Strumigenys mukkaliensis

A single specimen was collected from leaf litter with approximately 2 cm in depth. The collecting area is situated at an altitude of 897 meters. It is a shady place with minimum of sunlight penetration. Mean annual temperature is 20.2°C. Average annual rainfall is 6,000 mm with 95% relative humidity. It is a primary undisturbed tropical moist evergreen forest.

Identification
Bharti & Akbar (2013) - The new species shares most affinities with members of the rare extemena group which is characterized by remarkable mandibular structure which when fully closed has the masticatory margins engaging only in the apical halves or less of their length; proximal to this with an elongate tooth-lined triangular space between the mandibles. Moreover the dorsal surface of each mandible near the base has a very distinct, sharp, transverse rim that extends across its width. The group currently is represented by 10 species (acheron, aello, atopogenys, carinognatha, deinognatha, extemena, ocypete, podarge, tarbosyne and yangi). S. mukkaliensis is aberrant with the leading edge of the scape has a row of conspicuous projecting spatulate curved hairs, of which one or more, distal to the sub-basal bend, distinctly curves towards the base of the scape; body lacking any erect pilosity (except a pair on last gastral segment) and eyes rudimentary, represented by small black spot.

Key to Strumigenys of India

Distribution based on Regional Taxon Lists
Oriental Region: India, India.

Nomenclature

 *  mukkaliensis. Strumigenys mukkaliensis Bharti & Akbar, 2013: 388, figs. 1, 2, 3 (w.) INDIA.

Worker
Measurements: HL 0.38; HW 0.37; ML 0.04; EL 0.01; SL 0.17; PW 0.22; WL 0.37;PTH 0.15; PTL 0.11; PPTH 0.15; PPTL 0.11; GL 0.44; GW 0.31; TL 1.45; CI 97; MI 10; SI 44.

Head as long as broad (CI 97), posterior head margin shallowly concave; when fully closed the masticatory margins only engage in the apical halves of their length. Proximal to this with an elongate tooth-lined triangular space between the mandibles. Mandibular dentitions not clear, probably with 12-14 teeth. In profile mandibles almost straight, distal half angled downward with respect to proximal half; outer margin of mandible in full-face view shallowly convex from base to apex. Dorsal surface of each mandible near base with a very distinct sharp transverse rim that extends across its width, parallel to the clypeal margin. Anterior clypeal margin transverse. Antennal scrobes broad shallow. Eyes rudimentary, represented by a single ommatidium which appears as a minute dot near posterior half of antennal scrobes. Antennae 6-segmented, with 3rd and 4th segment reduced, appearing as a single segment; apical segment large, elongate and cylinder shaped.

Mesosoma. Pronotum slightly marginate dorsolaterally, the dorsum depressed between the marginations. When viewed in profile mesonotum appears convex, the dorsum raised slightly. Propodeum convex; propodeal spines absent, the declivity on each side with broad lamellae.

Metasoma. Node of petiole high; broader than long; lateral spongiform lobe in profile well developed; ventral surface with well developed spongiform tissue; postpetiolar spongiform tissue prominent throughout the node.

Sculpture. Body uniformly reticulate- punctuate. Head densely and mesosomal dorsum finely reticulate-punctate; petiole and postpetiole finely reticulate-punctate with disc of both petiole and postpetiole smooth and shining. Basigastral costulae well developed.

Vestiture. Leading edge of the scape with a row of conspicuous projecting spatulate curved hairs, of which one or more, distal to the sub-basal bend, distinctly curves towards the base of the scape; basal stem of each hair erect with respect to the long axis of the scape. Cephalic dorsum with appressed, ground-pilosity without any erect hairs, even lacking the usual row near the occipital margin. Dorsal surface of mesosoma without standing pilosity of any form; without pronotal humeral hair. Dorsal surfaces of petiole, postpetiole and first gastral tergite also, without any standing hairs. Last gastral segment with few erect hairs.

Colour. Light yellowish brown.

Type Material
Holotype (worker): India. Kerala, Silent Valley National Park, 11°5`N, 76°26`E, 897m.a.s.l., 25.ix.2011, Winkler method (coll. Shahid A. Akbar). Holotype in.

Etymology
The species is named after its type locality Mukkali, part of Silent Valley National Park.