Tetramorium cordatum

The type was collected on the grounds of Calicut University Campus.

Identification
Sheela & Narendran (1998) - This species is unique among the species of Tetramorium in having peculiar shape for its gaster. Gaster is cordate. But in all other species gaster is not cordate.

Distribution based on Regional Taxon Lists
Oriental Region: India.

Nomenclature

 *  cordatum. Tetramorium cordatus Sheela & Narendran, 1998a: 37, figs. 1-3 (w.) INDIA.

Worker
Holotype. Head finely reticulate, posteriorly transverse in front view; sides straight, mandibles feebly striate with three acute apical teeth followed by three or four small denticles; anterior margin of clypeus nearly arched, with a thin flange, clypeus broad, antero-medially a little depressed; a strong median carina and two or three pairs of feeble lateral carinae present on mid lobe, frontal area not distinctly defined; posterior clypeal margin not distinct; frontal lobes short, wide apart, frontal grooves reaching beyond eye by 1.2x length of eye, a median longitudinal carina separates scrobe into two distinct grooves for reception of scape and flagellum separately; scrobe deep rugulose, posterior margin clearly defined. Antennae 12-jointed, scape slender, flagellar segments 2-7 transverse, club formed of apical 3 joints, which is longer than remaining flagellar segments together ( 13:8); terminal club segment: preceding two together= 7:5. Eyes prominent, oval lateral, placed at mid transverse line, in profile more to anterior portion.

Thorax: Finely reticulate, laterally a little compressed, anterolateral corners of pro notum rounded; no sutures on thorax, in profile evenly convex; propodeal spines in dorsal view a little longer than distance between its bases (4 : 3.5); in profile its length: basal width = 4 : 2; metapleural lobes triangular, flat, acute at apex, but distinctly shorter than propodeal spines. Legs smooth, femora and tibiae swollen, tibial spur on mid and hind legs not conspicuous.

Abdomen: Pedicel reticulate, ventrolateral portions smooth, petiole more stoutly built with a short peduncle in front; petiole nod~: peduncle 5 : 3; petiole higher in a position than postpetiole; dorsal and anterior margins meet smoothly so that no angle at their junction, posteriorly no constriction on petiole, anterior margin almost vertical, dorsally convexS; in dorsal view post petiole broader than petiole (9.5: 9), and both nodes anteroposteriorly compressed, transverse; petiole length : breadth 4 : 9; postpetiole 3.5 : 9.5. Gaster cordate, anterior 1/3 of T1 finely longitudinally striate, remaining portions smooth; junction between gaster and postpetiole not conspicuous due to presence of a thick felt of pubscence; T1 covering almost entire dorsum, in profile gaster slightly convex above and highly convex below.

Head, thorax and pedicel yellowish brown; gaster brownish black; antennae, mandibles and legs pale yellow; whole body except flagellum of antennae and tarsi of legs with abundant, short, trifid and quadrifid hairs; flagellum and tarsi with minute single pubescence.

Total length 2.2 mm; Head length- 0.59mm; Head width- 0.59mm; Cephalic index-100; eye diameter- 0.12mm; Scape length-0.34mm; Scape index-58; Pronotal width-0.46mm; Alitrunk length- 0.59mm.

Type Material
Holotype: Worker; India, Kerala, Calicut University Campus; Sheela S, 8-12-1991 (Department of Zoology, University of Calicut).

Etymology
The species is named as cordatus to indicate its heart shaped gaster.