Blakistonia plata, 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 : 59-60

Blakistonia plata , sp. n.

( Fig. 24 A–L)

Type material. AUSTRALIA: Queensland: Holotype male, Texas , 28°52’0.01”S, 151°10’0.12”E, 24 November 1996, found in tree clearing, T.B. Churchill (QMB S48356).

Diagnosis. Males of B. plata 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. 24 G–I); from those of B. parva , B. olea , B. tariae , B. carnarvon and B. raveni by the presence of one, rather than two, prolateral macroseta on tibia I ( Fig. 24 G–I); from those of B. maryae , B. hortoni and B. newtoni by a subquadrate eye group ( Fig. 24D ); and from those of B. birksi by the absence of cuspules on the maxillae ( Fig. 24F ) and by the absence of a strongly patterned abdomen ( Fig. 24A ). Females are unknown.

Description. Holotype male (QMB S48356). Small idiopid spider (total length 9.3).

Colour (in ethanol; Fig. 24 A–C): Carapace very pale yellow-brown, darker around caput ( Fig. 24A ); sternum pale yellow, darker towards anterior and lateral margins; labium and maxillae pale yellow, chelicerae pale orangebrown ( Fig. 24E, F ); abdomen pale yellow-brown with only a faint chevron pattern towards anterior end ( Fig. 24A, C ); legs and pedipalp very pale yellow-brown ( Fig. 24 G–L).

Cephalothorax: Carapace 4.0 long, 3.5 wide, 3.1 high, 1.1 times longer than wide; oval ( Fig. 24A ), caput low, ocular area raised ( Fig. 24C ); cuticle smooth, with pits outward from fovea and both sides of caput; fovea straight; row of setae between fovea and eye group; carapace very sparsely setose, with indistinct lines of setae radiating outwards from fovea, concentrated and form fringe on lateral margins; median clump of thickened setae on clypeus ( Fig. 24D ). Length of median clypeus less than 1.0; anterior margin slightly convex. Eye group 0.9 wide, 2.2 long, 0.3 of carapace width; anterior eye row strongly procurved, PLE–PLE/ALE–ALE ratio 1.0; posterior eye row straight; AME equal in size to ALE and separated by less than the diameter of AME/ALE; PLE two-thirds of ALE and separated by about ALE diameter; PME pale, just over half the size of PLE, and separated from PLE by less than its own diameter ( Fig. 24D ). Labium without cuspules ( Fig. 24F ). Sternum 2.2 long, 1.6 wide, evenly setose; sigilla indistinct ( Fig. 24E ). Maxillae without cuspules ( Fig. 24E, F ).

Legs: diffusely setose and spinose on all surfaces, more setose on ventral tibiae, metatarsi and tarsi III, IV; tarsi I, II slightly ventrally swollen; tarsi I, II weakly scopulate ( Fig. 24 G–I). Paired tarsal claws: right leg I p5 (4 large, 1 small) r6 (3 large, 3 small); right leg II p4 (3 large, 1 small), r4 (2 large, 2 small); right leg III p3 (2 large, 1 small), r4 (2 large, 2 small); right leg IV p5 (3 large, 2 small, r5 2 (3 large, 2 small).

Spination: Tibia I with single prolateral macroseta ( Fig. 24 G–I). All legs diffusely setose and spinose, without clear demarcation between lanceolate setae and smaller spine-like setae.

Leg and pedipalp measurements: Length of legs IV> I> II> III. Leg I: femur 4.2, patella 2.1, tibia 3.2, metatarsus 4.5, tarsus 1.7, total = 15.7. Leg II: femur 4.0, patella 2.0, tibia 2.9, metatarsus 4.5, tarsus 1.7, total = 15.7. Leg III: femur 3.4, patella 1.7, tibia 2.3, metatarsus 2.8, tarsus 1.7, total = 11.9. Leg IV: femur 4.4, patella 1.9, tibia 4.1, metatarsus 4.7, tarsus 2.1, total = 17.2. Pedipalp: femur 2.1, patella 1.2, tibia 1.9, tarsus 0.9, total = 6.1.

Pedipalp: Femur with dorsal spines, patella with thickened ventral setae; tibia very short and swollen, RTA short and very pointed, covered in short, dense spinules for ca. half distance between base of apophysis and distal tibia, becoming more sparse towards distal tibia; long, erect setae on ventral tibia; bulb uniform, globular; embolus simple, slender, tapering, tip slightly twisted, just over the length of bulb; cymbium covered in rows of spinules of moderate length, becoming longer and denser towards distal edge ( Fig. 24 J–L).

Abdomen: Abdomen setose, oval, dorsal sigilla not evident; 5.3 long, 3.4 wide ( Fig. 24A ).

Variation: None.

Etymology. The specific name is taken from the Latin plata (meaning ‘silver’), in reference to the silver mining industry in Texas, Queensland.

Distribution. Blakistonia plata is known only from Texas, in south-eastern Queensland ( Fig. 34 ).

Remarks. This male specimen was found in a tree clearing.

Figures

FIGURE 24. Blakistonia plata sp. n., holotype male (QMB S48356): 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, right leg I, macroseta, 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 = 2 mm (A, G), 1 mm (J).

FIGURE 34. Distribution of Blakistonia species: B. emmottorum sp. n. (black square), B. raveni sp. n. (black triangle), B. carnarvon sp. n. (black circle), and B. plata sp. n. (white circle).