Stigmatomma trilobum

One of the types was collected from sub-alpine moist evergreen broad-leaf forest.

Identification
Xu (2001) - This new species is close to Stigmatomma silvestrii, but anterior margin of clypeus strongly convex and divided into 3 lobes; eyes absent; subpetiolar process large and nearly square.

Distribution
Yunnan Province, China.

Distribution based on Regional Taxon Lists
Palaearctic Region: China.

Nomenclature

 *  trilobum. Amblyopone triloba Xu, 2001d: 552, figs. 11-13 (w.) CHINA. Combination in Stigmatomma: Yoshimura & Fisher, 2012: 19.

Worker
Holotype. TL4.5, HL1.00, HW 0.85, CI 85, SL 0.53, SI 62, PW 0.55, AL 1.23, ED 0.00, ML 0.65, DPW 0.50, DPL 0.45, PH 0.55. Head roughly trapezoid, longer than broad, widened forward. Occipital margin weakly concave, occipital corners roundly prominent, lateral sides weakly convex. Anterolateral corner of head with acute genal tooth. Mandibles slender, relatively straight, inner and masticatory margins about equal in length, inner margin with 5-6 teeth, masticatory margin with 4 teeth. Anterior margin of clypeus roundly convex and divided into 3 lobes, middle lobe with 4 denticles, lateral lobes each with 2 denticles, besides an extra tooth present between middle lobe and right lateral lobe. Antennae short, 12-segmented, apex of scape reached to 2/3 of the distance from antennal socket to occipital corner, segments 2-10 each broader than long. Eyes absent. In profile view, dorsum of thorax weakly convex, promesonotal suture distinctly notched, metanotal groove slightly depressed. Dorsum of propodeum straight, longer than declivity, declivity flat, posterodorsal corner of propodeum bluntly angled. In profile view, petiolar node roughly trapezoid, narrowed backward, anterior face truncate and straight, dorsum weakly convex, anterodorsal corner nearly a right angle, ventral face oblique. Subpetiolar process large, nearly square, with large elliptic fenestra, anteroventral corner rounded, posteroventral corner bluntly angled. In dorsal view, petiolar node nearly square, length: width = 9:10, anterior and lateral borders weakly convex, posterior border nearly straight. Constriction distinct between the 2 basal segments of gaster. Mandibles longitudinally striate, with apex smooth and shining. Clypeus finely and longitudinally striate. Head densely and coarsely punctured, with the longitudinal central stripe of dorsum finely and longitudinally striate, dull. Pronotum with lateral sides densely and coarsely punctured, but smooth on the dorsum. Lateral sides of mesothorax, metathorax and propodeum finely and longitudinally striate, dorsum of propodeum punctured, declivity smooth. Petiole with lateral sides densely punctured but smooth on dorsum. First segment of gaster with lateral sides finely and densely punctured but smooth on dorsum. Segments 2-5 of gaster smooth. The whole body surface and appendages with sparse suberect short hairs and dense decumbent pubescence. Body in color reddish brown. Legs brownish yellow.

Type Material
Deposited in the Insect Collection, Southwest Forestry College, Kun-ming, Yunnan Province, China. Holotype worker, No.A99-27, 2500m, Pianma, Lushui County, Yunnan Province, 25.Apr.1999, collected by Mr. XU Zheng-Hui in sub-alpine moist evergreen broad-leaf forest of the Gaoligong Mountain Nature Reserve in western Yunnan.

References based on Global Ant Biodiversity Informatics

 * Fontanilla A. M., A. Nakamura, Z. Xu, M. Cao, R. L. Kitching, Y. Tang, and C. J. Burwell. 2019. Taxonomic and functional ant diversity along tropical, subtropical, and subalpine elevational transects in southwest China. Insects 10, 128; doi:10.3390/insects10050128
 * Guénard B., and R. R. Dunn. 2012. A checklist of the ants of China. Zootaxa 3558: 1-77.
 * Xu Z. H. 2001. A systematic study on the ant genus Amblyopone Erichson from China (Hymenoptera: Formicidae). Acta Zootaxonomica Sinica 26: 551-556.
 * Xu Z.-H., and J. J. Chu. 2012. Four New Species of the Amblyoponine Ant Genus Amblyopone (Hymenoptera: Formicidae) from Southwestern China with a Key to the Known Asian Species. Sociobiology 59(4): 1175-1196.
 * Xu Zheng-hui. 2001. A systematic study on the ant genus Amblyopone Erichson from China (Hymenoptera: Formicidae). Acta Zootaxonomica Sinica 26(4): 551-556.