Polyrhachis hespera

Polyrhachis hespera is known only from a single specimen collected at Eneabba in the Batavia Coast region of Western Australia.

Identification
A member of the Polyrhachis gravis species-group. Kohout (2013) - Polyrhachis hespera is quite similar to Polyrhachis gravis. They share a distinctly raised carina on the anterior margin of first gastral tergite and have quite similar configurations of the petiole. It differs from the latter by its shorter antennal scapes (SI 115 in hespera versus 125-131 in gravis), distinctly smaller and strongly convex eyes, and by having the pronotal dorsum widest across the humeri. In contrast, the eyes in P. gravis are comparatively larger and less convex and the pronotal dorsum is widest at about its midlength.

Key to Polyrhachis gravis species-group workers

Distribution based on Regional Taxon Lists
Australasian Region: Australia.

Castes
Sexuals and immature stages unknown.

Nomenclature

 *  hespera. Polyrhachis (Campomyrma) hespera Kohout, 2013: 101, figs. 3C-D, G-H (w.) AUSTRALIA.

Worker
TL c. 9.42; HL 2.25; HW 2.03; CI 90; SL 2.34; SI 115; PW 1.65; MIL 2.99 (1 measured).

Mandibles with 6 teeth. Anterior clypeal margin widely truncate, truncate portion irregularly denticulate, laterally delimited by blunt angles. Clypeus without distinct median carina; straight in profile with flat base. Frontal triangle weakly impressed. Frontal carinae sinuate with moderately raised margins; central area with rather indistinct frontal furrow. Sides of head m front of eyes evenly convex towards mandibular bases; behind eyes sides narrowly rounding into distinct occipital corners. Eyes strongly convex, in full face view clearly breaking lateral cephalic outline. Ocelli lacking. Pronotal humeri bluntly angular, wither lateal margins converging posteriorly towards weakly impressed promesonotal suture. Mesonotal and propodeal lateral margins weakly sinuate, converging posteriorly and terminating in upturned teeth; propodeal dorsum curving through narrow gap between teeth into steep, weakly concave declivity. Petiole scale-like lateral view; dorsum armed with a pair of closely approximate spines; outer margins of spines descending into acute, shorter and slender lateral spines. Gaster in lateral view with anterior face flat; anterior margin of first gastral tergite with distinct transverse carina.

Mandibles finely, longitudinally striate with nunerous piliferous pits. Clypeus reticulate-punctate; head distinctly irregularly rugose, with sculpture on vertex and along frontal carinae somewhat longitudinally striate-rugose. Pronotal dorsum mostly longitudinally striate; dorsa of mesonotum and propodeum mostly longitudinally striate-rugose. Sides of mesosoma and petiole finely wrinkled. Gaster very finely and closely reticulate-striate.

Mandibles with numerous, curved, golden hairs at masticatory and outer borders; anterior clypeal margin with numerous, relatively long, somewhat reddish-golden setae medially and fringe of shorter setae laterally. Several semierect, rather short, golden hairs, on clypeus; very short, bristle-like hairs on head and mesosomal dorsum, metapleura and a few hairs along lateral margins of petiole. Dorsum of gaster numerous, very short, golden hairs, hairs increasing in length towards gastral apex and on venter, where they are distinctly longer and posteriorly inclined. Antennae and legs with numerous, very short, bristle like hairs on all surfaces. Closely appressed, rather grey or silvery pubescence very sporadic on various body surfaces, virtually absent from dorsum of head, mesosoma and petiole.

Mandibles light reddish-brown at masticatory borders, distinctly darkening towards bases; teeth and outer edges bordered black. Antennal scapes black; basal funicular segments black at bases, subsequent funicular segments progressively lighter, reddish-brown towards apices. Most of body, including fore coxae and petiole black; middle and hind coxae and femora medium reddish-brown; tibiae and tarsi black. Gaster black with gastral segments bordered reddish-brown; apex of gaster reddish-brown.

Etymology
Derived from the Latin hesperius, meaning western, refering to its WA origin.