Megalomyrmex balzani

Brandão (1990) - Mann (1916) described the nest of this species (misidentified by him as M. bituberculatus) as subterraneous with entrances, in general, at tree bases. Locality labels from workers collected near Rio Tambopata, Peru by C. Kugler indicate “nests in very rotten stump and soil beneath”. According to Mann these ants are rather slow and may tend membracid nymphs. I found at the Museu de Zoologia workers from Manaus associated with nymphs of Aconophora sp (Membracidae). Dr. W. Benson (personal communication) observed workers of M. balzani tendind nymphs and adults of Tragopa sp (Membracidae) kept in silk-spinned “nests” over small branches no higher than 1m.

Identification
Brandão (1990) - Megalomyrmex balzani workers can be easily separated from those of Megalomyrmex leoninus by the presence of paired sharpened acrotergites at the mesosternum and metasternum of M. balzani.

Some workers from Cavinas, Beni, Bolivia as well as individuals from some other localities, have an anterior ocellus and the gaster swollen. The Cavinas specimens also have a modification at the venom apparatus. These workers are probaly gamergates.

The specimens from Humaita, AM and Pto. Maldonado, Peru are distinctly darker than any others series. In general gasters are darker than the rest of body.

All samples from Humaita and Porto Velho as well as part of the Tumupasa series have the dorsal margin of the petiole, in frontal view, rounded and not notched. These species also present the declivity with lower and profuse pilosity. From Tumupasa I studied 70 workers. Both forms were never found pinned together, suggesting they came from different nests. As all cited characters also variates within other nests series I believe they represent intraspecific variation.

Males from Rurrenabaque, Beni, Bolivia do not have notaulus at the mesonotum. but can not be distinguished from other males in any other characters.

Distribution based on Regional Taxon Lists
Neotropical Region: Bolivia, Brazil, Colombia, Ecuador, Peru.

Biology
Brandão (1990) - Oliveira (1982) observed that workers of M. balzani are the model for the yellow form of the mimetic spider Myrmecium bifasciatum (Clubionidae ). He found the ants in small groups tending membracids in bushes also no higher than 1 m.

M. balzani is the better represented species in museum collections, due to Mann collections at Mulford Biological Expedition from 1921 to 1922, Rio Beni, Bolivia. Part of the scientific results from this expediton can be found in Snyder (1926), including a map with all visited localites. A account of the same trip has been written by Mac Creagh (1961).

Brandão (2003) - J. Diniz and I collected in October 1, 1987, a large colony of M. balzani on the campus grounds of the Universidade Federal do Amazonas, in Manaus. Most individuals occupied a space hidden among the root system, litter and moss of a large tree, but a trail led to a space under bark some 1 m high on the live trunk, where part of the colony was found. The colony had more than 400 workers and several immatures, all brought alive to the Museu de Zoologia but they did not survive for more than a few weeks in artificial conditions.

Nomenclature

 * . Megalomyrmex balzani Emery, 1894c: 153 (w.) BOLIVIA.
 * Type-material: lectotype worker (by designation of Brandão, 1990b: 431), 3 paralectotype workers.
 * Type-locality: lectotype Bolivia: Cantoni di Coroico, Chilumani-Yungas, 1600 m. (L. Balzan); paralectotypes with same data.
 * Type-depository: MSNG.
 * Viehmeyer, 1922: 209 (m.).
 * Status as species: Wheeler, W.M. 1909b: 237 (in key); Emery, 1922e: 190; Viehmeyer, 1922: 209; Wheeler, W.M. 1925a: 29; Borgmeier, 1927c: 99; Borgmeier, 1930: 33; Ettershank, 1966: 105; Kempf, 1972a: 139; Brandão, 1990b: 431 (redescription); Brandão, 1991: 355; Bolton, 1995b: 249; Brandão, 2003: 151; Bezděčková, et al. 2015: 117; Fernández & Serna, 2019: 806.
 * Senior synonym of duckei: Brandão, 1990b: 431; Brandão, 1991: 355; Bolton, 1995b: 249.
 * Distribution: Bolivia, Brazil, Colombia, Peru.
 * duckei. Megalomyrmex duckei Forel, 1912g: 13 (w.) BRAZIL (Amazonas).
 * Type-material: syntype workers (number not stated).
 * Type-locality: Brazil: Santo Antonio de Iça (Ducke).
 * Type-depository: MHNG.
 * Status as species: Wheeler, W.M. 1909b: 237 (in key); Emery, 1922e: 190; Wheeler, W.M. 1925a: 34 (in key); Borgmeier, 1927c: 100; Ettershank, 1966: 105; Kempf, 1972a: 139.
 * Junior synonym of balzani: Brandão, 1990b: 431; Brandão, 1991: 355; Bolton, 1995b: 249.

Worker
Brandão (1990) - Mandibles smooth; anterior clypeal border round with median denticle; 3-segmented antennal club; frontal suture impressed; 18-20 ocular facets at compound eye largest diameter; occipital margin raised, visible only in head lateral view: pronotum dorsum with low lateral elevations; promesonotal suture impressed dorsally; mesosternum and metasternum with sharpened paired acrotergites; propodeum dorsum not impressed; declivity smooth; epipetiolar carina complete; non-pedunculate petiole with anteroventral denticle originating a longitudinal translucid flange; dorsal margin of petiolar node, in frontal view, generally notched at apex; ventral face of postpetiole without process; apex of femura sharpened.

Color: shiny orange-brown to deep brown.

Type Material
Brandão (1990) - Cantoni di Coroico, Chulumani - Yungas, Bolivia (16°10'S, 67°44'W). Viehmeyer, 1922: 209-211, male. Wheeler, 1925a: 29, male. Lectotype designation Lectotype and 3 paralectotypes at Museo Civico di Storia Naturale Giacomo Doria. Genova.

References based on Global Ant Biodiversity Informatics

 * Brandão C. R. F. 1990. Systematic revision of the Neotropical ant genus Megalomyrmex Forel (Hymenoptera: Formicidae: Myrmicinae), with the description of thirteen new species. Arquivos de Zoologia (São Paulo) 31: 411-481
 * Emery C. 1894. Studi sulle formiche della fauna neotropica. VI-XVI. Bullettino della Società Entomologica Italiana 26: 137-241.
 * Escalante Gutiérrez J. A. 1993. Especies de hormigas conocidas del Perú (Hymenoptera: Formicidae). Revista Peruana de Entomología 34:1-13.
 * Ettershank G. 1966. A generic revision of the world Myrmicinae related to Solenopsis and Pheidologeton (Hymenoptera: Formicidae). Aust. J. Zool. 14: 73-171.
 * Fernandes I., and J. de Souza. 2018. Dataset of long-term monitoring of ground-dwelling ants (Hymenoptera: Formicidae) in the influence areas of a hydroelectric power plant on the Madeira River in the Amazon Basin. Biodiversity Data Journal 6: e24375.
 * Fernández, F. and S. Sendoya. 2004. Lista de las hormigas neotropicales. Biota Colombiana Volume 5, Number 1.
 * Franco W., N. Ladino, J. H. C. Delabie, A. Dejean, J. Orivel, M. Fichaux, S. Groc, M. Leponce, and R. M. Feitosa. 2019. First checklist of the ants (Hymenoptera: Formicidae) of French Guiana. Zootaxa 4674(5): 509-543.
 * Kempf, W.W. 1972. Catalago abreviado das formigas da regiao Neotropical (Hym. Formicidae) Studia Entomologica 15(1-4).
 * Kusnezov N. 1953. La fauna mirmecológica de Bolivia. Folia Universitaria. Cochabamba 6: 211-229.
 * Mertl A. L., J. F. A. Traniello, K. Ryder Wilkie, and R. Constantino. 2012. Associations of two ecologically significant social insect taxa in the litter of an amazonian rainforest: is there a relationship between ant and termite species richness? Psyche doi:10.1155/2012/312054
 * Miranda P. N., F. B. Baccaro, E. F. Morato, M. A. Oliveira. J. H. C. Delabie. 2017. Limited effects of low-intensity forest management on ant assemblages in southwestern Amazonian forests. Biodivers. Conserv. DOI 10.1007/s10531-017-1368-y
 * Wheeler W. M. 1925. Neotropical ants in the collections of the Royal Museum of Stockholm. Arkiv för Zoologi 17A(8): 1-55.