Polyrhachis cyaniventris species-group

This is a small species group, comprised of species in the subgenus Myrma (Polyrhachis), that occurs in the Philippines. The group was defined in [[Media:Sorger & Zettel 2009.pdf|Sorger, D. M. and H. Zettel. 2009. Polyrhachis (Myrma) cyaniventris F. Smith, 1858 (Hymenoptera: Formicidae) and a related new ant species from the Philippines. Zootaxa 2174: 27-37. PDF]], as detailed below.

Kohout (2008) presents a key to the subgenera and species groups of Polyrhachis occurring on Sulawesi, recognizing five species groups in Myrma from this island. Although P. cyaniventris fits the character set of Kohout's (1989, 2008) P. relucens group, there are several differences from typical species of this clade (in the sense of Kohout 1989), e.g., P. relucens (Latreille 1802) and Polyrhachis illaudata, which in our opinion justifies the separation of P. cyaniventris and related species and the establishment of a separate group. The main distinguishing characteristics of the P. cyaniventris group, if compared with Kohout's (1989) P. relucens group, are the metallic shimmer of the integument, a strong reduction in pilosity, small and less protruding eyes (most peculiar in workers), short legs, a high propodeum, and long dorsal spines of the petiole, that are curved posterolaterad and embrace the gaster's base in the worker caste.

Species

 * Polyrhachis baca
 * Polyrhachis cyaniventris
 * Polyrhachis pirata

Key to Polyrhachis cyaniventris species-group workers

Worker
Large (TL 7.9–11.5 mm), stout, finely sculptured, matte ants with peculiar metallic, in most species bluish, shimmer. Setae short, black, and in low numbers on body, scape, and legs, or totally absent. Eyes not surpassing outlines of head in full face view. Ventrolateral margin of head rectangular or obtuse. Antennae and legs rather short (compared with species of the Polyrhachis relucens group), scape strongly widened towards apex, there about twice as wide as at base, SI 132–155. Dorsolateral margin of mesosoma sharp and protruded, strongly indented between nota. Pronotal spines prominent. Propodeum without spines, with distinct transverse carina separating slightly convex dorsal from concave caudal face which is higher than petiole. Petiole wide, with two pairs of spines dorsolaterally; ventral pair short, dorsal pair very long, curved and embracing base of gaster. Anterior face of gaster concave.

Worker description: Body with metallic shimmer, petiole and gaster dark bluish. Mandibles black. Palpi brown. Antennae in most species black, except tip of apical segment reddish brown. Legs, except femora, usually black.

Body, legs and antennae with isodiametric reticulum or very fine and dense puncturation, locally overlaid with longitudinal rugae; with fine, short, appressed golden or silverish white pubescence.

Head stout, longer than wide, broadest at level of antennal fossae, sides and venter forming right to obtuse angle; dorsum and sides with appressed pubescence; sides of head convex. Venter of head almost smooth, with very sparse pubescence. Eyes very small, in frontal view located in upper third of head and laterally not breaking its outline in full face view. Ocelli usually absent or very indistinct. Occipital margin with medial lobe. Frontal carinae high. Clypeus in profile slightly sinuate, proximally convex, distally concave; with obtuse elevation along midline; anterior margin with row of long golden setae. Mandibles with longitudinal striation, fine at base, coarser towards masticatory margin; numerous pits with long, golden setae distally.

Mesosoma dorsolaterally with strongly developed, sharp margin deeply indented between segments. Dorsal face in side view convex, with fine, short, appressed pubescence. Pronotal spines long, directed anterolaterad. Propodeum with transverse ridge separating dorsal and posterior face and laterally forming short, blunt teeth.

Petiole stout, biconvex in lateral view, armed with two pairs of spines dorsolaterally; the slightly more ventral pair short, but acute, the dorsal pair very long, curved and embracing base of gaster. Gaster with anterior face slightly concave, tergites with varying number of short, black setae.

Queen
(gyne of Polyrhachis pirata unknown): Similar to worker, except the following: TL 9.4–10.9 mm. Eyes slightly surpassing head sides. Dorsolateral margin of mesosoma incomplete, but present on anterior three-fourths of pronotum and on propodeum. Spines of petiole shorter than in worker and hardly curved.