Blakistonia hortoni, 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 : 40-42

Blakistonia hortoni , sp. n.

( Fig. 14 A–L)

Type material. AUSTRALIA: South Australia: Holotype male, Mount Crawford Forest Reserve, Mount Lofty Ranges , 34°42’S, 138°58’E, 27 May–9 September 1988, pitfall, R. Tuckwell (SAM NN20090 ). Paratypes: 8 males, same data ( SAM NN20089 , NN20091 , NN20092 , NN20095 , NN20100 , NN20101 , NN20102 , NN20103 ) .

Other material examined. AUSTRALIA: South Australia: 1 male, Padthaway Conservation Park , 36°36’S, 140°31’E, May 1982, pitfall, B. Guerin (SAM NN20076 ).

Diagnosis. Males of B. hortoni can be distinguished from B. bella , B. pidax , B. tunstilli , B. emmottorum , B. gemmelli , and B. aurea by the absence of prolateral clasping spurs on tibia I ( Fig. 14 G–I); from 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. 14 G–I); from those of B. birksi and B. plata by the square eye group ( Fig. 14D ); and from those of B. newtoni and B. maryae by the field of spinules on the palpal tibia being broad and not in a rounded crescentshape ( Fig. 14J ). Females are unknown.

Description. Holotype male (SAM NN20090). Medium idiopid spider (total length 10.0).

Colour (in ethanol; Fig. 14 A–C): Carapace uniform pale golden orange-brown ( Fig. 14A ); sternum, labium and maxillae very similar, chelicerae slightly darker red-brown ( Fig. 14E, F ); abdomen same golden orange-brown with pattern of seven mottled chevrons, dark, with darker mottling also between chevrons ( Fig. 14A, C ); legs and pedipalp same colour as cephalothorax ( Fig. 14 G–L).

Cephalothorax: Carapace 4.9 long, 3.9 wide, 3.3 high, 1.3 times longer than wide; oval ( Fig. 14A ), caput moderately raised, ocular area raised ( Fig. 14C ); cuticle smooth, with pits outward from fovea and both sides of caput; fovea straight; row of thick setae between fovea and eye group; carapace quite setose, with smaller fine setae distributed evenly across carapace, concentrated and forming fringe around lateral margins; clump of thickened setae on clypeus ( Fig. 14D ). Length of median clypeus less than 1.0; anterior margin slightly convex. Eye group 0.9 wide, 0.8 long, 0.2 of carapace width; anterior eye row strongly procurved, PLE–APLE/ALE–ALE ratio 1.0; posterior eye row slightly procurved; AME approximately half the size of ALE and separated by about the diameter of AME; ALE and PLE separated by about twice the diameter of PLE; PME pale, similar in size to AME and about two-thirds size of PLE, and separated from PLE by about its own diameter ( Fig. 14D ). Labium with 5 cuspules ( Fig. 14F ). Sternum 2.8 long, 2.1 wide, evenly setose ( Fig. 14E ). Maxillae with ca. 20 cuspules on both sides ( Fig. 14E, F ).

Legs: setose and spinose; tarsi I, II ventrally swollen; tarsi and distal metatarsi I, II weakly scopulate ( Fig. 14 G–I). Paired tarsal claws: leg I p7 (7 large) r6 (6 large); leg II p6 (6 large), r6 (6 large); leg III p6 (2 large, 4 small), r4 (1 large, 3 small); leg IV p5 (2 large, 3 small), r5 (2 large, 3 small).

Spination: Tibia I with single prolateral macroseta ( Fig. 14 G–I). All other legs heavily setose and 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 4.6, patella 2.3, tibia 3.3, metatarsus 3.3, tarsus 2.1, total = 15.6. Leg II: femur 4.4, patella 2.0, tibia 3.2, metatarsus 3.4, tarsus 2.1, total = 15.1. Leg III: femur 3.6, patella 1.8, tibia 2.6, metatarsus 3.2, tarsus 2.2, total = 13.4. Leg IV: femur 4.4, patella 2.2, tibia 4.5, metatarsus 4.4, tarsus 2.6, total = 18.1. Pedipalp: femur 2.7, patella 1.3, tibia 2.5, tarsus 1.1, total = 7.6.

Pedipalp: Patella with thickened ventral setae; tibia short and swollen, RTA short, pointed, with thick clump of setae on tip, and covered in short, dense spinules for two-thirds distance between base of apophysis and distal tibia, becoming only slightly sparser towards distal dibia; long, erect setae on ventral tibia; bulb uniform, globular; embolus simple, slender, tapering, tip slightly twisted, just under twice the length of bulb; cymbium covered in rows of short spinules, becoming longer closer to distal edge ( Fig. 14 J–L).

Abdomen: Setose, oval, dorsal sigilla not evident; 5.1 long, 3.2 wide ( Fig. 14A ).

Variation (n=10): Carapace 3.0–5.0 long, 3.0–3.3 wide, 5 labial cuspules.

Etymology. This species is named in honour of Benjamin Horton, for his commitment to wildlife education and conservation, and for his efforts in saving the lives of countless animals during the Sampson Flat bushfires of 2015.

Distribution. Blakistonia hortoni is known only from Mount Crawford Conservation Park and Padthaway Conservation Park in the Mount Lofty Ranges ( Fig. 31 ).

Remarks. Further specimens of this species, including females, could not be located at the type locality by one of the authors (SEH). Mount Crawford is now mostly covered in plantation forests and is quite sandy, which is an unusual habitat for Blakistonia . Blakistonia aurea is also found in roadside banks just outside the forest reserve, but has not been found within the reserve itself.

Figures

FIGURE 14. Blakistonia hortoni sp. n., holotype male (SAM NN20090): 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, 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, 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).