Plebs arletteae, Joseph & Framenau, 2012

Joseph, Mathew M. & Framenau, Volker W., 2012, Systematic review of a new orb-weaving spider genus (Araneae: Araneidae), with special reference to the Australasian-Pacific and South-East Asian fauna, Zoological Journal of the Linnean Society 166 (2), pp. 279-341 : 303-307

publication ID	https://doi.org/ 10.1111/j.1096-3642.2012.00845.x
persistent identifier	https://treatment.plazi.org/id/EB7687FC-FF8D-8566-7482-FD89FD3DE2E0
treatment provided by	Marcus
scientific name	Plebs arletteae
status	sp. nov.

Treatment

PLEBS ARLETTEAE View in CoL SP. NOV.

ARLETTE’ s GRASS ORB- WEAVER ( FIGS 12–14 View Figure 12 View Figure 13 View Figure 14 )

Types: Holotype. ♂ from New South Wales ( Australia), Lord Howe Island , Goat House Cave area, 31°33 ′ 50 ′′ S, 159°05 ′ 11 ′′ E, 23.ii.2001, G. Milledge ( AM KS70738 ) GoogleMaps . Paratype. ♀ from New South Wales ( Australia), Lord Howe Island , track to Valley of the Shadows, 31°31 ′ 50 ′′ S, 159°04 ′ 32 ′′ E, 27.ii.2001, G. Milledge, beating ( AM KS70660 ) GoogleMaps .

Other material examined: Nine males, 19 females, and one juvenile from 18 records (Appendix S1).

Diagnosis: Plebs arleneae is morphologically most similar to P. eburnus (see Diagnosis above).

Description

Male: Based on holotype. Carapace light orangebrown, patches of dark pigmentation along the lateral margins and a central patch of dark pigmentation covering the entire length of fovea ( Fig. 12A View Figure 12 ); overall glabrous; fovea cross-shaped, longer than wide. Chelicerae yellow-brown, a small band of dark pigmentation at the proximal dorsal surface; a few black setae mainly in the apical half. Sternum orange-brown, with scattered dark pigmentation along the periphery; a weak cover of brown bristles. Abdomen dorsally glabrous, a very weak cover of white setae; covered with off-white pigmentation, interspersed with a greenishbrown folium ( Fig. 12A View Figure 12 ); six prominent orange-brown sigillae mid-dorsally; ventrally with greenish-brown pigmentation ( Fig. 12B View Figure 12 ); weakly covered with white setae and light brown bristles. Spinnerets light brown. Legs orange-brown with dark annulations, weakly spined, more spination on patella and metatarsus; leg IV with the right coxa bearing two and the left bearing three stout setae ventrally; leg formula 1> 2> 4> 3. Pedipalps ( Fig. 13A–C View Figure 13 ): apex of the median apophysis curved in and with two sclerotized apical tips, base sinuous; tegulum with a prominent apical protrusion; terminal apophysis with sinuous base and a marginally sclerotized tip; embolus bulbous at the base; conductor ovate.

Dimensions: total length (excluding chelicerae) 4.30. Carapace length 2.06, width 1.82, height 0.63. Eyes: AME 0.19, ALE 0.15, PME 0.15, PLE 0.12, AME–AME 0.10, AME–ALE 0.13, PME–PME 0.02, PME–PLE 0.23, PLE–ALE 0.02, MOQ width front 0.42, MOQ width back 0.31, MOQ length 0.33, eye group width 0.90. Sternum length 0.97, width 0.73. Abdomen length 2.91, width 1.52. Pedipalp: femur 0.30, patella + tibia 0.48, tarsus 0.79, total 1.57. Leg I: femur 3.03, patella + tibia 2.85, metatarsus 1.82, tarsus 0.67, total 8.37. Leg II: femur 2.55, patella + tibia 2.18, metatarsus 1.52, tarsus 0.61, total 6.86. Leg III: femur 1.52, patella + tibia 1.09, metatarsus 0.73, tarsus 0.48, total 3.82. Leg IV: femur 2.42, patella + tibia 2.06, metatarsus 1.45, tarsus 0.61, total 6.54.

Variation (range): TL 4.06–4.67; CL 2.06–2.42; CW 1.64–1.82; AL 2.12–2.91; AW 1.39–1.64; N = 6.

Female: Based on paratype: carapace as male; fovea longitudinal ( Fig. 12C View Figure 12 ). Chelicerae and sternum as male. Abdomen with general coloration as male ( Fig. 12C View Figure 12 ); humeral humps present; ventrally as male; the area enclosing the inverted U-shaped pattern with brown bristles ( Fig. 12D, F View Figure 12 ); brown bristles also around the spinnerets. Spinnerets light brown. Legs orange-brown with black annulations; weakly spined; leg formula 1> 4> 2> 3. Epigyne with elongated scape that is widest at its base. ( Fig. 13E View Figure 13 ); spermathecae elongate kidney-shaped ( Fig. 13D View Figure 13 ).

Dimensions: total length (excluding chelicerae) 5.58. Carapace length 2.30, width 2.06, height 0.81. Eyes: AME 0.19, ALE 0.12, PME 0.15, PLE 0.12, AME–AME 0.10, AME–ALE 0.21, PME–PME 0.04, PME–PLE 0.29, PLE–ALE 0.02, MOQ width front 0.46, MOQ width back 0.38, MOQ length 0.38, eye group width 1.09. Sternum length 1.09, width 0.97. Abdomen length 3.64, width 2.42. Palp: femur 0.73, patella + tibia 0.91, tarsus 0.73, total 2.37. Leg I: femur 2.55, patella + tibia 3.58, metatarsus 2.42, tarsus 0.85, total 9.40. Leg II: femur 2.30, patella + tibia 3.03, metatarsus 1.94, tarsus 0.67, total 7.94. Leg III: femur 1.52, patella + tibia 1.45, metatarsus 0.91, tarsus 0.55, total 4.43. Leg IV: femur 2.67, patella + tibia 3.03, metatarsus 1.12, tarsus 0.85, total 8.67.

Variation (range): TL 5.58–8.61; CL 2.15–2.55; CW 1.58–2.08; AL 3.58–6.23; AW 2.24–3.85; N = 7. Abdominal coloration varies from the presence of a greenish-brown folium ( Fig. 12C View Figure 12 ) to its absence, but then with patches of dark pigmentation along the lateral edges of abdomen ( Fig. 12E View Figure 12 ).

Distribution: Only known from Lord Howe Island ( Fig. 14 View Figure 14 ).

Life history and habitat preferences: Mature specimens of P. arletteae were only collected in January and February, which, in all likelihood, represents a sampling bias of the Australian Museum surveys. Habitat information is scarce and includes ‘on Pandanus ’, ‘on small cedar’, and ‘dense vine understorey’.

Etymology: The specific epithet is a matronym in honour of the senior author’s daughter Arlette Mathew. We propose the common name ‘Arlette’s grass orb-weaver’ for this species.

PLEBS BRADLEYI ( KEYSERLING, 1887) View in CoL COMB. NOV.