Probolomyrmex guanacastensis, O'Keefe, S. T. & Agosti, D., 1997

O'Keefe, S. T. & Agosti, D., 1997, A new species of Probolomyrmex (Hymenoptera: Formicidae) from Guanacaste, Costa Rica., Journal of the New York Entomological Society 105, pp. 190-192 : 106-107

Probolomyrmex guanacastensis , new species

Holotype: 1 worker, Costa Rica, Guanacaste, 8.5 km NW Bagaces, Plazuela Hacienda Monteverde, 31 - VIII- 1996, S. 0 ' Keefe, sift leaf debris. Holotype deposited at InBio, Costa Rica.

Paratype: 1 queen, same data as holotype. Deposited in American Museum of Natural History.

QUEEN. HL 0.63, HW 0.41, SL 0.40, TL 0.81, CI 66, SI 97, Figures 1, 2 (1 examined).

WORKER. HL 0.65, HW 0.39, SL 0.41, TL 0.79, CI 0.60, SI 106, Figures 3, 4 (1 examined).

Comments: This species is easily separated from P. petiolatus by the shape of the petiolar process, and from P. 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 P. brujitae , but differs in having a relatively larger head and longer scape.

Despite repeated sampling in July 1995, February 1996, and July 1996, only two specimens were collected of this genus from the type locality and none were collected in nearby localities of similar habitat. The specimens 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. This site is unique in that numerous (> 150) specimens of Homoconnus (Coleoptera: Scydmaenidae) were collected, while less than five were collected at ali other sites sampled combined.

P. guanacastensis is the first record of an ergatoid female in this genus, in which ali the other known sexuais are of the normal winged type (Taylor, 1965). This species belongs to the exceptions among ants with ergatoid queens, which normally have large colonies (Peeters, 1997). The only completely collected colony so far included only 20 workers (Taylor, 1965: 360).