Idiosoma jarrah Rix & Harvey

Rix, Michael G., Huey, Joel A., Cooper, Steven J. B., Austin, Andrew D. & Harvey, Mark S., 2018, Conservation systematics of the shield-backed trapdoor spiders of the nigrum-group (Mygalomorphae, Idiopidae, Idiosoma): integrative taxonomy reveals a diverse and threatened fauna from south-western Australia, ZooKeys 756, pp. 1-121 : 44-46

Idiosoma jarrah Rix & Harvey sp. n. Figs 7, 22, 23, 25, 228-237, 238-240, 241-249, 375

Type material.

Holotype male. Lesmurdie, 42 Wheelwright Road (IBRA_JAF), Western Australia, Australia, 32°00'20"S, 116°02'59"E, walking in garden on overcast day, 13 June 2012, D. & R. Roberts (WAM T124143DNA_Voucher_124).

Paratype. 1 ♀, Lesmurdie, Armour Way (IBRA_JAF), Western Australia, Australia, 32°01'S, 116°03'E, inside house, 28 July 1996, J. Barkla (WAM T44390).

Other material examined.

AUSTRALIA: Western Australia: 1 ♀, Lesmurdie (IBRA_JAF), 32°01'S, 116°03'E, 1 November 1975, C. O’Neill (WAM T26108); 1 juvenile, off Albany Highway, just N. of Arthur River bridge (IBRA_JAF), 33°16'22"S, 117°00'54"E, hand collected, Allocasuarina forest, 4 October 2013, M.G. Rix, M.S. Harvey (WAM T131632DNA_Voucher_90); 1 ♂, SW. of Boddington, Worsley Alumina Overland Conveyor Belt, conveyor #1, line stand 5527 (IBRA_JAF), 33°02'S, 116°16'E, 29 June 2006, J. Hynes (WAM T99952DNA_Voucher_131); 1 ♂, SW. of Boddington, Worsley Alumina , near Lower Hotham Road, Overland Conveyor Belt #1, line stand 900 (IBRA_JAF), 32°57'S, 116°25'E, hand collected, Jan–November 2005, J. Hynes (WAM T74623); 1 ♀, Boya (IBRA_JAF), 31°54'56"S, 116°03'23"E, 24 November 1979, L. Webb (WAM T26821); 1 ♂, Bullsbrook (IBRA_SWA), 31°40'S, 116°02'E, 1 June 2001, B. Leslie (WAM T44228); 1 ♂, Bullsbrook, Smith Road (IBRA_JAF), 31°39'S, 116°06'E, 31 July 2015, T. Solig (WAM T136943DNA_Voucher_NCB_002); 1 ♂, Darlington (IBRA_JAF), 31°55'S, 116°04'E, 15 June 1986, M. McNab (WAM T26822); 1 ♀, same locality data except 260 Ryecroft Road, 31°55'18"S, 116°05'05"E, 31 July 2015, T. Rudas (WAM T136937); 1 ♂, Glen Forrest (IBRA_JAF), 31°54'50"S, 116°06'05"E, 4 July 1976, S.M. Postmus (WAM T26125); 1 ♂, Gooseberry Hill (IBRA_JAF), 31°58'S, 116°03'E, 14 July 1980, P. Kleins (WAM T139475); 1 ♀, same locality data except 31°57'20"S, 116°02'52"E, 15 January 1974, V.R. McDonald (WAM T18585); 1 ♀, same locality data except 3 Rich Road, 31°57'S, 116°03'E, 28 May 1998, C. Loos (WAM T44389); 1 ♀, Kalamunda (IBRA_JAF), 31°58'30"S, 116°03'25"E, 28 September 1959, M. Morton (WAM T26824); 1 ♀, same locality data, 12 August 1974, G.H. Lucas (WAM T26825); 1 ♀, Kelmscott (IBRA_SWA), 32°07'S, 116°01'E, 1 February 1977, J. Evans (WAM T26827); 1 ♀, Midland Junction (IBRA_SWA), 31°53'S, 115°59'E, 25 July 1928, Mr Marshall (WAM T1982); 1 ♂, Mount Cooke (IBRA_JAF), 32°25'S, 116°18'E, pitfall trap, 15 May– 16 June 1991, M.S. Harvey, J.M. Waldock (WAM T26111); 1 ♂, Mount Helena (IBRA_JAF), 31°53'S, 116°12'E, 1 June 1999, K. Simmons (WAM T40601DNA_Voucher_129); 1 ♂, same locality data except 5 Treetop Way, 31°52'S, 116°13'E, 23 May 2005, T. Warda (WAM T63354); 1 ♂, Mount Nasura, 12 Westview Close (IBRA_JAF), 32°08'18"S, 116°01'50"E, 3 August 2006, C. & F. Motas (WAM T77021); 1 ♂, Mundaring (IBRA_JAF), 31°53'44"S, 116°10'11"E, 4 July 1972, N. Giles (WAM T26830); 1 ♀, same locality data except Primary School, 31°54'S, 116°10'E, 12 September 2000, C. Sander (WAM T42205); 1 ♂, Mundaring Weir Road, Kalamunda (IBRA_JAF), 31°58'30"S, 116°03'25"E, hand collected, 27 June 1976, K.L. Morrison (WAM T18582); 1 juvenile, Red Hill Valley, site 6 (IBRA_JAF), 31°51'S, 116°06'E, 22 June 1967, L.E. Koch, L.N. McKenna (WAM T28385); 1 ♂, Roleystone (IBRA_JAF), 32°06'51"S, 116°04'21"E, hand collected, 5 June 1984, A. Wright (WAM T18583); 1 ♀, same data except 6 August 1983, R. Herdsman (WAM T18586); 1 ♀, same data except 6 June 1987, R.E. Alexander (WAM T18587); 1 ♂, same locality data except 32°06'S, 116°04'E, 7 May 1977, D. Edward (WAM T139474); 1 ♂, Sawyers Valley (IBRA_JAF), 31°53'55"S, 116°12'05"E, hand collected, 8 September 1975, D. Parkinson (WAM T18584); 1 ♂, Stoneville (IBRA_JAF), 31°53'S, 116°10'E, 27 June 1999, K.W. Thomas (WAM T40632DNA_Voucher_130); 1 ♀, same locality data except 31°52'43"S, 116°10'03"E, 3 June 1982, L. Bosworth (WAM T26829); 1 ♂, Talbot Road Reserve, site TR3 (IBRA_SWA), 31°52'25"S, 116°03'03"E, wet pitfall trap, 24 June– 28 July 1993, M.S. Harvey, J.M. Waldock (WAM T30019); 1 ♂, same data except site TR4, 31°52'23"S, 116°02'46"E (WAM T30020); 1 ♀, Walyunga National Park (IBRA_JAF), 31°44'S, 116°05'E, 17 April 1986, J. Wheeler (WAM T21181); 1 ♀, same data except 22 April 1986, K. Huskin (WAM T26831); 1 ♀, same data (WAM T26832); 1 juvenile, same data (WAM T26833); 1 juvenile, same data (WAM T26834); 1 juvenile, same data (WAM T26835); 1 juvenile, same data (WAM T26836); 1 juvenile, same data (WAM T26837); 1 juvenile, same data (WAM T26838); 1 juvenile, same data (WAM T26839); 1 juvenile, same data (WAM T26840); 1 juvenile, same data (WAM T26841); 1 juvenile, same data (WAM T26842); 1 juvenile, same data (WAM T26843); 1 juvenile, same data (WAM T26844); 1 juvenile, same data (WAM T26845); 1 juvenile, same data (WAM T26846); 1 juvenile, same data (WAM T26847); 1 juvenile, same data (WAM T26848); 1 juvenile, same data (WAM T26849); 1 juvenile, same data (WAM T26850); 1 juvenile, same data (WAM T26851); 1 juvenile, same data (WAM T26852); 1 juvenile, same data (WAM T26853); 1 juvenile, same data (WAM T26854); 1 ♂, West Midland (IBRA_SWA), 31°53'S, 116°00'E, August 1949, E. Clough (WAM T139473); 1 ♀, Whistlepipe Gully, Forrestfield (IBRA_SWA), 31°59'S, 116°01'E, 1 July 1965, W. Greenham (WAM T26823).

Etymology.

The specific epithet is a noun in apposition, in reference to the Jarrah Forest bioregion in which this species occurs.

Diagnosis.

Idiosoma jarrah is one of nine south-western Australian species in the intermedium- and sigillatum-clades which does not belong to the distinctive 'sigillate complex’ (Fig. 25); these nine species can be distinguished from those 'sigillate complex’ taxa (i.e., I. arenaceum , I. clypeatum , I. dandaragan , I. kopejtkaorum , I. kwongan , I. nigrum and I. schoknechtorum ) by the absence of well-defined lateral sclerotic strips on the male abdomen (e.g., Figs 151, 212, 234), and by the significantly less sclerotised morphology of the female abdomen (which may be strongly corrugate but never leathery and ‘shield-like’) (e.g., Figs 4, 7, 8, 159, 220, 242). Males of I. jarrah can be further distinguished from those of I. gutharuka and I. incomptum by the presence of enlarged (i.e., clearly visible) SP4 sclerites (Fig. 234; cf. Figs 186, 199); from I. formosum , I. gardneri , I. intermedium , I. mcnamarai and I. sigillatum by the colour of the legs, which are bi-coloured with strongly contrasting bright yellow or orange-yellow femora (Fig. 235; cf. Figs 152, 174, 213, 314, 358); and from I. mcclementsorum by the size of the SP3 sclerites, which are relatively small (Fig. 234; cf. Fig. 291), and by the size of the SP4 sclerites, which are weakly sclerotised spots (Fig. 234; cf. Fig. 291).

Females can be distinguished from those of I. mcclementsorum and I. sigillatum by the absence of reinforced, sclerotised ridges on the abdomen (Figs 220, 223; cf. Figs 299, 302, 365, 368); from I. formosum and I. mcnamarai by the size of the SP4 sclerites, which are not significantly larger than the SP2 sclerites (Fig. 245; cf. Figs 162, 324); and from I. intermedium by the slightly smaller size of the SP3 and SP4 sclerites (Fig. 245; cf. Fig. 223) [NB. females of I. gardneri , I. gutharuka and I. incomptum are unknown].

This species can also be distinguished from I. corrugatum (from the Eyre Peninsula of South Australia) by the shape of the prolateral clasping spurs on the male tibia I, which are oriented longitudinally (Fig. 236; cf. Fig. 109), and by the shape of the female eye group, which is broadly trapezoidal (Fig. 244; cf. Fig. 117).

Description (male holotype).

Total length 18.7. Carapace 8.3 long, 6.5 wide. Abdomen 8.3 long, 5.4 wide. Carapace (Fig. 228) dark tan and chocolate-brown, with darker ocular region; lateral margins with uniformly-spaced fringe of porrect black setae; fovea procurved. Eye group (Fig. 231) trapezoidal (anterior eye row strongly procurved), 0.7 × as long as wide, PLE–PLE/ALE–ALE ratio 2.1; ALE almost contiguous; AME separated by less than their own diameter; PME separated by 3.3 × their own diameter; PME and PLE separated by slightly more than diameter of PME, PME positioned in line with level of PLE. Maxillae with field of small cuspules confined to inner corner; labium without cuspules. Abdomen (Figs 229, 234) oval, charcoal-brown in dorsal view with tan mottling and assortment of stiff, porrect black setae, each with slightly raised, dark brown sclerotic base. Posterior abdomen weakly sigillate (Figs 229, 234); SP2 sclerites comma-shaped spots; SP3 sclerites subcircular with irregular margins, each surrounded by pad of unsclerotised cuticle; SP4 sclerites oval, each surrounded by chevron-like pad of unsclerotised cuticle laterally; SP5 obscured. Legs (Figs 235-237) bicoloured, variable shades of dark brown on patellae, tibiae, metatarsi and tarsi, and bright beige-tan on femora, with light scopulae on tarsi I–II; distal tibia I with pair of large prolateral clasping spurs oriented longitudinally. Leg I: femur 7.7; patella 3.8; tibia 5.4; metatarsus 6.4; tarsus 3.5; total 26.8. Leg I femur–tarsus /carapace length ratio 3.2. Pedipalpal tibia (Figs 238-240) 2.3 × longer than wide; RTA burr-like, with conical basal protuberance and field of retroventral spinules; digital process porrect, unmodified. Cymbium (Figs 238-240) setose, with field of spinules disto-dorsally. Embolus (Figs 238-240) broadly twisted and sharply tapering distally (broken at tip), with prominent longitudinal flange and very small triangular (sub-distal) embolic apophysis.

Description (female WAM T44390).

Total length 31.2. Carapace 12.7 long, 8.9 wide. Abdomen 14.6 long, 13.5 wide. Carapace (Fig. 241) dark tan and chocolate-brown, with darker ocular region; fovea procurved. Eye group (Fig. 244) trapezoidal (anterior eye row strongly procurved), 0.6 × as long as wide, PLE–PLE/ALE–ALE ratio 2.3; ALE almost contiguous; AME separated by approximately their own diameter; PME separated by 3.3 × their own diameter; PME and PLE separated by more than diameter of PME, PME positioned in line with level of PLE. Maxillae with field of cuspules confined to inner corner (Fig. 246); labium without cuspules. Abdomen (Figs 242, 245) broadly oval, dark brown in dorsal view with tan mottling. Posterior abdomen weakly sigillate (Figs 242, 245); SP2 sclerites irregular, comma-shaped spots; SP3 sclerites subcircular with irregular margins, each surrounded by broad pad of unsclerotised cuticle; SP4 sclerites oval, each surrounded by chevron-like pad of unsclerotised cuticle laterally; SP5 obscured. Legs (Figs 247-248) variable shades of dark tan; scopulae present on tarsi and metatarsi I–II; tibia I with one stout pro-distal macroseta and row of five longer retroventral macrosetae; metatarsus I with six stout macrosetae; tarsus I with distal cluster of short macrosetae. Leg I: femur 7.3; patella 4.6; tibia 4.6; metatarsus 3.7; tarsus 2.7; total 22.9. Leg I femur–tarsus /carapace length ratio 1.8. Pedipalp dark tan, spinose on tibia and tarsus, with thick tarsal scopula. Genitalia (Fig. 249) with pair of short, obliquely angled spermathecae, each bearing dense field of glandular vesicles distally, and more sparsely distributed glandular field sub-distally.

Distribution and remarks.

Idiosoma jarrah (formerly known by WAM identification code ‘MYG156’) (Fig. 7), a member of the yellow legs-clade within the diverse sigillatum-clade (Fig. 25), is endemic to south-western Australia’s Jarrah Forest bioregion, where it occurs widely in mixed jarrah ( Eucalyptus marginata ) and marri ( Corymbia calophylla ) forest on and east of the Darling Escarpment, from Bullsbrook south to at least Boddington and Arthur River (Fig. 375). North of the Avon Valley it is replaced by its closely related sister species I. mcclementsorum , both of which are characterised by yellow leg femora in males (Figs 235, 292). Like I. formosum , I. intermedium , and I. mcnamarai , I. jarrah exhibits a transitional morphology between largely unmodified species in the intermedium-clade (i.e. I. incomptum and I. gutharuka ), and the more obviously phragmotic taxa in the clypeatum- and sigillatum-clades. Burrows of this species are adorned with a ‘moustache-like’ arrangement of twig-lines (Figs 22, 23), and often occur under Casuarina or Allocasuarina , the leaves of which are used as twig-lines. Like I. sigillatum (see below), most males have been collected wandering in search of females during May–July (82% of n = 17), with a sudden onset of activity in May (with the first winter rains) and a peak of activity in June.

Conservation assessment.

Idiosoma jarrah has a known extent of occurrence (EOO) of nearly 4,000 km2 [3,907 km2], although this value is likely to be an underestimate due to the paucity of records throughout the south of its range. The area of occupancy within that range is similarly difficult to estimate, although is likely to be quite high as a proportion of EOO due to the amount of forest still present throughout most of its range. As such, we do not currently consider this species to be of conservation concern.