Polyrhachis equina

Identification
Polyrhachis equina and Polyrhachis gribodoi are very similar and share numerous characters including almost identical, bilobed anterior clypeal margins, distinctly concave mesonotal and propodeal dorsa, dorso posteriorly extended propodeal spines and similarly shaped petioles. They differ in their relative size (HL <1.80 in P. equina versus HL >1.90 in P. gribodoi) and in several other characters, including the shape of the head and the sculpturation of the mesosomal dorsum. In P. equina, the sides of the head in front of the eyes converge towards the mandibular bases in an almost straight line, while behind the eyes the sides round into a moderately convex occipital margin. In P. gribodoi the sides of the head in front of the eyes are distinctly convex, and behind the eyes the sides round into a virtually flat occipital margin. The mesosomal dosum of P. equina is finely, rather irregularly, reticulate-punctate, with the reticulae on the pronotum somewhat bowed towards its lateral margins. The sculpturation of the mesosomal dorsum in P. gribodoi is distinctly more intense and more regularly, longitudinally striate on pronotum. (Kohout 1988)

Distribution based on Regional Taxon Lists
Indo-Australian Region: Borneo, Indonesia, Malaysia.

Nomenclature

 *  equina. Polyrhachis equinus Smith, F. 1857a: 63 (w.) BORNEO. Combination in P. (Campomyrma): Wheeler, W.M. 1919e: 122. Senior synonym of biloba: Wheeler, W.M. 1919e: 122. See also: Kohout, 2007c: 10.
 * biloba. Polyrhachis biloba Forel, 1911a: 58 (w.) BORNEO. Junior synonym of equina: Wheeler, W.M. 1919e: 122.

Polyrhachis equinus

Holotype worker in. Labelled “SAR. 21” (= Sarawak) and with a Donisthorpe type-label.

Worker
Kohout (1988) - Dimensions (holotype cited first): TL c. 6.40, 6.05- 6.65; HL 1.72, 1.56-1.80; HW 1.43, 1.25-1.50; CI 83, 79-83; SL (missing), 2.03-2.18; SI (missing), 159- 164; PW 0.87, 0.75-0.90; MTL 2.09, 2.00-2.25 (12 measured).