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| Atrax christenseni Dupérré & Smith in Loria, Frank, Dupérré, Smith, Jones, Buzatto & Harms, 2025. |
Abstract
The Sydney funnel-web spider Atrax robustus O. Pickard-Cambridge, 1877 is an iconic Australian species and considered among the most dangerously venomous spiders for humans. Originally described in 1877 from a single specimen collected in “New Holland”, this spider has a complex taxonomic history. The most recent morphological revision of funnel-web spiders (Atracidae) lists this species as both widespread and common in the Sydney Basin bioregion and beyond, roughly 250 km from the Newcastle area south to the Illawarra, and extending inland across the Blue Mountains. Morphological variability and venom diversity in this species appear to be unusually high, raising questions about species concepts and diversity in these spiders. In this study, we use a combination of molecular phylogenetics, divergence time analyses and morphology to establish the Sydney funnel-web spider as a complex of three species. The “real” Sydney funnel-web spider Atrax robustus is relatively widespread in the Sydney metropolitan region. A second species, Atrax montanus (Rainbow, 1914), which is revalidated here, overlaps but mainly occurs further south and west, and a third larger species, Atrax christenseni sp. nov., is found in a small area surrounding Newcastle to the north. The revised taxonomy for funnel-web spiders may have practical implications for antivenom production and biochemical studies on spider venoms. Although no human fatalities have occurred since the development of antivenom in the 1980s, antivenom for Sydney funnel-web spiders might be optimized by considering biological differentiation at the species level.
Keywords: Antivenoms, Biodiversity, Biogeography, Mygalomorph spiders, Systematics, Taxonomy
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| Habitat of Atrax O. Pickard-Cambridge, 1877 species. A. Atrax montanus (Rainbow, 1914), forest habitat in Blue Mountains. B. Atrax christenseni sp. nov., near Newcastle, burrow under rock. C, D. Atrax robustus O. Pickard-Cambridge, 1877, burrow under rock (C), and female with spiderlings (D). Photo credit: (A) H. Smith/Australian Museum, Sydney; (B, C) D. Harms; (D) B. Jones |
Infraorder Mygalomorphae Pocock, 1892.
Family Atracidae Hogg, 1901.
Genus Atrax O. Pickard-Cambridge, 1877.
Atrax robustus O. Pickard-Cambridge, 1877
Atrax montanus (Rainbow, 1914), status revised
Atrax christenseni Dupérré & Smith sp. nov.
Diagnosis. Adult males are distinguished from all species by their extremely long embolus (12x longer than wide) and widely open embolus tip (Figs. 5C and 17G and H), while shorter in A. robustus (6.5x longer than wide), A. montanus (8x longer than wide) and A. sutherlandi (3.8x longer than wide) (see ...
Etymology. The specific epithet was chosen in honour of Kane Christensen, whose contributions in collecting spiders were vital to the description of this species.
Distribution. This species is distributed north of Sydney with all records situated in a 25 km radius around Newcastle (Fig. 3). Exact locations are hidden to protect this species, which occurs across a restricted area and may be endangered by collecting.
Conclusions:
Antivenom and biomedical research on medically important species ultimately relies on sound taxonomic concepts for the species in question. Here we show that the iconic Sydney funnel-web spider Atrax robustus sensu Gray, 2010 is a complex of three species (A. robustus sensu stricto, A. montanus and A. christenseni) that differ phylogenetically and morphologically. Targeted venom analyses of these species might follow, but the findings of past biochemical studies should be re-evaluated in light of a modern taxonomic framework. Antivenom seems to be effective for all Atrax species but antivenom specificity to the “real” Sydney funnel-web spider might benefit from acknowledging interspecific boundaries, intraspecific genetic variation, and from considering the distributional range of this species and its congeners. Conservation measures may be warranted to preserve genetic diversity in Atrax spp. lineages.
Stephanie F. Loria, Svea-Celina Frank, Nadine Dupérré, Helen M. Smith, Braxton Jones, Bruno A. Buzatto and Danilo Harms. 2025. The World’s Most Venomous Spider is A Species Complex: Systematics of the Sydney Funnel-web Spider (Atracidae: Atrax robustus). BMC Ecology and Evolution. 25: 7. DOI: doi.org/10.1186/s12862-024-02332-0
Newcastle Funnel-web Spider, Atrax christenseni
