Pseudomyrmex filiformis

Ward (1996) suggests this ant is a temporary social parasite of a number of common, co-occurring Pseudomyrmex species.

Distribution based on Regional Taxon Lists
Neotropical Region: Brazil, Colombia, Costa Rica, Ecuador, French Guiana, Guatemala, Guyana, Mexico, Panama, Paraguay, Peru, Suriname, Trinidad and Tobago, Venezuela.

Biology
Ward (1996) - Incipient colonies of this species have been found inhabiting a nest in small dead twigs with several workers of a different Pseudomyrmex species. This contrasts with mature colonies, which form large monospecific nests with a single functional queen. This suggests the queens are temporary social parasites.

Gillette et al. (2015) in a Chaipas, Mexico field study of twig-nesting ants in coffee plants found P. ejectus occurred in 9% of the twigs with nests. All of its nests were below 1300 m.

Nomenclature

 *  filiformis. Formica filiformis Fabricius, 1804: 405 (q.) CENTRAL AMERICA. Wheeler, W.M. 1919i: 125 (w.m.); Wheeler, G.C. & Wheeler, J. 1956: 384 (l.). Combination in Leptalea: Erichson, 1839: 309; in Pseudomyrma: Roger, 1862c: 289; in Pseudomyrmex: Wheeler, G.C. & Wheeler, J. 1956: 384. Senior synonym of cephalica: Roger, 1862c: 289; of biconvexa: Wheeler, W.M. 1919i: 125; of longiceps Forel, longiceps Stitz: Ward, 1989: 438.
 * cephalica. Pseudomyrma cephalica Smith, F. 1855c: 168 (w.q.m.) BRAZIL. Junior synonym of filiformis: Roger, 1862c: 289.
 * biconvexa. Pseudomyrma biconvexa Forel, 1899c: 95, pl. 4, fig. 10 (w.) GUATEMALA. Junior synonym of filiformis: Wheeler, W.M. 1919i: 125.
 * longiceps. Pseudomyrma biconvexa var. longiceps Forel, 1906d: 229 (w.) COLOMBIA. Combination in Pseudomyrmex: Kempf, 1972a: 218. Subspecies of filiformis: Wheeler, W.M. 1919i: 131. Junior synonym of filiformis: Ward, 1989: 438.
 * longiceps. Pseudomyrma longiceps Stitz, 1933: 68 (q.) VENEZUELA. [Unresolved junior primary homonym of longiceps Wheeler, above.] Combination in Pseudomyrmex: Kempf, 1972a: 221. Junior synonym of filiformis: Ward, 1989: 438.

Type Material
Ward (1989):

Syntype dealate queen, Essequibo, Guyana (Smidt) [Examined]; here designated as LECTOTYPE. A second syntype dealate queen in ZMUC, lacking head, metasoma, and a locality label, has been labelled paralectotype.

Pseudomyrma cephalica F. Smith, 1855:168. Dealate queen, labelled as type, Santarem, Brazil (Bates); two workers. probable syntypes, Villa Nova, Brazil (Bates) [Examined].

Pseudomyrma biconvexa Forel, 1899:95. Syntype workers, Pantaleon, Guatemala (Champion) (BMNH, ); Costa Rica (Tonduz) (BMNH) [Examined].

Pseudamyrma biconvexa var. longiceps Forel, 1906:229. Syntype worker, Santa Marta, Colombia (A. Forel) (MHNG) [Examined].

Pseudomyrma longiceps Stitz, 1933:69. Holotype queen, Macuto, near La Guayra, Venezuela (e. Gazgo) (not in . probably destroyed during World War II).

The syntype worker of P. longiceps (Forel) is simply a large P. filiformis worker, with a rather elongate head and a conspicuous subpetiolar tooth. I have seen such variant workers within nest-series of typical P. filiformis from elsewhere in Central and South America. Although the unique type of P. longiceps (Stitz) is lost, the original description (particularly as it pertains to head length, position of eyes, and petiole shape) is closer to that of P. filiformis than any other species known to me.