Genus Blakistonia Hogg, 1902

Blakistonia Hogg, 1902: 131. Type species Blakistonia aurea Hogg, 1902, by original designation. Rix et al, 2017c: 582. Cantuarides Strand, 1907: 8. Type species Cantuarides exsiccatus Strand, 1907, by original designation (synonymised by Main, 1985: 39).

Diagnosis. Most species of Blakistonia can be distinguished from those of other Arbanitinae by the following combination of characters (sensu Rix et al. 2017c): a relatively narrow carapace in dorsal view (e.g., Figs 5A, 6A) (relative to species of Euoplos Rainbow, 1914); a square or subquadrate eye group (e.g., Figs 5D, 7D); the presence of scopulae on tarsi I and II of females (e.g., Fig. 18G, H); and the absence of a distal retrolateral tibial apophysis on the male pedipalp (e.g., Fig. 5J, L). Species of Blakistonia can be further distinguished from those of most Euoplini, Arbanitini and Aganippini by the square or subquadrate eye group. Some species of Eucyrtops (tribe Aganippini) have a similar subquadrate eye group to species of Blakistonia (e.g., Eucyrtops eremaeus Main, 1957), and some Blakistonia can have a marginally trapezoidal eye group (e.g., B. nullarborensis sp. n. [Fig. 20D] and B. wingellina sp. n. [Fig. 28D]). However, similar species of Aganippini can be distinguished from Blakistonia by a more strongly attenuate base to the RTA (Rix et al. 2017c). See Rix et al. (2017c) for diagnostic molecular characters.

Description. Small to large idiopid spiders, usually dark brown to golden or orange-brown in colour (Fig. 1 A–I). Carapace oval-shaped (e.g., Figs 6A, 9A, 10A), commonly with line of setae between fovea and eye group (Fig. 8D), and males with fringe of setae around lateral carapace (Fig. 14A); fovea procurved in females and commonly straight in males (Fig. 5A) or slightly procurved (Fig. 6A). Eye group square (Fig. 5A) or subquadrate (Figs 7D, 22D), rarely trapezoidal (Figs 20D, 28D); anterior eye row always strongly procurved (Figs 5D, 6D, 7D). Chelicerae with rastellum of several strong conical spines in both males and females and with a row of teeth on each edge of furrow, the teeth decreasing in size from distal to proximal end. Maxillae rectanguloid, wider behind than in front, with setae becoming longer towards interior margins; maxillary cuspules present in some males (Fig. 17F) and all females (Fig. 6F), becoming denser towards interior margins; labium wider than long, with slightly recurved or straight posterior edge, with two longer clumps of curved setae on anterior lateral edges; labial cuspules present in some males (Fig. 14F) and some females (Fig. 15F). Sternum without distinct sigilla or with three distinct pairs in which anterior pair are smallest, the median pair bigger and the posterior pair largest, as in most mygalomorphs. Abdomen oval, typically with chevron pattern dorsally (Figs 9A, 10A) and 1–5 pairs of unsclerotised sigilla (Figs 15A, 28A) in females and also males of B. olea sp. n., but not distinct in B. nullaborensis. Legs with scopulae ventrally on tarsi I, II (Fig. 7G, H) and metatarsi I, II of all females and some males (Fig. 11A), and palpal tarsus of females. Male tibia I with either prolateral clasping spurs on tibia I, each with raised cuticular bases and bearing multiple terminal peg-like macrosetae (Fig. 8 G–I), two prolateral macrosetae (Fig. 11 G–I), or a single prolateral macroseta (Fig. 9 G–I). Leg tarsi with three claws, one row of teeth on paired claws; female pedipalp claw without teeth. Male pedipalp with short, pointed RTA with broad base; RTA covered in spinules (Fig. 14 J–L); cymbium with field of spinules disto-dorsally in most species, sometimes spine-like; embolus simple, slightly twisted, most species with broad base (Fig. 5 J–L). Spermathecae paired, simple, unbranched, stout and outward facing, oval-shaped in most species, covered in opaque mottled brown glandular nodules (Fig. 18I). Four spinnerets, posterior lateral pair three-segmented, apical article short with domed or conical tip, posterior median pair small, digitiform.

Distribution. Blakistonia has a distribution that is centred on southern South Australia (Rix et al. 2017c), especially Adelaide and the Mount Lofty Ranges, and extending north into the central arid zone and into the southern Northern Territory around Uluru-Kata Tjuta National Park. They are also sparsely distributed in Queensland, western inland New South Wales, western Victoria, south-western Western Australia and eastern inland Western Australia, near the Western Australian/South Australian/ Northern Territory border. Blakistonia are absent from mesic south-eastern Australia (east of the Grampians Range), the northern half of the Northern Territory and most of arid New South Wales and western inland/northern Western Australia (see Rix et al. 2017c, fig. 68 and Figures 29–34 for summary distribution maps.)

Composition. Blakistonia includes one previously described species, B. aurea Hogg, 1902, and 19 new species: B. bassi sp. n., B. bella sp. n., B. birksi sp. n., B. carnarvon sp. n., sp. n., B. emmottorum sp. n., B. gemmelli sp. n., B. hortoni sp. n., B. mainae sp. n., B. maryae sp. n., B. newtoni sp. n., B. nullarborensis sp. n., B. olea sp. n., B. parva sp. n., B. pidax sp. n., B. plata sp. n., B. raveni sp. n., B. tariae sp. n., B. tunstilli sp. nov. and B. wingellina sp. n.

Biology and remarks. Blakistonia is a diverse group, both in distribution and number of species. Spiders are found in a variety of habitats, from mossy banks in the mesic, high rainfall zone of the Mount Lofty Ranges, to arid desert areas such as those in northern and inland South Australia and Western Australia. The burrows of the most common species, B. aurea, are characteristically D-shaped, slightly indented and plug-like (Fig. 2B, 2L); however, other species build a variety of different burrows, including round, indented, plug-like lids (Fig. 2 F–G, K), wafer-like lids (Fig. 2D, E), and also burrows that are twig-lined (Fig. 2 H–J). Wandering Blakistonia males are usually collected after rainfall events, most frequently in March to May, but have also been collected later in the year from June to September.