Pseudomyrmex tenuissimus

Identification
P. tenuissimus can be distinguished from Pseudomyrmex subtilissimus by its darker color, smaller size, and longer petiole. It differs from Pseudomyrmex spiculus by its smaller size and more elongate head (compare HW and CI).

Distribution based on Regional Taxon Lists
Neotropical Region: Belize, Bolivia, Brazil, Colombia, Costa Rica, Ecuador, El Salvador, French Guiana, Greater Antilles, Guatemala, Guyana, Honduras, Jamaica, Mexico, Nicaragua, Panama, Paraguay, Peru, Suriname, Trinidad and Tobago, Venezuela.

Biology
Although P. tenuissimus is the most common member of the P. subtilissimus group, most collections appear to based on scattered foragers. In Costa Rica, Panama, and Colombia, I have encountered workers foraging on vegetation in a variety of habitats including rain forest, rain forest edge, old field/pasture, and tropical dry forest. I have seen nests only twice: one was a small colony containing a single dealate queen, seven workers, and brood, in the dead, fibrous twig of a woody liana, in tropical dry forest (northern Colombia); the other was a nest of 13 workers, 16 alate queens, and brood in the dead twig of a thorny vine at the edge of disturbed second-growth rain forest (Edo. Barinas, Venezuela). Mann (1916:426) recorded a colony from Maranhao, Brazil "taken from beneath a loose piece of bark", an unusual nest-site for Pseudomyrmex as Mann himself remarks.

Nomenclature

 *  tenuissimus. Pseudomyrma subtilissima subsp. tenuissima Emery, 1906c: 119 (w.) BRAZIL. Wheeler, G.C. & Wheeler, J. 1973d: 207 (l.). Combination in Pseudomyrmex: Kempf, 1972a: 224. Raised to species and senior synonym of culmicola: Ward, 1989: 432.
 * culmicola. Pseudomyrma culmicola Forel, 1912g: 27 (w.) TRINIDAD. Combination in Pseudomyrmex: Kempf, 1972a: 217. Junior synonym of tenuissimus: Ward, 1989: 432.

Worker
Ward (1989) - measurements (n=30, except for FI where n=29). HL 0.S2-0.93, HW 0.48-0.53, MFC 0.0l1-0.033, CI 0.56-0.62, OI 0.50-0.58, REL 0.48-0.53, REL2 0.84-0.92, OOI 0.22-0.89, VI 0.85-0.90, FCI 0.023-0.066, SI 0.39-0.46, SI2 0.44-0.54, FI 0.52-0.60, PDI 1.58-2.14, MPI 0.022-0.055, NI 0.55-0.64, PLI 0.54-0.66, PWI 0.49-0.60, PPWI 1.05-1.34.

diagnosis. Similar to P. spiculus (q.v.) except as follows: distinctly smaller, head more elongate (HW 0.48-0.53, CI 0.56-0.62). Basal face of propodeum flatter, forming a more distinct angle with the dec1ivitous face. Body color more uniformly brown to grey-brown, the pronotum, petiole, and postpetiole only slightly, or not at all, contrastingly lighter.

Type Material
Ward (1989) - Holotype (unique syntype) worker, Corumba, Matta Grosso [do Sui], Brazil, 15.viii.1900, [Examined].

Pseudomyrma culmicola Holotype (unique syntype) worker, Trinidad (Forel) [Examined].