Mycetomoellerius dichrous

Mycetomoellerius dichrous
Scientific classification
Kingdom:	Animalia
Phylum:	Arthropoda
Class:	Insecta
Order:	Hymenoptera
Family:	Formicidae
Subfamily:	Myrmicinae
Tribe:	Attini
Genus:	Mycetomoellerius
Species:	M. dichrous
Binomial name
Mycetomoellerius dichrous (Kempf, 1967) Specimen labels

Walter Kempf and his student Jorge Diniz discovered numerous nests of this species in recently burned cerrado.

Identification

Mayhé-Nunes & Brandão (2002) - This is perhaps the most aberrant species both in the entire genus and in the present species-group. Within the latter, the worker (and female) may be distinguished by the following features: bicolored, head dark brown, body and appendages brown; frontal lobes subtriangular, slightly expanded laterad, the interfrontal width not exceeding one half of head width; supraocular tumulus indistinct; antennal scrobe not delimited postero-laterally behind eyes, nor projecting posteriorly in a tuberous fashion; occiput rounded laterally; vertex lacking paired carinae; anterior half of sides of tergum I of gaster weakly to indistinctly marginate. The following characters are shared only with Mycetomoellerius compactus: occipital tooth absent; antero-inferior corner of pronotum rounded, not angular nor dentate; second and third pairs of mesonotal projections vestigial; postero-dorsal border of postpetiole broadly excised.

Specimens from Aguas Emendadas, northern Brasilia, have the propodeal teeth more developed than in the other samples.

Santos et al. (2025) provide a multi-entry interactive key based on the xper3 platform which contains 27 characters and, as terminals, 30 species of Mycetomoellerius, representing almost all described species except for Mycetomoellerius echinus, Mycetomoellerius gaigei and Mycetomoellerius guianensis, which are excluded due to lack of clear information or available specimens for study.

Keys including this Species

• Key to Trachymyrmex opulentus species group workers

Distribution

Latitudinal Distribution Pattern

Latitudinal Range: -15.43333333° to -22.809943°.

North Temperate	North Subtropical	Tropical	South Subtropical	South Temperate

• Source: AntMaps

Distribution based on Regional Taxon Lists

Neotropical Region: Argentina, Brazil (type locality), Paraguay.

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.

Biology

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. some Crematogaster some Lasius 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. some Apterostigma Cyatta (1 species) some Cyphomyrmex Kalathomyrmex (1 species) Mycocepurus (6 species) Myrmicocrypta (31 species) Mycetarotes (4 species) Mycetosoritis (2 species) Mycetophylax (21 species) Paramycetophylax (1 species) Xerolitor (1 species) Coral Fungus Agriculture Practiced by species in the Apterostigma pilosum species-group, which cultivate fungi within the Pterulaceae. some Apterostigma 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. some Cyphomyrmex 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. Mycetomoellerius (33 species) Paratrachymyrmex (9 species) Sericomyrmex (11 species) Trachymyrmex (9 species) 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. Acromyrmex (51 species) Amoimyrmex (3 species) Atta (20 species) 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. ‎

Mayhé-Nunes & Brandão (2002) - We have found the following account by W. W. Kempf in the MZSP collection: “Recently, on October 21, 1975, at the beginning of the rainy season, Jorge Diniz and myself located several nests of this species in a small, already disturbed and recently burned ‘cerrado’ at the northern limit of the city of Brasilia. Although not prepared for a careful excavation, we tried nevertheless to dig out one nest with a small gardener's shovel. We were able to find the nest chamber with the fungus garden and to secure nearly the total population of the colony, although the chamber itself was destroyed before we could make out its size and shape, and verify if the fungus garden was a suspended one from rootlets, in the true Mycetomoellerius-fashion. The results of our findings may be summarized as follows:

The nest entrance was marked by a circular orifice of about 5 mm in diameter, around which the excavated soil had been heaped up in low and irregular mounds by the ants, not forming a regular crater. From the nest entrance, a vertical canal went down for nearly one meter, to open in the nest chamber with the fungus garden. 384 workers, 2 dealate queens, 23 alate males, 8 pupae and 39 larvae of different sizes and instars were retrieved from the nest, which probably represents the total population, inasmuch as at the moment of our digging no activity was going on at the outside of the nest, and we examined carefully any lump of earth taken out by our digging. The fungus-garden, secured only in somewhat smashed condition, seemed to contain cut-up stems of grasses or other plants. Probably there was no second chamber, because several visits to the excavation site after taking out the nest did not reveal any further activity.”

Castes

Known only from the worker caste.

Mayhé-Nunes & Brandão (2002) - In Kempfs notebook (# 11806) we found a mention to a complete series of this species, including workers, females, males, pupae and larvae, from Distrito Federal, Brasilia, northwestern city limit, 21.x.1975, W. W. Kempf & J. Diniz leg. (see detail in Biology). Despite several attempts we were not able to locate this sample, even with the help of Reginaldo Constantino at Universidade de Brasilia, where Kempf’s collection was deposited before being transferred to the MZSP, and of Jorge Diniz (Universidade de Goias), a student of Kempf at the time of his death.

Phylogeny

Mycetomoellerius	Mycetomoellerius urichii Mycetomoellerius papulatus Mycetomoellerius papulatus Mycetomoellerius holmgreni Mycetomoellerius cirratus Mycetomoellerius kempfi Mycetomoellerius iheringi Mycetomoellerius sp. near cirratus
	Mycetomoellerius ruthae Mycetomoellerius jamaicensis Mycetomoellerius atlanticus Mycetomoellerius near haytianus Mycetomoellerius opulentus Mycetomoellerius dichrous Mycetomoellerius relictus Mycetomoellerius turrifex Mycetomoellerius zeteki

Based on Micolino et al., 2020 (selected species only).

Nomenclature

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

• dichrous. Trachymyrmex dichrous Kempf, 1967a: 126, figs. 7-9 (w.) BRAZIL.
  • Combination in Mycetomoellerius: Solomon et al., 2019: 948.

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

Description

Worker

Mayhé-Nunes & Brandão (2002) - TL 4.5-5.1; HL 0.99-1.07; HW 1.03-1.11; IFW 0.51-0.57; ScL 0.93-1.07; TrL 1.51-1.70; WL mm; Hfl 1.49-1.70. Strikingly bicolored, head capsule deep brown, body and appendages medium brown or ferruginous. Integument finely but indistinctly shagreened, opaque. Long, dense, mostly curved or inclined hairs on head, alitrunk, and pedicel; same hairs but denser and less curved and more uniformly inclined on gaster, scapes and legs. Alitrunk hairs not arising from prominent tubercles which are lacking. Dense and much shorter pubescence of lighter color, inclined or appressed on head, pedicel, gaster and appendages. erect or suberect on thorax, never masking the integument.

Head. Mandibles smooth and shining except laterally on base where they are finely longitudinally striate; masticatory margin with apical tooth and approximately 8 teeth. slightly smaller towards the base. Frontal lobe triangular, little expanded laterad, interfrontal width scarcely or not at all surpassing one half of head width across the eyes. Frontal carinae diverging caudad, fading out at posterior fourth of head. Front and vertex inconspicuously tuberculate. Preocular carinae slightly curving mesad above eye but not intersecting the antennal scrobe, fading out shortly behind eyes. Posterior half of antennal scrobe indistinct, the apex not projecting in a tuberous fashion on occiput; supraocular tumulus vestigial. Occipital corners rounded and edentate. Occipital tooth absent. Occiput in full-face view distinctly notched in the middle. Vertex lacking paired carinae. Inferior occipital corner indistinctly marginate and rounded. Eyes moderately convex, with about 13 facets across the greatest diameter. Antennal scapes as long, or nearly as long, as head capsule, without prominent spicules, surpassing the occipital corner when laid back over the head as much as possible by one fifth of its length. All funicular segments distinctly longer than broad.

Alitrunk. Prominent piligerous tubercles lacking. Pronotum with indistinct humeral angles, its antero-inferior corners rounded and toothless. The lateral spines very low and tubercular. Mesonotum with a pair of high anterior conical spines, facing obliquely laterad, followed by two pairs of very low and little distinct denticulate tubercles, the posterior pair almost obsolete. AI trunk shallowly impressed at metanonotal groove. Basal face of propodeum narrow, lateral borders indistinctly marginate, bearing a few piligerous tubercles. Propodeal spines very short and inconspicuous. Hind femora about as long as alitrunk.

Waist and gaster. Petiole pedunculate, the node proper longer than broad, the dorsal armature obsolete; anterior ventral process developed as a small blunt spine. Postpetiole not much broader than long, flattened above, the postero-dorsal border broadly excised between the non-tubercular corners. Gaster opaque; tergum I with dense, minute and evenly distributed piligerous tubercles; vestigially marginate on sides in the anterior half.

Type Material

Mayhé-Nunes & Brandão (2002) - Holotype and 6 paratypes from type locality, one paratype from Brasil: Mato Grosso, Chapada dos Guimaraes, and one paratype from Brasil: Sao Paulo, Agudos at Museu de Zoologia da Universidade de Sao Paulo (examined).

References

• Kempf, W. W. 1967a [1966]. New ants from southeastern and central Brazil (Hymenoptera, Formicidae). Stud. Entomol. 9: 121-128 (page 126, figs. 7-9 worker described)
• Mayhé-Nunes, A. J. and Brandão, C. 2002. Revisionary studies on the attine ant genus Trachymyrmex Forel. Part 1: definition of the genus and the opulentus group (Hymenoptera: Formicidae). Sociobiology. 40: 667-698.
• Santos, C.D.A.D., Chaul, J.C.M., Serrao, J.E. 2025. Taxonomic contributions to Mycetomoellerius Solomon et al., 2019 (Hymenoptera: Formicidae: Myrmicinae): description of two new species and a key for the genus. Zootaxa 5569(1), 93–118 (doi:10.11646/zootaxa.5569.1.3).
• Solomon, S.E., Rabeling, C., Sosa-Calvo, J., Lopes, C.T., Rodrigues, A., Vasconcelos, H.L., Bacci Jr, M., Mueller, U.G., Schultz, T.R. 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 (doi:10.1111/syen.12370).

References based on Global Ant Biodiversity Informatics

• Costa-Milanez C. B., F. F. Ribeiro, P. T. A. Castro, J. D. Majer, S. P. Ribeiro. 2015. Effct of fire on ant assemblages in Brazilian Cerrado in areas containing Vereda wetlands. Sociobiology 62(4): 494-505.
• Costa-Milanez C. B., G. Lourenco-Silva, P. T. A. Castro, J. D. Majer, and S. P. Ribeiro. 2014. Are ant assemblages of Brazilian veredas characterised by location or habitat type? Braz. J. Biol. 74(1): 89-99.
• Kempf W. W. 1967. New ants from southeastern and central Brazil (Hymenoptera, Formicidae). Studia Entomologica 9: 121-128.
• Kempf W. W. 1978. A preliminary zoogeographical analysis of a regional ant fauna in Latin America. 114. Studia Entomologica 20: 43-62.
• Kempf, W.W. 1972. Catalago abreviado das formigas da regiao Neotropical (Hym. Formicidae) Studia Entomologica 15(1-4).
• 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
• Lapola D. M., and H. G. Fowler. 2008. Questioning the implementation of habitat corridors: a case study in interior São Paulo using ants as bioindicators. Braz. J. Biol., 68(1): 11-20.
• Leal, I.R. and P.S. Oliveira. 2000. Foraging ecology of attine ants in a Neotropical savanna: seasonal use of fungal substrate in the cerrado vegetation of Brazil. Insectes Sociaux 47:376-382
• Mayhe-Nunes A. J., and C. R. F. Brandao. 2002. Revisionary studies on the Attine ant genus Trachmyrmex Forel. Part 1: Definition of the Genus and the Opulentus Group (Hymenoptera: Formicidae). Sociobiology 40(3): 667-698.
• Mayhe-Nunes A. J., and K. Jaffe. 1998. On the biogeography of attini (Hymenoptera: Formicidae). Ecotropicos 11(1): 45-54.
• Silvestre R., C. R. F. Brandão, and R. R. Silva da 2003. Grupos funcionales de hormigas: el caso de los gremios del cerrado. Pp. 113-148 in: Fernández, F. (ed.) 2003. Introducción a las hormigas de la región Neotropical. Bogotá: Instituto de Investigación de Recursos Biológicos Alexander von Humboldt, xxvi + 424 pp.
• 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.
• Vasconcelos H. L., B. B. Araujo, A. J. Mayhé-Nunes. 2008. Patterns of diversity and abundance of fungus-growing ants (Formicidae: Attini) in areas of the Brazilian Cerrado. Revista Brasileira de Zoologia 25(3): 445-450.