Crematogaster rothneyi

Crematogaster rothneyi is known from South Asia to Southeast Asia, making it one of the most widely distributed ant species in Asia. However, the species is rarely encountered in the field (Hosoishi & Ogata, 2019).

Identification
Hosoishi and Ogata (2019) - C. rothneyi is easily distinguished from other subgenus Crematogaster species by its strongly sculpted body, deep metanotal groove, distinctly bilobed postpetiole and stout body setae.

This species is very similar to Crematogaster yaharai, but can be distinguished by the broader than long antennal segments V to VI, sculptured mesopleuron, and reticulately or areolately sculptured propodeum. The Indian specimen examined does not have distinctly developed longitudinal rugulae on the higher half of the dorsal surface of the head. The Thai specimens have broader or as broad as long antennal segments V and VI and a sculptured propodeal dorsum.

Distribution based on Regional Taxon Lists
Indo-Australian Region: Indonesia, Philippines. Oriental Region: Bangladesh, Cambodia, India, Myanmar, Thailand, Vietnam. Palaearctic Region: China.

Biology
This species is arboreal and inhabits lowland forests.

Nomenclature

 *  rothneyi. Crematogaster rothneyi Mayr, 1879: 685 (w.) INDIA.
 * [Crematogaster rothneyi Smith, F. 1873: viii. Nomen nudum, attributed to Mayr.]
 * Imai, et al. 1984: 6 (k.).
 * Combination in C. (Acrocoelia): Emery, 1922e: 151.
 * Combination in C. (Crematogaster): Bolton, 1995b: 166.
 * Senior synonym of civa: Hosoishi & Ogata, 2019: 6.
 * Current subspecies: nominal plus haputalensis.
 * civa. Crematogaster rothneyi var. civa Forel, 1902c: 203 (w.) INDIA.
 * Combination in C. (Acrocoelia): Emery, 1922e: 151.
 * Combination in C. (Crematogaster): Bolton, 1995b: 166.
 * Junior synonym of rothneyi: Hosoishi & Ogata, 2019: 6.

Taxonomic Notes
The syntype workers of C. rothneyi civa match well with syntype workers of C. rothneyi. We treated C. rothneyi civa as a junior synonym of C. rothneyi (Hosoishi & Ogata, 2019).

Worker
Hosoishi and Ogata (2019) - Polymorphic workers with moderate size variation.

Head subquadrate in full-face view, with weakly concave posterior margin, angular posterior corners and convex sides. Occipital carinae developed. Mandible with four teeth, apical and subapical teeth large. Anterior margin of clypeus convex with slightly impressed median portion; anterolateral margins of clypeus protruded anteriorly; posterior margin of clypeus rounded between frontal lobes. Frontal carinae almost parallel. Antennae 11 segmented; relative scape length variable with worker size (SI, 99-117); SI lower in larger specimens; antennal club 3-segmented. Scape exceeding posterior corner of head by 1/4 of its length or more. Antennal segments V and VI each broader than long or as broad as long. Compound eyes distinctly projecting beyond lateral margins of head in full-face view, especially in large workers.

Pronotum and mesonotum fully fused without defined suture. In lateral view, posterior half of dorsolateral margin of mesonotum forming triangle shaped process, anterior half forming almost flat outline. Mesothoracic spiracle reduced to form small pit dorsoventrally. Metapleural gland opening slit-shaped. Propodeal spiracle elliptical, situated at posterolateral corner, apart from metapleural gland bulla. Metanotal groove straight in dorsal view, deep and forming concave region between mesonotum and propodeum. In dorsal view, longitudinal rugulae not connecting between mesonotum and propodeum; the boundary distinct. Propodeal spines developed; length variable in several specimens.

Petiole scoop-shaped, broader anteriorly, longer than broad in dorsal view; spiracle situated at midportion between dorsal and ventral margin of petiole in lateral view, directed posterolaterally. Postpetiole with distinct longitudinal median sulcus, bilobed in dorsal view; spiracle situated anteriorly on lateral surface in lateral view. Dorsum of head sculptured with longitudinal rugulae, but weakly developed on posterior half. Clypeus with longitudinal rugulae. Promesonotum sculptured reticulately or areolately. Mesopleuron densely sculptured in Indian specimen, or central region of mesopleuron smooth with weakly sculptured surrounding in other specimens. Dorsal surface of propodeum sculptured reticulately. Lateral surface of propodeum sculptured reticulately or areolately. Dorsal and lateral surface of petiole sculptured. Dorsal and lateral surface of postpetiole sculptured. Median sulcus of postpetiole smooth.

Standing pilosity sparse. Dorsum of head with short and erect setae. Clypeus with some pairs of erect setae. Anterior clypeal margin with one pair of long setae mixed with short setae laterally. Mesonotal dorsum with sparse erect setae. Petiole with suberect setae. Postpetiole with suberect setae. Fourth abdominal tergite with sparse erect setae.

Body almost entirely yellow, or brown, except for antenna yellowish.

Type Material
Hosoishi and Ogata (2019) - Lectotype worker (by present designation) and two paralectotype workers, INDIA, Calcutta (Rothney leg.). Type locality: INDIA, Calcutta (Rothney) (NHMW).