Mycetagroicus triangularis

AntWiki: The Ants --- Online
Mycetagroicus triangularis
Scientific classification
Kingdom: Animalia
Phylum: Arthropoda
Class: Insecta
Order: Hymenoptera
Family: Formicidae
Subfamily: Myrmicinae
Tribe: Attini
Genus: Mycetagroicus
Species: M. triangularis
Binomial name
Mycetagroicus triangularis
Brandão & Mayhé-Nunes, 2001

Mycetagroicus triangularis W profile.jpg

Mycetagroicus triangularis W dorsal.jpg

The paratypes are from The Fazenda Agua Limpa, a typical cerrado reserve. The lack of further information on the exact collecting place in Encruzilhada, Bahia state, prevents us from deriving any conclusion on its distribution or preferred habitats. In his notebook. Goncalves recorded for sample # 1677: “Attini, subterranean nest,” which is the only available information on the biology of this species. A dealated female was collected in November, at the onset of the rainy season in Eastern Brazil. (Brandao and Mayhe-Nunes 2001)


Brandao and Mayhe-Nunes (2001) - The triangular teeth or projections at the lateral areas of the clypeus readily distinguishes this species from all other known Mycetagroicus.

Keys including this Species


Latitudinal Distribution Pattern

Latitudinal Range: -15.51666667° to -15.94872°.

Tropical South

Distribution based on Regional Taxon Lists

Neotropical Region: Brazil (type locality).

Distribution based on AntMaps


Distribution based on AntWeb specimens

Check data from AntWeb

Countries Occupied

Number of countries occupied by this species based on AntWiki Regional Taxon Lists. In general, fewer countries occupied indicates a narrower range, while more countries indicates a more widespread species.

Estimated Abundance

Relative abundance based on number of AntMaps records per species (this species within the purple bar). Fewer records (to the left) indicates a less abundant/encountered species while more records (to the right) indicates more abundant/encountered species.


Explore-icon.png Explore Fungus Growing 
For additional details see Fungus growing ants.

A handful of ant species (approx. 275 out of the known 15,000 species) have developed the ability to cultivate fungus within their nests. In most species the fungus is used as the sole food source for the larvae and is an important resource for the adults as well. Additionally, in a limited number of cases, the fungus is used to construct part of the nest structure but is not as a food source.

These fungus-feeding species are limited to North and South America, extending from the pine barrens of New Jersey, United States, in the north (Trachymyrmex septentrionalis) to the cold deserts in Argentina in the south (several species of Acromyrmex). Species that use fungi in nest construction are known from Europe and Africa (a few species in the genera Crematogaster, Lasius).

The details of fungal cultivation are rich and complex. First, a wide variety of materials are used as substrate for fungus cultivating. The so-called lower genera include species that prefer dead vegetation, seeds, flowers, fruits, insect corpses, and feces, which are collected in the vicinity of their nests. The higher genera include non leaf-cutting species that collect mostly fallen leaflets, fruit, and flowers, as well as the leafcutters that collect fresh leaves from shrubs and trees. Second, while the majority of fungi that are farmed by fungus-feeding ants belong to the family Lepiotaceae, mostly the genera Leucoagaricus and Leucocoprinus, other fungi are also involved. Some species utilise fungi in the family Tricholomataceae while a few others cultivate yeast. The fungi used by the higher genera no longer produce spores. Their fungi produce nutritious and swollen hyphal tips (gongylidia) that grow in bundles called staphylae, to specifically feed the ants. Finally, colony size varies tremendously among these ants. Lower taxa mostly live in inconspicuous nests with 100–1000 individuals and relatively small fungus gardens. Higher taxa, in contrast, live in colonies made of 5–10 million ants that live and work within hundreds of interconnected fungus-bearing chambers in huge subterranean nests. Some colonies are so large, they can be seen from satellite photos, measuring up to 600 m3.

Based on these habits, and taking phylogenetic information into consideration, these ants can be divided into six biologically distinct agricultural systems (with a list of genera involved in each category):

Nest Construction

A limited number of species that use fungi in the construction of their nests.

Lower Agriculture

Practiced by species in the majority of fungus-feeding genera, including those thought to retain more primitive features, which cultivate a wide range of fungal species in the tribe Leucocoprineae.

Coral Fungus Agriculture

Practiced by species in the Apterostigma pilosum species-group, which cultivate fungi within the Pterulaceae.

Yeast Agriculture

Practiced by species within the Cyphomyrmex rimosus species-group, which cultivate a distinct clade of leucocoprineaceous fungi derived from the lower attine fungi.

Generalized Higher Agriculture

Practiced by species in several genera of non-leaf-cutting "higher attine" ants, which cultivate a distinct clade of leucocoprineaceous fungi separately derived from the lower attine fungi.

Leaf-Cutter Agriculture

A subdivision of higher attine agriculture practiced by species within several ecologically dominant genera, which cultivate a single highly derived species of higher attine fungus.

Note that the farming habits of Mycetagroicus (4 species) are unknown. Also, while species of Pseudoatta (2 species) are closely related to the fungus-feeding genus Acromyrmex, they are social parasites, living in the nests of their hosts and are not actively involved in fungus growing. ‎



Mycetagroicus triangularis Q head.jpgMycetagroicus triangularis Q.jpg



Mycetagroicus inflatus

Mycetagroicus cerradensis

Mycetagroicus triangularis

Based on Micolino et al., 2020 (note Mycetagroicus urbanus not included).


The following information is derived from Barry Bolton's Online Catalogue of the Ants of the World.

  • triangularis. Mycetagroicus triangularis Brandão & Mayhé-Nunes, 2001: 649, figs. 8-16 (w.q.) BRAZIL.

Unless otherwise noted the text for the remainder of this section is reported from the publication that includes the original description.



Brandão and Mayhé-Nunes. 2001. Figure11.
Brandão and Mayhé-Nunes. 2001. Figure 10.
Brandão and Mayhé-Nunes. 2001. Figure 13.

TL 2.72: HL 0.80; HW 0.75; IFW 0.43: ScL 0.62; TrL 1.07; HfL 0.85. Color brown. Hairs all over the body, denser on antennae and legs.

Head. Mandibular external margin strongly rugulose, irregularly sculptured in relation to Mycetagroicus cerradensis (some 20 rugulae in a perpendicular line arising from the mandible external margin at midlength) with an apical tooth and 7 regularly developed teeth; external margin straight from the base to the subapical tooth level, where it curves inwards. Clypeus lateral region near the base of frontal lobes with a triangular teeth, better seen in oblique view. Frontal area inconspicuous. Frontal lobes rounded, their largest width posterior to the antennal insertions, from where they curve inwards, forming a constriction. Frontal carinae slightly sinuous, fading well before reaching the occiput. Eyes with about 10 facets across the greatest diameter. Antennal scapes surpassing the occipital corners by near 5/6 of their chord length, when laid back over the head as much as possible. Only funicular segments I and VIII-X longer than broad, the other sub-equal.

Alitrunk. Height of pronotal anterior face shorter than in the other Mycetagroicus species. Lateral pranotal spines triangular. projecting from lateral margin. Pronotum with a pair of short but conspicuous median projections, widely separated; antero-inferior corners angulated or each with a minuscule tooth at apex. Mesonotum without projections on anterior portion: middle of posterior portion with a relatively low triangular protuberance microscopically tuberculated. Anepisternum separated from katepisternum by a strong ridge. Metanotal groove shallowly impressed. Propodeum spiracle opening slit shaped in side view.

Petiole, postpetiole and gaster. Dorsum of petiole with two faint longitudinal ridges: the node proper, as seem from above, slightly broader than long (Fig. 12). Postpetiole longer than broad in dorsal view. Gaster with irregularly spaced hair pits. Dorsal disk of the gaster without longitudinal keels.


TL 3.75; HL 0.91, HW 0.94; IFW 0.51; ScL 0.66; TrL 1.38; HfL 1.00. Color ferrugineous brown, with the front of the head and gaster darker. Except by the short hairs on appendages, the whole body covered by moderately long curved or inclined hairs.

Head. Very similar to those of the workers, except for the presence of three similarly developed ocelli; the presence of a distinct median longitudinal ridge posterior to the frontal area: and the more pronounced triangular clypeal projections.

Alitrunk. Pronotum without the median projections. Scutum without noticeable divisions: anterior border with a small longitudinal ridge: parapsidal furrows in low longitudinal keels: parapses slightly depressed, each with two minute transversal carinae. Mesothoracic paraptera impressed, with external borders smoothly rounded: the median area narrower than the lateral areas. Scutellum with two low and blunt tubercles: posterior margin with two close, flat and blunt spines, directed backwards: the distance among them at apices similar to their width at base. Metathoracic paraptera small and narrow, covered by the scutellum spines in dorsal view. Propodeum with two big, blunt and flat spines, at the meeting of the basal and declivitous faces.

Petiole, postpetioie and gaster. Dorsum of petiole with two minute projections close to the posterior border. Postpetiole almost two times broader than petiole, shallowly impressed on the middle. Disc of the first gastric tergite with pronounced rugulae, forming a conspicuous net; and a short longitudinal ridge at each side.

Type Material

Holotype: Worker BRAZIL, Mato Grosso State: Gustavo Dutra [15° 49' S, 55° 24' W), 25.x.1953, RCG (C. R. Goncalves col.) # 1677 (Goncalves notebook), deposited at Museu de Zoologia da Universidade de Sao Paulo. Notes: on the original label, the acronym for the collector is wrongly spelled as RCG. Information on this collector and locality, related however to different species, matches exactly the same information as for this sample (Brandao. 1990). Mayhe Nunes visited the area recently and found that Gustavo Dutra was the name of an Agricultural School, now a small village known as Sao Vicente, at the Santo Antonio do Leverger county, some 100 Km SE of the State capital, Cuiaba. Paratypes: 3 workers, same data as holotype (one specimen at each collection: MZSP -one intact plus one prepared for SEM; Instituto de Biologia Universidade Federal Rural do Rio de Janeiro, National Museum of Natural History): one worker, BRAZIL. Distrito Federal: Brasilia (15° 47' S, 47° 55' W), Fazenda Agua Limpa “cerrado”, 2.viii.1988. T. Schultz col. TRS # 92 0802 03 (USNM); one dealated queen, BRAZIL. Bahia: Encruzilhada (15° 31' S, 40° 54' W), 960 m, xi.1972, Seabra & Alvarenga col. # 8869 [Kempf notebook] (MZSP).


The name was given in reference to the triangular shape of the clypeal teeth (Latin: triangularis).


References based on Global Ant Biodiversity Informatics

  • Brandão C. R. F., and A. J. Mayhé-Nunes. 2001. A new fungus-growing ant genus, Mycetoagroicus gen. n., with the description of three new species and comments on the monophyly of the Attini (Hymenoptera: Formicidae). Sociobiology 38: 639-665.
  • Brandão, C.R.F. and Mayhe-Nunes. 2008. Uma nova espécie de formiga cultivadora de fungo, do gênero Mycetagroicus Brandão & Mayhé-Nunes (Hymenoptera, Formicidae, Attini). Revista Brasileira de Entomologia 52(3)
  • Klingenberg, C. and C.R.F. Brandao. 2005. The type specimens of fungus growing ants, Attini (Hymenoptera, Formicidae, Myrmicinae) deposited in the Museu de Zoologia da Universidade de Sao Paulo, Brazil. Papeis Avulsos de Zoologia 45(4):41-50
  • Solomon S. E., C. Rabeling, J. Sosa-Calvo, C. Lopes, A. Rodrigues, H. L. Vasconcelos, M. Bacci, U. G. Mueller, and T. R. Schultz. 2019. The molecular phylogenetics of Trachymyrmex Forel ants and their fungal cultivars provide insights into the origin and coevolutionary history of ‘higher-attine’ ant agriculture. Systematic Entomology 44: 939–956.