Polyrhachis (Aulacomyrma) exarata Emery, 1887

Kohout, R. J., 2007, Revision of the subgenus Aulacomyrma Emery of the genus Polyrhachis F. Smith, with descriptions of new species., Advances in ant systematics (Hymenoptera: Formicidae): Homage to E. O. Wilson - 50 years of contributions. (Memoirs of the American Entomological Institute 80), pp. 186-253 : 198-199

Polyrhachis (Aulacomyrma) exarata Emery, 1887

Figures 3, 6, 9

Polyrhachis exarata Emery, 1887: 226 . Holotype worker. Type locality: INDONESIA, Misool I. , Waigamma (O. Beccari), MCSN (examined) .

Polyrhachis (Aulacomyrma) exarata Emery ; Emery, 1921: 17. Combination in P. (Aulacomyrma) .

WORKER

Dimensions of holotype: TL c. 4.84; HL 1.18; HW 1.06; CI 90; SL 1.31; SI 123; PW 1.00; MTL 1.21.

Clypeus with anterior margin shallowly truncate in middle; median longitudinal carina distinct. Sides of head in front of eyes only weakly convex. Eyes convex, in full face view clearly breaking lateral cephalic outline. Mesosoma marginate along entire length. Pronotal humeri with rather strong, forward directed, broad-based teeth; propodeal margins terminating posteriorly in short, rounded processes, that appear in profile as minute, weakly upturned teeth. Propodeal dorsum separated from declivity by a distinct, slightly inward bowed, transverse ridge. Petiole with dorsal margin sharp, somewhat sinuate in dorsal view; lateral spines acute, bent outwards and backwards. First gastral segment only shallowly concave; dorso-medial margin of concavity blunt, not raised above dorsal face of segment.

Dorsum of head and pronotum with shiny, regularly spaced, striae, longitudinal on pronotum and posteriorly converging towards midline on mesonotal-propodeal dorsum. Petiole with both faces finely shagreened. Sides of first gastral segment distinctly, longitudinally striate with sculpture becoming more reticulate-puncate on dorsum.

Mandibles and sides of head with a few short semi-erect to erect hairs that are virtually absent from dorsum of head, vertex, mesosoma and petiole, except for a few scattered hairs at base of pronotal teeth. Sides and apex of gaster with numerous semi-erect to erect, medium length hairs and with somewhat dilute, silvery, appressed pubescence lining posterior margin of first gastral segment. Antennae and legs with yellow, appressed pubescence and numerous relatively short erect hairs.

Black, with mandibular masticatory border and antennal scapes reddish brown. Funiculus a shade lighter with extreme tip of last segment narrowly black. Legs mostly yellow, except distal portion of femora, proximal ends of tibiae and first tarsal segment, that are medium to dark reddish brown.

Sexuals and immature stages unknown.

REMARKS

In general appearance, P. exarata resembles P. parva . They share rather strong, broad-based pronotal teeth that are somewhat weakly emarginate at their bases; a distinct, weakly inward bowed, transverse ridge separating the propodeal dorsum from the declivity and an almost identical color scheme. However, they differ in several characters, including the longitudinal striation of the pronotal dorsum. In P. exarata the striation is parallel with the pronotal margins, while in parva the striae distinctly converge anteriorly. The propodeal margins in exarata terminate in narrowly rounded processes that are weakly widened before rounding into the posterior margin. In contrast, the propodeal margins in parva terminate in minute blunt angles. The anterior face of first gastral segment is medially concave in exarata with the anterodorsal margin of the concavity bluntly rounding onto the dorsum of the segment. In parva the concavity is strongly and acutely marginate, with its anterodorsal margin produced dorso-medially and raised above the dorsal face of the gaster.