Blakistonia birksi, sp. n.

(Figs 9 A–L, 10A–I)

Type material. AUSTRALIA: South Australia: holotype male, Ngarkat Conservation Park, 35°37’00”S, 140°46’00”E, July 2006, pitfall trap in heath on sand, L. Jansen (SAM NN29003 DNA). Paratypes: 12 males, Ngarkat Conservation Park, 35°37’00”S, 140°46’00”E, July 2006, pitfall trap in heath on sand, L. Jansen (SAM NN29642– 53); 2 females, Cleland Conservation Park, 34°58’32.178”S, 138°42’40.799”E, 22 December 2014, hand collected from burrows in clay bank, S. and M. Harrison (SAM NN29618 DNA).

Other material examined. AUSTRALIA: South Australia: 1 juvenile, Cleland Conservation Park, 34°58’32.178”S, 138°42’40.799”E, 22 December 2014, hand collected from burrows in clay bank, S. Harrison, M. Harrison (SAM NN29617 DNA); 2 juveniles, Mark Oliphant Conservation Park, 35°01’50.879”S, 138°42’26.579”E, 20 August 2015, dug from mossy bank, S.E. Harrison, S. Stringer, A. Lewis (SAM NN29635 and NN29636); 2 females, same data except 25 August 2015, S.E. Harrison, N. Birks (SAM NN29638 DNA and NN29639). Victoria: 1 juvenile, Grampians National Park, Reid’s Lookout Road, 37°08’49”S, 142°26’48”E, 16 November 2013, hand collected from burrow in clay bank in sclerophyll forest, M.G. Rix, S. Harrison (WAM T131984 DNA).

Diagnosis. Males of B. birksi can be distinguished from those of B. bella, B. pidax, B. tunstilli, B. emmottorum, B. gemmelli, and B. aurea by the absence of prolateral clasping spurs on tibia I (Fig. 9 G–I); from those of B. parva, B. maryae, B. olea, B. tariae, B. carnarvon and B. raveni by the presence of one, rather than two, prolateral macroseta on tibia I (Fig. 9 G–I); from those of B. hortoni, B. maryae and B. newtoni by a subquadrate rather than square eye group (Fig. 9D); and from those of B. plata by the presence of cuspules on the maxillae (Fig. 9F) and a strong abdominal pattern (Fig. 9A). Females of B. birksi can be distinguished from those of all other Blakistonia except B. bassi by abdominal chevrons that are almost black, and very dark brown between the chevrons (Fig. 10A); and from those of B. bassi by the absence of light golden hairs on the carapace (Fig. 10A).

All life stages of B. birksi can also be distinguished from those of other species with sequence data except B. aurea by the following nucleotide substitution (n = 5 specimens): C(387); and from by B. aurea by the following unique nucleotide substitution: A(520).

Description. Holotype male (SAM NN29003). Small idiopid spider (total length 8.0).

Colour (in ethanol; Fig. 9 A–C): Carapace uniform dark chocolate brown (Fig. 9A); labium, maxillae sternum orange-brown, darker towards anterior and lateral margins; chelicerae dark brown (Fig. 9E, F); abdomen dark chocolate brown, distinctive pattern of seven mottled chevrons, for full width of abdomen (Fig. 9A, C); legs and pedipalp concolorous with sternum but darker dorsally (Fig. 9 G–L).

Cephalothorax: Carapace 3.8 long, 3.6 wide, 2.8 high, 1.1 times longer than wide; oval (Fig. 9A), caput low, ocular area raised (Fig. 9C); cuticle smooth, with pits outward from fovea and both sides of caput; fovea straight; two thick setae posterior to eye area smaller, fine setae scattered very sparsely across carapace, concentrated and form fringe around lateral margins; median clump of thickened setae on clypeus (Fig. 9D). Length of median clypeus less than 1.0; anterior margin slightly convex. Eye group 0.9 wide, 0.5 long, 0.3 of carapace width; anterior eye row strongly procurved, PLE–PLE/ALE–ALE ratio 1.0; posterior eye row straight; AME similar in size to ALE and separated by about AME diameter; ALE and PLE separated by about twice ALE diameter; PME about one-third of AME and about half of PLE, and separated from PLE by less than its own diameter (Fig. 9D). Labium without cuspules (Fig. 9F). Sternum 2.7 long, 2.1 wide, evenly setose; three pairs of small sigilla (Fig. 9E). Maxillae with 29 (left) and 38 (right) (Fig. 9E, F).

Legs: setose and diffusely spinose; tarsi I, II ventrally swollen; tarsi and distal metatarsi I, II weakly scopulate (Fig. 9 G–I). Paired tarsal claws: leg I p7 (6 large, 1 small), r9 (8 large, 1 small); leg II p7 (6 large 1 small), r7 (6 large, 1 small); leg III p6 (6 large), r6 (6 large); leg IV p8 (8 large), r9 (6 large, 3 small).

Spination: Leg I tibia with single prolateral macroseta (Fig. 9 G–I), r2; metatarsus p1, r1. Leg II tibia p1 r1; metatarsus p1 r2; legs III and IV setose and diffusely spinose, with no clear demarcation between lanceolate setae and smaller spine-like setae.

Leg and pedipalp measurements: Length of legs IV> I> II> III. Leg I: femur 4.3, patella 2.0, tibia 3.2, metatarsus 2.7, tarsus 1.8, total = 14.0. Leg II: femur 4.1, patella 2.0, tibia 2.9, metatarsus 2.7, tarsus 2.0, total = 13.7. Leg III: femur 3.4, patella 1.5, tibia 2.2, metatarsus 2.7, tarsus 1.8, total = 11.6 Leg IV: femur 4.6, patella 2.1, tibia 3.8, metatarsus 4.0, tarsus 2.3, total = 16.8. Pedipalp: femur 2.3, patella 1.3, tibia 2.4, tarsus 1.2, total = 7.2.

Pedipalp: All segments without spines; patella with thickened ventral setae distally; tibia short and swollen, RTA short and pointed, covered in long setae and short, dense spinules, forming a line about as wide as apophysis and covering about two-thirds of the distance to distal tibia, becoming sparser towards distal tibia; long, erect setae on ventral tibia; bulb uniform, globular; embolus simple, slender, tapering, slightly twisted at end and without flanged tip, about twice length of bulb; cymbium covered in rows of short, sparse spinules, becoming longer closer to distal edge (Fig. 9 J–L).

Abdomen: Setose, oval, dorsal sigilla not evident; 4.2 long, 2.7 wide (Fig. 9A).

Variation (n=13): Carapace 3.8–4.6 long, 3.1–3.6 wide, labial cuspules 0–5. Spination: Leg I: tibia p0–2, r1–2; metatarsus p0–1, r1–2. Leg II: tibia p0–1, r1–3; metatarsus p0–1, r1–4.

Paratype female (SAM NN29618). Medium-sized idiopid spider (total length 15.4).

Colour (in ethanol; Fig. 10 A–I): Legs, pedipalp and carapace dark golden-brown, slightly darker on both sides of caput and around margins (Fig. 10A); sternum golden-brown, darker towards anterior and lateral margins; labium and maxillae golden-brown, chelicerae red-brown (Fig. 10E, F); abdomen brown with distinct pattern of seven mottled chevrons (Fig. 10A, C).

Cephalothorax: Carapace 7.0 long, 5.2 wide, 5.2 high, 1.3 times longer than wide; oval (Fig. 10A); caput high, with ocular area raised (Fig. 10C); cuticle uniformly smooth; fovea procurved; one row of thickened setae between fovea and eye group; small, fine setae also scattered very sparsely across carapace, slightly more concentrated on caput, and form fine, indistinct fringe around lateral margins; median clump of thickened setae on clypeus (Fig. 10D). Length of median clypeus less than 1.0; anterior margin slightly convex. Eye group 1.2 wide, 0.8 long, 0.2 of carapace width; anterior eye row strongly procurved, PLE–PLE/ALE–ALE ratio 1.1; posterior eye row slightly recurved; AME slightly smaller than ALE and separated by ca. 1.5 diameter of ALE; ALE and PLE separated by ca. twice diameter of ALE; PME pale, about 0.67 of PLE, and separated from PLE by just less than its own diameter (Fig. 10D). Labium with ca. 11 cuspules (Fig. 10F). Sternum 4.1 long, 2.8 wide, moderately setose with setae becoming denser and longer around margins; 2 pairs of faint sigilla evident (Fig. 10E). Maxillae with 11 (left) and 15 (right) cuspules, (Fig. 5E, F).

Legs: moderately setose and diffusely spinose; femora I, II, and pedipalp laterally bowed; tarsi and distal twothirds of metatarsi I, II, and palpal tarsus scopulate ventrally and laterally (Fig. 10G, H). Paired tarsal claws: leg I p2 (1 large, 1 small) r0; leg II p2 (1 large, 1 small), r2 (1 large, 1 small); leg III p0, r0; right leg IV p2 (2 large), r0. Pedipalp claw with 2 large teeth.

Spination: Leg I: tibia p3, r4; metatarsus p2, r5; tarsus p1 r3. Leg II: tibia p2, r4; metatarsus p3, r7; tarsus p1, r3. Leg III: patella p3; tibia p6, metatarsus p7, r6; tarsus with ventral patch of 9 short spines. Right leg IV: metatarsus p2, r1; tarsus with ventral 16 short spines ventrally. Pedipalp: tibia p6, r6; tarsus p3, r3.

Leg and pedipalp measurements: Length of legs IV> I> II> III. Leg I femur 3.7, patella 2.5, tibia 2.1, metatarsus 1.7, tarsus 1.3, total = 11.3. Leg II femur 3.3, patella 2.3, tibia 2.0, metatarsus 2.6, tarsus 1.3, total = 11.5. Leg III femur 2.9, patella 2.1, tibia 1.8, metatarsus 2.8, tarsus 1.6, total = 11.2. Leg IV (right): femur 4.1, patella 2.9, tibia 3.6, metatarsus 3.1, tarsus 2.0, total = 15.7. Pedipalp: femur 3.1, patella 1.29 tibia 1.8, tarsus 2.2, total = 9.1.

Abdomen: Setose, oval, one pair of indistinct, unsclerotised dorsal sigilla; 8.4 long, 6.3 wide (Fig. 10A).

Genitalia: Spermathecae paired, simple, unbranched, stout and outward facing, oval-shaped, covered in opaque mottled brown nodules, becoming more concentrated in median band.

Variation (n=2) Carapace 6.9–7.0 long, 5.2–5.6 wide, 3–11 labial cuspules. Spination: Leg I: tibia p3, r4; metatarsus p2–4, r4; tarsus p1, r2–3. Leg II: tibia p1–2, r4; metatarsus p3–4, r5–7; tarsus p2, r3–5. Leg III: patella p3, tibia p0–1, metatarsus p5–6, r4–6; tarsus with 8–9 spines ventrally. Leg IV: metatarsus p2–9, r1–2. Pedipalp: tibia p6, r5–5; tarsus p3–4, r 3–4.

Etymology. This species is named in honour of Nicholas Birks, for his generous efforts in collecting and photographing specimens for this project.

Distribution. Blakistonia birksi is known from Ngarkat Conservation Park in south-eastern South Australia, Cleland Conservation Park and Mark Oliphant Conservation Park in the Mount Lofty Ranges, and the Grampians National Park in Victoria (Fig. 32).

Remarks. The sandy habitat of Ngarkat Conservation Park is unusual for the genus, as most species of Blakistonia generally prefer to build burrows in clay. This species is further unusual in that it exists in two locations in the Mount Lofty Ranges, which have historically been well collected; however, this species was not found in the SAM collection. This could potentially be due to the cryptic nature and small size of the burrow lids.