Polyrhachis (Aulacomyrma) gentilis, Kohout, R. J., 2007

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 : 200-201

Polyrhachis (Aulacomyrma) gentilis , new species

Figures 10, 13, 16

TYPE MATERIAL

HOLOTYPE: PAPUA NEW GUINEA, Morobe Prov., Huon Pen. , Mongi Watershed , Zingzingu , 1200 m, 9 - 10. iv. 1955, E. O. Wilson # 761 (worker). Type distribution: unique holotype in MCZC .

WORKER

Dimensions of holotype: TL c. 4.84; HL 1.28; HW 1.09; CI 85; SL 1.31; SI 120; PW 0.87; MTL 1.22.

Anterior clypeal margin with shallow notch medially. In profile clypeus almost straight anteriorly, weakly convex posteriorly with shallow basal margin. Frontal carinae sinuate with raised laminate lobes; frontal triangle indistinct. Sides of head almost straight in front of eyes, converging anteriorly towards bases of mandibles; gently rounding behind eyes into preoccipital margin. Eyes moderately convex, in full face view breaking lateral cephalic outline. Mesosoma laterally marginate, virtually parallel-sided. Pronotal humeri armed with broad-based teeth that are laterally continuous with pronotal margins; margins weakened posteriorly before reaching distinct promesonotal suture. Metanotal groove absent. Propodeal dorsum terminating in rather distinct, rounded prominences, their posterior margins continued medially but failing to meet, leaving a very narrow gap through which propodeal dorsum descends into declivity; viewed from behind, posterior margin forming an open inverted ‘ V ’; propodeal declivity concave in lateral view. Petiole with dorsal margin acute, entire; lateral spines relatively short, curved backwards, sinuate in dorsal view. Anterior face of first gastral segment concave, anterodorsal margin of concavity rather acute, but not raised above dorsal face of segment.

Mandibles with rather distinct striae radiating from bases towards masticatory borders. Head mostly longitudinally striate, striae on sides curving inwards from posterolateral corners and continuing anteriorly towards mandibular bases. Striae on vertex mostly longitudinal, a few irregular, mostly transversely bowed striae, medially along preoccipital margin. Pronotal dorsum with striae converging anteriorly towards pronotal collar; striae on mesonotal-propodeal dorsum longitudinal for most of their length, curving strongly inwards before reaching posterior margin. Petiole with both faces and first gastral segment laterally and dorsally shagreened.

Head with numerous, erect and semi-erect, relatively short, hairs that do not exceed the greatest diameter of the eyes in length; hairs distinctly less abundant on mesosomal dorsum and first gastral segment, where they are posteriorly curved. Posterior and ventral gaster with more abundant hairs, some as long as greatest diameter of eyes. Mostly medium length, pale yellow to golden, diluted appressed pubescence on all body surfaces, most abundant and golden on gastral dorsum, almost hiding underlying sculpture; pale yellow or silvery on metapleuron, propodeal declivity and posterior margins of gastral segments.

Black, with legs dark to medium reddish brown. Tibiae, except proximal ends, apical segments of tarsi and funiculi distinctly light yellowish brown.

Sexuals and immature stages unknown.

ETYMOLOGY

Name derived from the Latin word gentilis , meaning gentle.

REMARKS

With its small size and parallel sided mesosoma, P. gentilis superficially resembles P. wamuki . However in wamuki the pronotal margins are lacking and the lateral margins of the pronotal spines curve directly onto the sides of the segment without continuing towards the promesonotal suture. The sculpture of the pronotal dorsum also differs with the striae in gentilis only weakly converging, while they are strongly inversely V-shaped and merge along the midline in wamuki.