Mycetomoellerius pruinosus

Mycetomoellerius pruinosus
Scientific classification
Kingdom:	Animalia
Phylum:	Arthropoda
Class:	Insecta
Order:	Hymenoptera
Family:	Formicidae
Subfamily:	Myrmicinae
Tribe:	Attini
Genus:	Mycetomoellerius
Species:	M. pruinosus
Binomial name
Mycetomoellerius pruinosus (Emery, 1906) Specimen Labels
Synonyms
Trachymyrmex pruinosus spinosior Santschi, 1922

Mayhe-Nunes and Brandão (2005) - Gallardo (1916) made detailed observations on this species, summarized as follows: The nests excavated in hard loamy soil had a circular entrance 3 to 4 mm in diameter, surrounded by a low crater of about 10 cm of diameter. Some nests can have a hole small 5 mm tower around the entrance, built with sticks and very fine earth grains used by the ants to make a funnel with borders curved outwards. The internal structure consists on a vertical and cylindrical duct that leads to a first some 5 cm deep chamber with arched roof and an almost flat floor. The other two spherical chambers were found at 10 to 12 cm (second chamber with 4 to 5 cm diameter) and 30 cm depth (third with 5 to 6 cm diameter). The workers are very timid and show stronger activity at sunset, when 5 or 6 workers leave the nest walking slowly, foraging for caterpillar excrements (Oeceticus platensis). Workers in laboratory nest accepted orange pieces as substrate for the fungus. The fungus garden rested on the floor of the chambers, not pending from the chamber roof as in nests of other Trachymyrmex species.

Identification

A member of the iheringi species group. Mayhe-Nunes and Brandão (2005) - The basal lobe of the antennal scape not enlarged transversely nor very prominent basally or dorsally is the main diagnostic character of M. pruinosus. This species is the only member of the iheringi group that has triangular frontal lobes.

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 iheringi species group workers

Distribution

Latitudinal Distribution Pattern

Latitudinal Range: -20.6039° to -37.533333°.

North Temperate	North Subtropical	Tropical	South Subtropical	South Temperate

• Source: AntMaps

Distribution based on Regional Taxon Lists

Neotropical Region: Argentina (type locality), Uruguay.

Distribution based on AntMaps

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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

Expand 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. ‎

Nomenclature

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

• pruinosus. Atta (Trachymyrmex) pruinosa Emery, 1906c: 163, fig. 25 (w.) ARGENTINA.
  • Gallardo, 1916b: 249 (q.m.).
  • Combination in Trachymyrmex: Gallardo, 1916b: 248.
  • Combination in Mycetomoellerius: Solomon et al., 2019: 948.
  • Senior synonym of spinosior: Mayhé-Nunes & Brandão, 2005: 294. .
• spinosior. Trachymyrmex pruinosus var. spinosior Santschi, 1922b: 359 (w.) ARGENTINA.
  • Junior synonym of pruinosus: Mayhé-Nunes & Brandão, 2005: 294.

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

Description

Worker

Mayhe-Nunes and Brandão (2005) - TL 3.4-3.7; HL 1.02-1.09; HW 0.92-1.02; IFW 0.60-0.64; ScL 0.71-0.77; TrL 1.31-1.42; HfL 1.11-1.20. Dark ferruginous brown, some specimens with darker head and gaster, and reddish brown mandibles, legs and tip of funiculus. Integument fine and indistinctly shagreened, opaque. Hairs moderately scarce on the body, short and erect or curved on appendages; hook-like mixed with oblique to decumbent hairs on other parts of body.

Head in full face view little longer than broad (CI 92). Mandible smooth and shining except laterally on base where it is finely transversely striate, and near the masticatory margin, which bears the apical and 7 regularly developed teeth. Frontal lobe triangular, moderately expanded laterad (FLI 64); anterior and posterior borders straight. Frontal carina diverging caudad, reaching the apex of scrobe. Front and vertex with small isolated piligerous tubercles. Posterior third of antennal scrobe clearly delimited by the frontal carina and weakly marked by the extension of the preocular ones. Supraocular projection vestigial. Occiptal corner rounded in full -face view, with many small piligerous tubercles. Occiput notched in the middle. Occipital tooth developed as a stout spine-like projection rather microtuberculated. Inferior occipital corner indistinctly emarginated with weak carina. Eye weakly convex, no more than 12 facets in a row across the greatest diameter. Antennal scape weakly surpassing the occipital corner, when laid back over head as much as possible; basal lobe not enlarged transversely not very prominent basally or dorsally, its anterior face forming an obtuse angle with the superior face of the slender base of the scape; anterior surface surmounted by small tubercles.

Alitrunk. Pronotum with an indistinct humeral angle; antero-inferior corner armed with a triangular and flattened spine-like projection; lateral pines long; median projections as two small microtuberculated spines. Mesonotum with the first pair of projections shorter than pronotal lateral ones; second pair represented by short teeth and the third by one or some minute teeth, forming a small and crenulated longitudinal ridge; mesopleura without hairs; acute triangular projection on superior border of katepisternum. Alitrunk constricted dorso-laterally at the deeply impressed metanotal groove. Basal face of propodeum narrow, laterally delimited by a row of small teeth; propodeal spines longer and slender than promesonotal projections.

Waist and gaster. Petiole shortly pedunculated, the node proper as long as broad with one or two pairs of minute dorsal teeth; subpetiolar process vestigial. Postpetiole slightly broader than long, shallowly excavate above; postero-dorsal border straight; postero-lateral corners without projections. Gaster opaque with minute piligerous tubercles randomly distributed on tergum 1.

Female and male. Gallardo (1916) described and illustrated properly the sexual castes of this species.

Type Material

Mayhe-Nunes and Brandão (2005) - worker; Argentina, Buenos Aires: Tandil.

Probably in Emerys collection; not examined. Two Syntypes workers labeled as “pruinosa var. spinosior (type) XXI.V.d .3418, Cordoba, Cabana, Scott col” in Naturhistorisches Museum, Basel (Dietz personnal communication); One syntype worker of Trachymyrmex pruinosus var. spinosior in Museu de Zoologia da Universidade de Sao Paulo, examined.

References

• Emery, C. 1906c [1905]. Studi sulle formiche della fauna neotropica. XXVI. Bull. Soc. Entomol. Ital. 37: 107-194 (page 163, fig. 25 worker described)
• Gallardo, A. 1916c. Notas acerca de la hormiga Trachymyrmex pruinosus Emery. An. Mus. Nac. Hist. Nat. B. Aires 28: 241-252 (page 249, queen, male described; page 248, Combination in Trachymyrmex)
• Mayhé-Nunes, A. J. and Brandão, C. R. F. 2005. Revisionary studies on the attine ant genus Trachymyrmex Forel. Part 2: the Iheringi group (Hymenoptera: Formicidae). Sociobiology. 45(2):271-305. (page 294, figs. 33-36 senior synonym of pruinosus var. spinosior)
• 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

• Bruch C. 1917. Costumbres y nidos de hormigas. Anales de la Sociedad Cientifica Argentina 83:302-316.
• Cuezzo, F. 1998. Formicidae. Chapter 42 in Morrone J.J., and S. Coscaron (dirs) Biodiversidad de artropodos argentinos: una perspectiva biotaxonomica Ediciones Sur, La Plata. Pages 452-462.
• Drose W., L. R. Podgaiski, C. Fagundes Dias, M. de Souza Mendonca. 2019. Local and regional drivers of ant communities in forest-grassland ecotones in South Brazil: A taxonomic and phylogenetic approach. Plos ONE 14(4): e0215310.
• Josens R., F. Sola, J. Lois-Milevicich, and W. MacKay. 2017. Urban ants of the city of Buenos Aires, Argentina: species survey and practical control. International Journal of pest Management 63(3): 213-223.
• 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
• Kusnezov N. 1978. Hormigas argentinas: clave para su identificación. Miscelánea. Instituto Miguel Lillo 61:1-147 + 28 pl.
• Kusnezov, N. "Lista de las hormigas de Tucumán con descripción de dos nuevos géneros (Hymenoptera, Formicidae)." Acta Zoologica Lilloana 13 (1953): 327-339.
• Mayhé-Nunes A. J., and C. R. F. Brandão. 2005. Revisionary studies on the attine ant genus Trachymyrmex Forel. Part 2: the Iheringi group (Hymenoptera: Formicidae). Sociobiology 45(2): 271-305.
• Pignalberi C. T. 1961. Contribución al conocimiento de los formícidos de la provincia de Santa Fé. Pp. 165-173 in: Comisión Investigación Científica; Consejo Nacional de Investigaciones Científicas y Técnicas (Argentina) 1961. Actas y trabajos del primer Congreso Sudamericano de Zoología (La Plata, 12-24 octubre 1959). Tomo III. Buenos Aires: Librart, 276 pp.
• Santoandre S., J. Filloy, G. A. Zurita, and M. I. Bellocq. 2019. Ant taxonomic and functional diversity show differential response to plantation age in two contrasting biomes. Forest Ecology and Management 437: 304-313.
• Santschi F. 1922. Myrmicines, dolichodérines et autres formicides néotropiques. Bulletin de la Société Vaudoise des Sciences Naturelles 54: 345-378.
• Vittar, F. 2008. Hormigas (Hymenoptera: Formicidae) de la Mesopotamia Argentina. INSUGEO Miscelania 17(2):447-466
• Vittar, F., and F. Cuezzo. "Hormigas (Hymenoptera: Formicidae) de la provincia de Santa Fe, Argentina." Revista de la Sociedad Entomológica Argentina (versión On-line ISSN 1851-7471) 67, no. 1-2 (2008).
• Zolessi L. C. de, Y. P. Abenante, and M. E. de Philippi. 1988. Lista sistematica de las especies de Formicidos del Uruguay. Comun. Zool. Mus. Hist. Nat. Montev. 11: 1-9.
• de Zolessi, L.C., Y.P. de Abenante and M.E. Phillipi. 1989. Catalago Systematico de las Especies de Formicidos del Uruguay (Hymenoptera: Formicidae). Oficina Regional de Ciencia y Technologia de la Unesco para America Latina y el Caribe- ORCYT. Montevideo, Uruguay