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Polyrhachis xiphias species-group
The Polyrhachis xiphias species-group is comprised of species in the subgenus Campomyrma.
Species
Identification
Key to Polyrhachis xiphias species-group workers
Diagnosis
Males are known only of P. shixingensis but have not been described. Immature stages are unknown.
Worker
Medium-sized ants (HL 1.50-1.81) with characteristics of the genus. Mandibles with 5 teeth, bases smooth or finely striate. Anterior clypeal margin arcuate, medially truncate; clypeus with more-or-less distinct median carina. Frontal carinae rather flat with relatively wide central area. Eyes flat (as in P. shixingensis), only weakly convex (as in P. hashimotoi), or convex (as in P. xiphias). Pronotum in dorsal view with lateral margins rounded, without distinct humeral angles; propodeal dorsum with lateral margins subparallel or only weakly divergent (as in P. xiphias), extending posteriorly and terminating in relatively long, dorsally or somewhat dorsomedially flattened spines; inner margins of spines continuous medially, forming an inverted ‘U’-shaped ridge that divides propodeal dorsum from declivity. Petiole armed with posteriorly-directed, subparallel (as in P. hashimotoi and P. shixingensis), or divergent (as in P. xiphias) more-or-less horizontal spines. Head, mesosoma and petiole mostly finely reticulate-punctate, gaster smooth and polished. Closely appressed pubescence very sporadically distributed over sides of body and gaster, virtually absent from dorsa of head and mesosoma. A few, medium length, semierect hairs on front of head, coxae, and venter and apex of gaster. Body black, appendages light to medium reddish-brown.
Queen
Closely similar to worker, but distinctly larger (HL >2.25 in queens versus <1.81 in workers), with characters identifying full sexuality, including three ocelli, full thoracic structure and wings). Sculpturation, pilosity and colour essentially as in worker.
Notes
The Polyrhachis xiphias species-group was introduced by Kohout (2007) to house three widely-distributed species of the subgenus Campomyrma Wheeler: Polyrhachis xiphias from New Guinea, Polyrhachis shixingensis from China and Polyrhachis hashimotoi from Borneo. The newly-erected group was characterised by a columnar petiole with a pair of horizontal, posteriorly-directed spines, rather similar to those in species of the subgenus P. (Hagiomyrma). All three species are very similar and share a rounded pronotal dorsum and a pair of horizontal, posteriorly-directed propodeal spines. They are apparently rare, with only a handful of specimens known from all collections examined. However, in the course of my studies I have discovered the previously-unknown workers of P. xiphias and queens of P. shixingensis.