Neivamyrmex macrodentatus

The type specimens of this species are from Apaicán, Volcan Irazú. Borgmeier (1955) examined a second collection by Schmidt from San José. Jack Longino found a column of workers beneath a stone at the edge of a gravel road. The habitat was an open pasture area that had been recently burned. The locality was the San Luis Valley, on the Pacific slope just below Monteverde, at 1050m elevation. The collection was made in the middle of a hot day. The smallest workers of this species were remarkably tiny, about the size of small Solenopsis species previously placed in the subgenus Diplorhoptrum.

This species is only known from queens and/or workers and has yet to be associated with males.

Identification
Jack Longino:

Posterior face of propodeum straight, not concave, as long or longer than dorsal face; eye completely absent; apex of scape does not exceed middle of face; anteroventral tooth of petiole large and triangular; basal tooth of mandible of major enormous; mesosoma of largest worker less than 1.2 mm long.

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

Biology
Baudier et al. (2015) studied thermal tolerances of a variety of army ant workers. Neivamyrmex macrodentatus was one of two army ant species sampled that are strictly subterranean, i.e. both bivouac and raid underground.

Nomenclature

 * . Eciton (Acamatus) macrodentatus Menozzi, 1931b: 260, fig. 1 (w.) COSTA RICA.
 * Type-material: 5 syntype workers.
 * Type-locality: Costa Rica: Vulcano Irazu, Apaicán (F.I. Tristan).
 * Type-depository: IEUB.
 * Combination in Neivamyrmex: Borgmeier, 1953: 11.
 * Status as species: Borgmeier, 1939: 414; Borgmeier, 1955: 434 (redescription); Kempf, 1972a: 156; Watkins, 1976: 14 (in key); Bolton, 1995b: 289; Branstetter & Sáenz, 2012: 254.
 * Material of the nomen nudum tristani referred here by Borgmeier, 1939: 414.
 * Distribution: Costa Rica, Guatemala.

References based on Global Ant Biodiversity Informatics

 * 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.
 * Watkins J. F., II 1976. The identification and distribution of New World army ants (Dorylinae: Formicidae). Waco, Texas: Baylor University Press, 102 pp