Orthobula bilobata, Deeleman-Reinhold, Christa, 2001

Deeleman-Reinhold, Christa, 2001, Forest Spiders of South East Asia With a revision of the sac and ground spiders (Araneae: Clubionidae, Corinnidae, Liocranidae, Gnaphosidae, Prodidomidae and Trochanteriidae)., Forest Spiders of South East Asia With a revision of the sac and ground spiders- Family Liocranidae, Leiden, Netherlands: Brill Leiden; Boston; Köln, pp. 400-505 : 433-435

publication ID

https://doi.org/ 10.5281/zenodo.814704



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scientific name

Orthobula bilobata

sp. nov.

Orthobula bilobata sp. n. ( figs 705-711 View Figs 705 - 711 , map 36 View Map 36 )

Type locality. — Indonesia, Lesser Sunda Island Sumbawa .

Type material.— Holotype ♂ from the type locality, Samokat, 20 km from Sumbawa Besar, 480 m, secondary forest, leaf litter, 1-3.i. 1990, S. Djojosudharmo; paratypes: 8 ♀, 1 ♀, same data.

Other material. — Borneo, W Sabah, Tuaran , 3 ♂ 1 ♀, Hevea rubber plantation, 1. vii. 1979, C.L. and PR. Deeleman, G. Perrault ; N Sumatra (Aceh), Gn. Leuser, Ketambe, trail 6.4 , 1 ♀, 2-5.iv. 1986, S. Djojosudharmo; Deli Serdang, Nature Reserve Tinggi Raja near Negridolok , 1 ♀ ( MHNG), primary forest, 400-440 m, 15.xi. 1985, C. Lienhard; W Sumatra. Lake Maninjau, 36 km from Bukittinggi , 1 ♀, 22.vii.1984, J. Robert ( MHNG).

Diagnosis. — This species is characterized by the colour pattern of the abdomen which is predominantly dark grey to black, and by the genital organs. In the male palp, the tegulum is much inflated and distally bipartite with a relatively large embolus. The configuration of the epigyne is distinctive. O. bilobata is closely related to O. trinotata , impressa , crucifera and yaginumai but distinct by the very wide, bilobed tegulum with relatively long embolus (ratio maximal tegulum width: cymbial width 3:1, in impressa and quadrinotata 2:1, in trinotata less than 2:1). O. impressa ( fig. 697 View Figs 697 - 699 ) has a large, compact, dark, longer than wide central mark in front on the abdomen which is absent in bilobata , it is also distinct from impressa by the proximal margin of the tegulum divided into two lobes, the lack of a hook at the base of the embolus and in the female by the larger central bulbous extensions on the ducts. In the dorsum of trinotata there is no dark mark in front, only a pair of lateral dark areas halfway and a dark patch on the rear, in the male palp the tegulum is much less widened, not much wider than cymbium. O. bilobata is distinct from crucifera by the more expanded tegulum and in the epigyne by the bulbous extensions of the ducts; from yaginumai by the presence of round impressed pits on the carapace and the dorsal abdominal pattern.

Description. — Male. Total length 2.20 mm. Carapace length 1.00 mm, width 0.75 mm, height at coxae II 0.45 mm, head width 0.48 mm; abdomen 0.90 mm long, 0.85 mm wide. Leg lengths: leg I 2.60 mm (0.75-0.95-0.60-0.30), leg II 2.20 mm (0.60-0.80-0.50-0.30), leg III 2.05 mm (0.55-0.70-0.55-0.25), leg IV 2.45 mm (0.65-0.80-0.70-0.30), palp 0.25- 0.15- 0.12-0.60 mm. Carapace ( figs 705-706 View Figs 705 - 711 ) and mouthparts chestnut to orange, legs chestnut brown, femora with dark grey basal and subapical ring which often is reduced to a retrolateral spot, most pronounced in leg IV, posterior tibae with dark retrolateral stripe, abdomen with a dark grey pattern as in figs 705-706 View Figs 705 - 711 , anteriorly a narrow transverse dark band, sometimes a small extension in the middle; underside uniform white. Carapace with radiating grooves from the centre and widely spaced pits, sternum with some round depressions. Thoracic groove obsolete. Anterior eye row occupying 1/2 of head width, eyes close together, ALE a little larger than AME, posterior eyes equally sized and spaced. Clypeus equal to 1 eye diameter. Underparts fig. 707 View Figs 705 - 711 . Ventral surface of anterior femora rugose. Leg spination: tibiae I and II with 5-6pv and 5rv very strong spines with tuberculate base, metatarsi with 4 pairs, tarsi I and II with 2 pairs, rest spineless. Abdomen shiny, dorsally entirely covered by scutum, ventrally an epigastric and a partial postgenital scutum. Palp figs 708-709 View Figs 705 - 711 , tibial apophysis acuminate, adjacent spine absent, 3 hairs instead, cymbium narrow, lanceolate; tegulum three times wider than cymbium, the proximal end divided into two lobes.

FEMALE. Total length 2.40 mm. Carapace length 1.20 mm, width 0.95 mm, head width 0.60 mm; abdomen 1.10 mm long, 1.00 mm wide, epigynal plate 0.35 mm wide, 0.40 mm long. Leg lengths: leg I 3.05 mm (0.85-1.15-0.70-0.35), leg II 2.60 mm (0.75-0.95-0.60- 0.30), leg III 2.45 mm (0.70-0.80-0.60-0.35), leg IV 3.10 mm (0.80-1.00-0.90-0.40), palp 0.35-0.15-0.20- 0.32 mm. Carapace, eyes, mouthparts and legs as in male. Abdomen without dorsal scutum, ventrally an epigastric scutum only; dorsally, anterior dark area more extended with a median and lateral strands connecting with the posterior dark area, ventral side mainly white. Epigyne fig. 710 View Figs 705 - 711 (cf. O. impressa , fig. 698 View Figs 697 - 699 ), a squarish plate with a large impressed area in the middle, in the anterior half a pair of strongly coloured openings; vulva fig. 711 View Figs 705 - 711 , with a pair of rod-shaped spermathecae posteriorly, a pair of large membranous sacs attached to the middle part of the duct.

Distribution.— Indonesia. At present only found yet in the Lesser Sunda Island Sumbawa, Sumatra and Malaysian Borneo.

Etymology. — The word bilobata (Lat.) refers to the shape of the male palpal tegulum.


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