Plebs arleneae, Joseph & Framenau, 2012, 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: 300-303

publication ID 10.1111/j.1096-3642.2012.00845.x


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scientific name

Plebs arleneae



ARLENE’ s GRASS ORB- WEAVER ( FIGS 10 View Figure 10 , 11 View Figure 11 , 14 View Figure 14 )

Types: Holotype. ♂ from Queensland ( Australia), Black Mountain , 26°25 ′ S, 152°51 ′ E, 1971–72, N.C. Coleman ( QM S88901 View Materials ) GoogleMaps   . Paratypes. Three ♂, data as holotype ( QM S88900 View Materials ) GoogleMaps   ; ♀ from New South Wales ( Australia), Hornsby , Waitara Creek, 33°42 ′ S, 151°06 ′ E, 28.x.2001, G. Milledge & H. Smith, beating shrubs ( AM KS74980) GoogleMaps   .

Other material examined: Forty-nine males, 70 females, and 12 juveniles from 79 records (Appendix S1).

Diagnosis: Plebs arleneae   can be easily distinguished from other members of the genus by the shape of the median apophysis, which is distally widened and protrudes significantly beyond the tegulum. It bears three tips in a three-dimensional pattern in contrast to the typical two-tipped median apophysis of all other Australian Plebs   (with the exception of P. patricius   ) ( Fig. 11A–C View Figure 11 ). Unique within Plebs   , a group of long, strong setae arises from the tip of the cymbium in P. arleneae   (‘cymbial setae’ in Fig. 11A View Figure 11 ). Males lack the coxal setae that are found in most other members of the genus (except P. patricius   ). The epigynal scape of females of P. arleneae   is the shortest in comparison to all other Plebs   ; however, it is almost always broken off (as in P. patricius   ).


Male: Based on holotype. Carapace light orangebrown; glabrous with the exception of sparse white setae mainly in cephalic area and in a narrow band along lateral margins, three light brown bristles behind PE; fovea shallow, longitudinal ( Fig. 10A View Figure 10 ). Chelicerae yellow-brown, a band of dark pigmentation running along the dorsal surface reaching up to the mid-region; a few black setae mainly in the apical half. Sternum orange-brown with dark pigmentation along the entire border, sparsely covered with brown bristles. Abdomen: dorsally with light greenish-brown folium; sparse cover of white setae; brown tubercles along the entire dorsum, each tubercle bearing a light brown bristle ( Fig. 10A View Figure 10 ); venter with light greenish-brown pigmentation, the typical U-shaped white pattern very faint and the two white spots lateral to the spinnerets absent ( Fig. 10B View Figure 10 ); weakly covered with light brown bristles. Spinnerets light brown. Legs orange-brown, moderately spined. Pedipalps ( Fig. 11A–C View Figure 11 ): median apophysis protruding beyond tegulum, apex widened, with three broad apical tips with the middle tip more pointed and sclerotized; tegulum with an apical protrusion; terminal apophysis with an unsclerotized, short tip; embolus with a heavily sclerotized tip; conductor short, ovate; a tuft of long setae arising from the apical tip of cymbium and extending over terminal apophysis.

Dimensions: total length (excluding chelicerae) 2.30. Carapace length 1.09, width 0.91, height 0.58. Eyes: AME 0.12, ALE 0.08, PME 0.10, PLE 0.04, AME–AME 0.04, AME–ALE 0.06, PME–PME 0.02, PME–PLE 0.07, PLE–ALE 0.02, MOQ width front 0.23, MOQ width back 0. 19, MOQ length 0.21, eye group width 0.40. Sternum length 0.85, width 0.61. Abdomen length 1.27, width 0.97. Pedipalp: femur 0.15, patella + tibia 0.23, tarsus 0.92, total 1.30. Leg I: femur 1.16, patella + tibia 1.31, metatarsus 0.69, tarsus 0.39, total 3.55. Leg II: femur 0.85, patella + tibia 1.04, metatarsus 0.58, tarsus 0.35, total 2.82. Leg III: femur 0.50, patella + tibia 0.54, metatarsus 0.31, tarsus 0.27, total 1.62. Leg IV: femur 0.77, patella + tibia 0.73, metatarsus 0.42, tarsus 0.35, total 2.27.

Variation (range): TL 2.12–2.31; CL 0.96–1.16; CW 0.89–0.96; AL 1.21–1.35; AW 1.09–1.16; N = 5.

Female: Based on paratype AM KS74980 from Hornsby, New South Wales. Carapace as male, except for absence of bristles (as in Fig. 10C View Figure 10 ). Chelicerae as male. Sternum as male. Abdomen subtriangular; dorsum as male, with a broad area of triangular greenish-brown pigmentation along the entire dorsum (as in Fig. 10C View Figure 10 ); venter as male. Spinnerets light brown. Legs orange-brown with dark annulations, weakly spined. Leg formula 1> 2> 4> 3. Epigyne with short, triangular scape ( Fig. 11F View Figure 11 ), which is almost always broken off ( Fig. 11E View Figure 11 ); spermathecae pear-shaped ( Fig. 11D View Figure 11 ).

Dimensions: total length (excluding chelicerae) 4.36. Carapace length 1.94, width 1.52, height 0.58. Eyes: AME 0.13, ALE 0.12, PME 0.13, PLE 0.12, AME–AME 0.04, AME–ALE 0.19, PME–PME 0.04, PME–PLE 0.21, PLE–ALE 0.02, MOQ width front 0.33, MOQ width back 0.33, MOQ length 0.35, eye group width 0.92. Sternum length 0.91, width 0.79. Abdomen length 2.67, width 2.00. Palp: femur 0.67, patella + tibia 0.48, tarsus 0.55, total 1.70. Leg I: femur 1.94, patella + tibia 2.55, metatarsus 1.58, tarsus 0.61, total 6.68. Leg II: femur 1.88, patella + tibia 2.06, metatarsus 1.39, tarsus 0.55, total 5.88. Leg III: femur 1.03, patella + tibia 1.82, metatarsus 0.61, tarsus 0.48, total 3.94. Leg IV: femur 1.94, patella + tibia 2.00, metatarsus 1.27, tarsus 0.61, total 5.82.

Variation (range): TL 3.43–4.36; CL 1.42–1.94; CW 1.16–1.52; AL 2.46–2.77; AW 1.96–2.23; N = 3. Abdominal colour variation ranges from a light brown folium ( Fig. 10C View Figure 10 ) to a greenish-brown triangular pattern covering the entire dorsum ( Fig. 10E View Figure 10 ). Epigynal scape morphology (when present) varies from conical to triangular ( Fig. 11F View Figure 11 ).

Distribution: Eastern Australia (Queensland, New South Wales) ( Fig. 14 View Figure 14 ).

Life history and habitat preferences: Mature P. arleneae   are generally found between October and May (most between November and February), although a single record from Queensland is from July. The species appears to be reproductively active in summer. Habitat descriptions include closed forest, coastal woodland, rainforest, and vine forests, but spiders have also been found on buildings and shrubs.

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


Queensland Museum


Australian Museum