Vombisidris humboldticola

One of two species of Vombrisidris from India, both known from Western Ghats. Ants in this genus nest and forage arboreally. Colonies of V. humboldticola that have been collected are small, with 20-30 individuals, and have been found in the domatia of two Humboldtia species (decurrens and brunonis). Workers feed from extrafloral nectaries of these plants.

Identification
A member of the philax group. V. humboldticola is similar to Vombisidris occidua (described from India) in the following characters: (1) subocular groove complete and (2) metanotal groove absent. However, V. humboldticola differs from V. occidua in the following characters: (1)faint vestiges of frontal carinae present that extend beyond the posterior margins of the eyes in contrast to their absence in V. occidua. (2) Propodeal spines longer and arched than in V. occidua. (3) In dorsal view, the sides of the petiole node are almost straight when compared to the convex petiole node in V. occidua. (4) Dorsal surface of petiolar node in profile less convex than in V. occidua. (5) Colour yellowish-brown with abdomen darker brown and legs yellow, whereas in V. occidua, the head, alitrunk and waist segments are all dark brown, contrasting strongly with the much lighter yellow legs.

Distribution based on Regional Taxon Lists
Oriental Region: India.

Castes
One of only a few Vombisidris species for which the queen has been collected and described. Males have yet to be collected.

Nomenclature

 * . Vombisidris humboldticola Zacharias & Rajan, 2004b: 1337, fig. 2 (w.q.) INDIA (Kerala, Karnataka).
 * Type-material: holotype worker, 1 paratype worker, 1 paratype queen.
 * Type-locality: holotype India: Kerala, Trivandrum, Shankilli (8°49’03’’N, 77°03’08’’E), 9.ii.2004, from domatia of Humboldtia decurrens (M. Zacharias); paratypes with same data.
 * Type-depositories: ATRE (holotype); ATRE, BMNH (paratypes).
 * Status as species: Xu & Yu, 2012: 1499 (in key); Bharti, Guénard, et al. 2016: 48.

Worker
Holotype. Total length 2.40 mm, head length (HL) 0.67 mm, head width (HW) 0.56 mm, cephalic index (HW/HL×100) 83, scape length (SL) 0.51mm, scape index (SL/HW×100) 91, pronotal width 0.36 mm, alitrunk length 0.90 mm, maximum diameter of eye 0.12 (0.21×HW).

Head longer than broad (CI). Sides of head behind eyes feebly convergent posteriorly with rounded occipital corners. Faint vestiges of frontal carinae present, extending back from the posterior extremities of the frontal lobes to beyond the level of the posterior margins of the eyes, subocular groove complete, the groove running from the mandibular insertion to the anteroventral margin of the eye, then passing through a shallow angle and continuing along the sides to the lateroccipital margin, the region of the lateroccipital margin of the head where the subocular groove ends slightly concave; antennal scape relatively long (SI); eyes relatively small (0.21×HW) with 10 ommatidia in the longest row.

Alitrunk elongate and low in profile, mesonotum unarmed, in dorsal view, sides of mesonotum slightly convex; metanotal groove absent, in profile, propodeal spines long and arched and appear to be set low down; propodeal spines four times longer than the distance separating their bases, propodeal spiracle below the level of the spine, propodeal declivity reticulate rugulose. Legs relatively long; maximum length of hind femur (0.61 mm) greater than head width.

In dorsal view, petiolar node distinctly longer than wide and sides of the node almost straight, petiolar spiracle at the midlength of the peduncle. First gastral tergite smooth, except for a band of short basigastral costulae feebly present immediately behind the post petiole, the spaces between the basigastral costulae smooth. Head, alitrunk, petiole and postpetiole reticulate-rugulose. Gaster smooth. Hairs on dorsal surface elongate and more densely present on head. Colour yellowish brown, with abdomen darker brown and legs yellow.

Queen
HL 0.74 mm, HW 0.60 mm, cephalic index (HW/HL×100) 81, SL 0.72mm, Scape index (SL/HW×100) 120, pronotal width 0.52mm, alitrunk length 1.12 mm, maximum diameter of eye 0.19 (0.32×HW) with 12 ommatidia in the longest row.

Relatively small when compared to other described queens of Vombisidris sp., i.e. Vombisidris australis, Vombisidris bilongrudi and Vombisidris renateae, but proportionately larger than the workers. The general features of shape, sculpturing and pilosity are similar to workers. It differs from the workers by the presence of relatively large eyes, presence of ocelli and propodeal spines being relatively shorter and less convergent.

Type Material
Holotype. Worker, India: Kerala, Trivandrum, Shankilli (8°49′03′′N and 77°03′08′′E), 9.ii.2004. Merry Zacharias. Collected from domatia of H. decurrens. Paratypes. One worker and one queen collection data same as holotype.

Holotype will be deposited at the Insect Museum of Ashoka Trust for Research in Ecology and the Environment, Bangalore, Karnataka, India and the paratype will be deposited at, London

Etymology
The species name indicates Vombisidris that dwells in Humboldtia plants.