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Males of M. tigrinus sp. nov. can be distinguished from all other Western Australian Maratus species by the combinations of its dorsal opisthosomal markings by which the lateral margins of dorsal opisthosoma are marked with a series of four to five transverse tracts of iridescent white to blue scales on each side, and by its genital structure by which the embolus of the pedipalp is narrow with a prominent outer ring terminating in two apices, and a short inner ring with pointed apex. The opisthosomal markings of the male resemble those of Maratus flavus Otto & Hill 2018, however, M. tigrinus can reliably be distinguished from M. flavus by its narrow palpal embolus (vs thickset in M. flavus) and by the absence of a serration or projection on the ventral edge of the outer apex of the embolus (vs present in M. flavus). Females of M. tigrinus can be distinguished from all other Western Australian Maratus species by the distinctive dark brown tracts of setae which mark the dorsal opisthosoma, and by the medial, longitudinal pale region of the dorsal opisthosoma.
Cephalothorax. Ocular quadrangle region of carapace dark brown and covered with dense mat of grey setae. Posterior slope of carapace light brown and marked with two longitudinal tracts of white setae which extend from posterior of margins of carapace towards the posteromedial margin of ocular quadrangle. Surface between white tracts covered with long, dark brown setae. Lateral slopes of carapace light brown and lightly covered with dark brown setae suffused with narrow, white tracts of setae which extend from rim of carapace towards ocular area. Medial thoracic tract absent. Clypeus with dense cover of long, white setae. Chelicerae black and glabrous. Coxae, labium, and endites pale and glabrous. Sternum dark brown with light covering of fine, white setae.
Opisthosoma. Dorsal opisthosoma densely covered with dark brown scales, cuticular surface bellow pale brown to yellow. Lateral margins of dorsal opisthosoma distinctively marked with a series of four to five transverse tracts of iridescent white to blue scales on each side, each of which are angled toward the median. Anterior margin of opisthosoma covered with a suffusion of dark brown and iridescent white to light blue scales which obscure the anterior-most lateral tracts. Stout, grey setae project anteriorly at the anterior margin of the opisthosoma. Ventral opisthosoma light brown to yellow with a quadrate dark brown marking situated posteriorly bordered by thin longitudinal tracts of dark brown setae. Ventral opisthosoma otherwise lightly covered with light brown and white setae. Spinnerets dark brown and enveloped by dark brown setae. Colular tuft of white setae absent.
Legs. Legs I and II subequal in length, legs III and IV longer, legs III by far longest. Legs uniformly light brown to yellow and covered in white setae, but femora of legs III bear a longitudinal tract of dark brown setae on the outer lateral surfaces. Spination of legs III and IV stronger than I and II.
Pedipalps. Pedipalp covered dorsally with long white setae. Relatively large male palpal bulb with retrolateral sperm duct loop, large, angular retrobasal tegular lobe, finger-like, distally serrated RTA with a projection at the tip. Embolic disc with anticlockwise coiled embolus (left pedipalp). Embolus narrow with prominent outer ring terminating in two apices, and short inner ring with pointed apex; heavily sclerotized cuticle on tegulum prolaterally below embolic disc.
Paratype female (REG NUMBER).
Cephalothorax. Cuticular surface of ocular quadrangle region dark brown, darker towards lateral and anterior margins surrounding each eye, and lightly covered with grey setae. Posterior and lateral slopes of carapace light brown and mostly glabrous. PME marginally closer to ALE than to PLE. Anterior eyes ringed with brown and white setae or scales. Long white setae project downwards from below AME forming triangular shape. Clypeus lightly covered with short, white setae. Chelicerae dark brown and glabrous. Coxae, endites, and labium dark brown, translucent and mostly glabrous. Sternum light brown with light covering of fine, white setae.
Opisthosoma. Opisthosoma light brown and distinctively marked with a series of dark brown tracts of setae by which the anterior ~1/3rd is marked with irregularly sized and spaced spots. Posterior ~2/3rds marked with four transverse sinuous tracts, the posterior-most of which are narrower and taller. Longitudinal, medial region of dorsal opisthosoma otherwise medially light brown and unmarked. Colular tuft of white setae situated above long, light brown spinnerets. Ventral opisthosoma uniformly light brown and covered with fine, white setae. Stout, black setae project anteriorly at the anterior margin of the opisthosoma.
Legs. Legs I and II subequal in length, legs III and IV longer, legs III longest. Each leg light cover of fine, black setae, integument below uniformly light brown. Spination of legs III and IV stronger than I and II. Pedipalps light brown with incomplete cover of short, black setae.
Epigynum. Epigynum with pair of large ovate fossae separated by septum. Ovate posterior spermatheca behind each fossa. Sclerotized ducts present anterior to each spermatheca.
Holotype male, Barrow Island [-20.729393°S, 115.472268°E, Western Australia, AUSTRALIA], 8 December 2016, J. Davies, suction sample (HBI N3095-22).
Other material examined. AUSTRALIA: Western Australia: 1 male, Barrow Island, Airport, 20°51'18.216''S, 115°24'41.947''E, 17 May 2017, M. Campos, suction sample (HBI N3951-22); 1 juv., Barrow Island, Airport, 20°51'51.602''S, 115°24'25.277''E, 22 May 2018, J. Davies, suction sample (HBI N6337-28); 1 juv., Barrow Island, Airport, 20°52'48.835''S, 115°23'19.795''E, 9 August 2019, F. Bokhari, vehicle vibration, (HBI N15903-7); 1 male, 1 juv., Barrow Island, Airport Beach, 20°52'07.846''S, 115°24'25.207''E, 19 February 2014, T. Ashcroft (HBI N14885-1); 1 male, Barrow Island, Butler Park, 20°49'02.176''S, 115°26'13.322''E, 24 January 2018, S. O'Connor, suction sample (HBI N5446-6); 1 male, Barrow Island, Butler Park, 20°49'10.157''S, 115°26'07.303''E, 5 August 2017, M. Campos, pitfall trap (HBI N4318-8); 1 male, Barrow Island, Butler Park, 20°49'22.936''S, 115°26'22.067''E, 14 August 2017, M. Campos, suction sample (HBI N4485-53); 1 male, Barrow Island, Construction and Operation Support Structure, outside hazardous materials yard, 20°47'54.468''S, 115°26'38.137''E, 28 February 2016, A. Williams, barrier trap (HBI N1486-9); 2 males, Barrow Island, Curtin University site ACC, 20°49'31.231''S, 115°26'40.877''E, 14–25 March 2014, N. Gunawardene, window trap (HBI N15667-1); 1 male, Barrow Island, Curtin University site CC2, 20°49'02.492''S, 115°26'23.982''E, 25 September 2006, S. Callan, suction sample (WAM T88864); 1 male, Barrow Island, Curtin University site N01a, 20°49'34.118''S, 115°26'43.858''E, 1 May 2007, S. Callan, suction sample (HBI N17962-1); 1 male, Barrow Island, Curtin University site N01b, 20°49'37.992''S, 115°26'39.6''E, 1 May 2007, S. Callan, suction sample (WAM T89136); 1 male, Barrow Island, Curtin University site N06b, 20°47'52.008''S, 115°25'55.92''E, 1 May 2007, S. Callan, suction sample (WAM T89154); 1 male, 1 female, Barrow Island, Curtin University site N11, 20°48'38.974''S, 115°22'32.2932''E, 1 May 2007, S. Callan, suction sample (WAM T89165); 1 male, Barrow Island, Curtin University site N26, 20°49'01.104''S, 115°26'06''E, 6 May 2006, S. Callan, suction sample (HBI N18284-1); 1 male, Barrow Island, Curtin University site T24W, 20°43'51.78''S, 115°27'05.8176''E, 7 July 2015, N. Gunawardene, suction sample (HBI N227-2); 2 males, Barrow Island, Old Airport, 20°47'19.3128''S, 115°27'47.52''E, 2 September 2015, N. Gunawardene, suction sample (HBI N594-7); 1 male, Barrow Island, Old Airport, rear of dome workshop, 20°47'36.8736''S, 115°25'24.8664''E, 22 January 2016, M. Hamilton, suction sample, shrubs and spinifex (HBI N1456-1); 1 male, Barrow Island, Production Village, opposite block F, 20°49'35.5692''S, 115°26'38.6052''E, 3 March 2016, A. Williams, window trap (HBI N1529-16); 1 female, Barrow Island, South side of Town Point, site BIHT08, 20°47'16.008''S, 115°27'45''E, 22 November 2003, R. Teale (WAM T57718); 1 male, Barrow Island, Temporary Laydown, 20°48'51.1092''S, 115°26'05.988''E, 2 June 2017, M. Hamilton, suction sample (HBI N4081-13); 1 male, 1 female, Barrow Island, Temporary Laydown, data well, 20°45'15.21''S, 115°26'41.9208''E, 3 March 2016, A. Williams, window trap (HBI N1521-12); 2 males, Barrow Island, WAPET Landing, 20°43'30.2988''S, 115°28'19.92''E, 16 September 2015, A. Williams, suction sample (HBI N886-14, N886-23); 1 male, 1 female, Barrow Island, WAPET Landing, 20°43'40.6128''S, 115°28'23.2248''E, 27 April 2017, J. Davies, suction sample (HBI N3847-33)
Variation.
Courtship display. Unknown.
Habitat and distribution. Currently only known from Barrow Island, where it appears to be a common and widespread species (Fig. xxx). Individuals were mostly found in suction samples on short bushes (mainly Acacia spp.) and spinifex (Triodia spp.) grasses. Few were found in human developments.
Remarks. Maratus tigrinus is the only species of Maratus known from Barrow Island, Western Australia. Barrow Island is the second largest island off Western Australia, originating approximately 6,800 years ago when rising sea levels severed its connection to Cape Range, located approximately 150km to the south (Veth et al., 2017). Barrow Island belongs to the Carnarvon Biogeographic Region (IBRA, 2008) and not the physically closer Pilbara Region, 50km to the east. The island was classified as an A-class reserve in 1910 due to its unique flora and fauna (Moro & Lagdon, 2013). It has since been developed by Chevron Australia who have constructed a gas treatment plant on the island (Gorgon Project) (EPA, 2006). Due to the high conservation status of the island, Chevron Australia have committed to strict quarantine regulations to adhere to the island’s conservation status. In most circumstances, we consider the inclusion of photographs of living males to be imperative for the descriptions of new Maratus species. However, due to the difficulty of attaining living individuals for study, the distinctiveness of this species, and the importance of documenting the fauna of Barrow Island for conservation and biosecurity purposes, we elected to describe this species based on preserved survey material from ongoing quarantine surveys of the island.