Blakistonia nullarborensis, Harrison & Rix & Harvey & Austin, 2018

Harrison, Sophie E., Rix, Michael G., Harvey, Mark S. & Austin, Andrew D., 2018, Systematics of the Australian spiny trapdoor spiders of the genus Blakistonia Hogg (Araneae: Idiopidae), Zootaxa 4518 (1), pp. 1-76 : 51-53

Blakistonia nullarborensis , sp. n.

( Fig. 20 A–I)

Type material. AUSTRALIA: Western Australia: Holotype female, east of Madura, Nullarbor Plain , 32°24’57”S, 124°20’34”E, 29 March 2014, dug from burrow in degraded roadside habitat, M.S. Harvey, S.E. Harrison (WAM T 141142 DNA).

Other material examined. AUSTRALIA: Western Australia: 1 female, east of Balladonia, Nullarbor Plain , 31°53’54”S, 126°54’30”E, 29 March 2014, dug from burrow in remnant native vegetation, M.S. Harvey, S.E. Harrison (WAM T 141139 DNA); 1 female, Cocklebiddy , 32°02’12”S, 126°05’28”E, 29 March 2014, dug from burrow in highly degraded roadside habitat, M.S. Harvey, S.E. Harrison ( WAM T 141140 DNA) ; 1 female, Moonera , 31°59’17”S, 126°33’11”E, 29 March 2014, dug from burrow in native vegetation, M.S. Harvey, S.E. Harrison ( WAM T 141141 DNA) .

Diagnosis. Females of B. nullarborensis can be distinguished from those of all other species of Blakistonia , except B. wingellina , by the strongly trapezoidal eye group ( Fig. 20D ); however, B. wingellina and B. nullarborensis are unable to be reliably distinguished using morphology alone. Males are unknown.

All life stages of B. wingellina can also be distinguished from those of other species with sequence data by the following nucleotide substitution (n = 4 specimens): G(171).

Description. Holotype female (WAM T 141142). Large idiopid spider (total length 23.0).

Colour (in ethanol; Fig. 20 A–C): Carapace, legs and pedipalp medium golden-brown, slightly darker around fovea and lateral margins of caput ( Fig. 20A ); sternum a lighter golden-brown, darker towards anterior margins; labium and maxillae same golden-brown as anterior margins of sternum, chelicerae dark brown ( Fig. 20E, F ); abdomen grey-brown with eight pale mottled chevrons of uniform width spaced over length of abdomen, more closely spaced at posterior abdomen ( Fig. 20A, C ).

Cephalothorax: Carapace 9.3 long, 7.5 wide, 7.5 high, 1.2 times longer than wide; oval ( Fig. 20A ); caput high, ocular area flat ( Fig. 20C ); cuticle uniformly smooth; fovea procurved; one large patch of thick setae posterior to eye area; smaller fine setae also scattered across the carapace, concentrated and forming fine, indistinct fringe around lateral margins; median clump of thickened setae on clypeus ( Fig. 20D ). Length of median clypeus less than 1.0; anterior margin slightly convex. Eye group 1.9 wide, 1.4 long, 0.3 of carapace width; anterior eye row strongly procurved, PLE–PLE/ALE–ALE ratio 1.3; posterior eye row slightly recurved; AME slightly larger than half ALE and separated by the diameter of AME; ALE and PLE separated by about diameter of PLE; PME pale, ca. 0.25 of PLE, and separated from PLE by about its own diameter ( Fig. 20D ). Labium without cuspules ( Fig. 20F ). Sternum 4.9 long, 3.7 wide, moderately setose with setae becoming denser and longer around margins; 3 pairs of sigilla, anterior-most pair ca. in margins, close to anterior margin; second pair at one-third length; third pair at ca. twice their width from edge ( Fig. 20E ). Maxillae with 21 (left) and 24 (right) cuspules, becoming denser near inner margins ( Fig. 20E, F ).

Legs: moderately setose and diffusely spinose, with retrolateral side of all legs being least setose and dorsal sides of III, IV with thick, dense, spine-like setae; distinct upright setae on tarsi, metatarsi and distal tibiae I and II; femora I, II, and pedipalp laterally bowed; tarsi and metatarsi I, II, and palpal tarsus heavily scopulate ( Fig. 20 G– H). Paired tarsal claws: leg I p2 (1 large, 1 small) r3 (2 large, 1 small); leg II p3 (2 large, 1 small), r2 (2 large); right leg III p2 (1 large, 1 small), r2 (1 large, small); right leg IV p0, r2 (2 small). Pedipalp claw with 1 large and 2 small teeth.

Spination: Leg I: tibia p2, r4; metatarsus p5, r4; tarsus with 10 short spines ventrally. Leg II: tibia p2, r4; metatarsus p4, r5; tarsus p0, r10. Leg II: tibia p2, r4; metatarsus p5, r5; tarsus p0, r10. Right leg III: patella p7; tibia p2, r0; metatarsus p5, r7. Right leg IV: metatarsus p2, r5; tarsus with 19 short spines ventrally. Pedipalp: tibia p5, r7; tarsus p2, r5.

Leg and pedipalp measurements: Length of legs IV> I> III> II. Leg I: femur 4.2, patella 2.6, tibia 2.4, metatarsus 2.8, tarsus 2.6, total = 14.6. Leg II: femur 4.2, patella 3.1, tibia 2.7, metatarsus 1.9, tarsus 1.8, total = 13.7. Leg III: femur 4.2, patella 3.0, tibia 2.5, metatarsus 2.5, tarsus 2.2, total = 14.4. Leg IV (right): femur 4.4, patella 2.4, tibia 3.8, metatarsus 3.0, tarsus 1.9, total = 15.5. Pedipalp: femur 4.7, patella 3.4, tibia 2.7, tarsus 2.2, total = 15.0.

Abdomen: Setose, oval, dorsal sigilla not evident; 16.0 long, 10.1 wide ( Fig. 20A ).

Genitalia: Spermathecae paired, simple, unbranched, stout and outward facing, circular, covered in opaque mottled brown nodules, more concentrated on lobe of spermathecae ( Fig. 20I ).

Variation (n=4): Carapace 6.2–9.3 long, 6.2–7.5 wide, no labial cuspules. Spination: Leg I: tibia p2, r3–6; metatarsus p3–5, r5–6; tarsus p0, r3–10. Leg II: tibia p1–3, r2–4; metatarsus p2–5, r5 tarsus p0, r10–12. Leg III: patella 3–7, tibia p0–2, r0; metatarsus p4–6, r5–7, tarsus with 5–13 short spines ventrally. Leg IV: metatarsus p3–6, r1–2; tarsus with 7–9 short spines ventrally. Pedipalp: p0-2, tibia p2–6, r4–7; tarsus p2, r3–5.

Etymology. The specific name refers to the Nullarbor Plain, where this species is found.

Distribution. Blakistonia nullarborensis is known only from the Nullarbor Plain ( Fig. 33 ).

Remarks. The burrow of B. nullarborensis is D-shaped and slightly indented. When collecting specimens, SEH and MSH were unable to locate burrows of juveniles, and many habitats near the Eyre Highway were highly degraded.

Figures

FIGURE 20. Blakistonia nullarborensis sp. n., holotype female (WAM T141142): A, habitus, dorsal view; B, habitus, ventral view; C, habitus, lateral view; D, eye group, dorsal view; E, sternum, ventral view; F, maxillae and labium, ventral view; G, left leg I, prolateral view; H, left leg I, retrolateral view; J, spermathecae. Scale bars = 5 mm (A), 2 mm (G).

FIGURE 33. Distribution of Blakistonia species: B. mainae sp. n. (white circle), B. wingellina sp. n. (white triangle), B. olea sp. n. (white square), B. nullarborensis sp. n. (black squares), Blakistonia ‘sp. 1’ (black circle), and B. tariae sp. n. (black triangles).