Polyrhachis watanasiti

Identification
Polyrhachis watanasiti is very similar to Polyrhachis pubescens but differs in having the bases of the antennal scapes distinctly broadened and flattened and the body pubescence greatly reduced.

Distribution based on Regional Taxon Lists
Oriental Region: Thailand.

Castes
Sexuals and immature stages unknown.

Nomenclature

 *  watanasiti. Polyrhachis (Myrma) watanasiti Kohout, 2013: 168, figs. 57-58, 61-62 (w.) THAILAND.

Worker
Dimensions: TL c.6.85; HL 1.75; HW 1.28; CI 73; SL 2.31; SI 180; PW 1.18; MTL 2.28.

Anterior clypeal margin arcuate, medially obtusely truncate. Clypeus with blunt, poorly indicated median carina; clypeus straight in profile with rather flat basal margin.Frontal triangle distinct. Frontal carinae very closely approximate anteriorly with sharply raised, almost vertical margins; central area very narrow with distinct frontal furrow. Antennal scapes with bases distinctly broadened (Fig. 58). Sides of head in front of eyes converging towards mandibular bases in even convex line; behind eyes sides rounding into moderately convex occipital margin. Eyes truncate posteriorly, in full face view clearly exceeding lateral cephalic outline. Ocelli lacking. Pronotal dorsum with slender, anterolaterally directed, acute spines, about 3x as long as basal width; outer edges of spines acute and basally continuous with virtually parallel pronotal margins, promesonotal suture distinctly impressed laterally, rather flat medially. Mesonotal lateral margins narrowly rounded and distinctly raised anteriorly, rather flat posteriorly before converging into medially flat metanotal groove. Propodeum with lateral margins distinctly converging posteriorly and terminating in distinct, upturned ridges that meet medially and form transverse carina dividing propodeal dorsum from shallowly concave declivity. Petiole biconvex in profile; transversely broad, convex dorsal margin armed with moderately long, dorsolaterally directed and outwardly curved spines; lateral margins of petiole with secondary, shorter, somewhat dorsally flattened tooth below each spine. Anterior face of first gastral segment concave to accommodate posterior face of petiole; anterodorsal margin narrowly rounding onto dorsum.

Mandibles finely, mostly longitudinally striate with piliferous pits. Clypeus and rest of head reticulate-punctate with sculpture on vertex and sides of head somewhat longitudinally directed; pronotal spines longitudinally striate, striae continued onto lateral margins of pronotum; mesosomal and propodeal dorsa striate medially. Petiole and gaster finely reticulate-punctate, opaque.

Mandibular masticatory and outer borders with numerous curved, golden hairs. Anterior clypeal margin with a few anteriorly directed setae medially. Numerous rather long hairs on clypeus, front and vertex of head, many breaking lateral cephalic outline. Antennal scapes with several shorter hairs along superior edge. Dorsum of mesosoma with only a few very short, bristle-like hairs on pronotal dorsum; several longer hairs on fore coxae and along subpetiolar process; no hairs on mesonotal and propodeal dorsa, petiole and legs.Gaster with numerous hairs on venter and towards apex. Closely appressed, silvery pubescence distributed in various densities over whole body, partly obscuring underlying sculpturation on head, dorsum of mesosoma and sides of petiole and gaster.

Colour. Black, virtually throughout; only condyla of scape and extreme tip of apical funicular segment reddish brown.

Etymology
Named after Prof. Dr Suparoek Watanasit of Prince of Songkla University, Hat Yai, Thailand, for his generous support during my visit to southern Thailand.