Probolomyrmex petiolatus

The holotype of P. petiolatus was collected among leaves and humus on the rainforest floor in Panama.

Identification
Oliveira & Feitosa (2019) - Postero-ventral lobe of petiole long and subquadrate. Subpetiolar process well developed and subrectangular. Prora and dorsal protuberance on posterior region of first gastral tergite absent.

The subrectangular shape of the subpetiolar process makes this species similar to Probolomyrmex dentinodis. However, the latter has a pair of petiolar teeth, the postero-ventral lobe of the petiole is short and rounded, and there are a prora and dorsal protuberance on the gaster.

Agosti (1994) - This species is easily recognized by the subpetiolar process.

Taylor (1965) - The worker of P. petiolatus differs from that of the sympatric Probolomyrmex angusticeps in its smaller size, with relatively broad head, much shorter scapes, and shorter, more compact petiolar node. The unknown worker of Probolomyrmex boliviensis is undoubtedly similar to P. angusticeps in these features.

Distribution based on Regional Taxon Lists
Neotropical Region: Brazil, Colombia, Ecuador, Guatemala, Mexico, Panama, Venezuela.

Nomenclature

 *  petiolatus. Probolomyrmex petiolatus Weber, 1940b: 76, fig. 1 (w.) PANAMA. Agosti, 1995: 433 (q.). See also: Taylor, 1965d: 363; Brown, 1975: 57.

Taxonomic Notes
There is a Brazilian record in the literature for this species (Delabie et al. 2001), but these were described as a new species, Probolomyrmex dentinodis, by Oliveira & Feitosa (2019).

Worker
Oliveira & Feitosa (2019) - (n=3) HL 0.50–0.57; HW 0.34–0.37; SL 0.26–0.30; WL 0.63–0.69; PL 0.26–0.30; PW 0.27–0.30; PH 0.28–0.30; TL 2.13–2.33; CI 61.5–68.5; SI 51.5; PI 93.5–107.

Frontoclypeal shelflike projection micropunctate. Mandibles foveated, interval between foveae covered by micropunctures; external surface of mandibular basal margin smooth; tip of apical segment of antennae bearing minute pits. Mesopleuron and metapleuron alveolate and foveated; lateral faces of propodeum foveated and micropunctate; alveoli denser just above metapleural gland orifice; opening of metapleural gland narrow, with smooth anterior region, surrounded by rows of hairs. Petiolar node and postero-ventral lobe of petiole with incomplete foveae and micropunctures; subpetiolar process alveolate. Posterior region of second gastral tergite with foveae.

Space between mesosomal foveae covered by dense pubescence. Pygidium with dense pubescence and some long and thick hairs. Head 1.5 times longer than wide. Hypostomal margin curved. Antennal scapes extend head midlength, distance from scape apex to of head more than two times the pedicel length (SI 51.5). Propodeum emarginated posteriorly on each side by a narrow carina, with teeth at their apexes. Petiole as long as high (PI 93.5–107), without teeth; posterior face short, straight and smooth; postero-ventral lobe long and subquadrate; subpetiolar process well developed and subrectangular, with the postero-ventral angle acute and directed ventrally. First gastral segment without prora and dorsal protuberance on posterior region of tergite.

Taylor (1965) - The unique holotype worker of this species has the following dimensions: HL, 0.51 mm.; HW, 0.36 mm.; SL, 0.29 mm.; CI, 71; SI, 81; WL, 0.65 mm.; PW, 0.27 mm.; dorsal petiole width, 0.14 mm.; petiolar node index, 52; petiole height, 0.27 mm.; petiolar node length, 0.23 mm.; lateral petiolar index, 85. Weber's original description adequately characterises this distinctive species.

Queen
Agosti (1994) - HL 0.61, HW 0.42, SL 0.44, TL 0.90. CI 70, SI 104, (1 examined).