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

 * . Probolomyrmex petiolatus Weber, 1940b: 76, fig. 1 (w.) PANAMA (Barro Colorado I.).
 * Type-material: holotype worker.
 * Type-locality: Panama: Canal Zone, Barro Colorado I., 29.vi.1938 (N.A. Weber).
 * Type-depository: MCZC.
 * Agosti, 1995: 433 (q.).
 * Status as species: Taylor, 1965d: 363 (redescription); Kempf, 1972a: 211; Brown, 1975: 11, 57; Brandão, 1991: 372; Bolton, 1995b: 366; Agosti, 1995: 433; O’Keefe & Agosti, 1998: 190 (in key); Sosa-Calvo & Longino, 2008: 234; Branstetter & Sáenz, 2012: 263; Feitosa, 2015c: 99 Oliveira & Feitosa, 2019: 90 (redescription); Escárraga, Longino & Sosa-Calvo, 2019: 684.
 * Distribution: Colombia, Guatemala, Mexico, Panama.

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).

References based on Global Ant Biodiversity Informatics

 * Brandao, C.R.F. 1991. Adendos ao catalogo abreviado das formigas da regiao neotropical (Hymenoptera: Formicidae). Rev. Bras. Entomol. 35: 319-412.
 * Branstetter M. G. and L. Sáenz. 2012. Las hormigas (Hymenoptera: Formicidae) de Guatemala. Pp. 221-268 in: Cano E. B. and J. C. Schuster. (eds.) 2012. Biodiversidad de Guatemala. Volumen 2. Guatemala: Universidad del Valle de Guatemala, iv + 328 pp
 * Dattilo W. et al. 2019. MEXICO ANTS: incidence and abundance along the Nearctic-Neotropical interface. Ecology https://doi.org/10.1002/ecy.2944
 * Delabie J. H. C., H. L. Vasconcelos; J. M. S. Vilhena, and D. Agosti. 2001. First record of the ant genus Probolomyrmex (Hymenoptera: Formicidae:  Ponerini:  Platythyreini) in Brazil. Rev. biol. trop 49(1): 397-398.
 * Donoso D. (personal communication, database containing the species by locality info included the catalogue of Ecuadorian ants to be published at Sociobiology 2015)
 * Fernández, F. and S. Sendoya. 2004. Lista de las hormigas neotropicales. Biota Colombiana Volume 5, Number 1.
 * Lapolla, J.S., T. Suman, J. Soso-Calvo and T.R. Schultz. 2006. Leaf litter ant diversity in Guyana. Biodiversity and Conservation 16:491510
 * Lattke J. E. 1991. Estudios de hormigas de Venezuela (Hymenoptera: Formicidae). Bol. Entomol. Venez. 6: 57-61.
 * Longino J. T. L., and M. G. Branstetter. 2018. The truncated bell: an enigmatic but pervasive elevational diversity pattern in Middle American ants. Ecography 41: 1-12.
 * Mirmecofauna de la reserva ecologica de San Felipe Bacalar
 * Nascimento I. C., J. H. C. Delabie, S. Campiolo,and E. M. Neto. 2004. Présence de Probolomyrmex brujitae Agosti, 1994, au Brésil (Hym., Formicidae). Bull. Soc. Entomol. Fr. 109(3): 321-322.
 * Oliveira A. M., and R. M. Feitosa. 2019. Taxonomic revision of the genus Probolomyrmex Mayr, 1901 (Hymenoptera: Formicidae: Proceratiinae) for the Neotropical Region. Zootaxa 4614: 61–94.
 * Ryder Wilkie K.T., A. L. Mertl, and J. F. A. Traniello. 2010. Species Diversity and Distribution Patterns of the Ants of Amazonian Ecuador. PLoS ONE 5(10): e13146.doi:10.1371/journal.pone.0013146
 * Silvestre R., M. F. Demetrio, and J. H. C. Delabie. 2012. Community Structure of Leaf-Litter Ants in a Neotropical Dry Forest: A Biogeographic Approach to Explain Betadiversity. Psyche doi:10.1155/2012/306925
 * Sosa-Calvo, J. and J.T. Longino. 2008. Subfamilia Proceratiinae. In: Sistemática, Biogeografía y Conservación de las Hormigas Cazadores de Colombia. E. Jiménez, F. Fernández, T. Arias and F. Lozano eds., 609 pp. Institutión de Investigación de Recursos Biológicos Alexander von Humboldt, pages 219-238.
 * Vasconcelos, H.L., J.M.S. Vilhena, W.E. Magnusson and A.L.K.M. Albernaz. 2006. Long-term effects of forest fragmentation on Amazonian ant communities. Journal of Biogeography 33:1348-1356
 * Vásquez-Bolaños M. 2011. Lista de especies de hormigas (Hymenoptera: Formicidae) para México. Dugesiana 18: 95-133
 * Weber N. A. 1940. Rare ponerine genera in Panama and British Guiana (Hym.: Formicidae). Psyche (Camb.) 47: 75-84.