Stenamma yaluzangbum

Workers have been collected from pine and broadleaf forest, from under stones and from a litter sample.

Identification
Liu & Xu (2011) - This new species is close to Stenamma kashmirense but with propodeal spines as long as propodeal plates; petiolar node relatively higher, densely finely punctuate; mesopleura densely coarsely punctuate.

Distribution
Sichuan Province, China; Tibet.

Distribution based on Regional Taxon Lists
Oriental Region: Tibet. Palaearctic Region: China.

Castes
Known only from the worker caste.

Nomenclature

 *  yaluzangbum. Stenamma yaluzangbum Liu & Xu, 2011: 744, figs. 7-9 (w.) CHINA.

Worker
Holotype. TL 3.8, HL 0.88, HW 0.78, CI 89, SL 0.65, SI 84, PW 0.55, AL l.13, ED 0.10, PL 0.48, PH 0.25, PI 53, DPW 0.18, PPL 0.28, PPH 0.24, PPI 86, PPW 0.24.

In full face view, head roughly rectangular, longer than broad. Occipital margin straight, occipital corners rounded, lateral sides weakly convex. Anterior margin of clypeus convex, and concave in the middle. Mandibles with 2 distinct apical teeth and followed by 7 indistinct denticles. Antennae short, 12-segmented; apices of scapes reached to 9/10 of the distance from antennal sockets to occipital corners; antennal clubs 4-segmented. Eyes located before the midpoints of lateral sides of head, with 4 ommatidia in the maximum diameter.

In profile view, promesonotum high, roundly convex and arched. Promesonotal suture absent. Metanotal groove wide, deeply depressed, and with a convex tubercle in the groove. Propodeum distinctly lower than promesonotum, dorsum straight and steeply sloped. Propodeal spines slender and acute, about l/3 length of declivity. Declivity straight, about ¾ length of dorsum. Propodeal plates broad, rounded at apices, about as long as propodeal spines. Petiole relatively long, length: height: width= 2: 1: 0.7. Petiolar node cone-shaped, about as long as anterior peduncle, and distinctly depressed between the node and peduncle. Ventral face of petiole nearly straight, but weakly concave at posterior 1/3, anteroventral corner weakly prominent. Postpetiolar dorsum roundly convex, ventral face weakly concave, anteroventral corner extruding and toothed.

Mandibles finely longitudinally striate. Head retirugose, but longitudinally rugose on central dorsum and before eyes, median portion of clypeus smooth and shining. Anterior 1/3 of pronotum with interweaved transverse rugae. Posterior 2/3 of pronotum and lateral sides with posteriorly divergent longitudinal rugae. Mesonotum, metapleura, and lateral sides of propodeum with interweaved longitudinal rugae. Mesopleura densely and coarsely punctuate. Metanotal groove with short longitudinal rugae. Propodeal dorsum finely retirugose. Petiole and postpetiole densely finely punctuate, dorsal faces with sparse fine longitudinal rugae, dorsum of postpetiolar node relatively smooth. Gaster smooth and shining, basal carinae about l/2 length of postpetiole.

Dorsa of head and body with abundant erect to suberect hairs and dense decumbent pubescence, but alitrunk dorsum with sparse pubescence. Dorsa of propodeum and petiolar peduncle without erect hairs. Antennal scapes and hind tibiae with dense decumbent pubescence, but without erect hairs. Head and body blackish brown, appendages and gaster yellowish brown, eyes and masticatory margins of mandibles black.

Paratypes. TL 2.9-3.8, HL 0.73-0.88, HW 0.60-0.73, CI 82-84, SL 0.53-0.65, SI 88-93, PW 0.41-0.53, AL 0.88-1.08, ED 0.06-0.09, PL 0.35-0.48, PH 0.20-0.23, PI 47-57, DPW 0.15-0.16, PPL 0.23-0.28, PPH 0.20-0.21, PPI 73-89, PPW 0.19-0.21 (n=4). As holotype, but specimen from Gengzhang Town, Linzhi County, Tibet, with anteroventral corner bluntly angled; specimens from Lulang Town, Linzhi County, Tibet, with smaller body size and reddish brown in body color; specimen from Pengta Town, Kangding County, Sichuan Province, with pronotum retirugose, upper portions of mesopleura sparsely longitudinally rugose.

Type Material
Holotype: worker, CHINA: Tibet, Milin County, Lilong Town, Lilongou, 3085 m, collected under stone in the forest of Pinus densata, 2008. VIII. 10, Zheng-H ui XU leg., No. AOS-3122. . Paratypes: 1 worker, CHINA: Tibet, Linzhi County, Gengzhang Town, Gengzhang, 3170 m, collected under stone in the forest of Pinus densata, 2008. VII. 19, Zheng-Hui XU leg., No. AOS-1491; 2 workers, CHINA: Tibet, Linzhi County, Lulang Town, Dongjiu, 2770 m, collected under stone in the forest of Pinus densata, 2007.IX.21, Long-Guan CHEN leg., No. A07-202; 1 worker, CH INA: Sichuan Province, Kangding County, Pengta Town, Tangling, 2450 m, collected from litter sample by Winkler in the broad leaf forest, 2005. VIII. 31, Zheng-Hui XU leg., No. A05-973.

Etymology
The new species is named after the big river Yarlungzangbo which flows over the main type localities in southeastern Tibet.

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.
 * Liu X. 2012. Taxonomy, diversity and spatial distribution characters of the ant family Formicidae (Insecta: Hymenoptera) in southeastern Tibet. PhD Thesis 139 pages
 * Liu X., and Z. H. Xu. 2011. Three New Species of the Ant Genus Stenamma (Hymenoptera: Formicidae) from Himalaya and the Hengduan Mountains With a Revised Key to the Known Species of the Palaearctic and Oriental Regions. Sociobiology 58: 733-748.