Crematogaster biroi

Nests in soil.

Identification
Hosoishi and Ogata (2016) - In the worker this species is very distinct among the C. biroi group in having the sculptured surface near occipital carinae of head, the strongly developed subpetiolar process, and acutely developed subpostpetiolar process.

Distribution based on Regional Taxon Lists
Oriental Region: India, Sri Lanka , Sri Lanka , Taiwan. Palaearctic Region: China.

Biology
In this and other species belonging to the subgenus Orthocrema, a third caste exists in addition to winged queens and workers; it is intermediate in size, weight and morphology. These individuals are numerically few in the colonies, and lay many unfertilized eggs that are mostly eaten by larvae. Histology confirmed the lack of a spermatheca. Using scanning electron microscopy and ovarian dissections, Peeters et al. (2013) showed that this third caste is a patchwork of queen-like and worker-like traits (refer to Crematogaster pygmaea). It is a soldier caste with a specialized trophic function.

Nomenclature

 *  biroi. Crematogaster biroi Mayr, 1897: 428 (w.) SRI LANKA. Bingham, 1903: 138 (q.); Imai, et al. 1984: 6 (k.). Combination in C. (Orthocrema): Emery, 1922e: 131. Senior synomym of aitkenii, smythiesii, urvijae: Hosoishi & Ogata, 2016: 577.
 * aitkenii. Crematogaster biroi var. aitkenii Forel, 1902c: 203 (w.) INDIA. Combination in C. (Orthocrema): Emery, 1922e: 132. Raised to species: Wu & Wang, 1992: 1319. Junior synonym of biroi: Hosoishi & Ogata, 2016: 577.
 * smythiesii. Crematogaster biroi var. smythiesii Forel, 1902c: 203 (w.q.) INDIA. Combination in C. (Orthocrema): Emery, 1922e: 132. Junior synonym of biroi: Hosoishi & Ogata, 2016: 577.
 * urvijae. Crematogaster (Crematogaster) urvijae Bharti, 2003c: 85, figs. 1-9 (w.q.) INDIA. Junior synonym of biroi: Hosoishi & Ogata, 2016: 577.

Type Material
Hosoishi and Ogata (2016) - Syntype workers, Columbo, Sri Lanka (Biró) (, examined). One syntype worker (with label of 160) in HNHM from Columbo here designated Lectotype.

Worker
Hosoishi and Ogata (2016) - (n=10) HW 0.44–0.55; HL 0.45–0.52; CI 98–106; SL 0.33–0.39; SI 70–75; EL 0.09–0.13; PW 0.30–0.34; WL 0.49–0.58; PSL 0.09–0.12; PtL 0.16–0.19; PtW 0.13–0.17; PtH 0.12–0.15; PpL 0.10–0.13; PpW 0.14–0.17; PtHI 72–82; PtWI 78–89; PpWI 125–141; WI 100–108.

Workers monomorphic, but intermediate worker as large as queen (details below).

Head subquadratic 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 reaching posterolateral corners of head.

Pronotal collar with almost straight anterior margin in dorsal view, distinctly lower than pronotum in lateral view. Pronotal dorsum with feeble ridges laterally. Mesonotal dorsum with lateral ridges that irregularly extend posteriad to tips of propodeal spines. Pronotum and mesonotum in lateral view forming slightly convex, continuous dorsal outline. Metanotal groove in dorsal view transverse, almost straight in median portion, forming deep concavity that is laterally margined by lamellate 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 directed posteriad.

Petiole in dorsal view with parallel sides and angulate shoulders anteriorly, 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 strongly developed as acute process. Postpetiole in lateral view with weakly convex dorsum, as high as petiole, in dorsal view as wide as or slightly wider than petiole, weakly bilobed posteriorly but without longitudinal sulcus. Subpostpetiolar process developed as process.

Integument essentially sculptured. Dorsal surface of head generally smooth on central region, but weakly sculptured reticulately laterally. Occipital region near margin weakly sculptured. Mandibles with feeble rugulae and smooth interspaces. Clypeus generally smooth, but with two distinct pairs of longitudinal rugulae and weakly sculptured interspaces; rugulae not extending to posterior clypeal margin. Anterolateral shoulders of pronotum with rugulae. Pronotum and mesonotum with longitudinal rugulae and sculptured interspaces. Lateral surface of pronotum smooth and shining on central portion, but weakly sculptured on surrounding. Mesopleura weakly sculptured, but relatively smooth in central areas. Rugula on higher portion of mesopleura extending to small pit of mesothoracic spiracles. One pair of rugulae running from metanotal groove to tips of propodeal spines (rugulae on mesonotum extending posteriorly to propodeal spines). Dorsal surface of propodeum weakly sculptured. Dorsal and lateral surfaces of petiole sculptured. Dorsal surface of postpetiole smooth and shining. Lateral surface of postpetiole weakly sculptured.

Standing pilosity sparse. Dorsal face of head with several pairs (six to seven) of erect and stout setae, and short and appressed setae abundantly. Clypeus with two pairs of long setae in anterior portion, one directed upward and the other downward. Anterior clypeal margin with two pairs of long setae medially and some pairs (three to four) of short setae laterally. Scapes with suberect setae. Mesosoma with four pairs of long erect and stout setae (ps1PN, psaMN, pspMN, and ps1PS) that are much longer than other erect setae. Posterolateral tubercles of petiole posteriorly with one pair of stout setae. Postpetiole with one pair of stout setae on disc posteriorly. Fourth abdominal tergite with three or six pairs of erect and stout setae, and short appressed setae abundantly.

Body yellow. All flagellar segments yellow.

Intermediate (n = 1): HW 0.82; HL 0.79; CI 104; SL 0.48; SI 59; EL 0.21; PW 0.58; WL 0.98; PSL 0.18; PtL 0.35; PtW 0.28; PtH 0.25; PpL 0.21; PpW 0.32; PtHI 71; PtWI 80; PpWI 152; WI 114.

With worker character conditions, except as follows.

Head subquadratic.

Mesonotum highly convex in lateral view. Mesonotal dorsum without lateral ridges. Pronotum forming same dorsal outline with mesonotum in lateral view, but posterior face forming vertical slope to metanotal groove. Propodeal spiracles elliptical.

Subpostpetiolar area not observable in the specimen examined.

Clypeus with some longitudinal rugulae: rugulae extending to frontal region between frontal carinae.

Dorsal face of head with erect setae sparsely. Clypeus with one pair of long setae around antennal bases; directed upper. Mesosoma without distinct erect setae. Fourth abdominal tergite with short decumbent to appressed setae sparsely.