Stigmatomma xui

This species was collected by Winkler’s extractor from an undisturbed dense forest. The thickness of leaf litter was about 4 inches. The floor of the forest receives limited sun light. The maximum recorded temperature of the area is 28°C with minimum -1°C and the region receives 325cm of rainfall per annum. (Bharti and Rilta 2015)

Identification
Bharti and Rilta (2015) - Most resembles Stigmatomma sakaii but can be distinguished from the latter by the presence of 6 dentiform setae which arise from flat cuticle; oblique subpetiolar process and rounded posterolateral corner of propodeum and anterodorsal corner of petiole, whilst S. sakaii is characterized by anterior clypeal margin with 8 dentiform setae which arise from tubercle-like cuticular projection; trapezoidal subpetiolar process; bluntly angled posterolateral corner of propodeum and anterodorsal corner of petiole.

Distribution based on Regional Taxon Lists
Oriental Region: India.

Nomenclature

 * . Stigmatomma xui Bharti & Rilta, 2015b: 507, figs. 1-3 (w.) INDIA (Sikkim).
 * Type-material: holotype worker.
 * Type-locality: India: East Sikkim, Rorathang, 27°11’49.91’’N, 88°36’12.44’’E, 587 m., 12.vi.2012, Winkler (J.S. Rilta).
 * Type-depository: PUAC.
 * Status as species: Bharti, Guénard, et al. 2016: 18; Hsu, F. et al. 2017: 90 (in key).
 * Distribution: India.

Worker
Holotype: TL: 1.87; HL: 0.43; HW: 0.34; SL: 0.22; ML: 0.29; PW: 0.21; WL: 0.46; PL: 0.18; PH: 0.19; DPW: 0.20; GL: 0.57; CI: 79; SI: 64; LPI: 106; DPI: 112. Paratype: TL: 1.94; HL: 0.44; HW: 0.33; SL: 0.21; ML: 0.30; PW: 0.21; WL: 0.49; PL: 0.17; PH: 0.20; DPW: 0.21; GL: 0.54; CI: 75; SI: 63; LPI: 117; DPI: 123.

Head: In full face view, head rectangular (CI:79); Occipital margin weakly concave, occipital corners rounded; mandibles narrow and slender, outer margins almost straight except at the apical part with 8 teeth (2 apical and 2 basal teeth are simple; middle 4 are paired arranged in two rows); anterior margin of clypeus convex, with 6 dentiform setae which arise from flat cuticle; median setae fused at base; posttorular flange close to each other, covering antennal insertion; antennae 11 segmented; scape short, not reaching to posterior corner of head (SI: 64); antennal segments 3-10 broader than long; segment 11 longer than broad; eyes absent (as seen under stereozoom optical microscope).

Mesosoma and Petiole: In lateral view, mesosoma weakly convex; promesonotal suture distinct; meso-metanotal suture effaced. propodeal dorsum straight, posterolateral corner of propodeum rounded; petiole broadly attached to ABIII, petiole quadrate in lateral view with anterior border almost straight, dorsal margin straight; subpetiolar process narrow, oblique with rounded anteroventral corner.

In dorsal view, mesonotum constricted, propodeum slightly widened backward, propodeal declivity concave, petiole broader than long (DPI: 112), anterodorsal corner rounded.

Gaster: First gastral segment broader than long, broader than dorsal petiolar width, second gastral segment broader than the first gastral segment.

Sculpture: Mandibles punctuated with rugosity. Head densely punctuated, interfaces appear as micro-reticulation and opaque; dorsal surface of pronotum and mesonotum densely punctured. Dorsum of propodeum sparsely punctured. Lateral sides of mesonotum and metanotum superficially striated. Petiole and gaster sparsely punctuated.

Pilosity and pubescence, Pilosity sparse few erect or suberect hairs on mandibles, apical antennal segments and apex of gaster; dorsal surfaces of head and body with dense decumbent pubescence. tibiae with dense decumbent pubescence, but without suberect hairs.

Color: reddish brown; antennae, mandibles, legs and tip of gaster yellow.

Type Material
Holotype (worker): India, East Sikkim, Rorathang, 27°11’49.91”N, 88°36’ 12.44”E, 587m,12.vi.2012, Winkler (coll. Joginder Singh Rilta). Paratype worker with same data as of holotype.

Etymology
The species is named in honor of Prof. Zhenghui Xu.