Odontomachus pararixosus

This species inhabits the forests, and nests in rotten woods or under accumulations of leaf litter. Colonies has brachypterous queens and no dealate queens were found. (Terayama & Ito 2014)

Identification
Terayama & Ito (2014) - Among the rixosus species group, this species especially resembles Odontomachus rixosus in the long antennal scape (SI over 140), the long subapical tooth of mandible with truncate apex, the largely smooth vertex, and the gently convex anterior margin of petiolar node. However O. pararixosus is separated from O. rixosus by the almost straight posterior margin of head (weakly notched in rixosus), the acute triangular tip of petiole (needle-shaped in O. rixosus), the almost straight posterior margin of petiolar node (weakly concave in O. rixosus) and the presence of long suberect setae on 1st gastral tergite (absent in O. rixosus).

Distribution based on Regional Taxon Lists
Indo-Australian Region: Malaysia.

Nomenclature

 *  pararixosus. Odontomachus pararixosus Terayama & Ito, 2014: 181, figs 1, 2 (w.) MALAYSIA.

Worker
Holotype; HL 2.58; HW 1.77; SL 2.64; ML 1.42; CI 69; SI 149; WL 3.50; PL 0.69; PH 1.07; DPW 0.42; TL 10.7. Paratype workers (n=10); HL 2.40–2.73; HW 1.62–1.91; SL 2.40–2.76; ML 1.40–1.49; CI 66–70; SI 142–151; WL 3.35–3.80; PL 0.64–0.72; PH 1.05–1.21; DPW 0.40–0.52; TL 10.1–11.2.

Holotype. Structure: Head long, 1.46 times as long as wide, widest at level of eyes, with almost straight posterior margin in full-face view; posterior 1/3 of head tapering to the posterior most; posterodorsal corner rounded, not forming an angle; extraocular furrow gently incised. Mandible linear, shaft only weakly broaden anteriorly, dorsal margin with 6 small teeth of which anterior-most one is largest; apical portion with 3 teeth of which ventral one is longest; dorsal tooth rectangular, ca. 2.5 times as long as wide at midlength; intercalary tooth smallest. Clypeus small, with weakly convex anterior margin. Antenna long and slender: scape exceeding posterior margin of head by ca. 1/5 its length; 2nd segment 2.5 times as long as wide, 3rd to 11th segments each longer than wide, the ratio of 2nd to 5th segments about 5: 10.5 : 9 : 8 in length from the base; terminal segment 6.7 times as long as wide. Eye weakly convex, 0.38 mm in maximum diameter, and situated anterior 2/7 of head.

Dorsal outline of pronotum moderately convex; in dorsal view disc 1.13 mm in maximum width, 1.2 times as long as wide, with convex sides. Dorsal outline from mesonotum to anterior 1/4 of propodeum shallow v-shaped; posterior 3/4 of propodeal dorsum straight; posterolateral corner of propodeum dully angulate in profile.

Petiole higher than long, with acute triangular tip; anterior margin weakly convex, posterior margin almost straight; subpetiolar process developed, with convex ventral margin; in dorsal view, node 1.5 times as long as wide, widest at posteriormost. Gaster oval; 1st gastral tergite 1.24 mm in maximum width in dorsal view.

Sculpture: Frons of head with many thin longitudinal striae; vertex smooth and shining; maler space and genal area smooth and shining. Mandible smooth and shining. Antenna weakly microreticulate. Pronotum semicircularly striate; mesonotum with weak transverse striae; mesopleura smooth and shining excepting anterior and posterior potions weakly striate; propodeum with many transverse striae. Petiole smooth and shining. Gaster smooth and shining. Legs smooth.

Pilosity: Dorsum of head scattered with short erect pubescences; frons with a pair of long erect setae which are ca. 0.25 mm in length; frontal lobe with a long erect seta which is ca. 0.20 mm in length. Dorsum of alitrunk and petiolar node with short decumbent pubescences and without distinct setae. First gastral tergite with moderately abundant long suberect setae which are 0.15–0.24 mm in length; 2nd to 5th terga with long erect to suberect setae. Antenna and legs with short pubescences.

Color: Head brown; alitrunk and petiole blackish brown; gaster brown; legs yellow; mandible brown; antenna yellow excepting scape brown.

Type Material
Holotype. Worker, Ulu Gombak, Malaysia, 29.viii.2009, F. Ito leg. [FI109-83]. Paratypes. All the locality is the same as holotype: 5 workers, 10.iii.1999, F. Ito leg. [FI99-133]; 15 workers, 12.iii.1999, F. Ito leg. [FI99-138]; 2 workers, 9.vi.1999, F. Ito leg. [FI99-251]; 1 worker, 14.xii.2004, F. Ito leg. [FI04-29]; 2 workers, 20.xii.2004, F. Ito leg. [FI04-127]; 1 worker, 21.xii.2004, Y. Ikeshita leg.; 1 worker, 22.xii.2004, Y. Ikeshita leg.; 9 workers, 29.viii.2009, F. Ito leg. [FI09-83]; 3 workers, 30.viii.2009, F. Ito leg. [FI09-91]; 1 worker, 31.viii.2009, [FI09-93]; 9 workers, 1.ix.2009, F. Ito leg. [FI09-107]; 1 worker, 16.iii.2011, F. Ito leg. [FI11-80]; 4 workers, 27.iii.2012, F. Ito leg. [FI12-43].

Type depository. The holotype and some paratypes are deposited in the National Institute for Agro-Environmental Sciences, Tsukuba, Japan, and other paratypes are in the Bogor Zoological Museum, Cibinong, Indonesia, and Thailand National Science Museum, Khlong Luang, Thailand.

Etymology
The specific epithet pararixosus is a compound word meaning ‘similar to rixsosus’.