Crematogaster treubi

Heterick & Kitching (2022) collected this species in a canopy malaise trap within a lowland dipterocarp forest in Brunei.

Identification
A member of the Crematogaster irritabilis group. Hosoishi and Ogata (2012) - This species is similar to C. kojimai, but can be distinguished by the long and slender propodeal spines.

Slight morphological variations are found not only in the specimens collected from different localities, but also within nest series collections. Some specimens collected in Bali have shorter propodeal spines in contrast to the usual long and slender spines. The mesopleuron is relatively smooth and shining in most specimens, but especially shining in Sepilok specimens or somewhat shagreened in Pulau Sebeku specimens. These variants are treated as intraspecific variation within C. treubi until molecular data are available.

Distribution based on Regional Taxon Lists
Indo-Australian Region: Brunei Darussalam, Indonesia, Malaysia, Singapore. Oriental Region: Cambodia, Laos, Myanmar, Thailand. Palaearctic Region: China.

Nomenclature

 * . Crematogaster treubi Emery, 1896f: 246 (w.) INDONESIA (Java).
 * Type-material: lectotype worker (by designation of Hosoishi & Ogata, 2012: 25), 2 paralectotype workers.
 * Type-locality: lectotype Indonesia: Java, Buitenzorg (= Bogor) (Massart); paralectotypes with same data.
 * Type-depositories: MSNG (lectotype); MHNG (paralectotypes).
 * Combination in C. (Orthocrema): Emery, 1922e: 132;
 * combination in C. (Acrocoelia): Santschi, 1928b: 34;
 * combination in C. (Mesocrema): Santschi, 1937e: 310.
 * Status as species: Emery, 1900d: 689; Emery, 1901g: 567; Emery, 1922e: 132; Stärcke, 1930: 374; Menozzi, 1935a: 106; Chapman & Capco, 1951: 99; Bolton, 1995b: 164; Terayama, 2009: 178 (in key); Hosoishi & Ogata, 2012: 25 (redescription); Jaitrong, Guénard, et al. 2016: 36; Khachonpisitsak, et al. 2020: 94.
 * Senior synonym of millardi: Hosoishi & Ogata, 2012: 25.
 * Senior synonym of sic: Forel, 1911a: 25 (in text); Emery, 1922e: 132; Bolton, 1995b: 164.
 * Senior synonym of vastatrix: Hosoishi & Ogata, 2012: 25.
 * Distribution: Brunei, Cambodia, Indonesia (Bali, Java, Kalimantan, Sulawesi, Sumatra, Sunda Strait), Malaysia (Peninsula, Sabah, Sarawak), Myanmar, Thailand.
 * Current subspecies: nominal plus apilis.
 * millardi. Crematogaster millardi Forel, 1902c: 205 (w.) MYANMAR.
 * Type-material: lectotype worker (by designation of Hosoishi & Ogata, 2012: 25), 1 paralectotype worker.
 * Type-locality: lectotype Myanmar (“Burma”): Moulmain (Hodgson); paralectotype with same data.
 * Type-depository: MHNG.
 * Viehmeyer, 1916a: 125 (q.).
 * Combination in C. (Orthocrema): Emery, 1922e: 132;
 * combination in C. (Mesocrema): Santschi, 1928b: 33.
 * Status as species: Forel, 1903a: 684; Bingham, 1903: 135; Viehmeyer, 1916a: 125; Emery, 1922e: 132; Stärcke, 1930: 374; Menozzi, 1935a: 112 (in key); Chapman & Capco, 1951: 98; Bolton, 1995b: 157; Guénard & Dunn, 2012: 42.
 * Junior synonym of treubi: Hosoishi & Ogata, 2012: 25.
 * sic. Crematogaster buddhae r. sic Forel, 1907a: 24 (w.) WEST MALAYSIA.
 * Type-material: syntype workers (number not stated).
 * Type-locality: Malaysia: Malacca, Kuala Lumpur (L. Biró).
 * Type-depositories: HNHM, MHNG.
 * Junior synonym of treubi: Forel, 1911a: 25 (in text); Emery, 1922e: 132; Bolton, 1995b: 162.
 * vastatrix. Crematogaster treubi var. vastatrix Forel, 1911a: 24 (w.q.) INDONESIA (Java).
 * Type-material: lectotype worker (by designation of Hosoishi & Ogata, 2012: 25), 7 paralectotype workers.
 * [Note: original syntype queen is not mentioned by Hosoishi & Ogata, 2012: 25.]
 * Type-locality: lectotype Indonesia: Java (Roepke); paralectotypes with same data.
 * Type-depositories: MHNG (lectotype); MHNG, NHMB (paralectotypes).
 * Combination in C. (Orthocrema): Emery, 1922e: 132;
 * combination in C. (Acrocoelia): Santschi, 1928b: 34.
 * Subspecies of treubi: Forel, 1912n: 57; Emery, 1922e: 132; Menozzi, 1935a: 113 (in key); Chapman & Capco, 1951: 99; Bolton, 1995b: 165.
 * Junior synonym of treubi: Hosoishi & Ogata, 2012: 25.

Worker
Hosoishi and Ogata (2012) - HW 0.51-0.74; HL 0.52-0.71; CI 94-104; SL 0.34-0.51; SI 65-74; EL 0.1-0.15; PW 0.28-0.44; WL 0.57-0.81; PSL 0.04-0.1; PtL 0.15-0.22; PtW 0.16-0.22; PtH 0.1-0.14; PpL 0.1-0.15; PpW 0.15-0.19; PtHI 55-78; PtWI 91-111; PpWI 113-150; WI 81-100 (Seventeen workers measured).

Workers monomorphic.

Compound eyes not projecting from lateral margin of head, the outer margin of eye almost flush with head capsule in full face view. Scape not reaching posterior corner of head, the scape with standing setae.

Anterior margin of pronotal collar almost straight or slightly concave in dorsal view. Metanotal groove shallow. Propodeal spines long and slender, their length longer than the diameter of propodeal spiracles. Anterior margin of metapleural gland bulla reaching or exceeding anterior margin of propodeal spiracle. Petiole in dorsal view broader anteriorly than posteriorly. Postpetiole weakly bilobed, without distinct longitudinal median sulcus. Subpetiolar and subpostpetiolar processes undeveloped.

Clypeus relatively smooth and shining, but with feeble rugulae. Dorsal face of mesosoma almost smooth and shining. Dorsolateral face of pronotum smooth in dorsal view. Lateral surface of pronotum smooth and shining. Lateral surface of mesonotum with rugulae. Mesopleuron relatively smooth and shining, but the anterodorsal and lower portions weakly sculptured. Longitudinal rugulae developed anteriorly and posteriorly of the metanotal groove in lateral view.

Dorsal face of head, clypeus and mesosoma with abundant standing setae. Fourth abdominal tergite with sparse standing setae.

Type Material
Hosoishi and Ogata (2012) - LECTOTYPE worker ( worker) (by present designation) and two paralectotype workers from INDONESIA: Java (M. Massart) [examined].

Crematogaster treubi type material

Lectotype designated by Hosoishi & Ogata, 2012: 25.

Crematogaster millardi type material

Lectotype designated by Hosoishi & Ogata, 2012: 25.

Crematogaster treubi vastatrix type material

Lectotype designated by Hosoishi & Ogata, 2012: 25.

References based on Global Ant Biodiversity Informatics

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