An update on the spider genus Hexophthalma ( Araneae : Sicariidae ) in the Afrotropical region , with descriptions of new species

The described Afrotropical species of the genus Hexophthalma Karsch, 1879 (under the genus name Sicarius Walckenaer, 1847), of the spider family Sicariidae Keyserling, 1880, were recently reviewed. In the present paper the Afrotropical species of the genus Hexophthalma are revisited. After a thorough examination of all the available specimens from nine major collections, the species H. testacea (Purcell, 1908) is here synonymized with H. hahni (Karsch, 1878), three new species are described – H. binfordae sp. nov., H. goanikontesensis sp. nov. (both from Namibia) and H. leroyi sp. nov. (from South Africa) – and the male of H. dolichocephala (Lawrence, 1928) is described for the fi rst time. The distribution of the species is also revised and a new updated key to the species is compiled.


Introduction
In a very recent paper on Sicariidae, Magalhaes et al. (2017) revalidated the genus name Hexophthalma Karsch, 1879 for six species occurring in Africa (World Spider Catalog 2017).The genus was firstly described as Hexomma (Karsch 1878) for the species H. hahni, but this name was preoccupied and replaced with Hexophthalma (Karsch 1879).Simon (1893) synonymized Hexophthalma with Sicarius Walckenaer, 1847.All subsequent authors published new Afrotropical species as Sicarius (Pocock 1900;Purcell 1908; Lawrence 1928).The Distribution of Hexophthalma is restricted to the southern part of the Afrotropical region.The majority of the species occur in the drier western half of southern Africa, extending eastward to the north.As very little collecting has been done in Angola, it is possible that the distribution may extend further north into this country.
In a recent paper on the Afrotropical species of Hexophthalma (Lotz 2012), a short review was given of the described species.This was based on the type specimens or specimens collected close to the type locality.Since then an intensive study of all available specimens from nine collections was undertaken.This led to the discovery of a lot of variation in the female genitalia and of unexpected prominent differences between the palps of the different species that can be used to differentiate between them.
The dorsal setae on the leg femora were found to be too variable to be used as a diagnostic character for species, except in the case of H. spatulata (Pocock, 1900), where the setae are scoop shaped and situated on a slight mound (Fig. 23).In all other species the setae vary from thin to broad, with some having both thin and broad setae.In this publication the female genitalia and male palps are drawn from photos of actual specimens.In some cases the female genitalia of several specimens of the same species are depicted to show the intraspecific variation as well as the variation between the left and right side of the same specimen.
During the study three new species and the male of H. dolichocephala (Lawrence, 1928) were discovered and are described here.The variation in female genitalia and the differences found in the male palps also led to the realization that H. testacea (Purcell, 1908) and H. hahni (Karsch, 1878) is one and the same species and H. testacea is therefore here synonymized with H. hahni.The distribution of the different species is also updated here with maps showing the localities of the studied specimens only, because not all specimens mentioned in published records (Newlands 1986) could be found to corroborate their identification.

Material and methods
All the specimens that could be obtained on loan, from the collections mentioned below, were studied and are discussed here (responsible curator(s) mentioned in parentheses).Illustrations of the male palps and female genitalia were made from photos of the actual genitalia studied.Male palps were taken from the right side and studied and drawn from the prolateral side.Illustrations were made with CorelDRAW X4.Photos of the genitalia were taken with a Paxcam 5 digital camera, mounted on a Novel dissection microscope.Photos are not included, as they are not of publishable quality.All female genitalia and male palps were photographed and compared.Coordinates given in square brackets are not included on the specimen labels, but were looked up on physical maps and added.

Diagnosis
Female inner spermathecae consist of one lateral extending sac and a divided round sac medially, on each side, with a small sclerotized reduced outer spermatheca (Fig. 1) which is unlike that of any of the other species.Male unknown.

Etymology
The species name is a matronym for Greta Binford, collector of the type specimen.

Natural history
Hexophthalma binfordae sp.nov.was collected from a savanna area.

Distribution
Hexophthalma binfordae sp.nov. is only known from the type locality in Namibia (Fig. 24).
Hexophthalma goanikontesensis sp.nov.urn:lsid:zoobank.org:act:EA012B80-652F-43DF-B071-33618A497072Figs 2-4, 18, 24 Diagnosis Female inner spermathecae consist of sac-like fingers on each side, with a sclerotized reduced outer spermatheca; the number of sac-like spermathecae varies from three to seven between specimens and from side to side (Figs 2-4); may at first glance resemble H. leroyi sp.nov., but with more than two spermathecae sacs, the other sacs hidden behind two top sacs.Male embolus with a thin apical part with small keel at the base and a thicker basal part with a slight hump on one side, similar to that of H. damarensis, but differing by the presence of the small keel and the side hump being apical of median, on the thicker part of the embolus (Fig. 18).

Etymology
The specific name is an adjective derived from the type locality.

Distribution
Hexophthalma goanikontesensis sp.nov. is known from the northern coastal areas in Namibia (Fig. 24).

Etymology
The specific name is a patronym for John Leroy, collector of the type specimen.

Natural history
Hexophthalma leroyi sp.nov.was collected in a grassy area in the Nama Karoo biome.

Distribution
Hexophthalma leroyi sp.nov. is known only from the type locality in South Africa (Fig. 24).

Revised diagnosis
Female inner spermathecae consist of long finger-like sacs that branch close to the copulatory tube end, similar to in H. hahni except that the finger-like tubes are longer and thinner (Figs 6-8).Male embolus consisting of a thin pointed apical part and straight-sided thicker basal section (Fig. 17), similar to in H. hahni except for the longer thin apical part in relation to the thicker basal part.(Purcell, 1908).Scale bar = 1 mm.

Natural history
Hexophthalma albospinosa have been collected in the Succulent Karoo biome, by pitfall traps and by hand from under rocks and old roofing tin.

Diagnosis
Female inner spermathecae unique, with short, bulbous, finger-like sacs that branch off the copulatory tube part, without reduced outer spermathecae (Fig. 9).Male embolus ending in a thin, pointed apex; thicker basal part of embolus with a hump on one side, slightly basal from median (Fig. 19); this is similar to in H. goanikontesensis sp.nov.except that the thinner apical part lacks a basal embolus keel and the hump on the side of the thicker part is more basal.

Natural history
Hexophthalma damarensis have been collected in Savanna biomes using pitfall traps.

Diagnosis
Female inner spermathecae consist of one finger-like sac on each side, with a very short outer spermatheca (Fig. 10).Male embolus apical part thin, blunt and slightly twisted and flattened, unlike the other species where the apical part is thin and pointed (Fig. 20).

Distribution
Hexophthalma dolichocephala is distributed in the northwestern corner of Namibia (Fig. 25).

Diagnosis
Female inner spermathecae consist of finger-like sacs that branch close to the copulatory tube end, similar to in H. albospinosa except that the finger-like tubes are shorter and more bulbous (Figs 11-15).Male embolus consisting of a thin pointed apical part and a straight-sided thicker basal section (Fig. 21), similar to in H. albospinosa except that the thin apical part is shorter in relation to the thicker basal part.

Natural history
Hexophthalma spatulata have been collected in a Fynbos biome.

Distribution
Hexophthalma spatulata is distributed along the southern coastal areas of South Africa (Fig. 25).

Discussion
Species of Hexophthalma, the former African Sicarius, have raised interest because of their supposed medical importance (Newlands & Atkinson 1988;Van Aswegen et al. 1997).The venom of some of the species has even been considered as one of the strongest spider venoms (Newlands 1986), but this has never been corroborated.Studies on this topic, mainly on the interspecific variation of the venom, which can be very large (Müller et al. 2012), are particularly difficult, because the identification of the species is virtually impossible.The study of Zobel-Thropp et al. (2010) is symptomatic: it was hindered by the lack of systematic knowledge and had to use approximate identifications like Sicarius cf.hahni and S. cf.damarensis.The present study has made a step forward, but it is clear that more efforts will be needed to facilitate studies on this genus, be it systematic, ecological or medical.In several species the males are still unknown, more species are to be expected and the monophyly of the genus is questionable because of the morphologically aberrant H. spatulata.Future studies will therefore have to be carried out along several axes.In the first place, further collecting will be needed to fill the gaps outlined above.Molecular studies in combination with detailed morphological assessments will be necessary to outline the interspecific relationships and the phylogenetic placement of the group, mainly in connection with its possible polyphyly.
Colour and spination as in female.Embolus with a thin apical part with small keel at the base and a thicker basal part with a slight hump on one side, apical of median on the thicker part of the embolus (Fig.17).
Carapace reddish-brown, cephalic area slightly darker; abdomen and legs yellow-brown.Body and legs with lancet-like curved macrosetae, more strongly curved on body than on legs.Embolus thick over most of the length, tapered apically, point blunt and slightly twisted at base of thinner part (Fig.20).