Racata brevis, 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

Racata brevis sp. nov.

Figs 5-6 , 16-17 , 24

Holotype: Male [Sum-00/12]; INDONESIA, Sumatra, Jambi Province, Mt Kerinci , footpath to summit, NW of Kersik Tua, 1°44’12”S, 101°15’35”E, evergreen hill forest, sifting, 1800-1980 m a.s.l.; 16.II.2000; leg. P. Schwendinger.

Paratype: 1 female; collected together with the holotype .

Diagnosis: The species is characterized by possessing the widest and shortest embolus among all known congeners, as well as the shortest copulatory ducts.

Etymology: The specific epithet is a Latin adjective meaning “short” referring to the relatively short embolus of the male.

Description: Male holotype. Total length 1.45. Carapace 0.70 long, 0.63 wide, rounded ( Fig. 5 ), pale greyish brown. Head part slightly elevated and protruded distad. Eyes enlarged, anterior median eyes much smaller than others. Chelicerae 0.30 long, mastidion absent. Legs pale greyish yellow, its segments slightly darkened distally. Leg I 2.60 long (0.75+0.15+0.65+0.67+0.38), IV 2.47 long (0.68+0.13+0.63+0.63+0.40). 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 0.24. Metatarsi IV without trichobothrium. Palp ( Figs 16-17 ): Tibia short, simple. Distal half of cymbium narrowed. Proximal part of paracymbium wide, distal part L-shaped. Tegulum weakly sclerotized, light in colour. Distal suprategular apophysis very small. Median membrane panicleshaped. Convector large, strongly sclerotized, covering base of embolus. Embolus very wide proximally, abruptly narrowing distally, its distal part relatively long and narrow. Abdomen ( Fig. 5 ) 0.85 long, 0.53 wide, grey.

Female. Total length 1.50. Carapace 0.60 long, 0.50 wide, unmodified, pale greyish yellow. Chelicerae 0.25 long. Legs yellow, its segments darkened distally. Leg I 2.67 long (0.70+0.18+0.68+0.63+0.48), IV 2.24 long (0.65+0.18+0.60+0.43+0.38). Chaetotaxy as in male. Length of spines 2-2.5 diameters of corresponding leg segment. TmI 0.26. Metatarsi IV without trichobothrium. Abdomen 0.85 long, 0.63 wide, grey. Epigyne ( Figs 6 , 24 ): Cavity relatively small, depression anterior to it narrow. Copulatory ducts very wide, forming half a loop. Receptacles curved, beanlike.

Taxonomic remarks: The male can be easily distinguished by its boat-shaped convector and by the bent, thick embolus with a narrow, rapier-like distal part. The epigyne of R. brevis slightly resembles that of R. grata , but the depression anterior to the cavity is narrow instead of rounded, almost the same size as the cavity ( Fig. 6 cf. Figs 3-4 ).

Distribution: Known only from the type locality on the densely forested southern slopes of the highest mountain of 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).