Rotastruma recava

Bolton noted that nests contained more than one dealate queen. Specimens have been collected in rainforest from dead twigs.

Identification
This species is easily distinguished from Rotastruma epispina and Rotastruma stenoceps by the concave occipital margin, convex lateral margin of head and sides of head not having hairs in the worker caste (Hosoishi et al., 2021).

Distribution based on Regional Taxon Lists
Indo-Australian Region: Borneo, Indonesia, Malaysia, Singapore.

Nomenclature

 * . Rotastruma recava Bolton, 1991: 9, figs. 12, 14 (w.q.) BORNEO (East Malaysia: Sarawak), SINGAPORE.
 * Type-material: holotype worker, 20 paratype workers, 4 paratype queens.
 * Type-locality: holotype Malaysia: Sarawak, 4th Division, G. Mulu N.P., 22.v.1978, mixed dipterocarp forest, on tree (N.M. Collins); paratypes: 18 workers, 2 queens Singapore: Bukit Timah Forest, 15.iii.1973 (D.H. Murphy), 2 workers, 2 queens Singapore: Bukit Timah, 100 m., 8.iv.1989, no. 10254, ex dead twig, vine, rainforest (P.S. Ward).
 * Type-depositories: BMNH (holotype); BMNH, MCZC, MHNG (paratypes).
 * Status as species: Bolton, 1995b: 382; Pfeiffer, et al. 2011: 51.
 * Distribution: Malaysia (Sarawak), Singapore.

Worker
Holotype. TL 3.6, HL 0.80, HW 0.69, CI 86, SL 0.56, SI 81, PW 0.48, AL 0.94. Maximum diameter of eye 0.24 (0.35 x HW). Mandibles finely longitudinally striolate. Central strip of dorsum of head with a number of longitudinal costulae which may run the length of the head or may be broken or interrupted. Occipital margin distinctly concave in full-face view, the sides of the head in front of the large eyes convex. Median portion of clypeus with 3 longitudinal carinae. Dorsal alitrunk with predominantly longitudinal sharp rugulae; cross-meshes present, especially on pronotum. Sides of alitrunk marginate, margination sharpest on mesonotum and propodeum. Propodeal spines long, depressed and down-curved along their length. Sides of alitrunk with weak longitudinal rugulae. Petiole and postpetiole rugulose to reticulate-rugulose dorsally. First gastral tergite unsculptured except for sparse short basi gastral costulae and feeble superficial reticular patterning. Standing hairs present on all dorsal surfaces, short fine and acutely pointed. Colour yellow, the first gastral tergite with a broad brown band.

Paratype. TL 3.6-4.0, HL 0.80-0.84, HW 0.66-0.70, CI83-86, SL 0.56-0.60, SI 81-86, PW 0.48-0.52, AL 0.94-1.02. Maximum diameter of eye 0.24-0.26 (0.35-0.37 x HW) (10 measured). As holotype.

Queen
Paratype. TL 3.9-4.0, HL 0.80-0.81, HW 0.69-0.70, CI 85-86, SL 0.54-0.56, Sl 78-81, PW 0.56-0.58, AL 1.08-1.12. Maximum diameter of eye 0.26-0.28 (0.37-0.40 x HW) (4 measured). The females are small, only the same size as the workers or slightly larger. Alate when virgin and with a complete complement of flight sclerites.

Type Material
Holotype worker, East Malaysia: Sarawak, 4th Division G. Mulu NP, 22.v.1978, mixed dipterocarp forest, on tree (N. M. Collins).

Paratypes, 18 workers and 2 females, Singapore: Bukit Timah Forest, 15.iii.1973 (D. H. Murphy); 2 workers and 2 females, Bukit Timah, 100 m, 8.iv.1989, no. 10254, ex dead twig, vine, rainforest (P. S. Ward) (BMNH; ; ).

Based on Hosoishi et al. (2021): Holotype and one paratype worker images examined.
 * Holotype: Malaysia • worker; Sarawak, 4th Division G. Mulu NP; 22 May 1978; N. M. Collins leg.; type image CASENT0901995 of AntWeb (http://www.antweb.org/); BMNH.
 * Paratype: SINGAPORE • one worker; Bukit Timah Forest; 15 Mar 1973; D. H. Murphy leg.; type image CASENT0178523 of AntWeb (http://www.antweb.org/); MCZC.

References based on Global Ant Biodiversity Informatics

 * Bolton B. 1991. New myrmicine genera from the Oriental Region (Hymenoptera: Formicidae). Systematic Entomology 16:1-13.
 * Pfeiffer M.; Mezger, D.; Hosoishi, S.; Bakhtiar, E. Y.; Kohout, R. J. 2011. The Formicidae of Borneo (Insecta: Hymenoptera): a preliminary species list. Asian Myrmecology 4:9-58
 * Zryanin V. A. 2011. An eco-faunistic review of ants (Hymenoptera: Formicidae). In: Structure and functions of soil communities of a monsoon tropical forest (Cat Tien National Park, southern Vietnam) / A.V. Tiunov (Editor). – M.: KMK Scientific Press. 2011. 277 р.101-124.