Hexophthalma hahni is a species of spider in the family Sicariidae.[2] It is endemic to deserts and other sandy places in southern Africa and is commonly known as Hahn's six-eyed sand spider.[3]
Due to their flattened stance and laterigrade legs, they are also sometimes known as six-eyed crab spiders.
Distribution
Hexophthalma hahni occurs in Namibia, Zimbabwe, and South Africa. In South Africa, it is recorded from five provinces occurring in more than 10 protected areas at altitudes ranging from 14 to 1466 m above sea level.[3]
Habitat and ecology
The species inhabits multiple biomes including Desertbiome, Grassland, Fynbos, Nama Karoo, Savanna and Succulent Karoo biomes. Specimens are found beneath stones in sandy areas, buried in sand at the entrances of animal burrows and at the base of rock overhangs or cliff faces.[3]
Venom
All species of Hexophthalma produce venom that can have 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. Most Hexophthalma species, though, including H.hahnii, have only been studied in vitro, and the detailed effects of their venom in humans and other vertebrates are unknown.[4] No records of bites in southern Africa have been proven.[5] The Hexophthalma hahni possesses venom of significant medical relevance due to its high concentration of sphingomyelinase D, an enzyme responsible for cytotoxic and hemolytic effects. This toxin induces dermonecrosis, hemolysis, and systemic toxicity, comparable to the effects observed in Loxosceles (recluse) spider envenomation. Although confirmed human bites are yet to be proven largely due to the species’ reclusive behaviour and distribution in arid regions of southern Africa experimental data demonstrate that the venom can cause extensive tissue destruction and lethality in animal models. The spider’s venom has therefore become a subject of toxicological and biomedical research, particularly for its role in understanding cell membrane degradation mechanisms, necrotic arachnidism, and the development of antivenom or therapeutic interventions targeting sphingomyelinase D–mediated pathology.
The species is named after Carl Wilhelm Hahn, a German arachnologist who made significant contributions to spider taxonomy.
Taxonomy
The species was originally described by Ferdinand Karsch in 1878 as Hexomma hahnii from Namibia. It was later moved to Hexophthalma by Karsch in 1879 as a generic replacement name. The species has been revised by Lotz (2012, 2018) and synonymized with Hexophthalma testacea. It is known from both sexes and serves as the type species for the genus Hexophthalma.[3]
References
↑ Karsch, F. (1878). "Exotisch-araneologisches". Zeitschrift für die Gesammten Naturwissenschaften. 51: 322–333.
1 2 3 4 5 Dippenaar-Schoeman, A.S.; Haddad, C.R.; Foord, S.H.; Lotz, L.N. (2021). The Sicariidae of South Africa. Version 1. South African National Survey of Arachnida Photo Identification Guide. pp.7–8. doi:10.5281/zenodo.7162164.This article incorporates text available under the CC BY 4.0 license.
↑ 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 (inactive 3 October 2025){{citation}}: CS1 maint: DOI inactive as of October 2025 (link)
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