Larinia sexta n. sp.

Figs 1–3, 7.

Larinia VWF sp. 1023. Majer et al. 2013, 31.

Type material. Male holotype from Barrow Island, old administration building, plot N23 (20°49`09”S, 115°23`40”E, Western Australia, AUSTRALIA), 6 May 2006, S. Callan, R. Graham, night hand collecting (WAM T 80638).

Other material examined. AUSTRALIA: Western Australia: 1 male, Barrow Island, old drill workshops, plot N22, 20°49`55”S, 115°25`13”E, 1 May 2007, S. Callan, K. Edwards, night hand collecting (WAM T 88943); 1 female, Barrow Island, site 22, 20°47`12”S, 115°27`17”E, 17 May 2005, Callan, S. et al., hand collecting, night (WAM T 77403); 1 female, 2 juv., Barrow Island, future construction village, 20°49`00”S, 115°26`16”E, 6 May 2006, Callan, S. Graham, R., nocturnal hand collecting (WAM T 77404); 1 female, Barrow Island, 20°44`41.98”S, 115°24`02.91”E, N. Gunawardene, night hand collection, 27 August 2010 (HBI N2969-4); 1 female, Barrow Island, 20°47`46.342”S, 115°25`59.710”E, 31 August 2017, S. O’Connor, night hand collecting (HBI N4572-1); 1 female, Barrow Island, 20°44`57.650”S, 115°27`47.386”E, V.W. Framenau, 12 August 2019, night hand collecting (HBI N15965 -8); 1 female, Barrow Island, 20°49`40.774”S, 115°26`49.884”E, S. O’Connor, 30 September 2019, vehicle vibration (HBI N16286 -7); 1 female, 20°44`57.939”S, 115°27`48.540”E, F. Bokhari, 12 August 2019, vehicle vibration (HBI N15963 -7); 1 female, Canning Stock Route, No. 23 Well, 23°05`S, 123°13`E, 9 August 1989, A. F. deJong (WAM T 74426); 1 female, same data (WAM T 80639).

Etymology. The specific epithet is an adjective in apposition derived from the Latin word for ‘sixth’ (sextus), indicating this being the sixth species of Larinia reported from Australia.

Diagnosis. Male and female L. sexta n. sp. key out to L. phthisica (L. Koch, 1871) in Framenau & Scharff (2008); however, L. sexta n. sp. males differ from those of that species in a number of characters, particularly the relatively shorter abdomen which is more than three times longer than wide in L. phthisica, but not so in L. sexta n. sp. (Fig. 1A, B). Males also vastly differ in their pedipalpal morphology (Figs 1C, D; 3A, B). Most evident are the lack of a tegular extension in L. sexta n. sp. (present in L. phthisica). In addition, the distance between the median apophysis prongs is smaller in L. phthisica and the prongs are of different size, whereas they are much more separated in L. sexta sp. nov. and of similar size. The epigynum has a much broader posterior rim in L. sexta n. sp. (Figs 2C, 3D) than in L. phthisica.

Description

Male (holotype).

Total length 4.05 Carapace (Fig. 1A): 2.21 long, 1.43 wide; yellow-brown, narrow dark median band and dark discolourations and spots in cephalic area; areas around eyes black. Eyes: AME 0.18, ALE 0.13, PME 0.14, PLE 0.09; row of eyes: AME 0.40, PME 0.34, PLE 083. Sternum (Fig. 1B): 0.98 long, 0.72 wide; yellow-brown; with dark irregular spots, denser towards margins. Labium (Fig. 1B): wider than long; basal half light brown with darker pigmentation, anterior part forms a nearly semi-circular white rim. Chelicerae (Fig. 1B): yellow-brown; three promarginal teeth, with the central one largest; three retromarginal teeth, with the basal smallest.

Pedipalp (Figs. 1C, D; 3A, B): conductor slightly curved and membranous; median apophysis with two pointed and curved prongs; embolus strongly sclerotised and almost straight; terminal apophysis forms hood over embolus. Legs (Figs. 1A, B; 3A, B): leg formula I>II>IV>III; uniformly yellow, with small black spots and black setal bases; lengths of segments (femur + patella + tibia + metatarsus + tarsus): pedipalp 0.65 + 0.26 + 0.33 + - + 0.59 = 1.82, I 2.28 + 0.91 + 2.28 + 2.54 + 0.91 = 8.91, II 2.08 + + 0.85 + 2.02 + 0.90 + 0.85 = 6.69, III 1.43 + 0.52 + 0.78 + 1.04 + 0.65 = 4.42, IV 1.50 + 0.52 + 0.85 + 1.63 + 0.72 = 5.20. Abdomen (Fig. 1A, B): 2.23 long, 1.08 wide; greenishbrown with darker folium pattern; reddish-brown irregular median line; venter olive-green with two light indistinct lateral lines; spinnerets olive-green (Fig. 1B).

Female (from Barrow Island; WAM T77403). Somatic characters of the female agree in general details with the male, except that dorsal median brown band on the abdomen is less distinct and the ventral light lateral bands are broader (Figs 2A, B). Total length 5.33. Carapace: 2.41 long, 1.63 wide. Eyes: AME 0.16, ALE 0.11, PME 0.11, PLE 0.11; row of eyes: AME 0.45, PME 0.34, PLE 0.88. Sternum: 1.11 long, 0.98 wide. Legs: leg formula I>II>IV>III; lengths of segments (femur + patella + tibia + metatarsus + tarsus): pedipalp 0.78 + 0.33 + 0.46 + - + 0.85 = 2.41, I 2.21 + 1.24 + 2.21 + 2.41 + 0.98 = 9.04, II 1.95 + 0.98 + 1.89 + 0.90 + 0.91 = 6.62, III 1.56 + 0.59 + 0.85 + 0.91 + 0.59 = 4.49, IV 1.69 + 0.85 + 1.63 + 1.50 + 0.72 = 6.37. Abdomen: 3.90 long, 2.86 wide.

Genitalia (Figs 2C–E, 3C, D): epigynum strongly sclerotised with large antero-lateral lobes; scape broken off in all specimens examined, but base narrow with parallel borders (Fig. 3D); spermathecae ovoid, slightly kidneyshaped in dorsal view, much less than their radius apart.

Variation. Total length males 4.05–4.20 (n = 2), females 4.85–5.40 (n = 8). There is very little colour variation between specimens of L. sexta n. sp., although the light median band on the abdomen can be somewhat more prominent than illustrated in the female (Fig. 2A). The scape was broken off in all females examined, but partially present in one (Fig. 3D) indicating it to have parallel borders.

Distribution. Currently only known from Barrow Island and a single locality in central Western Australia (Fig. 7). Habitat preferences and life history. Mature spiders of L. sexta n. sp. have so far only been found in May, August and September, i.e. in the dry season. Locations where the species was found are generally dominated by spinifex (Triodia spp.) grassland with sparse bushy vegetation.