Idiosoma kopejtkaorum 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 : 47-51

Idiosoma kopejtkaorum Rix & Harvey sp. n. Figs 9, 21, 250-259, 260-262, 263-271, 374

Idiosoma ‘nigrum’ Main, 1957b: 440 (in part; cited specimens from NE. of Rabbit Proof Fence and N. of Mt Gibson turnoff).

Type material.

Holotype male. Snake Gully Nature Reserve, site WU11 (IBRA_AVW), Western Australia, Australia, 30°13'05"S, 116°56'36"E, wet pitfall traps, 15 September 1997-7 April 1998, N. Guthrie, CALM Survey (WAM T144621).

Paratypes. 1 ♂, same data as holotype (WAM T139498); 1 ♂, same data (WAM T139499).

Other material examined.

AUSTRALIA: Western Australia: 1 juvenile, Buntine Nature Reserve (IBRA_AVW), 29°59'58"S, 116°38'06"E, 6 January 2010, B. Durrant (WAM T108518DNA_Voucher_147); 1 ♀, Charles Darwin Nature Reserve (IBRA_AVW), 29°39'44"S, 117°07'15"E, 14 January 2010, B. Durrant (WAM T108519DNA_Voucher_144); 1 ♀, same locality data except 29°33'28"S, 117°01'28"E, 4 May 2016, K. Gruber, D. Schoknecht, J.A. Huey, M.S. Harvey (WAM T140751DNA_Voucher_NCB_003); 1 ♀, E. of Coorow (IBRA_AVW), 29°52'05"S, 116°09'07"E, 29 May 2008, F. Falconer (WAM T56344); 1 ♀, NE. of Goodlands (IBRA_AVW), 30°07'S, 117°10'E, 4 June 1984, B.Y. Main (WAM T144625); 1 ♂, Lake Goorly, north-west, site WU9 (IBRA_AVW), 29°49'50"S, 116°57'19"E, wet pitfall traps, 15 September 1998-25 October 1999, L. King, CALM Survey (WAM T139497); 1 ♀, Maya Nature Reserve (IBRA_AVW), 29°49'24"S, 116°31'48"E, 7 January 2010, B. Durrant (WAM T108523DNA_Voucher_145); 1 ♀, Mummaloo, ca. 72 km NE. of Wubin (IBRA_AVW), 29°40'18"S, 117°10'59"E, 13 August 2012, M.K. Curran, S.R. Bennett (WAM T126455DNA_Voucher_NCB_019); 1 juvenile, same data except 29°38'17"S, 117°09'05"E, 7 August 2012 (WAM T126451); 1 juvenile, same data except 29°38'46"S, 117°10'17"E, 8 August 2012 (WAM T126452); 1 ♀, same data except ca. 75 km NE. of Wubin, 29°38'17"S, 117°13'52"E, 4 July 2012 (WAM T125765DNA_Voucher_143); 1 ♀, same data except ca. 76 km NE. of Wubin, 29°40'20"S, 117°14'27"E, 10 August 2012 (WAM T126453); 1 ♀, same data except 29°41'07"S, 117°16'04"E, 9 August 2012 (WAM T126454); 1 juvenile, same data except ca. 58 km NE. of Wubin, 29°46'04"S, 117°04'39"E, 16 August 2012 (WAM T126457); 1 juvenile, same data except 29°48'20"S, 117°07'24"E (WAM T126456); 1 juvenile, same data except ca. 65 km NE. of Wubin, 29°41'03"S, 117°06'12"E (WAM T126458); 1 ♀, 17 miles NE. of Rabbit Proof Fence no. 2, 32 miles NE. of Wubin (IBRA_AVW), 29°47'S, 117°01'E, 4 September 1955, B.Y. Main (WAM T144795); 1 juvenile, same data (WAM T144796); 1 ♀, 39 miles NE. of Rabbit Proof Fence, 5 miles N. of Mt Gibson turnoff (IBRA_AVW), 29°35'S, 117°07'E, 4 September 1955, B.Y. Main (WAM T144797).

Etymology.

The specific epithet is named in honour of Paul and Karen Kopejtka, in recognition of their generous support for the Western Australian Museum Foundation.

Diagnosis.

Idiosoma kopejtkaorum is one of seven highly autapomorphic species in the polyphyletic 'sigillate complex’ (Fig. 25); members of this complex can be distin guished from all other species in the nigrum-group from south-western Australia (i.e., I. formosum , I. gardneri , I. gutharuka , I. incomptum , I. intermedium , I. jarrah , I. mcclementsorum , I. mcnamarai and I. sigillatum ) by the presence of well-defined lateral sclerotic strips on the male abdomen (e.g., Figs 32, 63, 256), and by the very heavily sclerotised, leathery, ‘shield-like’ morphology of the female abdomen (e.g., Figs 1-3, 9-12, 52, 74, 96). Males of I. kopejtkaorum can be further distinguished from those of I. arenaceum by the shape of the SP4 sclerites, which are not elongate-oval (Fig. 256; cf. Fig. 63); from I. kwongan by the absence of semi-circular lateral indentations adjacent to the SP4 sclerites (Fig. 256; cf. Fig. 278, Key pane 13.1); from I. dandaragan , I. nigrum and I. schoknechtorum by the absence of a prominent sub-distal embolic apophysis (Key pane 14.2; cf. Key pane 14.1); and from I. clypeatum by the less heavily setose morphology of metatarsus I (Fig. 257, Key pane 16.2; cf. Fig. 86, Key pane 16.1).

Females can be distinguished from those of I. arenaceum by the shape of the SP4 sclerites, which are not elongate-oval (Fig. 267, Key pane 22.1; cf. Fig. 74, Key pane 21.1); and from I. dandaragan , I. nigrum and I. schoknechtorum by the size of the SP4 sclerites, which are approximately half the size of the SP3 sclerites (Fig. 267, Key pane 22.1; cf. Figs 43, 52, 140, 346, Key panes 23.1-23.3) [NB. females of I. kwongan are unknown]. By our assessment, females of I. kopejtkaorum are morphologically indistinguishable from those of I. clypeatum ; males, molecular data (Fig. 25) or geographic distribution (Fig. 374) are required for accurate identification.

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. 258; cf. Fig. 109), and by the shape of the female eye group, which is broadly trapezoidal (Fig. 266; cf. Fig. 117).

Description (male holotype).

Total length 14.1. Carapace 5.9 long, 4.4 wide. Abdomen 7.2 long, 5.6 wide. Carapace (Fig. 250) dark tan and chocolate-brown, with darker ocular region; lateral margins with uniformly-spaced fringe of porrect black setae; fovea procurved. Eye group (Fig. 253) trapezoidal (anterior eye row strongly procurved), 0.7 × as long as wide, PLE–PLE/ALE–ALE ratio 1.9; ALE almost contiguous; AME separated by less than their own diameter; PME separated by 2.6 × their own diameter; PME and PLE separated by slightly more than diameter of PME, PME positioned slightly posterior to level of PLE. Maxillae with field of small cuspules confined to inner corner; labium without cuspules. Abdomen (Figs 251, 256) broadly oval, light beige-brown in dorsal view with lateral sclerotic strips, dorso-lateral corrugations, and scattered dorsal sclerotic spots. Dorsal surface of abdomen (Fig. 251) more heavily setose anteriorly, with assortment of stiff, porrect black setae, each with slightly raised, dark brown sclerotic base. Posterior abdomen strongly sigillate (Figs 251, 256); SP2 sclerites comma-shaped spots; SP3 sclerites very large and circular; SP4 sclerites broadly oval; SP5 obscured. Legs (Figs 257-259) variable shades of dark tan, with light scopulae on tarsi I–II; distal tibia I with pair of large prolateral clasping spurs oriented longitudinally. Leg I: femur 5.8; patella 2.9; tibia 4.1; metatarsus 4.1; tarsus 2.4; total 19.3. Leg I femur–tarsus /carapace length ratio 3.2. Pedipalpal tibia (Figs 260-262) 2.4 × longer than wide; RTA burr-like, with conical basal protuberance and field of retroventral spi nules; digital process porrect, unmodified. Cymbium (Figs 260-262) setose, with field of spinules disto-dorsally. Embolus (Figs 260-262) broadly twisted and sharply tapering distally, with prominent longitudinal flange; embolic apophysis absent.

Description (female WAM T108519).

Total length 25.4. Carapace 9.1 long, 6.6 wide. Abdomen 12.4 long, 11.7 wide. Carapace (Fig. 263) dark tan, with darker ocular region; fovea procurved. Eye group (Fig. 266) trapezoidal (anterior eye row strongly procurved), 0.6 × as long as wide, PLE–PLE/ALE–ALE ratio 2.2; ALE almost contiguous; AME separated by approximately their own diameter; PME separated by 3.4 × 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. 268); labium without cuspules. Abdomen (Figs 264, 267) dark brown-black, corrugate and highly sclerotised, with leathery appearance typical of those species in the 'sigillate complex’ (see Fig. 25). Posterior face of abdomen (Fig. 267, Key pane 22.1) with truncate ‘shield-like’ morphology; SP3 sclerites very large and circular; SP4 sclerites broadly oval; SP5 obscured by thickened cuticle. Legs (Figs 269-270) variable shades of dark tan; scopulae present on tarsi and metatarsi I–II; tibia I with one stout pro-distal macroseta and row of six longer retroventral macrosetae; metatarsus I with 9 stout macrosetae; tarsus I with distal cluster of short macrosetae. Leg I: femur 5.4; patella 3.4; tibia 3.3; metatarsus 2.7; tarsus 1.9; total 16.7. Leg I femur–tarsus /carapace length ratio 1.8. Pedipalp dark tan, spinose on tibia and tarsus, with thick tarsal scopula. Genitalia (Fig. 271) 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 kopejtkaorum (formerly known by WAM identification code ‘MYG521’) (Fig. 9), a 'sigillate complex’ member of the northern clypeatum-clade (Fig. 25), is restricted to the north-eastern Wheatbelt bioregion of south-western Western Australia, in a relatively small area surrounding Lake Goorly (Fig. 374). It extends from Charles Darwin Nature Reserve, Mount Gibson, and Mummaloo-Wyebubba Hill in the north, south-west to near Coorow, and south to near Goodlands and the Maya, Buntine and Snake Gully Nature Reserves, all north of Dalwallinu. South of Dalwallinu it is replaced by I. nigrum , to the west it is replaced by I. dandaragan , and to the north it is replaced by I. clypeatum ; all four species have a strongly sigillate (sclerotised) abdominal morphology. This distribution seems to be strongly correlated with annual rainfall of 250-300 mm, and red clay soils in the Lake Goorly and southern Lake Moore catchments.

Although first collected by Barbara Main near Mount Gibson in the 1950s, and subsequently collected from a handful of nature reserves during the 'Salinity Action Plan Survey’ of the late 1990s ( Keighery 2004), this species came to prominence during environmental impact assessment surveys conducted in the resource-rich Mummaloo region in 2012. Although it was originally confused with I. nigrum , morphological and molecular data were concordant in evidencing two nigrum-group species in the Mummaloo/Mount Gibson area. Following detailed molecular analysis of a suite northern I. nigrum -like taxa, I. kopejtkaorum was designated the working code ‘MYG521’, to distinguish it from what is now known to be I. formosum . Under this code name, I. kopejtkaorum was also formally assessed in 2017 for threatened species listing under the Western Australian Wildlife Conservation Act 1950 (see below). Burrows of this species are adorned with a ‘moustache-like’ arrangement of twig-lines (Fig. 21), and males likely wander in search of females in winter.

Conservation assessment.

In 2017, Idiosoma kopejtkaorum was formally assessed and listed as Endangered (B1ab[iii] + B2ab[iii]) under the Western Australian Wildlife Conservation Act 1950 (approved 16 January 2018; see W. A. Government Gazette 2018); this assessment incorporated the latest taxonomic, geographic and genetic data summarised in the current study (with a number of additional records also identified subsequently). In the heavily cleared north-eastern Wheatbelt, the threats to the species are manifold (as they are for I. nigrum ; see above), and in the Mummaloo/Mount Gibson region to the west of Lake Moore, the species is (and will continue to be) at risk from mining and minerals resource development. It has a known extent of occurrence of nearly 4,000 km2 [3,571 km2], and an area of occupancy within that range of <500 km2. Further close assessment under both Criteria A and B will be crucial to the continued survival of this species.