Strumigenys rotogenys

Identification
Bolton (2000) - A member of the Strumigenys chapmani-group.Most specimens of this species are covered with a dense coat of fine soil or mud particles on the dorsal surfaces of the head and alitrunk that is held in place by the curved pilosity.

Within the group only this species and its sibling Strumigenys gyrogenys have flagellate hairs on the first gastral tergite. All others have gastral pilosity that is stout and stiff, remiform to weakly clavate. Characters distinguishing rotogenys and gyrogenys are given under the latter.

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

Nomenclature

 *  rotogenys. Strumigenys rotogenys Bolton, 2000: 769, figs. 426, 491 (w.) BORNEO.

Worker
Holotype. TL 3.1, HL 0.96, HW 0.94, CI 98, ML 0.44, MI 46, SL 0.45, SI 48, PW 0.34, AL 0.78. Head very broad and markedly dorsoventrally flattened. Apicoventral tooth of the tridentate apical fork strongly rolled under, in dorsal view arising from the ventral surface of the mandible some distance proximal of the apex; with the appearence of a ventrally-arising preapical tooth. Apicoventral tooth with a poorly defined minute denticle or short crest dorsally, close to its midlength. Scapes strongly dorsoventrally flattened, the leading edge lamellate and convex. Ventrolateral margin of head with a deep, evenly concave preocular impression. Ventral surface of head behind eyes with a deep transverse impression that is separated from the preocular impression only by a narrow convex isthmus of cuticle immediately below the eye. In profile ventrolateral margin of head strongly concave and sharply marginate immediately behind the eye. Cephalic dorsum finely reticulate-rugulose. Cuticle within the deep scrobe very finely shagreenate and dull. Promesonotal dorsum smooth and shining, propodeal dorsum weakly superficially reticulate-punctate. Side of alitrunk and disc of postpetiole smooth. Basigastral costulae weakly defined and shorter than the length of the postpetiole disc. Cephalic dorsum with ground-pilosity of abundant short curved hairs that are spatulate to spoon-shaped. In full-face view similar hairs form a dense row along entire dorsolateral margin of head. A longer, stouter, flattened apicoscrobal hair is present and a similar but less conspicuous hair occurs at the extreme posterior apex of the occipital lobe (this hair apparently very easily lost); cephalic dorsum otherwise without standing pilosity of any form. Promesonotum with elevated but strongly curved thick hairs that are spatulate to weakly remiform and quite short. Postpetiole and gaster with numerous long fine flagellate hairs that contrast strongly with the promesonotal pilosity. Hairs that project from hind basitarsi flagellate and very long.

Paratypes. TL 3.0-3.2, HL 0.91-1.00, HW 0.93-1.00, CI 98-102, ML 0.44-0.46, MI 45-49, SL 0.42-0.47, SI 43-48, PW 0.32-0.36, AL 0.72-0.80 (12 measured).

Dimensions of non-paratypic workers. TL 3.0-3.6, HL 0.93-1.12, HW 0.93-1.08, CI 96-102, ML 0.44-0.50, MI 45-51, SL 0.42-0.51, SI 45-50, PW 0.32-0.40, AL 0.72-0.90 (15 measured).

Type Material
Holotype worker, Malaysia: Sarawak, 4th Division, G. Mulu Nat. Pk, RGS Expd., Long Pala, 27.ix.1977, lowland rainforest, soil nest (B. Bolton).

Paratypes, 41 workers with same data as holotype (BMNH,, , , , ).

Determination Clarifications
This species was referred to as Strumigenys sp. 8 in Bolton, 1998b: 92.