Stigmatomma boltoni

Stigmatomma boltoni is only known from India. It is the fourth species of the genus from India, together with Stigmatomma bellii, Stigmatomma pertinax and Stigmatomma rothneyi. This is the first species of the subfamily Amblyoponinae reported from the Northwest Himalaya. This species is uncommon in the Shivalik range of North-west Himalaya and was found only in 3 localities of Himachal Pradesh adjacent to each other during the intensive surveys. The species inhabits well developed lowland subtropical, semi-evergreen forests influenced by a relatively strong dry season, it constructs nests in soil, forages in soil, under leaf litter and has been collected only by soil core and winkler extraction methods. (Bharti & Wachkoo 2011)

Identification
Bharti & Wachkoo (2011) - This species is quite different from the previously known Indian species. It is easily distinguishable from Stigmatomma pertinax by its 12 segmented antennae (in S. pertinax antennae are 11 segmented); whereas it separates from Stigmatomma bellii and Stigmatomma rothneyi by a combination of several characters: reduced eyes without distinct facets, 7 strong clypeal teeth with a unique arrangement, delicate sculpture, prominent sub petiolar process, smaller size etc. However, it is somewhat allied to Mediterranean Stigmatomma emeryi (Saunders, 1890), but can be easily distinguished from it by combination of sculpture, scape length, shape of alitrunk, meso-metanotal suture and structure and arrangemenr of clypeal teeth. In S. boltoni sp.nov., the sculpture of the head is more pronounced and regular on the frontal part, with clypeal teeth blunt and 3 median teeth bordered by a pair of fused teeth on each side, and scapes are shorter SL: 0.42·0.45, which is not the case in S. emeryi, having feebler sculpture, free and pointed teeth, scape length SL: 0.64-0.67, and mesonotum strongly constricted, resembling a dumbbell in dorsal view.

Distribution based on Regional Taxon Lists
Oriental Region: India.

Castes
Known only from the worker caste.

Nomenclature

 *  boltoni. Amblyopone boltoni Bharti & Wachkoo, 2011: 586, figs. 1-3 (w.) INDIA. Combination in Stigmatomma: Yoshimura & Fisher, 2012: 19.

Worker
Worker measurements: TL: 3.2-3.4: HL: 0.72-0.77; HW: 0.58-0.64; ML: 0.53-0.56; WL: 0.88-0.95; PL: 0.36-0.41; PW: 0.36-0.4; PH: 0.37-0.39; SL: 0.42-0.45; GL: 1.2-1.27. Indices: CI: 80.26-85.33; 51: 69.35-72.4 1; PI: 94.44-105.88 (9 individuals measured).

Head: Head nearly trapezoidal, widened forward: much longer than broad, occiput emarginate, occipital corners round and prominent. Anterior margin of clypeus convex., with 7 teeth: 3 median bordered by a pair of fused teeth on each side. Anterolateral corners of head, near mandibular insertions, each with a distinct, well developed tooth. Mandibles narrow and slender, with 8 teeth, the 2 apical and 2 basal teeth are simple; middle 4 teeth are paired, arranged in two rows, wide outer row, having smaller teeth than inner row; apical tooth projecting and long; basal most sub quadrate and broad. Antennae 12 segmented; scape reaching up to 2/3rd of posterior margin of head. Eyes rudimentary without distinct facets represented by a tiny black dot; placed above the middle line of head.

Alitrunk. Petiole: Alitrunk with flat dorsal margin, promesonotal suture marked, metanotal suture entirely effaced. Propodeal dorsum slightly higher than rest of mesosomal dorsum, broadly curving into oblique declivious face. Alitrunk widest at pronotum, constricted at mesonotum; propodeum has broadly convex sides that diverge caudally. Periole dorsally square shaped, sub petiolar process cuneiform, without any fenestra.

Gaster: Gaster elongate, sting exerted.

Sculpture: Head with regular punctures and noticeable longitudinal rugulae on anterior l/3rd of head, much weaker rugulae, barely discernible extend toward vertex; oblique rugulae on gena and transverse on posterior 1/4th of head. A narrow longitudinal median strip of smoother sculpture extends from posterior end of frontal carinae to vertex. Clypeus with regular longitudinal striations. Mandibles densely sculptured with coarse striations. Alitrunk sculpturing consists of scattered punctures, restricted mainly to sides and anterior of pronotum. Pronotal sides smooth and shinning, with few scattered punctures. Metepisternum and lateral propodeal faces shining except for inferoposterior transverse striations below propodeal spiracle. Katepisternum with transverse striations, anepisternum smooth and shining. Petiole and gaster shining covered with scattered shallow punctures.

Pilosity: Moderate; reclinate, suberect, denser on flagellum of antennae; longest on mandibles and at apex of gaster.

Color: Reddish-yellow to brown with antennae and legs pale.

Type Material
Holotype worker: India. Himachal Pradesh. Terrace 31.9234°N 75.9294°E., 430m above msl, 17 July, 2010, winkler. Paratypes: 2 workers, India, Himachal Pradesh. Ghati Hilwan. 31.9300°N 75.9302°E. 400m above msl, 18 October, 2008: 6 workers. India, Himachal Pradesh Khatiar, 32.0057°N 75.9388°E. 450m above msl. 18 October, 2010, soil core (coll. Aijaz A. Wachkoo).

Holotype and paratypes in Dr. Himender Bharti Collections-MoEF I, Department of Zoology, Punjabi University, Patiala, India; one of the paratypes in California Academy of Sciences. San Francisco, United States of America.

Etymology
The species is named in the honor of Barry Bolton.