Polyrhachis sulcata

This distinctive and beautiful species is known only from the female holotype and the two collections made more recently in Ghana. Both these collections were made by pyrethrum knock-down in areas reasonably well-collected by methods which were more normal but which had failed to produce this species. This seems to indicate that Polyrhachis sulcata is an arboreal form which hardly, if ever, descends to ground level. Gynes of P. sulcata were collected at lights on Jan 11, 1998 (Bioko, Moka, Equatorial Guinea). (Bolton 1973)

Identification
A member of the Polyrhachis militaris species-group. Bolton (1973) - Its affinities definitely lie with the Polyrhachis militaris group of species but it is easily separated from the other constituent species by the lack of propodeal margination and the unique sculpturation.

Distribution based on Regional Taxon Lists
Afrotropical Region: Congo, Equatorial Guinea, Ghana.

Nomenclature

 *  sulcata. Polyrhachis sulcata André, 1895a: 1 (q.) CONGO. Bolton, 1973b: 322 (w.). Combination in P. (Myrma): Wheeler, W.M. 1922a: 1004.

Worker
Bolton (1973) - TL 7.8-9.2, HL 1.89-2.07, HW 1.52-1.67, CI 78-80, SL 2.18-2.24, SI 134-143, PW 1.29-1.37, MTL 2.29-2.48. (6 measured.)

Anterior clypeal margin arcuate, entire; the clypeal suture forming a distinct break in the sculpture. Sides of head weakly convex in front of the strongly protuberant eyes, convex and converging behind the eyes. Lateroventral margins of head concave. Frontal carinae with strongly sinuate, laminate lobes. Sides of pronotum and mesonotum marginate, propodeum immarginate, the sides rounding into the dorsum. Pronotum armed with a pair of spines, the propodeum with a pair of spines which curve upwards and outwards and are somewhat longer than those of the pronotum. Propodeum also with a pair of small triangular prominences anterolaterally, just posterior to the impressed metanotal groove. Petiole with a pair of long, acute, almost parallel dorsal spines and a pair of shorter, upcurved lateral spines. Anterior face of first gastral segment vertical, not concave.

Off-white to yellowish white erect hairs present on all surfaces of body and appendages, most dense on the legs, antenna! scapes and the gaster. Pubescence virtually absent, distinctive only on the funiculi and tarsal segments, sparse on the scapes and the remainder of the legs and completely absent from the dorsum of the alitrunk.

Sculpture of head, alitrunk, petiole and gaster of very deep, regularly spaced striae, the areas between them strongly convex so that the surface has a ploughed appearance. In direction they are longitudinal on the head, pronotal, mesonotal and gastral dorsa and on the pronotum and gaster laterally; transverse on the propodeal declivity, posterior face of the scale and anterior face of the gaster, and oblique on the rriesopleuron, metapleuron and sides of the propodeum. On the propodeal dorsum the striae are V-shaped dorsally.

Colour black, with the apical margins of the mandibles sometimes lighter, brown or yellow-brown.

The tips of the. apical funicular segments, palpi, and apices of the pretarsi yellow or dull yellow-brown. The eyes of one worker are white, but this is an artifact common in stored Polyrhachis specimens.

Queen
Bolton (1973) - Agreeing with the above description except for the following points which are noted by Andre in the original description of the female:

1. Erect hairs dirty yellow. This colouration would appear to fall well within the range of the species, as is noted above.

2. Striae transversely arched on pronotum. In the worker the striae are longitudinal; the transverse direction in the female may be accounted for by the foreshortening of this segment in the queen caste, as is seen in other species with similar sculpturation (e.g. Polyrhachis latispina).

Type Material
Bolton (1973) - Holotype queen, CONGO (Brazzaville):Ogowe (probably in ).

References based on Global Ant Biodiversity Informatics

 * André E. 1895. Formicides de l'Ogooué (Congo français). Rev. Entomol. (Caen) 14: 1-5.
 * Bolton B. 1973. The ant genus Polyrhachis F. Smith in the Ethiopian region (Hymenoptera: Formicidae). Bulletin of the British Museum (Natural History). Entomology 28: 283-369.
 * Rigato F. 2016. The ant genus Polyrhachis F. Smith in sub-Saharan Africa, with descriptions of ten new species. (Hymenoptera: Formicidae). Zootaxa 4088: 1-50.
 * Robson Simon Database Polyrhachis -05 Sept 2014
 * Wheeler W. M. 1922. Ants of the American Museum Congo expedition. A contribution to the myrmecology of Africa. VIII. A synonymic list of the ants of the Ethiopian region. Bulletin of the American Museum of Natural History 45: 711-1004