Strumigenys assamensis

Nothing is known about the biology of .

Identification
Bolton (2000) - A member of the Strumigenys leptothrix-group. This very distinctive species was fully characterized in the original description. It is easily separated from all other known members of the leptothrix-group by the following combination of characters in the worker.

1 Standing hairs absent from all dorsal surfaces of head and alitrunk.

2 With head in full-face view the dorsolateral margins without projecting hairs anywhere along the length.

3 Leading edge of scape and dorsal (outer) surface of middle and hind tibiae with short appressed hairs only, without long outstanding simple hairs.

4 Scape relatively very short, SI 57-60.

5 Clypeus with a low narrow median longitudinal carina, strongest posteriorly and fading out just before the anterior margin.

6 Lateral spongiform lobe of petiole large and blister-like, extending from posterior margin of node as far forward as the spiracle on the peduncle.

7 Propodeum without spines or teeth, instead with only a broad translucent lamella that runs the depth of the declivity, becoming broader basally.

8 Standing hairs on first gastral tergite confined to extreme base of the sclerite.

The habitus of assamensis makes the closest approach to the Malagasy hoplites-complex of any of the Oriental and Malesian species. However, the pronotum is marginate in assamensis and characters 1, 5, and 6 above are unique in this species, not applying to the Malagasy representatives of the group. Character 5 is unique in the whole group. Only Strumigenys euryale has a clypeal crest but it is very high, densely clothed with spatulate hairs, and confined to the anterior half of the sclerite. The dentition of assamensis is described in the introduction to the group.

Distribution based on Regional Taxon Lists
Oriental Region: India.

Nomenclature

 *  assamensis. Strumigenys assamensis De Andrade, in Baroni Urbani & De Andrade, 1994: 61, figs. 35, 36 (w.) INDIA. Combination in Smithistruma: Bolton, 1995b: 384; in Pyramica: Bolton, 1999: 1673; in Strumigenys: Baroni Urbani & De Andrade, 2007: 115. See also: Bolton, 2000: 430.

Worker
TL holotype 2.78, paratypes 2.75-2.77; HL holotype 0.65, paratypes 0.64-0.65; HW holotype 0.51, paratypes 0.50-0.51; SL holotype 0.30, paratypes 0.29-0.30; ML holotype and paratypes 0.12; AL holotype 0.76, paratypes 0.72-0.75; PW holotype 0.27, paratypes 0.26-0.27; petiolar node maximum length holotype 0.26, paratypes 0.25-0.26; petiolar node maximum width holotype 0.14, paratypes 0.14-0.15; postpetiole maximum length holotype 0.17, paratypes 0.16-0.18; postpetiole maximum width, holotype 0.20, paratypes 0.19-0.22; gaster maximum width, holotype 0.47, paratypes 0.45-0.47. CI, holotype 78.5, paratypes 78-79.7; SI holotype 59, paratypes 57-59; MI holotype 18.5, para types 18.5-18.7; SMI holotype 250, paratypes 241-250.

Head with the dorsum posteriomedially raised into a broad tumulus. Occipital lobes small and flattened. Eyes small and ventral to the scrobes. Clypeus in dorsal view with a median carina, its latera-posterior sides connected with a narrow preocular lamina. Sides of the clypeus convex and converging anteriorly. Anterior clypeal margin convex. Preocular lamina narrow. Scape slightly less than half the head length, narrow and with marginate external border. Antennae six-jointed.

Labrum bilobed, triangular and hidden by the mandibles at rest. Mandibles with a triangular basal tooth followed by three acuminate, long teeth and four denticles alternating in size; five smaller denticles on the apical part.

Trunk: anterior border of the pronotum slightly marginate, its sides strongly marginate and rounded. Pronotum flat and with a feebly median longitudinal carina. Promesonotal suture well visible laterally and terminally impressed towards the dorsum. Sides of mesonotum and propodeum dorsally marginate but without transversal crest or carina. Mesopleural presumed glandular area well developed and bearing a brush of long setae. Propodeal suture feebly impressed only on the lower pleural area. Propodeal teeth short and stout with a broad infradental lamella originating from their apex.

Spongiform process on the ventral side of the petiole well developed longitudinally and as high as the petiolar node. Sides of the petiole with a broad lamella directed ventrally. Posterior border of the petiole with a thin transversal lamella. Ventral spongiform process of the postpetiole broad and rounded. Postpetiole with a well developed lamella embracing its lateral and posterior sides. Petiolar node rounded, 2/3 longer than the postpetiole. Postpetiole 1/4 broader than the petiolar node, slightly convex and hexagonal in dorsal view.

Gaster oval, slightly broader than the postpetiole. Sting protruding. Anterior border of the gaster with a broad, transverse lamella in part covered by the postpetiolar lamella.

Sculpture: head irregularly striate and punctate on the lateral and anterior parts and on the posterior border of the clypeus. Cephalic tumulus only slightly reticulo-punctate. Clypeus, antennae, mandibles and legs punctate. Alitrunk and abdomen shining and feebly punctate.

Pilosity: dorsum of the head, clypeus, antennae and legs with sparse appressed short hairs, longer over the antennae, the sides of the mandibles, and legs, and denser over the funiculi and mandibular sides. Dorsum of the mandibles covered by thick, spatulate hairs (Fig. 36 A). Thorax and abdomen with rare, appressed hairs as long as those on the dorsum of the head. Dorsum of the postpetiole with a pair of subdecumbent hairs as long as those on the antennae. Erect, thick, truncate, slightly longer hairs over the dorsum of the gaster arranged as follows: a row of four on the anterior border of the first segment and on the posterior border of the third segment, two on the posterior border of the second segment, and four on the fourth gastral segment.

Colour: body reddish-brown, shining, lighter on the clypeus, the antennae and the legs. A dark brown rim marks the posterior border of the clypeus, the antennal scrobes, the ventral border of the mesopleura, the dorsal margin of the alitrunk and propodeal declivity, and the dorsal border of the pedicel. Postpetiole with a thick dark, lateral expansion appearing as a spine embedded in the lamelliform process. A similar but much less evident spiniform colour pattern on the posterior border of the petiole and on the anterior border of the postpetiole.

Bolton (2000) - TL 2.7-2.8, HL 0.64-0.65, HW 0.50-0.51, CI 78-79, ML 0.12, MI 18-19, SL 0.29-0.30, SI 57-60, PW 0.26-0.27, AL 0.72-0.76 (measurements after Baroni Urbani & De Andrade, 1994).

Type Material
Holotype worker and paratype workers, INDIA: Megalaya, Cherrapunjee, 1200 m., 16.v.1976 (Wittmer & Baroni Urbani) [examined].

Etymology
assamensis is a Latin neologism to indicate the provenance of this species from the Indian state of Megalaya, formerly considered part of Assam.

References based on Global Ant Biodiversity Informatics

 * Baroni Urbani C., and M. L. De Andrade. 1994. First description of fossil Dacetini ants with a critical analysis of the current classification of the tribe (Amber Collection Stuttgart: Hymenoptera, Formicidae. VI: Dacetini). Stuttgarter Beiträge zur Naturkunde. Serie B (Geologie und Paläontologie) 198: 1-65.
 * 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