Stigmatomma octodentatum

Specimens have been collected from a Pinus armandii forest, a ground sample in a Cunninghamia lanceolata (Taxodiaceae) forest and a soil sample in the deciduous broad-leaf forest. (Xu 2006, Xu and Chu 2012)

Identification
Close to Stigmatomma silvestrii, but with different mandibular dentation, in profile view anterior face of petiolar node weakly concave, posteroventral corner of subpetiolar process acutely toothed. (Xu 2006)

Distribution based on Regional Taxon Lists
Palaearctic Region: China.

Nomenclature

 *  octodentatum. Amblyopone octodentata Xu, 2006: 152, figs. 1  7 (w.q.) CHINA. Combination in Stigmatomma: Yoshimura & Fisher, 2012: 19.

Worker
Holotype. TL 4.3, HL 0.93, HW 0.80, CI 86, SL 0.47, SI 58, ML 0.67, ED 0.06, PW 0.52, AL 1.20, PL 0.58, PH 0.43, DPW 0.50. Head nearly trapezoid and widened forward, longer than broad. In full face view, occipital margin weakly concave, occipital corners roundly prominent. Lateral sides of head relatively straight. Mandibles narrow and slender, with 8 teeth, the basal 2 teeth and the apical 2 ones simple, the middle 4 teeth each bifurcated, the apical tooth slender. Anterolateral corner of head elongated into an acute tooth. Anterior margin of clypeus roundly convex, with 8 simple teeth. Antennae 12-segmented, apices of scapes reached to 3/5 of the distance from antennal socket to occipital corner. Eyes small, with 5-6 facets, placed at posterior 2/5 of lateral side of head. In profile view, pronotum weakly convex. Promesonotal suture depressed. Mesonotum very short, with straight dorsum. Metanotal groove only visible on sides. Dorsum of propodeum very long, straight and sloped posteriad, posterodorsal corner rounded, declivity weakly convex. In profile view, petiole narrowed backward, anterior face weakly concave, dorsal face nearly straight, anterodorsal corner right-angled. Subpetiolar process cuneiform, with large elliptic translucent fenestra, anterior face roundly convex, ventral face straight, posteroventral corner acutely toothed. In dorsal view, petiole about as broad as long, anterior and lateral borders weakly convex, anterolateral corners rounded, posterior border straight.

Mandibles finely longitudinally striate. Head, pronotum, dorsal faces of mesonotum and propodeum densely and coarsely punctate, interstices appear as fine reticulations. Lateral sides of mesothorax, metathorax and propodeum densely, finely and longitudinally striate. Petiole and first gastral segment densely and finely punctate. Second gastral segment sparsely and finely punctate, interstices smooth. Remaining gastral segments smooth and shining. Dorsal faces of head and body with dense erect or suberect short hairs and dense decumbent pubescence. Scapes and tibiae with sparse erect or suberect hairs and dense decumbent pubescence. Body color brown, legs brownish yellow.

Paratype. Measurements in order minimum to maximum, arithmetic means in parentheses. TL 4.2-4.5 (4.3), HL 0.87-0.93 (0.90), HW 0.77-0.78 (0.78), CI 84-88 (87), SL 0.43-0.47 (0.45), SI 57-60 (59), ML 0.63-0.67 (0.64), ED 0.05 (0.05), PW 0.52-0.53 (0.52), AL 1.17-1.20 (1.19), PL 0.47-0.53 (0.49), PH 0.42-0.47 (0.44), DPW 0.45-0.48 (0.48) (4 individuals measured).

Xu and Chu (2012) - TL 4.8-5.8, HL 1.03-1.38, HW 0.90-1.13, CI 82-91, SL 0.55-0.75, SI 58-67, ED 0.04-0.08, ML 0.75-1.10, PW 0.60-0.75, AL 1.38-1.70, PL 0.55-0.68, PH 0.58-0.68, DPW 0.53-0.68, LPI 100-114, DPI 95-109 (10 individuals measured).

Queen
Paratype. (Figs. 5-7). TL 5.2, HL 0.97, HW 0.82, CI 84, SL 0.48, SI 59, ML 0.67, ED 0.15, PW 0.60, AL 1.43, PL 0.53, PH 0.48, DPW 0.53 (1 individual measured). Similar to holotype, but body larger. Eyes normal, with 3 ocelli. Alitrunk with alary sclerites. Posterior margin of pronotum deeply emarginate. Anterior scutum of mesonotum large and trapezoid, lateral scutum small and nearly triangular, posterior margin of scutellum rounded. Dorsum of metanotum short and transverse. Head and alitrunk darkish brown, petiole and gaster brown. Antennae and legs yellowish brown, eyes and pteralia black.

Type Material
Holotype worker. China: Yunnan Province, Kunming City, Xishan Mountain Forest Park, Nie'ermu, Pinus armandii forest, 2150 m, 3.V.2001, leg. Yuxiang Zhao, No. A00476. Paratypes. Same data as holotype, 4 workers and 1 gyne.

Etymology
The species name octodentata combines Latin octo- (eight) + word root dent (tooth) + suffix –atus (feminine form -ata, with), it refers to the eight teeth of the anterior margin of the clypeus.

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.
 * Liu X. 2012. Taxonomy, diversity and spatial distribution characters of the ant family Formicidae (Insecta: Hymenoptera) in southeastern Tibet. PhD Thesis 139 pages
 * Terayama, M. 2009. A synopsis of the family Formicidae of Taiwan (Insecta; Hymenoptera). The Research Bulletin of Kanto Gakuen University 17: 81-266.
 * 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 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.