Solenopsis subterranea

Specimens of S. subterranea were captured in subterranean Vienna sausage baited traps at 10 cm in depth in the United States (Mackay and Vinson 1989) and in the same type of traps in Costa Rica and Venezuela. They were collected in a subterranean trap baited with a mealworm in Louisiana. Habitats include an open grassy area in an oak forest in the US, brushy grasslands in Venezuela and a weedy area in a pine and hardwood forest in Mexico.

Identification
A New World thief ant that is a member of the pygmaea species complex.

Pacheco and Mackay (2013) – Worker - This species is recognized by having an elongated, coarsely punctated head. The eyes are minute with about one ommatidium. The head and mesosoma are covered with short (0.020 mm) erect and sub erect hairs. The minor funicular segments are short at 0.060 mm.

The short erect and suberect hairs on the head and mesosoma would easily separate this species from all other species in the United States in the pygmaea complex, except Solenopsis tonsa. It can be separated from S. tonsa as the head of S. subterranea is slender viewed laterally, compared to the robust, thick profile of S. tonsa. It could be easily confused with the Mexican species Solenopsis isopilis and the South American Solenopsis minutissima, which both have short hairs on the pronotum and gaster, which are all about equal in length (0.030-0.048 mm in length). It can be separated from S. isopilis by being more hairy, with more than 20 erect hairs on the outline of the pronotum when seen in profile (S. isopilis only has approximately 10 erect hairs). It can be separated from S. minutissima as its eyes are small, but well-defined (poorly defined, nearly absent in S. minutissima).

Keys

 * Key to New World Solenopsis Species Complexes
 * Key to Solenopsis pygmaea species complex / Clave a las obreras del complejo Solenopsis pygmaea

Distribution
Louisiana and Texas south to Colombia and Venezuala.

Distribution based on Regional Taxon Lists
Nearctic Region: United States. Neotropical Region: Colombia, Costa Rica, Guatemala, Honduras, Mexico, Venezuela.

Castes
Known only from the worker caste.

Nomenclature

 *  subterranea. Solenopsis (Diplorhoptrum) subterranea Mackay, W.P. & Vinson, 1989a: 175, figs. 1-4 (w.) U.S.A.

Worker
Pacheco and Mackay (2013) - Measurements (n=5). TL 1.02-1.14 (1.07); HL 0.318-0.342 (0.326); HW 0.240-0.270 (0.252); EL 0.018-0.030 (0.023); ED 0.018-0.030 (0.022); SL 0.192-0.198 (0.193); FSL 0.060-0.066 (0.062); CI 74.1-83.3 (77.2); SI 57.9-60.4 (59.2); PL 0.066-0.078 (0.072); PW 0.084-0.090 (0.086); PI 78.6-86.7 (83.3); PPL 0.072-0.084 (0.078); PPW 0.078-0.102 (0.091); PPI 80.0-92.3 (85.8); WL 0.210-0.240 (0.222); PSL 0.024-0.030 (0.025); PSW 0.018-0.030 (0.024).

Head elongate, densely, coarsely and evenly punctate; eyes small, round, with at least one ommatidium; scape short, does not reach posterior border of head; clypeal lateral teeth well developed; extralateral teeth angular, poorly defined, but interrupt anterior clypeal border; clypeal carinae weakly developed; minor segments 3-8 of funiculus short; petiole wider than postpetiole viewed laterally; subpeduncular process lacking tooth; postpetiolar node oval when viewed laterally and dorsally.

Head and mesosoma covered with short (0.020 mm), erect and suberect hairs approximately equal in length.

Type Material
(holotype worker and 20 paratypes workers are deposited in the, additional 180 paratype workers are deposited in the , , , , , , , , , , MACN, TAMU [Mackay and Vinson, 1989]), USA, Texas, Brazos Co., 10k N Kurten.