Proceratium longmenense

The type worker was collected in subtropical evergreen broadleaf forest at 2050 m asl.

Identification
Close to Proceratium zhaoi but central clypeal process wide and triangular, subpetiolar process posteriorly without pointed tooth, propodeal teeth extrudent. (Xu 2006)

Staab et al. (2018) - Proceratium longmenense differs from the other members of the Proceratium itoi clade by the following character combination: medium-sized species (TL 3.2); sides of head and vertex weakly convex, almost straight; head (CI 85) and scapes (SI 68) relatively long; frontal carinae developed, their lateral lamellae relatively narrow, touching each other at their anteriormost level, not conspicuously broader above antennal insertions; posterodorsal corners of the propodeum broadly angular; posterior face of petiolar node in profile shorter and steeper than anterior face; petiole almost as broad as long (DPeI 91); subpetiolar process developed, roughly trapezoid; in addition to dense pubescence erect hairs present on dorsal surface of body, but only sparsely on head, scapes without erect hairs.

The unique hair patterns separate Proceratium longmenense from the other species of the Proceratium itoi clade. Proceratium williamsi and Proceratium zhaoi have no erect hairs that protrude from the dense pubescence on the dorsal surface of body (hairs present in Proceratium longmenense, but relatively sparsely, especially on head). All other species (Proceratium bruelheidei, Proceratium itoi, Proceratium kepingmai, Proceratium malesianum) have also such hairs on the scapes (absent on scapes in Proceratium longmenense). In addition to hairs, which may be worn down in old specimens, Proceratium longmenense is unique by the relatively long scapes (SI 68) combined with the relatively narrow head (CI 85). Among the other Chinese Proceratium itoi clade species, it differs furthermore from Proceratium zhaoi in size (WL 0.97; WL<80 in Proceratium zhaoi), from Proceratium itoi by the shape of the posterodorsal corners of the propodeum (broadly angular; rounded in Proceratium itoi), and from Proceratium bruelheidei, Proceratium itoi, and Proceratium kepingmai by the lamellae of the frontal carinae (touching each other at their anteriormost level; separated in the other three species).

Distribution based on Regional Taxon Lists
Palaearctic Region: China.

Nomenclature

 *  longmenense. Proceratium longmenense Xu, 2006: 154, figs. 14  16 (w.) CHINA.

Worker
Holotype. TL 3.2, HL 0.87, HW 0.73, CI 85, SL 0.50, SI 68, ML 0.40, ED 0.02, PW 0.52, AL 0.97, PL 0.35, PH 0.33, DPW 0.32. Head nearly square, slightly longer than broad. Occipital margin straight. Occipital corners rounded. Lateral sides weakly convex. Masticatory margins of mandibles with 4 teeth, which reduced in sized from apex to base. Frontal carinae straight, convergent forward. Anterior margin of clypeus with a wide and triangular projection in the middle. Antennae thick, with 12 segments. Apices of scapes reached to 4/5 of the distance from antennal socket to occipital corner. Eyes with only one facet. In profile view, dorsum of alitrunk complete and weakly convex. Promesonotal suture and metanotal groove vanished on dorsum. Posterodorsal corner of propodeum extrudent into a right-angled tooth. Lateral lobes of propodeum blunt and rounded. Petiole roughly triangular and included backward, anterior and dorsal faces convex, anterodorsal corner rounded, posterior face short and straight. Subpetiolar process small and nearly rectangular, ventral face straight, anteroventral corner rightly angled, posterventral corner bluntly angled. Constriction between the two basal segments of gaster distinct, second segment very large, apical three segments short and under the second one.

Mandibles finely longitudinally striate. Head, alitrunk, petiole, and gaster finely densely punctate and dim. Gastral segments 3-5 smooth and shining. Dorsum of whole body with sparse short erect hairs and dense decumbent pubescence. Erect hairs abundant on dorsum of alitrunk. Dorsal faces of scapes and tibiae with dense decumbent pubescence, but without erect hairs. The while body yellowish brown. Mandibles, antenna, legs, and apex of gaster brownish yellow.

Type Material
China: Yunnan Province, Kunming City, Xishan Mountain Forest Park, Longmen, subtropical evergreen broadleaf forest, 2050 m, 5.V.2001, leg. Zhenghui Xu, No. A00514.

Staab et al. (2018) - Holotype. Pinned worker, ), examined.

Etymology
Named after the type specimen locality Longmen, a place of the Xishan Mountain Forest Park.

References based on Global Ant Biodiversity Informatics

 * Guénard B., and R. R. Dunn. 2012. A checklist of the ants of China. Zootaxa 3558: 1-77.
 * Xu Z. 2006. Three new species of the ant genera Amblyopone Erichson, 1842 and Proceratium Roger, 1863 (Hymenoptera: Formicidae) from Yunnan, China. Myrmecologische Nachrichten 8: 151-155.