Blakistonia pidax Harrison & Rix & Harvey & Austin 2018, sp. n.
Creators: name: Harrison, Sophie E.
name: Rix, Michael G.
name: Harvey, Mark S.
name: Austin, Andrew D.
Publisher: name: Zenodo
Year: 2018
Subjects: Biodiversity
Taxonomy
Animalia
Arthropoda
Arachnida
Araneae
Idiopidae
Blakistonia
Blakistonia pidax

description: Blakistonia pidax, sp. n.
(Fig. 23 A–L)
Type material. AUSTRALIA: South Australia: Holotype male, Strangways Springs, 29°08’14”S, 136°34’00”E, 25–30 September 1995, pitfall trap, D.E.L.M. Stony Deserts Survey (SAM NN20064 DNA). Paratype: 1 male, same data (SAM NN20065).
Diagnosis. Males of B. pidax can be distinguished from those of B. maryae, B. plata, B. birksi, B. newtoni, B. hortoni, B. parva, B. maryae, B. olea, B. tariae, B. carnarvon and B. raveni by the presence of prolateral clasping spurs on tibia I, each with raised cuticular bases and bearing multiple terminal peg-like macrosetae (Fig. 23 G–I); and from those of B. bella, B. tunstilli, B. emmottorum, B. gemmelli and B. aurea by the absence of spinules on the cymbium (Fig. 23 J–L). Females are unknown.
All life stages of B. pidax can also be distinguished from those of other species with sequence data by the following nucleotide substitutions (n = 1 specimen): G(128), T(198), T(327), T(378), C(459), T(519), A(538) and the following unique motif: TA(321–322).
Description. Holotype male (SAM NN20064). Medium idiopid spider (total length 10.2).
Colour (in ethanol; Fig. 23 A–C): Carapace, legs and pedipalp uniform pale golden orange-brown (Fig. 23A); sternum, labium and maxillae very similar, sternum darker towards anterior margins; chelicerae slightly darker than carapace (Fig. 23E, F); abdomen golden orange-brown with distinctive pattern of seven mottled dark chevrons dorsally not laterally (Fig. 23A, C).
Cephalothorax: Carapace 4.6 long, 3.9 wide, 3.3 high,1.2 times longer than wide; oval (Fig. 23A), caput low, ocular area raised (Fig. 23C); cuticle smooth, with pits outward from fovea and both sides of caput; fovea straight; distinct row of setae from halfway between fovea and eye group to eye group, culminating in a group of longer, thickened setae directly posterior to eye group; smaller fine setae also scattered very sparsely across the carapace, concentrated and form fringe around lateral margins; median clump of thickened setae on clypeus (Fig. 23D). Length of median clypeus less than 1.0; anterior margin slightly convex. Eye group 0.8 wide, 0.7 long, 0.2 of carapace width; anterior eye row strongly procurved, PLE–PLE/ALE–ALE ratio 1.1; posterior eye row straight; AME ca. two-thirds of ALE and separated by about AME diameter; ALE and PLE separated by about twice ALE diameter; PME about two-thirds of the size of AME and only slightly smaller than PLE, and separated from PLE by about its own diameter (Fig. 23D). Labium without cuspules (Fig. 23F). Sternum 2.9 long, 2.2 wide, evenly setose; three pairs of small sigilla (Fig. 23E). Maxillae without cuspules (Fig. 23E, F).
Legs: moderately setose and very sparsely spinose; tarsi I, II ventrally swollen; tarsi I II weakly scopulate (Fig. 23 G–I). Paired tarsal claws: leg I p8 (8 large) 75 (6 large, 1 small); leg II p8 (8 large), r5 (4 large, 1 small); leg III p4 (3 large, 1 small), r5 (4 large, 1 small); leg IV p5 (4 large, 1 small), r5 (2 large, 3 small).
Spination: Tibia I with prolateral clasping spurs, distal-most spur with 2 terminal peg-like macrosetae, proximal-most with 3 terminal peg-like macrosetae (Fig. 23 G–I). Leg II without spines. Leg III: patella p4; metatarsus p2, r2; tarsus p4, r1. Leg IV: metatarsus p5, r2.
Leg and pedipalp measurements: Length of legs IV> I> II> III. Leg I: femur 4.3 patella 2.0, tibia 3.1, metatarsus 3.1, tarsus 1.7, total = 14.2. Leg II: femur 4.3, patella 2.1, tibia 3.0, metatarsus 3.0, tarsus 1.7, total = 14.1. Leg III: femur 3.7, patella 1.6, tibia 2.1, metatarsus 1.9, tarsus 1.9, total = 13.0. Leg IV: femur 4.2, patella 2.3, tibia 4.1, metatarsus 4.9, tarsus 2.4, total = 18.1. Pedipalp: femur 2.3, patella 1.0, tibia 2.2, tarsus 1.1, total = 6.6.
Pedipalp: All segments without spines; patella with thickened ventral setae distally; tibia short and swollen, RTA short, thin and pointed, covered in dense spinules in line ca. as wide as apophysis halfway to distal tibia, becoming only slightly sparser; long, erect setae ventrally; bulb uniform, globular; embolus simple, slender, tapering, slightly twisted with a flanged tip, slightly longer than length of bulb; cymbium covered in rows of sparse, thickened setae, becoming longer closer to distal edge (Fig. 23 J–L).
Abdomen: Setose, oval, dorsal sigilla not evident; 5.6 long, 3.2 wide (Fig. 23A).
Variation (n=2): Carapace 4.4–4.6 long, 3.5–3.9 wide, no labial cuspules. Spination: leg III patella p4, metatarsus p2, r1-3. Leg IV: metatarsus p4-5, r1-2.
Etymology. The specific name is taken from the Greek pidax (meaning ‘spring’), and refers to the location where the species was found.
Distribution. Blakistonia pidax is known only from Strangways Springs, south-west of Lake Eyre in central South Australia (Fig. 32).
Remarks. This male was collected in a pitfall trap during the ‘Stony Deserts Biological Survey’, which was conducted between 1994 and 1997 (see Brandle 1998).
description: Published as part of 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), pp. 1-76 in Zootaxa 4518 (1) on pages 57-58, DOI: 10.11646/zootaxa.4518.1.1, http://zenodo.org/record/2609500