this laid down and resorbed with growth, and its position relative to aperture edge thus variable; a series of up to three such tubercles may be present at any one time, progressing inward from aperture edge and separated by 0.25-0.5 whorl. Shell almost transparent when fresh; orange-red dried remains of animal visible internally.

Anatomy
Unknown. On account of its minute size, this species has only been obtained from dried leaf-litter samples. Although a number of specimens were evidently alive when collected, none were preserved in ethanol.  Herbert, Seddon and Tattersfield, 30 November 1998 (V7660).

Remarks
Specimens of this species have previously been recorded as G. bushmanensis Burnup, 1926 (Bruggen andAppleton 1977). The material concerned was collected by H. J. Puzey in the St Lucia area, in 1944, and Prof. C. Appleton in the Lake Sibaya area in 1973. Examination of Puzey's specimens, after return to the Natal Museum from long-term loan, and Appleton's material housed in the RMNH, showed these to be referable to the present species. This eliminates the record of G. bushmanensis, an otherwise inland mid-altitude species, from coastal localities, a distribution noted as unusual, though not without precedent, by Bruggen and Appleton (1977).
In terms of its apertural dentition and sculpture, G. lindae falls within Group 3B of Herbert and Kilburn (2004). It is, however, very much smaller than any of the other species within this group. Its apertural dentition also resembles that of G. bushmanensis, but that species is much more elongate and almost completely smooth, and its labral tooth is in the form of one bicuspid tooth rather than two separate teeth on a shared base (although the distinctness of these is admittedly somewhat variable in G. lindae). Gulella maritzburgensis (Melvill and Ponsonby, 1893), from the KwaZulu-Natal Midlands, is likewise aperturally similar and also has subsutural sculpture, but it is larger (length up to 4.5 mm), has a much more weakly indented suture and its subsutural riblets are extremely fine. Perhaps the most unusual feature of G. lindae is the brevity and relative strength of the subsutural ribbing which gives the suture a milled appearance. This, together with its minute size and five-fold apertural dentition, render the species distinctive.
The distribution of G. lindae resembles that of G. appletoni Bruggen, 1975, G. browni Bruggen, 1969, and G. daedalea (Melvill and Ponsonby, 1903, and it is clearly a tropical element of the fauna. Although currently not recorded from Mozambique, it will undoubtedly prove to occur at least in the southern parts of that country. The northernmost record available (Kosi Bay) lies immediately to the south of the Mozambique border. Whether G. lindae represents an element endemic to the southern extremity of the Indian Ocean coastal belt or is more widespread remains to be established. It was not found in samples collected recently in the Ponta da Barra Falsa area, between Inhambane and Vilanculos, but in general the molluscan fauna of the coastal forests of Mozambique remains almost unknown.

Conservation
Gulella lindae is evidently not rare. Although its currently known area of occupancy is relatively restricted, it is has been found in some numbers in coastal dune forest. Much of this habitat in Zululand falls within the Greater St Lucia Wetland Park World Heritage Site and is thus afforded a high level of protection. Records from inland localities also fall within a conservation area, namely the Hluhluwe-Imfolosi Park.

Distribution and habitat
Known only from the coastal hinterland of the Transkei region, E. Cape, South Africa; from Mkambati Nature Reserve in the north, to the vicinity of Xora River mouth in the south ( Figure 30); in leaf-litter of coastal forests.

Remarks
Connolly's (1939) description of G. fraudator was based on a sample collected at Mbotyi by W. Falcon in March, 1934. The holotype and two paratypes are in the BMNH (1937.12.30.862-5), and three further paratypes are present in the NMSA (W1574/ T560), the latter recently returned from long-term loan. Although a second locality, ''Hole in the Wall'' (Transkei region, E. Cape), was recorded by Aiken (1995), for which there is no voucher specimen, no further material of the species has been collected and it has remained poorly known. In the absence of reference material, Herbert and Kilburn (2004) were unable to adequately discuss the taxon and tentatively postulated that it might represent a synonym of G. mariae (Melvill and Ponsonby, 1892). Recently, regular field visits to the Transkei region of E. Cape have brought to light much new streptaxid material (Bursey and Herbert 2004), including specimens which are clearly referable to G. fraudator. This has been confirmed by comparison with the holotype and the recently returned paratypes. Connolly's figure of the species, though accurate, is typically small and I take this opportunity to refigure the holotype ( Figure 24) and illustrate additional features using the recently collected material (Figures 25-29). The original description of the species is adequate and redescription is unwarranted, although it is puzzling that Connolly treated the species in his Group 4iia, comprising species with Mpumalanga, and Swaziland, likewise lacks subsutural riblets and has a labral tooth complex of very different form.

Conservation
Gulella fraudator is an element of the endemic subtropical/warm-temperate subtraction zone fauna characteristic of the Transkei region, E. Cape. Such species typically have narrow distribution ranges and frequently meet the IUCN criteria for red-listing. Issues relevant to the conservation of these species have been discussed by Bursey and Herbert (2004). The distribution of G. fraudator is similar to that of G. latimerae Bursey and Herbert, 2004, although it ranges slightly further northward than that species.