Ponera petila

The single worker (holotype) was collected as a stray in the superficial layers of soil beneath a rotting log on the ground in primary lowland rainforest.

Identification
Taylor (1967) - The species group characters (4-segmented antennal club, absence of an incised mesmetanotal suture), and the small size, allow preliminary diagnosis. Petila may be separated from Ponera szaboi and Ponera szentivanyi by the following characters: From the probably sympatric szaboi, by slightly larger size (HW 0.32 mm, DPW 0.18 mm, opposed to 0.30-0.31 mm, and 0.15 mm respectively in szaboi). Proportionately longer scapes (SI 88; in szaboi 78-83), and broader petiolar node (PNI 72 against 65 in szaboi). Sculpturation of petila is considerably less intense than that of szaboi (compare the description below and for szaboi).

2. From szentivanyi, by smaller size (HW 0.34 mm in szentivanyi), broader head (CI 78, opposed to 75 in szentivanyi), and other dimensional differences (e.g., SI 88 in petila, 94 in szentivanyi, etc.). Sculpturation of the head and mesosoma of szentivanyi is about intermediate between that described for petila and that of szaboi discussed below.

Distribution based on Regional Taxon Lists
Indo-Australian Region: Papua New Guinea.

Nomenclature

 *  petila. Ponera petila Wilson, 1957b: 368, fig. 2 (w.) NEW GUINEA. See also: Taylor, 1967a: 102.

Worker
Holotype. HW 0.32 mm, HL 0.41 mm, SL 0.28 mm, CI 78, SI 88, PW 0.25 mm, petiolar height 0.25 mm, petiolar node length 0.13 mm, dorsal petiole width 0.18 mm. Very similar to Ponera szentivanyi, differing slightly in body and appendage proportions as given in the measurements cited above, and in the much feebler body sculpturing, which can be described as follows. Sides of head densely but shallowly punctate, and feebly shining. Entire dorsal and lateral surfaces of the alitrunk with puncturation or shagreening of variable density but everywhere shallow and feeble, so that the surface is feebly to strongly shining. The gastric tergites are also more feebly sculptured than in szentivanyi and their surfaces overall feebly shining.

Taylor (1967) - Wilson’s description did not mention lack of an incised mesometanotal suture in the workers, or that the palpal formula appears to be Maxillary 2: Labial 2 (the mouthparts are only partially exposed; so a positive count is impossible).

Sculptural details required for diagnosis are: head moderately shining, with small point punctures separated by distances about equal to their maximum diameter. Pronotal dorsum fairly strongly shining, with scattered minute punctures; mesonotum almost imperceptibly more closely punctate. Lateral surfaces of mesosoma feebly shagreened to smooth and shining.

Wilson’s dimensions of the holotype are: HW 0.32 mm; HL 0.41 mm; SL 0.28 mm; CI 78; SI 88; PW 0.25 mm; PNL 0.13 mm; PH 0.25 mm; DPW 0.18 mm; PNU 72.

Type Material
N-E. NEW GUINEA: lower Busu River, near Lae; May 10, 1955; a single worker (Wilson, acc. no. 999). {{{MCZ}}