Perissomyrmex monticola

The types were collected together with some workers of Myrmica rugosa s.l. from which they ate virtually indistinguishable in size and colour without microscopic examination.

Identification
De Andrade (1993). A Perissomyrmex species in which the worker has no subpetiolar process, essentially smooth pleuron 2 and propodeum, and very lightly striate mandibles.

Distribution based on Regional Taxon Lists
Oriental Region: Bhutan, India, Nepal.

Nomenclature

 *  monticola. Perissomyrmex monticola De Andrade, in Baroni Urbani & De Andrade, 1993: 90, figs. 1-3 (w.q.) BHUTAN. Senior synonym of nepalensis: Xu & Zhang, 2012: 153. See also: Ogata & Okido, 2007: 360.
 * nepalensis. Perissomyrmex nepalensis Radchenko, 2003: 14, figs. 1-10 (w.) NEPAL. Junior synonym of monticola: Xu & Zhang, 2012: 153. See also: Ogata & Okido, 2007: 361.

Worker
Head large, with convex sides. No ocelli. Eyes protruding, at about the middle of the sides of the head, their maximum diameter ca equal to scape width. Frontal area subtriangular. Frontal carinae with a small lobe leaving both the base of the scape and the antennal fossae exposed. Clypeus with four teeth on its anterior border: the central pair 3 times as large as the two external teeth. Funiculi 8-jointed with the last three joints enlarged to form a poorly distinct club, the last joint subequal in length to the first and second joints combined. Mandibles elongate, very lightly striate, with four teeth interpretable as: one basal, one median, one preapical, and one apical. The median tooth is separated by a wide diastema from the preapical tooth.

Trunk with a poorly distinguishable promesonotal suture. Propodeal impression well developed. Propodeum with a pair of sharp divergent spines directed backwards. Propodeal spiracles round, well visible. Posterior legs almost as long as the whole body. Middle and posterior tibiae without spurs.

Petiole about 3 times longer than broad, its node oval in dorsal view and rounded in profile. Subpetiolar process absent. Postpetiole equally round in profile, almost 1/3 broader than the petiole, approximately subequal in length and height. Gaster round, with the first segment approximately 3 times longer than the sum of the remaining ones.

Sculpture. Head capsule and thorax heavily striate. Mandibles very lightly striate. Pleuron 2 and propodeum smooth. Petiolar and postpetiolar nodes smooth and with the dorsal and lateral portions very lightly striate. Legs and gaster smooth, completely without sculpture.

Colour dominantly shining brown, antennae, mandibles and legs shining yellowish.

Pilosity. Body hairs essentially of four different types: a) generalized body hairs, pointed and slender, ca 0.08-0.20 mm long, regularly distributed on most body surfaces except the sides of the trunk where they are missing; b) mandibular hairs, very similar to the previous ones, but consistently slightly shorter; c) a row of macrochetae of variable length but longer than the remaining body pilosity, and located on the anterior border of the clypeus; d) a much more dense and minute appressed pilosity on the feet and on the funiculi.

Queen
Measurements (in mm) and indices: total length (mandibles included) 5.32; head length 1.20; head width 1.20; scape length 1.00; eye length 0.16; trunk length 1.40; pronotum width 0.84; petiole length 0.48; petiole maximum width 0.20; postpetiole length 0.32; postpetiole maximum width 0.24; gaster width 1.20; Cephalic Index 100; Scape Index 83.3; Petiolar Index 41.6; Postpetiolar Index 75.0.

Besides the differences in size, very similar to the worker from which it differs essentially in the following characters that are obviously correlated with caste determination.

Head with three ocelli disposed on the vertices of an inverted triangle. Trunk dorsally flat at the propodeal declivity. Promesonotal suture deep. Mesonotal disc circular. Scutellum constituted by two regions: a rectangular prescutellum, 3 times broader than long and an inverted triangular postscutellum, its maximum length about twice as long as the prescutellum.

Gaster round, with the first segment approximately 2 times longer than the sum of the remaining ones.

Colour. Head, trunk and abdominal pedicel shining dark brown, gaster shining brownish, antennae, mandibles and legs shining yellowish.

Type Material
Holotype. Worker, Nobding, 41 km E, of Wangdi Phodrang, 2800 m, Natural History Museum Basel Bhutan Expedition, 1972. Deposited in the collection of the. Paratypes. One worker missing the right antenna and the right second leg and one dealate female, same data and same collection as the holotype.

Etymology
From the Latin substantive monticola (=living on the mountains).

References based on Global Ant Biodiversity Informatics

 * Ogata K.; H. Okido. 2007. Revision of the ant genus Perissomyrmex with notes on the phylogeny of the tribe Myrmecinini. Memoirs of the American Entomological Institute 80:352-369.
 * Radchenko A. 2003. Perissomyrmex nepalensis sp. nov. - new evidence of Old World origins for the genus (Hymenoptera, Formicidae). Entomologica Basiliensia 25: 13-22.