|Unidentified species from coastal Namibia|
Hexophthalma is a genus of spiders in the family Sicariidae. Although the genus was originally erected in 1878 (then with the name Hexomma), it was merged into the genus Sicarius in the 1890s, and remained unused until revived in 2017, when it was discovered that the African species then placed in Sicarius were distinct. The English name six-eyed sand spiders is used for members of the genus, particularly Hexophthalma hahni. Species in the genus have necrotic (dermonecrotic) venom, and can potentially cause serious or even life-threatening wounds.
The genus was first created in 1878 by Friedrich Karsch as Hexomma, with the sole species Hexomma hahni. However, by 1879, Karsch had realized that this name had already been used in 1877 for a species of harvestman, so he published the replacement name Hexophthalma. In 1893, Eugène Simon transferred Hexophthalma hahni to the genus Sicarius, and Hexophthalma fell out of use, until a phylogenetic study in 2017 showed that the African species of Sicarius, including Sicarius hahni, were distinct, and revived the genus Hexophthalma for them.
Two new species were added to the genus in 2018, and one previously accepted species, H. testacea, synonymized with H. hahnii. The number of species is expected to increase with further study. H. spatulata differs in a number of respects from other species in the genus, which may thus not be monophyletic.
- Hexophthalma albospinosa (Purcell, 1908) – Namibia, South Africa
- Hexophthalma binfordae Lotz, 2018 – Namibia
- Hexophthalma damarensis (Lawrence, 1928) – Namibia
- Hexophthalma dolichocephala (Lawrence, 1928) – Namibia
- Hexophthalma goanikontesensis Lotz, 2018 – Namibia
- Hexophthalma hahni (Karsch, 1878) (type species) – Namibia, South Africa
- Hexophthalma leroyi Lotz, 2018 – South Africa
- Hexophthalma spatulata (Pocock, 1900) – South Africa
Species of Hexophthalma produce venom that can have necrotic (dermonecrotic) effects, capable of causing serious or even life-threatening wounds, particularly if the wound becomes infected or the venom spreads in the body. The necrotic effects are caused by a family of proteins related to sphingomyelinase D, present in the venom of all sicariid spiders. In this respect, the genus resembles Loxosceles, the recluse spiders. However, most Hexophthalama species have only been studied in vitro, and the detailed effects of their venom in humans and other vertebrates are unknown.
- "Gen. Hexophthalma Karsch, 1879", World Spider Catalog, Natural History Museum Bern, retrieved 2018-07-16
- Lotz, Leon (2018), "An update on the spider genus Hexophthalma (Araneae: Sicariidae) in the Afrotropical region, with descriptions of new species", European Journal of Taxonomy, 424: 1–18, doi:10.5852/ejt.2018.424
- Magalhães, I.L.F.; Brescovit, A.D. & Santos, A.J. (2017), "Phylogeny of Sicariidae spiders (Araneae: Haplogynae), with a monograph on Neotropical Sicarius", Zoological Journal of the Linnean Society, 179 (4): 767–864, doi:10.1111/zoj.12442
- "Family Sicariidae Keyserling, 1880", World Spider Catalog, Natural History Museum Bern, retrieved 2018-07-17
- Binford, Greta J. & Wells, Michael A. (2003), "The phylogenetic distribution of sphingomyelinase D activity in venoms of Haplogyne spiders" (PDF), Comparative Biochemistry and Physiology B, 135: 25–33, doi:10.1016/S1096-4959(03)00045-9, retrieved 2018-07-19
- Snyman, C. & Larsen, N. (2005), "Spider bite and its treatment in southern Africa", Occupational Health Southern Africa, 11 (2): 22–26, retrieved 2018-07-23 – includes southern African Sicarius, now Hexophthalma