Dorymyrmex bicolor

A desert species with common desert ant behaviors; fast moving and forages at high temperatures. Nests in unshaded areas surmounted by a crater of fine sand. Feeds on living and dead insects and honeydew.

Identification
Cuezzo and Guerrero (2011) - Worker CI equal or over 90. Worker bicolored: head, mesosoma, and petiole, dark reddish; gaster black. Same pattern of color is found in queen. Posterior margin of the head slightly concave in frontal view. Dorsal face of pronotum with no erect setae. Mesonotal profile continuous with pronotum, with a distinct dorsal and declivitous face before mesopropodeal suture. Queen Head slightly wider than long with the posterior margin of head strongly concave. Maximum diameter the head behind of compound eyes.

Several species of Dorymyrmex (Dorymyrmex pyramicus, Dorymyrmex thoracicus, etc.) have the same pattern of colors and could be confused with D. bicolor s. str. In some papers, D. bicolor was confused with D. pyramicus, because of its pattern of colors (orange head, mesosoma and petiole with dark gaster), but two main characters are useful to identify and to differentiate both species: head width (larger in workers and queens of D. bicolor) and mesonotum interrupted in lateral view, with a well-defined dorsal and declivitous faces, often descending vertically or nearly so, into mesopropodeal suture, (as described below, D. pyramicus has a promesonotal profile continuous, convex in lateral view). Apparently, D. bicolor belongs to a complex of species, as observed by Forel (1911). The identity of this complex could be solved with a more detailed and extensive research, especially comparing nest series from the west part of USA.

Distribution
Southwestern US to Peru.

Distribution based on Regional Taxon Lists
Nearctic Region: United States. Neotropical Region: Belize, Colombia, El Salvador, Honduras, Jamaica, Mexico, Peru.

Biology
Cuezzo and Guerrero (2011) - The nest, briefly described by Wilson (1957), has a small entrance hall with more regularly formed craters than Dorymyrmex insanus. Dorymyrmex insanus and Dorymyrmex pyramicus are sympatric in the northern part of its distributional range. Both species mentioned above are very active in open areas between 11:00 a.m. and 3:30 p.m and share similar habits of foraging according to Wilson’s observations.

Nomenclature

 *  bicolor. Dorymyrmex pyramicus var. bicolor Wheeler, W.M. 1906d: 342 (w.q.) U.S.A. Gallardo, 1916a: 63 (q.); Crozier, 1970: 114 (k.). Combination in D. (Conomyrma): Gallardo, 1916a: 63; in D. (Biconomyrma): Kusnezov, 1952g: 430; in Conomyrma: Snelling, R.R. 1973b: 4; in Dorymyrmex: Shattuck, 1992c: 85. Subspecies of pyramicus: Creighton, 1950a: 349. Raised to species: Kusnezov, 1952g: 430; Cole, 1958b: 130. See also: Wilson, 1958b: 76; Johnson, C. 1989b: 192; Shattuck, 1994: 75; Cuezzo & Guerrero, 2011: 6.

Worker
Cuezzo and Guerrero (2011) - (n = 25):HL: 0.78–1.1;HW: 0.7–1; EL: 0.18–0.28; EW: 0.15–0.2; SL: 0.78–1.05; WL: 1.25–1.53; CI: 90-91; SI: 105–111; REL: 23–25; OI: 73–86; TLI: 139–161.

Worker bicolored: head, mesosoma, and petiole, dark reddish; gaster black. Funicle and legs darker than rest of the body in some specimens. Head: square in frontal view, almost as wide as long, sides slightly convex. Posterior margin of head feebly convex medially. Scape short (SI: 105–111). Psammophore with short hairs disposed in a triangle, far from the foramen magnum, slightly reaching the oral cavity. Mesosoma: promesonotum in profile, forming a continuous convexity; end of mesonotum with well-differentiated dorsal and declivitous faces, anterior to metanotal suture. Propodeal tubercle short, upward directed, with wide base. Metasoma: petiolar scale forward directed.

Queen
Cuezzo and Guerrero (2011) - (n = 7): HL: 1.18–1.23; HW: 1.25–1.33; EL: 0.38–0.4; EW: 0.18–0.23; SL: 1.08–1.13; WL: 2.43–2.6; CI: 106–108; SI: 91-92; REL: 32-33; OI: 47–56; TLI: 206–212.

Similar to worker in color. Whitish pubescence covering all body tagma. Head: Wider than long, with convex sides, in frontal view. Posterolateral corner rounded, posteriormargin of head slightly concave. Masticatory margin of mandible with six teeth and two or three denticles; basal margin completely dentate with a well-differentiated angle between both margins. Scape surpassing posterior margin of the head by more than twice its maximum diameter. Mesosoma: Parapsidal furrow well developed, diverging forward, axilla not divided. Anepisternum and katepisternum incompletely divided by a short pleural suture. Wings: forewing with only one close radial cell, one cubital cell, and no discoidal cell; pterostigma well developed, longer than wide. Hindwing with three cells closed in basal area; hamuli with 12 hooks. Metasoma: petiolar scale tall, stout, forward directed, and rounded apically. Ventral face of petiole slightly convex. Gaster with dark brown tergites and covered with whitish pubescence.



Etymology
Cuezzo and Guerrero (2011) - The name of bicolor is referred to the particular pattern of colors found in all known castes (worker and queen).