Systematic review of a new orb-weaving spider genus (Araneae: Araneidae), with special reference to the Australasian-Pacific and South-East Asian fauna Author Joseph, Mathew M. Author Framenau, Volker W. text Zoological Journal of the Linnean Society 2012 2012-09-28 166 2 279 341 http://dx.doi.org/10.1111/j.1096-3642.2012.00845.x journal article 10.1111/j.1096-3642.2012.00845.x 0024-4082 5408725 PLEBS SEBASTIANI SP. NOV. SEBASTIAN’ s GRASS ORB- WEAVER ( FIG. 33 ) Type: Holotype . ♂ from Palawan Province ( The Philippines ), Mantalingajan , Tagembung , 8°49 ′ N , 117°40 ′ E , 19.ix.1961 , Noona Dan Expedition 1961– 1962, 1150 m a.s.l. ( ZMUC 12270 ). Diagnosis: Plebs sebastiani males differ from other Plebs species in the overall shape of the pedipalp as well as individual sclerites. The tips of the median apophysis are positioned in a distinct U-shaped pattern with the tips pointing at each other unlike most other Plebs in which the tips are generally curved in and arranged parallel. The conductor also is unique in that it is a two-lobed structure with a wide, ovate, unsclerotized lobe and highly sclerotized slender lobe ( Fig. 33E ). The embolus is short with a highly bulbous base when compared to other Plebs males. The conductor is situated far apart from the embolus and terminal apophysis whereas these three sclerites are in close proximity in other species. Figure 33. Plebs sebastiani sp. nov. A–E, male holotype from Palawan, Mantalingajan, Tagembung, The Philippines (ZMUC 12270). A, dorsal view; B, ventral view; C, pedipalp, ventral view; D, pedipalp, dorsal view; E, pedipalp, apicoventral view. Scale bar = 1.0 mm in A, B; 0.25 mm in C- E. Description Male: Based on holotype . Carapace orange-brown ( Fig. 33A ); glabrous with the exception of sparse white setae mainly in cephalic area and in a wide band along lateral margins, one light brown bristle behind PE; fovea longitudinal. 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, interspersed with small streaks of black pigmentation; a sparse cover of brown bristles. Abdomen dorsally glabrous, with a sparse cover of white bristles; dorsum covered with off-white pigmentation, interspersed with a median pale greenish-brown folium; two larger and two smaller orange-brown sigillae mid-dorsally ( Fig. 33A ). Venter with greenish-brown pigmentation ( Fig. 33B ); weakly covered with white setae. Spinnerets light brown. Legs orange-brown, weakly spined, more so on the patella and metatarsus; coxae of leg IV with three stout setae ventrally. Pedipalps ( Fig. 33C–E ): apex of the median apophysis curved towards cymbium and with two sclerotized apical tips positioned in a U-shaped pattern; tegulum with an apical protrusion; terminal apophysis with a marginally sclerotized tip, base highly sinuous; embolus with sclerotized tip, base bulbous; conductor bilobed with a wide, ovate, unsclerotized lobe and highly sclerotized slender lobe. Dimensions : total length (excluding chelicerae) 3.21. Carapace length 1.64, width 1.39, height 0.77. Eyes: AME 0.15, ALE 0.12, PME 0.12, PLE 0.12, AME–AME 0.06, AME–ALE 0.08, PME–PME 0.04, PME–PLE 0.19, PLE–ALE 0.02, MOQ width front 0.33, MOQ width back 0.29, MOQ length 0.29, eye group width 0.67. Sternum length 0.79, width 0.61. Abdomen length 2.06, width 1.39. Pedipalp: femur 0.36, patella + tibia 0.24, tarsus 0.48, total 1.08. Leg I: femur 1.94, patella + tibia 2.18, metatarsus 0.91, tarsus 0.61, total 5.64. Leg II: femur 1.64, patella + tibia 1.82, metatarsus 0.91, tarsus 0.48, total 4.85. Leg III: femur 1.03, patella + tibia 0.91, metatarsus 0.48, tarsus 0.36, total 2.78. Leg IV: femur 1.39, patella + tibia 1.58, metatarsus 0.97, tarsus 0.48, total 4.42. Variation: only known from holotype . Female: Unknown. Remarks: In their exhaustive review of Philippine rice field spiders, Barrion & Litsinger (1995) did not treat P. sebastiani , suggesting that this species is not common in the country. This may be explained by a preference for higher elevations as the holotype was found above 1000 m asl. Distribution: Only known from holotype , The Philippines . Etymology: The specific epithet is a patronym in honour of Pothalil Antony Sebastian ( India ), for his contribution to arachnological research in India .