Azteca schimperi

This species makes large external carton nests. I have observed four nests, three in Costa Rica and one in Panama, and all have been in Cecropia trees (C. peltata, C. obtusifolia, and C. longipes). Benson (1985) also observed A. schimperi in Cecropia trees. However Forel (1908b), describing the queen and male from a collection from Bahia, Brazil, explicitly stated that the carton nest was perched on the branches of a tree that was not Cecropia. (Longino 2007)

Identification
A member of the Azteca aurita group. See the group page and keys for identification.

Longino (2007) - A relatively distinctive species with little discernible variation over its range; specimens from Argentina and Paraguay look very like specimens from Central America and Mexico. Workers possess a middle and posterior tibia without an apical spur, mandible with typical thickness at base, concave masticatory edge curved towards an enlarged apical tooth, apical tooth much larger than penultimate tooth, medial clypeal lobe strongly convex and protruding, extending far beyond the lateral clypeal lobes, head with convex sides, and strongly cordate posterior margin.

Distribution
Mexico to Argentina. Azteca schimperi has a very broad range, vying with Azteca alfari for the Azteca species with the largest range.

Distribution based on Regional Taxon Lists
Neotropical Region: Argentina, Belize, Brazil, Colombia, Costa Rica, French Guiana, Guatemala, Guyana, Mexico, Nicaragua, Panama, Paraguay, Peru, Suriname.

Biology
Longino (2007) - The three nests I have seen in Costa Rica were all at the edges of roads in highly human altered landscapes (pasture edges, coffee farms) in seasonally dry areas. The globular carton nests are very conspicuous on the highly visible branches of Cecropia trees, and in my studies of Cecropia in Costa Rica I always looked for them. Yet I have only seen these three over many years of work in Costa Rica. I have never been able to examine a nest closely, but I have been able to observe the base of the trees in which they occurred. In one case workers were foraging not only on the base of the tree but also on surrounding low vegetation. In another case, on a tree with stump sprouts at the base, workers were swarming over the sprouts but not actually entering the internodes. These observations contrast with typical Cecropia ants, which never forage off the host plant and usually enter and occupy any sprouts at the base of the tree. Thus A. schimperi seems to occupy Cecropia trees more “lightly” than the dominant obligate Cecropia ants.

A. schimperi could be a temporary social parasite of Cecropia ants, usurping an existing Azteca colony as a means of establishing its own. Such a scenario might explain the somewhat less specialized use of Cecropia by A. schimperi; it may be a specialist on Cecropia ants rather than Cecropia trees.

Guerreo et al. (2010) - Until now, Tapinoma nigerrimum (Nylander) is the only species in the Dolichoderinae subfamily for which winged or stumped workers have been reported (Scupola 2008), something that is always considered to be a characteristic of gynes. Unexpectedly, the examination of the Azteca aurita group material coming from MZSP allowed us to observe a major worker of Azteca schimperi coming from Costa Rica with all of the morphological characters of a worker except for its vestigial wings. This worker presents some characteristics that differentiate it from normal workers: the head is a little larger than the normal major workers from the same species (HLA: 1.56 vs. 1.16–1.51 mm), the median ocellus a little more developed and similar to that of the gynes of A. schimperi, and there is the presence of wing rudiments on the mesosoma. The elements that determine these kinds of morphological anomalies are generally considered to be environmental factors, as these are essential for the determination and development of the casts (Scupola 2008); these environmental factors, which have a decisive function in the formation of a hybrid phenotype, are poor nutrition and different chemicals (Heinze 1998). Nevertheless, simple genetic accidents, viruses or parasites can also provoke the development of abnormalities. This is the first report of the intercast syndrome in the genus Azteca and the second for the Dolichoderinae subfamily, after the results reported by Scupola (2008) for Tapinoma nigerrimum.

De Oliveira et al. (2015), studying ant occupancy of Cecropia trees in southwest Bahia, Brazil, found a colony of  opportunistically nesting in a Cecropia pachystachya tree.

Vanoye-Eligio et al. (2020) provide the following notes based on collections using Multilure-type traps from northeastern Mexico: A total of 4 workers and a queen were collected. Nests of this species are difficult to detect because of its arboreal habit, as documented by Longino (2007), who reported 3 nests of A. schimperi on Cecropia (Urticaceae) after several years of sampling in Costa Rica. It forms large nests constructed from gnawed plant material and is reported elsewhere nesting in trees of the genus Cecropia (Benson 1985). Visual searches near the location of the traps indicated that their foraging territories were not limited to the host tree, but extended into the surrounding undergrowth. Additional searching detected A. schimperi nesting in cavities of broken or rotten branches of mango trees (Mangifera indica L.; Anacardiaceae), which are common components of the tropical forest in the region.

Nomenclature

 *  schimperi. Azteca schimperi Emery, 1893b: 140, pl. 2, figs. 43-46 (s.w.) COSTA RICA. Forel, 1908c: 387 (q.m.). Senior synonym of clariceps, fiebrigi, pallidula: Longino, 2007: 58.
 * fiebrigi. Azteca fiebrigi Forel, 1909a: 261 (s.w.q.m.) PARAGUAY. Junior synonym of schimperi: Longino, 2007: 58.
 * clariceps. Azteca lanuginosa var. clariceps Santschi, 1933e: 121 (w.) ARGENTINA. Junior synonym of schimperi: Longino, 2007: 58.
 * pallida. Azteca muelleri var. pallida Stitz, 1937: 135 (w.) MEXICO. Junior synonym of schimperi: Longino, 2007: 59.

Worker
Longino (2007) - (n=4): HLA 1.42 (1.16–1.51), HW 1.41 (1.18–1.45), SL 0.94 (0.85–1.01), CI 99 (96–102), SI 68 (64–73).

Palpal formula 4,3; middle and hind tibia lacking apical spur; mandible of typical thickness at base, with microareolate sculpture, dull, becoming smooth and shiny, somewhat flattened toward masticatory margin; masticatory margin concave, curving toward enlarged apical tooth, apical tooth much larger than penultimate tooth; medial clypeal lobe strongly convex and protruding, extending well beyond lateral clypeal lobes; head with convex sides, strongly cordate posterior margin; in lateral profile promesonotum forming single convexity, evenly convex to middle of mesonotum, posterior mesonotum drops steeply to depressed basal face of propodeum; petiolar node somewhat pillow-shaped, blunt and weakly bilobed apically, posteroventral lobe shallow, weakly convex from front to back, ending posteriorly in a somewhat abrupt shelf, rising steeply to tergosternal suture, leaving distinct posterior rim on sternite, laterally very strongly compressed, forming sharp median carina (this character less developed on South American material); scape, entire head capsule, mesosoma, legs, petiolar node, and gastral dorsum with appressed pubescence but completely lacking erect setae; color clear yellow orange to red brown, face shining.

Queen
Longino (2007) - (n=3 queens from Colombia, Brazil, and Paraguay): HLA 1.44 (1.40–1.47), HW 1.05 (1.04–1.06), SL 0.97 (0.94–1.01), CI 72 (71–76), SI 69 (65–69).

Palpal formula 4,3; middle and hind tibia lacking apical spur; apical tooth of mandible about twice as long as penultimate tooth, dorsal surface shiny, smooth, with sparse piligerous puncta; medial clypeal lobe strongly convex and protruding, extending well beyond lateral clypeal lobes; head rectangular, sides parallel and flat, posterolateral margins subangular but rounded, posterior margin a moderately developed V-shaped impression; petiolar node triangular; posteroventral petiolar lobe developed, moderately convex from front to back, laterally compressed and tectiform; scape, sides and posterior margin of head with dense vestiture of short, erect setae; femora with similar setae but erect setae nearly absent from outer margins of middle and hind tibia; pronotum and mesoscutum with these short setae very sparse, more abundant on scutellum and propodeum; petiolar node and ventral margin of petiole with abundant short setae; gaster devoid of erect setae; entire body red brown, with smooth, highly polished and reflective surface.

Type Material
Longino (2007) - Syntype workers: Costa Rica, Alajuela [10°01'N, 84°13'W, 1100m] (Alfaro), , (examined).