Crematogaster masukoi

Crematogaster masukoi inhabits developed forests and nests in soil. The reduced eyes and depigmented yellowish body suggest this species is a subterranean species.

Identification
Hosoishi and Ogata (2016) - In the worker this species is very distinct among the Crematogaster biroi group in having reduced compound eyes (with c. 6 ommatidia). It is similar to Crematogaster myops (Crematogaster quadriruga group) in having reduced compound eyes, but can be easily distinguished from it by the smooth surface of clypeus, developed subpetiolar process and acutely developed subpostpetiolar process.

Distribution
This species is known from Borneo (Malaysia:Sabah; Indonesia: Kalimantan).

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

Castes
Known only from the worker caste.

Nomenclature

 *  masukoi. Crematogaster (Orthocrema) masukoi Hosoishi, Yamane & Ogata, 2010b: 347, figs. 1-3, 5 (w.) BORNEO.

Worker
Hosoishi and Ogata (2016) - (n=6) HW 0.46–0.50; HL 0.44–0.48; CI 100–109; SL 0.35–0.37; SI 74–78; EL 0.04–0.06; PW 0.28–0.31; WL 0.53–0.57; PSL 0.08–0.11; PtL 0.16–0.18; PtW 0.16–0.17; PtH 0.11–0.13; PpL 0.10–0.12; PpW 0.15–0.16; PtHI 61–76; PtWI 94–106; PpWI 133–160; WI 88–100.

Monomorphic. Head subquadratic in full-face view. Mandibles with four teeth, basal tooth arranged away from the third apical one, apical and subapical teeth large, basal two teeth smaller. Anterior clypeal margin weakly convex or almost straight in medial portion. Compound eyes not 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 without distinct ridges laterally. Mesonotal dorsum without lateral ridges. 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 thin lamellate ridges. Propodeal spiracles oval, situated at posterolateral corners of propodeum, touching metapleural gland bullae. Propodeal spines developed, longer than diameter of propodeal spiracles, in dorsal view directed posteriad.

Petiole in dorsal view with subparallel sides or weakly convex sides and narrow anteriorly, longer than wide. Posterior portion of petiole without distinct process in lateral view. Subpetiolar process developed, acute apically. Postpetiole in lateral view with weakly convex dorsum, as high as petiole, in dorsal view as wide as or slightly narrower than petiole, weakly bilobed posteriorly, but without longitudinal sulcus. Subpostpetiolar process developed as small process.

Integument weakly sculptured. Dorsal surface of head generally smooth, but with rugulae on surrounding region of antennal sockets. Mandibles with feeble rugulae and smooth interspaces. Clypeus smooth and shining without distinct longitudinal rugulae. Dorsal and lateral surfaces of pronotum smooth and shining; anterolateral shoulders of pronotum without rugulae. Mesopleura smooth on central areas, but sculptured with rugulae on their marginal areas. Rugula on higher portion of mesopleura developed. One pair of rugulae running from metanotal groove extending posteriorly and diverging to propodeal spines. Horizontal rugula on dorsal surface of propodeum interruptedly extending to tips of propodeal spines. Dorsal surface of propodeum sculptured. Lateral surface of propodeum generally smooth and shining, but weakly sculptured with rugulae on anterior areas. Dorsal surface of petiole generally smooth. Lateral surface of petiole weakly sculptured. Dorsal surface of postpetiole smooth and shining. Lateral surface of postpetiole weakly sculptured.

Standing pilosity sparse. Dorsal face of head with three pairs of long erect and stout setae, and short and appressed setae sparsely. Clypeus with two pairs of long and stout setae in anterior portion, one directed upward and the other downward. Anterior clypeal margin with one single short setae medially and one pair of long setae laterally, and some pair of short setae laterally. Scapes with suberect to decumbent setae. Mesosoma with five pairs of long erect and stout setae (ps1PN, psaMN, pspMN, ps1PS, and ps2PS) that are much longer than other erect setae. Posterolateral tubercles of petiole posteriorly with two pairs of stout setae. Postpetiole with three pairs of stout setae on disc anterodorsally, anterolaterally, posteriorly. Fourth abdominal tergite with suberect setae sparsely, but no decumbent to appressed setae.

Body yellow to brown. All flagellar segments yellow.

Type Material
Hosoishi and Ogata (2016) - Holotype worker, Sepilok, Sandakan, Borneo, Malaysia, 17.viii.1981 (K. Masuko) (, examined). Two paratype workers, same data as holotype (,, examined) and five paratype workers, Sangkimah, Kutai N. P., E. Kalimantan, Indonesia, 13.ix.1993 (P-2 soil-2) (Sk. Yamane) (, , , KUEC, , examined).

Etymology
This species is dedicated to Prof Dr Keiichi Masuko, Senshu University, who collected the type material.