Probolomyrmex guanacastensis

This species is only known from a single collection of two specimens.

Identification
Oliveira & Feitosa (2019) - Postero-ventral lobe of petiole short and rounded. Subpetiolar process weakly developed. First gastral segment with prora and a dorsal protuberance on the posterior region of gaster.

This species is easily separated from Probolomyrmex petiolatus by the shape of the petiolar process, and from Probolomyrmex boliviensis by the smaller size, shorter scape, lack of a gastral collar, and similar coloration of the petiolar process and tergite. The ergatoid female has eyes and ocelli, but flight sclerites are not developed. This species is phenotypically very similar to Probolomyrmex brujitae, but differs in having a relatively larger head and longer scape.

Distribution based on Regional Taxon Lists
Neotropical Region: Costa Rica.

Biology
More collections are needed to confirm the presence of ergatoids in this species. It is possible the paratype was a worker that aberrantly developed eyes and ocelli.

O'Keefe and Agosti (1997) - The specimens (type material) were found in sifted debris processed through a modified Berlese-Tulgren funnel from a riparian habitat that included Ochroma pyramidale, Albizzia samen, Anacardium excelsum, Ceiba pentadra, Hymenia courbaril, Bursera simiruba, Andira inermis, Spondias mombin, Sweetenia macrophylla, Cedrela odorata, Enterolobium cyclocarpum, Hirtella racemosa, and Ardesia revoluta. The paratype represents the first record of an ergatoid female in this genus. All other known sexuals of Probolomyrmex are of the normal winged type (Taylor, 1965). Ergatoids typically occur in species with large colonies (Peeters, 1997) but it is believed that colony size is small in this genus. The only colony collection contained less than 30 individuals.

Castes
The ergatoid female has eyes and ocelli, unlike workers (O'Keefe & Agosti 1997). Body sizes are very similar.

Nomenclature

 *  guanacastensis. Probolomyrmex guanacastensis O'Keefe & Agosti, 1998: 191, figs. 1-4 (w.q.) COSTA RICA.

Worker
HL 0.65, HW 0.39, SL 0.41, TL 0.79, CI 0.60, SI 106, (1 examined).

Oliveira & Feitosa (2019) - Similar to ergatoid queen, except by the absence of eyes and ocelli.

Queen
Oliveira & Feitosa (2019) - Ergatoid (from original description): (n=1) HL 0.63; HW 0.41; SL 0.40; WL 0.81; CI 65; SI 63.5.

Ergatoid description: Head 1.6 times longer than wide. Antennal scapes extends beyond head midlength, distance from scape apex to of head more than two times pedicel length (SI 63.5). Compound eyes and three equally sized ocelli present. Propodeal declivity laterally with narrow carina, dorsolateral teeth present, almost in same plane as dorsal profile of the propodeum in lateral view. Petiole longer than high, without teeth; anterior face of petiolar node long and inclined; posterior face short and concave; postero-ventral lobe short and rounded; subpetiolar process weakly developed. First gastral segment with prora and dorsal protuberance on posterior region of tergite, characterized by gentle elevation of the integument.

Type Material

 * Holotype: COSTA RICA: Guanacaste, 8.5 km NW Bagaces: Plazuela Hacienda Monteverde, 31.viii.1996, S. O’Keefe, sift leaf debris (worker).
 * Paratype: same data as holotype, except: 1 ergatoid queen, (see www.antweb.org; specimen CASENT0104673).