Crematogaster brunensis

The type material was collected from a fogging sample. Heterick & Kitching (2022) collected this species in the canopy of a lowland dipterocarp forest in Brunei.

Identification
Hosoishi and Ogata (2016) - In the worker this species can be distinguished from all other members of the Crematogaster baduvi group by the smooth and shining surface of mesosoma, smooth surface of propodeal dorsum, and propodeal spines developed straight at the tip. This species is similar to C. baduvi, but can be distinguished from it by the smaller head (HW 0.43–0.47, HL 0.46–0.49 vs. 0.47–0.57 and 0.48–0.59 in the latter) and longer propodeal spines (PSL 0.20–0.22 vs. 0.15–0.21).

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

Nomenclature

 * . Crematogaster brunensis Hosoishi & Ogata, 2016a: 579, fig. 102 (w.) BORNEO (Brunei).
 * Type-material: holotype worker, 5 paratype workers.
 * Type-locality: holotype Brunei: nr Lamunin, Bukit Sulang, BM1982-388, fogging, 20.viii.-10.ix.1982 (N.E. Stork); paratypes with same data.
 * Type-depositories: BMNH (holotype); CASC, KUEC, MBSM, MHNG, TNHM (paratypes).
 * Distribution: Brunei.

Worker
(n = 6): HW 0.43–0.47; HL 0.46–0.49; CI 92–100; SL 0.51–0.53; SI 113–118; EL 0.12–0.13; PW 0.26–0.29; WL 0.60–0.63; PSL 0.20–0.22; PtL 0.23–0.26; PtW 0.14–0.17; PtH 0.14–0.15; PpL 0.12–0.13; PpW 0.15–0.17; PtHI 56–61; PtWI 60–67; PpWI 123–133; WI 100–107.

Workers monomorphic. Head round in full-face view. Mandibles with four teeth arranged at an equal distance, apical and subapical teeth large, basal two teeth smaller. Anterior clypeal margin convex in medial portion. Compound eyes distinctly projecting beyond lateral margins of head in full-face view. Scapes exceeding posterolateral corners of head.

Pronotal collar with concave anterior margin in dorsal view, slightly lower than pronotum in lateral view. Pronotal dorsum without distinct ridges laterally. Mesonotal dorsum with lateral ridges that irregularly extend posteriad to tips of propoedal spines. Pronotum and mesonotum in lateral view forming evenly arched, continuous dorsal outline. Metanotal groove in dorsal view transverse, almost straight in median portion, forming shallow concavity that is laterally margined by ridges. Propodeal spiracles oval, situated at posterolateral corners of propodeum, apart from metapleural gland bullae. Propodeal spines developed, longer than diameter of propodeal spiracles, in dorsal view strongly divergent.

Petiole in dorsal view with subparallel sides and narrow short peduncle anteriorly, distinctly longer than wide. Posterior portion of petiole with short process that is slightly higher than posterior margin of petiole disc in lateral view. Subpetiolar process undeveloped. Postpetiole in lateral view with strongly convex dorsum, distinctly higher than petiole, in dorsal view as wide as petiole, globular, not bilobed. Subpostpetiolar process undeveloped, but venter of postpetiole convex.

Integument essentially smooth and shining. Dorsal surface of head smooth and shining. Mandibles with feeble rugulae and smooth interspaces. Clypeus generally smooth and shining, but with one pair of longitudinal rugulae; rugulae not extending to the posterior clypeal margin. Dorsal and lateral surfaces of pronotum smooth and shining; anterolateral shoulders of pronotum with feeble rugulae. Mesopleura generally sculptured, but sometimes smooth except for their marginal areas in some specimens. Dorsal surface of propodeum generally smooth and shining, but with rugulae dorsolateral areas. Dorsal surface of petiole smooth and shining. Lateral surface of petiole weakly sculptured. Dorsal and lateral surfaces of postpetiole smooth and shining.

Standing pilosity sparse. Dorsal face of head with long erect (three pairs) and short appressed setae sparsely. Clypeus with two pairs of long setae in anterior portion, one directed upward and the other downward. Anterior clypeal margin with one pair of long setae medially and some pairs of short setae laterally. Scapes with suberect to decumbent setae. Mesosoma with three pairs of long erect and stout setae (ps1PN, psaMN, and pspMN) that are much longer than other erect setae. Posterolateral tubercles of petiole posteriorly with one pair of long setae. Postpetiole with two pairs of long setae on disc anteriorly, posteriorly. Fourth abdominal tergite with erect setae sparsely, but no decumbent to appressed setae.

Body red-brown. Apical two flagellar segments light yellow, contracting with other flagellar segments that are yellow.

Type Material
Holotype worker. nr. Lamunin, Bukit Sulang, BRUNEI, B. M. 1982-388 Fogging, 20.viii–10.ix.1982 (N. E. Stork). Paratypes. Five workers, same data as holotype.

Etymology
The specific name refers to the country of origin, Brunei.

References based on Global Ant Biodiversity Informatics

 * Hosoichi S., and K. Ogata. 2016. Systematics and biogeography of the ant genus Crematogaster Lund subgenus Orthocrema Santschi in Asia (Hymenoptera: Formicidae). Zoological Journal of the Linnean Society 176: 547–606.