This species was described from two samples collected in Gustavo Dutra and another locality in the Chapada dos Guimarães, near Cuiabá, Mato Grosso state, Brazil. Dr. Antonio Mayhé-Nunes visited the area recently and found out that Gustavo Dutra was actually the name of an Agricultural School. The small village is now known as São Vicente, and is located in the county of Santo Antonio do Leverger, some 100 Km East of the state capital, Cuiabá.

Megalomyrmex acauna is the only Leoninus group species recorded in the “cerrados”. The Leoninus group is otherwise an entirely Amazonian group. In fact, Prof. Marcelo Tavares sent me recently a sample from the Indian Reserve Tadarimana, Rondonópolis, state of Mato Grosso state, Brazil (16°28’S, 54°38’W). I collected in May 6 to 29, 1996, two colonies of M. acauna in Uruaçu, northwestern Goiás, Brazil (14°17’06”S, 48°55’01”W). Both localities are situated within the “cerrado” biome. The ants live in fairly large colonies that occupy spaces among stones, in a way that is very similar to the most closely related species, M. balzani. In both cases the colonies were found along gallery forests and all attempts to rear them in the lab failed.

From LACM, I received a male of M. acauna (undescribed) collected by F.S. Truxal in June 13, 1956, in a locality 24 Km East of Formoso (13°37’S, 48°54’W), Goiás state, Brazil.

Male (first description)

Clypeus smooth without anterior denticle; cephalic integument smooth next to the compound eyes: first funicular segment similar in size to scape, second and third smaller; mesonotum with parapsidal furrows impressed, but no notaulus; epipetiolar carina complete; dorsal face of propodeum smooth; petiole compressed dorso-ventrally; petiolar spiracles laterally produced; petiolar and postpetiolar nodes almost indistinct; postpetiole without ventral process; genual plates rounded.