Racata Millidge 1995
Creators: name: Tanasevitch, Andrei V.
Publisher: name: Zenodo
Year: 2019
Subjects: Biodiversity
Taxonomy
Animalia
Arthropoda
Arachnida
Araneae
Linyphiidae
Racata

description: Racata Millidge, 1995
Type species: Racata grata Millidge, 1995, by original designation and monotypy.
Diagnosis: Members of the genus Racata can be easily recognised by the “micronetine”-like chaetotaxy, by the highly developed convector and by the presence of a panicle-shaped median membrane in the palpal organ. Females are distinguished by a distinct epigynal cavity, which is often surrounded by sclerotized swellings, and by mostly helical copulatory ducts. The genus contains medium-sized spiders with a total length of 1.45-1.75, which are characterized by the following combination of somatic and genitalic characters:
1) Carapace unmodified in both sexes, eyes somewhat enlarged, cephalic pits (= sulci) absent.
2) Chaetotaxy formula: TiI: 2-1-1-0; II: 2-0-1-0, III- IV: 2-0-0-0; MtI-IV without spines; MtIV without trichobothrium; TmI 0.20-0.30.
3) Palpal tibia simple, unmodified.
4) Distal part of cymbium narrowed.
5) Convector highly developed and sclerotized.
6) Median membrane panicle-shaped.
7) Epigyne with distinct cavity, usually surrounded by sclerotized swellings.
8) Copulatory ducts mostly wide, helical.
Species included: Racata brevis sp. nov., R. sumatera sp. nov. (Indonesia: Sumatra), R. grata Millidge, 1995 (Indonesia: Krakatoa, Java and Belitung) and R. laxa sp. nov. (Indonesia: Sumatra; Thailand: Ko Chang).
Taxonomic remarks: The genus Racata was established from a male and placed into the subfamily Dubiaraneinae (Millidge, 1995) on the basis of the structure of its embolic division. Due to the same reason Millidge (1995) also placed the following Southeast Asian genera into the Dubiaraneinae: Kenocymbium Millidge & Russell-Smith, 1992, Ketambea Millidge & Russell-Smith, 1992, Prosoponoides Millidge & Russell-Smith, 1992 and Thainetes Millidge, 1995. The subfamily Dubiaraneinae is defined by only a single character of the vulva, i.e.: “… the seminal [= copulatory] duct of the epigynum running along the margins of a lamina, as in the Mynogleninae; in the majority of the species, the lamina is coiled into a short, almost planar helix, the axis of which is more or less perpendicular to the plane of the epigynum…” (Millidge, 1993). However, as pointed out by Millidge & Russell-Smith (1992), the epigyne in all above mentioned genera (including Racata) is of the linyphiine type and is quite different from that of Dubiaranea Mello-Leitão, 1943, the type genus of the Dubiaraneinae. At present it is premature to discuss the position of these genera in the system of subfamilies in the Linyphiidae until the subfamily Dubiaraneinae is clearly diagnosed. In the meantime I provisionally consider the genus Racata as belonging to the Erigoninae. The small size and erigoninelike general appearance, and the structure of the genitalia, which are similar to that of some Southeast Asian erigonines, i.e., Asiagone Tanasevitch, 2014a, Houshenzinus Tanasevitch, 2006, Laogone Tanasevitch, 2014a, Nasoona Locket, 1982, Oedothorax Bertkau in Förster & Bertkau, 1883, etc., support the preliminarily inclusion of Racata in the Erigoninae. The only problem I see here is in the chaetotaxy formula, which is absolutely not characteristic for the subfamily, but rather for the Micronetinae or Linyphiinae.
The genus is closely related to Aperturina Tanasevitch, 2014b, known from Thailand and West Malaysia (Tanasevitch, 2014b).
Distribution: So far known only from Indonesia and Thailand.
description: Published as part of Tanasevitch, Andrei V., 2019, On the spider genus Racata Millidge, 1995, with the description of three new species (Araneae, Linyphiidae), pp. 53-59 in Revue suisse de Zoologie 126 (1) on pages 53-54, DOI: 10.5281/zenodo.2619518