title: Nest architecture, fungus gardens, queen, males and larvae of the fungus-growing antMycetagroicus inflatusBrandão & Mayhé-Nunes.
abstract: All known fungus-growing ants (tribe Attini) are obligately symbiotic with their cultivated fungi. The fungal cultivars of "lower" attine ants are facultative symbionts, capable of living apart from ants, whereas the fungal cultivars of "higher" attine ants, including leaf-cutting generaAttaandAcromyrmex, are highly specialized, obligate symbionts. Since higher attine ants and fungi are derived from lower attine ants and fungi, understanding the evolutionary transition from lower to higher attine agriculture requires understanding the historical sequence of change in both ants and fungi. The biology of the poorly known ant genusMycetagroicusis of special interest in this regard because it occupies a phylogenetic position intermediate between lower and higher ant agriculture. Here, based on the excavations of four nests in Pará, Brazil, we report the first biological data for the recently described speciesMycetagroicus inflatus, including the first descriptions ofMycetagroicusmales and larvae. LikeM. cerradensis, the only other species in the genus for which nesting biology is known, the garden chambers ofM.inflatusare unusually deep and the garden is most likely relocated vertically in rainy and dry seasons. Due to the proximity of nests to the Araguaia River, it is likely that even the uppermost chambers and nest entrances ofM. inflatusare submerged during the rainy season. Most remarkably, all three examined colonies ofM. inflatuscultivate the same fungal species as their congener,M. cerradensis, over 1,000 km away, raising the possibility of long-term symbiont fidelity spanning speciation events within the genus.
authors.affiliation: Department of Entomology, Maryland Center for Systematic Entomology, University of Maryland, 4112 Plant Science Bldg., College Park, MD 20742 USA ; Department of Entomology, National Museum of Natural History, Smithsonian Institution, PO Box 37012, MRC 188 CE517, Washington, DC 20013-7012 USA.
authors.forename: A
authors.initials: A
authors.lastname: Jesovnik
authors.forename: J
authors.initials: J
authors.lastname: Sosa-Calvo
authors.forename: C T
authors.initials: CT
authors.lastname: Lopes
authors.forename: H L
authors.initials: HL
authors.lastname: Vasconcelos
authors.forename: T R
authors.initials: TR
authors.lastname: Schultz
keywords: Ants; Attini; Fungus-growing ants; Mycetagroicus inflatus; Nest architecture; Symbiont fidelity