Crematogaster macracantha

Heterick & Kitching (2022) collected this species on tree trunks within a lowland dipterocarp forest in Brunei.

Identification
Hosoishi and Ogata (2016) - Orthocrema subgenus, Crematogaster baduvi group: clearly differentiated two-segmented antennal club; laterally directed propodeal spines; petiole with subparallel sides; node-like process on posterior portion of petiole; highly convex postpetiolar dorsum; and subpostpetiolar venter convex.

In the worker this species can be easily distinguished from the other species of the Crematogaster baduvi group by the long propodeal spines (PSL 0.50–0.59 vs. 0.15–0.22 in the others) and sculptured surface of the body.

Distribution
Malaysia (Borneo)

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

Nomenclature

 * . Crematogaster (Rhachiocrema) macracantha Creighton, 1945: 114, pl. 12, figs. 4, 5 (w.) BORNEO (East Malaysia: Sarawak).
 * Type-material: 30 syntype workers.
 * Type-locality: Malaysia: Borneo, Sarawak, Mt Penrissen (E. Mjöberg).
 * Type-depository: LACM (probably also in MCZC, NHRS).
 * Status as species: Bolton, 1995b: 157; Pfeiffer, et al. 2011: 45; Hosoishi & Ogata, 2016a: 586 (redescription).
 * Distribution: Malaysia (Sabah, Sarawak).

Worker
Hosoishi and Ogata (2016) - (n=3) HW 0.57–0.60; HL 0.61–0.63; CI 93–98; SL 0.65–0.68; SI 111–114; EL 0.14–0.15; PW 0.38–0.39; WL 0.84–0.89; PSL 0.50–0.59; PtL 0.37–0.38; PtW 0.21–0.25; PtH 0.19–0.22; PpL 0.18–0.20; PpW 0.22–0.24; PtHI 50–58; PtWI 57–66; PpWI 118–122; WI 88–105.

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 longitudinal ridges laterally. Mesonotal dorsum with lateral ridges that irregularly extend posteriad to tips of propodeal 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 deep concavity that is laterally margined by ridges. Propodeal spiracles oval, situated at posterolateral corners of propodeum, apart from metapleural gland bullae. Propodeal spines developed, distinctly 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 developed as acute tubercle. 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 sculptured. Dorsal surface of head smooth and shining. Mandibles with rugulae and smooth interspaces. Clypeus generally smooth and shining, but with one distinct pair of longitudinal rugulae; distinct rugulae not extending to posterior clypeal margin. Anterolateral shoulders of pronotum with feeble rugulae. Dorsal surface of pronotum sculptured reticulaterly. Lateral surface of pronotum weakly punctate. Mesopleura generally sculptured. Dorsal surface of propodeum sculptured. Dorsal and lateral surfaces of petiole sculptured. Dorsal and lateral surfaces of postpetiole weakly sculptured.

Standing pilosity sparse. Dorsal face of head with three pairs of long erect setae and 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 decumbent to appressed setae. Mesosoma with three pairs of long erect and stout setae (ps1PN, ps2PN, and psaMN) that are much longer than other erect setae. Posterolateral tubercles of petiole posteriorly with one pair of long setae. Postpetiole with three pairs of long setae on disc anteriorly, posteriorly and laterally. Fourth abdominal tergite with erect setae sparsely, but no decumbent to appressed setae.

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

Type Material
Mt. Penrissen, Sarawak, Borneo. Described from a series of thirty workers taken by E. Mjoberg and given to me many years ago by Dr. W. M. Wheeler.

References based on Global Ant Biodiversity Informatics

 * Creighton W. S. 1945. Observations on the subgenus Rhachiocrema (Hymenoptera: Formicidae) with the description of a new species from Borneo. Psyche (Cambridge) 52: 109-118.
 * 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.
 * Hosoishi S. and K. Ogata. 2009. A check list of the ant genus Crematogaster in Asia (Hymenoptera: Formicidae). Bull. Inst. Trop. Agr. Kyushu Univ. 32: 43-83.
 * 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