Nomamyrmex esenbeckii

Identification
Watkins (1977) - N. esenbecki. Workers: postoccipital sulcus distinct; dorsum of petiole with longitudinal rugae. Males: median border of head behind ocellar peduncle with a narrow lamella; first gastric tergite usually with longitudinal rugae; width of, blade of stipes about one-half its length; volsella blunt, gradually tapered or snout-shaped.

N. esenbecki s. str. Workers: transversely keeled posterior margin of mesonotum usually straight or slightly convex in the middle; anterior corners of postpetiole prominent and abruptly rounded causing the postpetiole to appear subquadrate with an anterior face as broad or broader than the petiole; entire body usually dark reddish brown with gaster sometimes slightly lighter. The mesonotal keel is occasionally slightly concave, but usually not in all specimens in a series. The posterior edge of the propodeum is often only slightly indented between the propodeal “teeth,” but a few specimens may be deeply indented (dorsal view). Males: setae on fifth gastric tergite broadly separated along the midline (i.e., the separation is about one half the width of the tergite near its base; distal portion of volsella distinctly snout-shaped, but the “snout” varies somewhat in detail.

N. esenbecki crassicornis. Workers: transversely keeled posterior margin of mesonotum usually straight or slightly convex in the middle; anterior corners of the postpetiole not prominent with the sides gradually curving inward to the anterior face which is slightly narrower than the petiole causing the postpetiole to appear trapezoidal; gaster usually yellowish brown, remainder of body reddish brown. A few workers from Panama have slightly concave mesonotal keels; however, these workers have postpetioles and yellowish brown gasters typical for crassicornis. Males: setae on fifth gastric tergite not distinctly separated along the midline; longitudinal rugae distinct on the second gastric tergite; apex of volsella slightly enlarged and rounded. The entire posterior half of the fifth tergite is usually covered with long thick setae; however, some specimens from Panama have the setae along the midline more confined to the posterior border and these setae are shorter than the more lateral setae. The distal portion of the volsella is slightly upturned with a gradually rounded apex in specimens from Panama, almost straight with a bluntly rounded apex in specimens from Trinidad, and somewhat more downturned in specimens from Peru.

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

Nomenclature

 *  esenbeckii. Labidus esenbeckii Westwood, 1842: 75, pl. 20, fig. 4 (m.) BRAZIL. Combination in Eciton: Emery, 1890b: 39; in E. (Labidus): Santschi, 1920d: 364; Creighton, 1950a: 64; in E. (Holopone): Santschi, 1925b: 11; in E. (Nomamyrmex): Borgmeier, 1936: 55; in Nomamyrmex: Borgmeier, 1953: 14. Senior synonym of fimbriatum, interrupta, terrificum: Borgmeier, 1953: 14; of afflictus, crudele, indomabile: Borgmeier, 1955: 139; of crassicornis: Wild, 2007b: 43. Current subspecies: nominal plus mordax, wilsoni. See also: Borgmeier, 1958: 201; Watkins, 1977a: 204.
 * crassicornis. Eciton crassicornis Smith, F. 1855c: 163, pl. 13, figs. 1, 2 (w.) BRAZIL. Borgmeier, 1958: 202 (q.). Combination in E. (Labidus): Wheeler, W.M. 1916d: 324; in E. (Holopone): Santschi, 1925b: 12; in E. (Nomamyrmex): Borgmeier, 1936: 55; in Nomamyrmex: Borgmeier, 1953: 16. Subspecies of esenbeckii, senior synonym of hirsutipodex, intrepidum and material of the unavailable name furiosum referred here: Borgmeier, 1955: 139. Junior synonym of esenbeckii: Wild, 2007b: 43. See also: Watkins, 1977a: 205.
 * afflictus. Acanthostichus afflictus Gallardo, 1919a: 239, fig. 3 (m.) ARGENTINA. Combination in Eciton: Emery, 1920a: 60. Junior synonym of esenbeckii: Borgmeier, 1955: 139.
 * fimbriatum. Eciton (Labidus) fimbriatum Santschi, 1920d: 363, figs. 1, 2 (m.) FRENCH GUIANA. Junior synonym of esenbeckii: Borgmeier, 1953: 14.
 * hirsutipodex. Eciton (Labidus) esenbecki st. hirsutipodex Santschi, 1920d: 364, fig. 2 (m.) MEXICO. Junior synonym of crassicornis: Borgmeier, 1955: 139.
 * interrupta. Eciton fimbriatum var. interrupta Santschi, 1923c: 249 (m.) BRAZIL. Junior synonym of esenbeckii: Borgmeier, 1953: 14.
 * crudele. Eciton (Holopone) crassicorne subsp. crudele Santschi, 1929a: 414, figs. c, g (w.) BOLIVIA. Junior synonym of esenbeckii: Borgmeier, 1955: 139.
 * intrepidum. Eciton (Holopone) crassicorne var. intrepidum Santschi, 1929a: 414, figs. b, f (w.) VENEZUELA. Junior synonym of crassicornis: Borgmeier, 1955: 139.
 * indomabile. Eciton (Holopone) crassicorne var. indomabile Santschi, 1930e: 82 (w.) BRAZIL. Junior synonym of esenbeckii: Borgmeier, 1955: 139.
 * terrificum. Eciton (Holopone) fimbriatum var. terrificum Santschi, 1930e: 82 (m.) BRAZIL. Junior synonym of esenbeckii: Borgmeier, 1953: 14.