Racata sumatera, Tanasevitch, 2019

Tanasevitch, Andrei V., 2019, On the spider genus Racata Millidge, 1995, with the description of three new species (Araneae, Linyphiidae), Revue suisse de Zoologie 126 (1), pp. 53-59 : 56-58

Racata sumatera sp. nov.

Figs 7-8 , 18-19, 21-22 , 25

Holotype: Male [Sum-06/33]; INDONESIA, Sumatra, North Sumatra Province, Mt Sibayak , 4 km N of Brastagi, 3°13’16”N, 98°29’50”E, primary forest, 1600- 1650 m a.s.l.; 6.-7.VII.2006; leg. P. Schwendinger.

Paratypes: 3 females, collected together with the holotype .

Diagnosis: The male can be easily distinguished from those of all known congeners by its very long, helical, gradually narrowing embolus; the female can be recognized by the wide anterior part of their epigyne, which is surrounded by slightly sclerotized swellings.

Etymology: The specific epithet is a name in apposition referring to the “terra typica”; “ Sumatera ” is the Indonesian name for “ Sumatra ”.

Description: Male (holotype). Total length 1.75. Carapace 0.85 long, 0.75 wide, rounded as shown in Fig. 7 , greyish yellow, with a narrow dark margin. Head part slightly elevated and protruded distad. Clypeus sparsely covered with long hairs. Eyes enlarged, anterior median eyes considerably smaller than others. Chelicerae 0.33 long, mastidion absent. Legs pale greyish yellow, its segments slightly darkened distally. Leg I 4.14 long (1.00+0.23+1.15+1.08+0.68), IV 3.46 long (0.93+0.20+0.90+0.90+0.53). Chaetotaxy: spines mostly lost, presumably as in female (see below). TmI 0.36. Metatarsi IV without trichobothrium. Palp ( Figs 18-19, 21-22 ): Tibia short, simple. Distal part of cymbium narrowed. Proximal part of paracymbium wide, distal part narrow, S-shaped. Tegulum distinctly protruded distad, light in colour. Distal suprategular apophysis long, bifurcated apically. Median membrane panicle-shaped ( Fig. 21 ). Convector massive, narrow, gradually curving. Embolus very long, forming three loops; very wide at base, gradually narrowing and in third loop becoming whip-shaped. Abdomen ( Fig. 7 ) 1.00 long, 0.53 wide, grey.

Female. Total length 1.60. Carapace 0.65 long, 0.58 wide, unmodified, pale yellow, with a narrow grey margin. Chelicerae 0.25 long. Legs pale yellow, its segments darkened distally. Leg I 3.23 long (0.85+0.18+0.85+0.80+0.55), IV 2.98 long (0.85+0.18+0.75+0.75+0.45). TmI 0.31. Chaetotaxy: TiI: 2-1-1-0; II: 2-0-1-0, III-IV: 2-0-0-0; MtI-IV without spines. Length of spines 1.5-2 diameters of corresponding leg segment. TmI 0.36. Metatarsi IV without trichobothrium. Abdomen 1.00 long, 0.63 wide, grey. Epigyne ( Figs 8 , 25 ) relatively large; anterior part of epigynal cavity surrounded by slightly sclerotized swellings. Copulatory ducts very wide, forming three loops. Receptacles small, indistinct.

Taxonomic remarks: The male clearly differs from those of all known congeners by its long embolus forming three loops, whereas in R. grata it forms one loop and in R. brevis only half a loop. The female is distinguished by its large epigynal cavity, the anterior part of which is surrounded by slightly sclerotized swellings.

Distribution: Known only from the type locality on the densely forested slopes of a volcano in northern Sumatra, Indonesia.

Figures

Figs 1-13. Racata grata Millidge, 1995 (1-4), R. brevis sp. nov., male holotype (5) and female paratype (6); R. sumatera sp. nov., male holotype (7) and female paratype (8); R. laxa sp. nov., female paratypes (9-13). (1, 5, 7) Male body, dorsal view. (2, 9) Female body, dorsal and ventral view, respectively. (3-4, 6, 8) Female abdomen, ventral view. (10-13) Epigyne, ventral view. Specimens from: near Cibodas (1-4), Mt Kerinci (5-6), Mt Sibayak (7-8), Bukittinggi (9, 12), Padangpanjang (10), Padangsidempuan (11), Taman Hutan Raya Bung Hatta (13).

Figs 14-22. Details of male palp structure of Racata grata Millidge, 1995, specimen from near Cibodas (14-15, 20); R. brevis sp. nov., holotype from Mt Kerinci (16-17); R. sumatera sp. nov., holotype from Mt Sibayak (18-19, 21-22). (14, 16, 18) Right palp, retrolateral view. (15, 17, 19) Right palp, prolateral view. (20-21) Median membrane. (22) Distal suprategular apophysis.

Figs 23-26. Vulva structure (dorsal view) of Racata grata Millidge, 1995, specimen from near Cibodas (23); R. brevis sp. nov., paratype from Mt Kerinci (24); R. sumatera sp. nov., paratype from Mt Sibayak (25); R. laxa sp. nov., paratype from Bukittinggi (26).