Blakistonia bella, 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 : 29-30

Blakistonia bella , sp. n.

( Fig. 8 A–L)

Type material. AUSTRALIA: South Australia: Holotype male, Johnson’s Bore , 29°10’59”S, 136°10’43”E, 6–7 October 1995, pitfall trap, D.E.L.M. Stony Deserts Survey (SAM NN20063 ).

Other material examined. AUSTRALIA: South Australia: 1 male, Strangways Springs , 29°28’58”S, 136°35’49”E, 25–30 September 1995, pitfall trap, D.E.L.M. Stony Deserts Survey ( SAM NN20087 ) .

Diagnosis. Males of B. bella can be distinguished from those of B. plata , B. birksi , B. newtoni , B. maryae , B. hortoni , B. parva , B. olea , B tariae , B. carnarvon , and B. raveni by the prolateral clasping spurs on tibia I, each with raised cuticular bases and bearing multiple terminal peg-like macrosetae ( Fig. 8 G–I). Males of B. bella can be distinguished from those of B. pidax , B. tunstilli , B. emmottorum , B. gemmelli and B. aurea by the strongly patterned abdomen with a dark dorsal cardiac stripe ( Fig. 8A ). Females are unknown.

Description. Holotype male (SAM NN20063). Large idiopid spider (total length 15.4mm).

Colour (in ethanol; Fig. 8 A–C): Carapace, legs and pedipalp uniform pale golden orange-brown ( Fig. 8A ); sternum very similar, darker towards anterior margins; labium and maxillae as sternum, chelicerae dark brown ( Fig. 8E, F ); abdomen golden orange-brown with distinctive pattern of seven dark chevrons not extending down sides of abdomen ( Fig. 8A, C ).

Cephalothorax: Carapace 7.4 long, 6.7 wide, 5.2 high, 1.1 times longer than wide; oval ( Fig. 8A ), caput low, ocular area flat ( Fig. 8C ); cuticle smooth, with pits outward from fovea and both sides of caput; fovea straight; thin, indistinct rows of fine setae radiating out from fovea, with thickest row between fovea and eye group, culminating in group of longer, thickened setae directly posterior to eye group; smaller fine setae also scattered across carapace, concentrated and forming fringe onlateral margins; median clump of thickened setae on clypeus ( Fig. 8D ). Length of median clypeus less than 1.0; anterior margin slightly convex. Eye group 1.2 wide, 1.2 long, 0.2 of carapace width; anterior eye row strongly procurved, PLE–PLE/ALE–ALE ratio 1.1; posterior eye row straight; AME ca. half size of ALE and separated by about diameter of AME; ALE and PLE separated by ca. two diameters of ALE; PME similar in size to AME and about half size of PLE, and separated from PLE by less than its own diameter ( Fig. 8D ). Labium without cuspules ( Fig. 8F ). Sternum 4.0 long, 3.2 wide, evenly setose; three pairs of sigilla, doubling in size from anterior to posterior, anterior two pairs separated from edge by their own diameter, posterior pair separated from margin by just over their own diameter ( Fig. 8E ). Maxillae without cuspules ( Fig. 8E, F ).

Legs: moderately setose; tibiae I, II without spines, legs III and IV with few spines; setae on patellae of legs III and IV thickened and in rows, with no setae between rows; tarsi I, II slightly ventrally flattened; tarsi and distal metatarsi I, II weakly scopulate ( Fig. 8 G–I). Paired tarsal claws: leg I p7 (7 large) r5 (5 large); leg II p5 (5 large), r5 (5 large); leg III p5 (5 large), r5 (4 large, 1 small); leg IV p4 (4 large), r5 (5 large).

Spination: Tibia I with prolateral bifid apophyses, distal-most apophysis with 2 teeth, proximal-most with 4 teeth ( Fig. 8 G–I). Leg II without spines. Leg III: patella p5; metatarsus p3, r5. Leg IV: patella p5; metatarsus IV p4, r5.

Leg and pedipalp measurements: Length of legs I> II> IV> III. Leg I: femur 7.9, patella 3.7, tibia 4.8, metatarsus 5.6, tarsus 2.9, total = 24.9. Leg II: femur 7.0, patella 3.5, tibia 4.7, metatarsus 4.8, tarsus 3.0, total = 23.0. Leg III: femur 5.7, patella 3.0, tibia 4.1, metatarsus 5.1, tarsus 3.0, total = 20.9. Leg IV (right): femur 5.7, patella 3.0, tibia 4.1, metatarsus 5.2, tarsus 3.0, total = 21.0. Pedipalp: femur 4.3, patella 2.2, tibia 3.7, tarsus 1.8, total = 12.0.

Pedipalp: All segments without spines; patella with thickened ventral setae; tibia short, swollen, RTA short, pointed, covered in short, dense spinules continuing almost to distal tibia, becoming sparser; long, erect setae on ventral tibia; bulb uniform, globular; embolus simple, slender, tapering, slightly twisted with flanged tip, slightly longer than bulb; cymbium covered in rows of short spinules, becoming longer towards distal edge ( Fig. 8 J–L).

Abdomen: Setose, oval, dorsal sigilla not evident; 8.0 long, 5.5 wide ( Fig. 8A ).

Variation (n=2): Carapace 7.4–6.1 long, 5.4–6.7 wide, no labial cuspules. Spination: invariable.

Etymology. The specific name is taken from the Latin bellus (meaning ‘beautiful’) and refers to the distinctively patterned abdomen.

Distribution. Blakistonia bella is known only from inland South Australia, at Johnson’s Bore, south-west of Lake Eyre, and Strangways Springs, on Stuart Creek Station ( Fig. 31 ).

Remarks. Both specimens of this species were collected in pitfall traps during the ‘Stony Deserts Biological Survey’, conducted between 1994 and 1997 ( Brandle 1998). The male holotype was collected in a tree-lined drainage channel in October, unusually late in the year for male Blakistonia to be out searching for females.

Figures

FIGURE 8. Blakistonia bella sp. n., holotype male (SAM NN20063): 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, clasping spur, prolateral view; I, left leg I, ventral view; J, left pedipalp, prolateral view; K, left pedipalp, retrolateral view; L, left pedipalp, proventral view. Scale bars = 5 mm (A), 2 mm (G, J).

FIGURE 31. Distributions of Blakistonia species: B. bassi sp. n. (black circle), B. hortoni sp. n. (white squares), B. bella sp. n. (white circles), and B. gemmelli sp. n. (black square).