Odontomachus brunneus

In the US, O. brunneus occurs in a wide variety of natural habitats including flatwoods, mesic forests, pine savannas, swamp forests, oak-pine scrub, upland scrub, sandhills, bayheads, edges of seasonal ponds, and elevated tussocks. Nests of O. brunneus have been found in leaf litter, rotting logs, at tree bases, and in open to partially covered sandy areas. Nest architecture has been explored and discussed by Cerquera and Tschinkel (2010). Workers occasionally forage during the day, but are more active at night. Upon colony disturbance, workers are not aggressive, but instead quickly retreat or vacate the nest. This is in sharp contrast to the aggressive defensive stinging behavior of Odontomachus haematodus. Alates have been collected from May through December. This broad time frame for alate activity contrasts sharply with the early summer activity of O. haematodus. (MacGown et al., 2014)

Identification
Deyrup and Trager (1985) - Worker: gaster densely covered with fine, almost contiguous appressed hairs; striations of pronotum not transverse posteriorly; petiolar node faintly rugose at extreme base only; inner side of hind femur at base finely pubescent; color piceous in n. Florida, body (except gaster) frequently lighter in s. Florida. Within the Southeast, there is some variation in workers, but apparently based on habitat rather than geographic variation. Specimens from dry habitats are often smaller and paler than specimens from wet habitats.

Male: each ocellus as wide as the ocello-ocular space, ocelli on a conspicuous turret: petiole smooth; head and body entirely yellowish orange.

Identification Keys including this Taxon

 * Key to US Odontomachus species
 * Key to Odontomachus of the New World

Distribution
MacGown et al. (2014) - Odontomachus brunneus appears to be restricted to the southeastern US. Previous records of O. brunneus from the Caribbean, and Central and South America (Brown 1976) all appear to be of Odontomachus ruginodis. The situation was clarified by Deyrup et al. (1985) who recognized the distinction between O. ruginodis and O. brunneus and revived the former from synonymy with the latter. Brown’s statement (1976) that O. brunneus is well adapted to “marginal habitats is consistent with the ecology of O. ruginodis, whereas O. brunneus in the Southeast is generally found in undisturbed natural habitats".

Deyrup and Cover (2004) - This species apparently occurs throughout Florida, although there are no records from the three westernmost counties. It is also known from southern Georgia and Alabama. We have seen specimens from low coastal areas in Alabama, and there is no obvious reason why it should not occur in coastal Mississippi, Louisiana and Texas, although it is not reported from any of those states. A report of brunneus from Cuba (Fontenla 1997) might refer to some other species, as we have seen specimens that would key to brunneus from the Dominican Republic, but are probably closer to Odontomachus insularis Guerin. Its distribution in Central and South America is unclear, since this species was combined with Odontomachus ruginodis in Brown’s revision of the genus (1976).

Distribution based on Regional Taxon Lists
Nearctic Region: United States. Neotropical Region: Brazil, Costa Rica, Cuba, Ecuador, Mexico, Trinidad and Tobago.

Biology
In Florida Deyrup and Trager (1985) found that brunneus occurred in wet areas such as hammocks and ditches. Males were found to fly in the spring.

Deyrup and Cover (2004) - Odontomachus brunneus occurs in both well-drained and poorly drained habitats; nests may be in soil or in rotten wood. This species was studied by Van Pelt (1958) at the Welaka Reserve (now Welaka State Forest) in Putnam Co., Florida. Van Pelt found many colonies, which occurred in all the terrestrial habitats in the area, including flatwoods, mesic forest, swamp forest, upland scrub and sandhill. Nests were in various microhabitats, including deep leaf litter, fallen logs, at the bases of trees, and open or sparsely covered sandy areas. At the Archbold Biological Station, brunneus occurs in moist habitats, including flatwoods, bayheads, the edges of seasonal ponds, and elevated tussocks or fallen pines within seasonal ponds. It has not been found in the more elevated upland areas of the Station, which are occupied by Odontomachus relictus. This distribution gives the impression that there is some competitive displacement based on differential adaptation to moisture conditions, but the evidence remains circumstantial. It may be relevant that in parts of its range devoid of relictus, where brunneus occurs in dry, upland areas individuals never achieve the large size and dark color seen in some specimens from wet areas. Nobody knows, however, whether the smaller, paler individuals represent stressed individuals in suboptimal conditions, or whether they represent an adaptive phenotypic response in a robust population.

Workers of brunneus sometimes emerge to forage on cloudy days, but are generally nocturnal. The formidable jaws of brunneus are not used as assertively as one might expect, and there is fragmentary evidence that brunneus is sensitive to chemical defenses. Prey are approached tentatively, and the ant recoils immediately after striking the prey (Brown 1976). There may be a delay before the prey is picked up and carried away; Brown (1976) suggested that these ants react to chemical defenses, which are allowed to dissipate before the prey is retrieved. Alex Wild, while a student at the Archbold Biological Station, twice observed brunneus retreating hastily when confronted by aroused workers of Dorymyrmex bureni (Trager) (unpublished natural history notes on file at the Archbold Biological Station). Dorymyrmex bureni is much smaller than O. brunneus, but can release large quantities of defensive chemicals that are pungent to the human nose. Van Pelt (1958) reported accumulations of brunneus head capsules in the nests of Formica archboldi Smith, and suggested the possibility that brunneus is a regular part of the diet of F. archboldi. If this is the case, it is more likely that the brunneus are subdued by chemical means than by mandible-to-mandible combat.

Fox et al. (2017) - This species was found to have three larval instars. Laboratory colonies were found to attach first and second instar larvae to the walls and ceilings of their artificial nest chambers. These individuals were always oriented with their dorsal side against the surface being suspended from their "doorknob" protuberances. Third instar larvae were only observed on the floors of the nest chamber, dorsal side oriented down, and arranged individually, not pilled together.

Cerquera and Tschinkel (2010) - O. brunneus excavates simple nests, each consisting of a single, vertical shaft connecting more or less horizontal, simple chambers. Nests contained between 11 and 177 workers, from 2 to 17 chambers, and 28 to 340 cm2 of chamber floor space and reached a maximum depth of 18 to 184 cm. All components of nest size increased simultaneously during nest enlargement, number of chambers, mean chamber size, and nest depth, making the nest shape (proportions) relatively size-independent. Regardless of nest size, all nests had approximately 2 cm2 of chamber floor space per worker. Chambers were closer together near the top and the bottom of the nest than in the middle, and total chamber area was greater near the bottom. Colonies occasionally incorporated cavities made by other animals into their nests.

Castes
Associating the various brunneus-like forms with their males in Central and South America and the West Indies would be an interesting and useful project for local myrmecologists, and might easily yield distributional surprises or new species (Deyrup and Cover 2004).

Nomenclature

 *  brunneus. Atta brunnea Patton, 1894: 618 (w.) U.S.A. Deyrup, Trager & Carlin, 1985: 191 (m.). Combination in Odontomachus: Emery, 1895c: 268. Junior synonym of insularis: Emery, 1895c: 268. Revived from synonymy and senior synonym of fuscus Stitz, 1925: Brown, 1976a: 103. See also: Brown, 1976a: 139.
 * fuscus. Odontomachus haematodes var. fuscus Stitz, 1925: 115, fig. 2 (w.) CUBA. [Unresolved junior primary homonym of fuscus Stitz, 1916, above. Note that the proposed replacement name repetita Baroni Urbani, 1971b: 361 is unavailable.] Junior synonym of brunneus: Brown, 1976a: 103.

Larva
Described by Fox et al. (2017).

Determination Clarifications
Southeastern records of insularis in the Formicidae section of the Catalog of the Hymenoptera (D. R. Smith 1979) refer to brunneus. Although the catalog appeared several years after Brown’s revision, the cut-off date for changes in the Formicidae section was mid-1975. Smith’s treatment of North American Odontomachus differs from those of Creighton (1950) and M. R. Smith (1951) in elevating to species level three subspecies of Odontomachus haematodus (Linnaeus). This was backed by no taxonomic references, and certainly was not intended to compete with the earlier, but unavailable, revision by Brown. (Deyrup and Cover 2004).

References based on Global Ant Biodiversity Informatics

 * Addison D. S., I. Bartoszek, V. Booher, M. A. Deyrup, M. Schuman, J. Schmid, and K. Worley. 2016. Baseline surveys for ants (Hymenoptera: Formicidae) of the western Everglades, Collier County, Florida. Florida Entomologist 99(3): 389-394.
 * Annotated Ant Species List Ordway-Swisher Biological Station. Downloaded at http://ordway-swisher.ufl.edu/species/os-hymenoptera.htm on 5th Oct 2010.
 * Araujo Castilho G., F. Barbosa Noll, E. R. da Silva, and E. F. dos Santos. 2011. Diversidade de Formicidae (Hymenoptera) em um fragmento de Floresta Estacional Semidecídua no Noroeste do estado de São Paulo, Brasil. R. bras. Bioci., Porto Alegre 9(2): 224-230.
 * Atchison R. A., J. Hulcr, and A. Lucky. 2018. Managed fire frequency significantly influences the litter arthropod community in longleaf pine flatwoods. Environmental Entomology 20(10): 1-11.
 * Brandao, C.R.F. 1991. Adendos ao catalogo abreviado das formigas da regiao neotropical (Hymenoptera: Formicidae). Rev. Bras. Entomol. 35: 319-412.
 * Brown W. L., Jr. 1976. Contributions toward a reclassification of the Formicidae. Part VI. Ponerinae, tribe Ponerini, subtribe Odontomachiti. Section A. Introduction, subtribal characters. Genus Odontomachus. Stud. Entomol. 19: 67-171.
 * Coronado-Blanco J. M., D. A. Dubovikoff, E. Ruiz-Cancino, M. Vasquez-Bolanos, K. Y. Flores-Maldonado, and J. V. Horta-Vega. 2013. Formicidae (Hymenoptera) del estado de Tamaulipas, Mexico. CienciaUat 25(1): 12-17.
 * Dattilo W. et al. 2019. MEXICO ANTS: incidence and abundance along the Nearctic-Neotropical interface. Ecology https://doi.org/10.1002/ecy.2944
 * Del Toro, I., M. Vázquez, W.P. Mackay, P. Rojas and R. Zapata-Mata. Hormigas (Hymenoptera: Formicidae) de Tabasco: explorando la diversidad de la mirmecofauna en las selvas tropicales de baja altitud. Dugesiana 16(1):1-14.
 * Deyrup M. and Cover S. 2004. A new species of Odontomachus ant (Hymenoptera: Formicidae) from inland ridges of Florida, with a key to Odontomachus of the United States. Florida Entomologist 87: 136-144
 * Deyrup M., C. Johnson, G. C. Wheeler, J. Wheeler. 1989. A preliminary list of the ants of Florida. Florida Entomologist 72: 91-101
 * Deyrup, M. 2003. An updated list of Florida ants (Hymenoptera: Formicidae). Florida Entomologist 86(1):43-48.
 * Deyrup, M. and J. Trager. 1986. Ants of the Archbold Biological Station, Highlands County, Florida (Hymenoptera: Formicidae). Florida Entomologist 69(1):206-228
 * Deyrup, M. and S. Cover. 2004. A new species of Odontomachus ant (Hymenoptera: Formicidae) from inland ridges of Florida, with a key to Odontomachus of the United States. Florida Entomologist 87(2):136-144
 * Deyrup, M., J. Trager and N. Carlin. 1985. The genus Odontomachus in the Southeastern United States (Hymenoptera: Formicidae). Entomological News 96(5):188-195
 * Deyrup, Mark A., Carlin, Norman, Trager, James and Umphrey, Gary. 1988. A Review of the Ants of the Florida Keys. The Florida Entomologist. 71(2):163-176.
 * Fernandes, P.R. XXXX. Los hormigas del suelo en Mexico: Diversidad, distribucion e importancia (Hymenoptera: Formicidae).
 * Fernández F., E. E. Palacio, W. P. Mackay, and E. S. MacKay. 1996. Introducción al estudio de las hormigas (Hymenoptera: Formicidae) de Colombia. Pp. 349-412 in: Andrade M. G., G. Amat García, and F. Fernández. (eds.) 1996. Insectos de Colombia. Estudios escogidos. Bogotá: Academia Colombiana de Ciencias Exactas, Físicas y Naturales, 541 pp
 * Fontanla Rizo J.L. 1997. Lista preliminar de las hormigas de Cuba. Cocuyo 6: 18-21.
 * Fontenla Rizo J. L. 1993. Mirmecofauna de Isla de la Juventud y de algunos cayos del archipielago cubano. Poeyana. Instituto de Ecologia y Sistematica, Academia de Ciencias de Cuba 444:1-7.
 * Fontenla Rizo J. L. 1997. Lista preliminar de las hormigas de Cuba (Hymenoptera: Formicidae). Cocuyo 6: 18-21.
 * Forster J.A. 2005. The Ants (hymenoptera: Formicidae) of Alabama. Master of Science, Auburn University. 242 pages.
 * Franco W., N. Ladino, J. H. C. Delabie, A. Dejean, J. Orivel, M. Fichaux, S. Groc, M. Leponce, and R. M. Feitosa. 2019. First checklist of the ants (Hymenoptera: Formicidae) of French Guiana. Zootaxa 4674(5): 509-543.
 * Gallego-Ropero M.C., R.M. Feitosa & J.R. Pujol-Luz, 2013. Formigas (Hymenoptera, Formicidae) Associadas a Ninhos de Cornitermes cumulans Kollar (Isoptera, Termitidae) no Cerrado do Planalto Central do Brasil. EntomoBrasilis, 6(1): 97-101.
 * Groc S., J. H. C. Delabie, F. Fernandez, F. Petitclerc, B. Corbara, M. Leponce, R. Cereghino, and A. Dejean. 2017. Litter-dwelling ants as bioindicators to gauge the sustainability of small arboreal monocultures embedded in the Amazonian rainforest. Ecological Indicators 82: 43-49.
 * Ipser R. M. 2004. Native and exotic ants (Hymenoptera: Formicidae) of Georgia: Ecological Relationships with implications for development of biologically-based management strategies. Doctor of Philosophy thesis, University of Georgia. 165 pages.
 * Ipser, R.M., M.A. Brinkman, W.A. Gardner and H.B. Peeler. 2004. A Survey of Ground-Dwelling Ants (Hymenoptera: Formicidae) in Georgia. The Florida Entomologist 87(3) 253-260.
 * Jeanne R. J. 1979. A latitudinal gradient in rates of ant predation. Ecology 60(6): 1211-1224.
 * Johnson C. 1986. A north Florida ant fauna (Hymenoptera: Formicidae). Insecta Mundi 1: 243-246
 * Klotz, J.H., J.R. Mangold, K.M. Vail, L.R. Davis Jr., R.S. Patterson. 1995. A survey of the urban pest ants (Hymenoptera: Formicidae) of Peninsular Florida. Florida Entomologist 78(1):109-118
 * Lozano-Zambrano F. H., E. Jimenez, T. M. Arias-Penna, A. M. Arcila, J. Rodriguez, and D. P. Ramirez. 2008. Biogeografía de las hormigas cazadoras de Colombia. Pp. 349-406. in: Jiménez, E.; Fernández, F.; Arias, T.M.; Lozano-Zambrano, F. H. (eds.) 2008. Sistemática, biogeografía y conservación de las hormigas cazadoras de Colombia. Bogotá: Instituto de Investigación de Recursos Biológicos Alexander von Humboldt, xiv + 609 pp.
 * Lubertazzi D. and Tschinkel WR. 2003. Ant community change across a ground vegetation gradient in north Floridas longleaf pine flatwoods. 17pp. Journal of Insect Science. 3:21
 * MacGown J. A., B. Boudinot, M. Deyrup, and D. M. Sorger. 2014. A review of the Nearctic Odontomachus (Hymenoptera: Formicidae: Ponerinae) with a treatment of the males. Zootaxa 3802(4): 515-552.
 * MacGown, J. A. and J. G. Hill. 2010. Two new exotic pest ants, Pseudomyrmex gracilis and Monomorium floricola (Hymenoptera: Formicidae) collected in Mississippi. Midsouth Entomologist 3 (2): 106-109.
 * MacGown, J.A and J.A. Forster. 2005. A preliminary list of the ants (Hymenoptera: Formicidae) of Alabama, U.S.A. Entomological News 116(2):61-74
 * Marinho C. G. S., R. Zanetti, J. H. C. Delabie, M. N. Schlindwein, and L. de S. Ramos. 2002. Ant (Hymenoptera: Formicidae) Diversity in Eucalyptus (Myrtaceae) Plantations and Cerrado Litter in Minas Gerais, Brazil. Neotropical Entomology 31(2): 187-195.
 * Moreau C. S., M. A. Deyrup, and L. R. David Jr. 2014. Ants of the Florida Keys: Species Accounts, Biogeography, and Conservation (Hymenoptera: Formicidae). J. Insect Sci. 14(295): DOI: 10.1093/jisesa/ieu157
 * Neves F. S., K. S. Queiroz-Dantas, W. D. da Rocha, and J. H. C. Delabie. 2013. Ants of Three Adjacent Habitats of a Transition Region Between the Cerrado and Caatinga Biomes: The Effects of Heterogeneity and Variation in Canopy Cover. Neotrop Entomol 42: 258268.
 * Pires de Prado L., R. M. Feitosa, S. Pinzon Triana, J. A. Munoz Gutierrez, G. X. Rousseau, R. Alves Silva, G. M. Siqueira, C. L. Caldas dos Santos, F. Veras Silva, T. Sanches Ranzani da Silva, A. Casadei-Ferreira, R. Rosa da Silva, and J. Andrade-Silva. 2019. An overview of the ant fauna (Hymenoptera: Formicidae) of the state of Maranhao, Brazil. Pap. Avulsos Zool. 59: e20195938.
 * Ramos L. S., R. Z. B. Filho, J. H. C. Delabie, S. Lacau, M. F. S. dos Santos, I. C. do Nascimento, and C. G. S. Marinho. 2003. Ant communities (Hymenoptera: Formicidae) of the leaf-litter in cerrado stricto sensu areas in Minas Gerais, Brazil. Lundiana 4(2): 95-102.
 * Ramos L. de S., C. G. S. Marinho, R. Zanetti, and J. H. C. Delabie. 2003. Impacto de iscas formicidas granuladas sobre a mirmecofauna não-alvo em eucaliptais segundo duas formas de aplicacação / Impact of formicid granulated baits on non-target ants in eucalyptus plantations according to two forms of application. Neotropical Entomology 32(2): 231-237.
 * Ramos L. de S., R. Zanetti, C. G. S. Marinho, J. H. C. Delabie, M. N. Schlindwein, and R. P. Almado. 2004. Impact of mechanical and chemical weedings of Eucalyptus grandis undergrowth on an ant community (Hymenoptera: Formicidae). Rev. Árvore 28(1): 139-146.
 * Rojas Fernandez P. 2010. Capítulo 24. Hormigas (Insecta: Hymenoptera: Formicidae). In: Diversidad Biológica de Veracruz. Volumen Invertebrados. CONABIO-Gobierno del Estado de Veracruz.
 * Rojas P., C. Fragoso, and W. P. MacKay. 2014. Ant communities along a gradient of plant succession in Mexican tropical coastal dunes. Sociobiology 61(2): 119-132.
 * Silva F. H. O., J. H. C. Delabie, G. B. dos Santos, E. Meurer, and M. I. Marques. 2013. Mini-Winkler Extractor and Pitfall Trap as Complementary Methods to Sample Formicidae. Neotrop Entomol 42: 351358.
 * Silva R.R., and C. R. F. Brandao. 2014. Ecosystem-Wide Morphological Structure of Leaf-Litter Ant Communities along a Tropical Latitudinal Gradient. PLoSONE 9(3): e93049. doi:10.1371/journal.pone.0093049
 * 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.
 * Sosa-Calvo J. 2007. Ants of the leaf litter of two plateaus in Eastern Suriname. In Alonso, L.E. and J.H. Mol (eds.). 2007. A rapid biological assessment of the Lely and Nassau plateaus, Suriname (with additional information on the Brownsberg Plateau). RAP Bulletin of Biological Assessment 43. Conservation International, Arlington, VA, USA.
 * Torres J.A. 1984. Niches and Coexistence of Ant Communities in Puerto Rico: Repeated Patterns. Biotropica 16(4): 284-295.
 * Trager, J. and C.Johnson. 1985. A slave-making ant in Florida: Polyergus lucidus with observations on the natural history of its host Formica archboldi (Hymenoptera: Formicidae). The Florida Entomologist 68(2):261-266.
 * Valenzuela-González J., Quiroz-Robledo L. y Martínez-Tlapa D. 2008. Capítulo 8. Hormigas (Insecta: Hymenoptera: Formicidae). En: Manson R., Hernández-Ortiz V., Gallina S y K. Mehltreter (eds) Agroecosistemas cafetaleros de Veracruz: biodiversidad, manejo y conservación.Instituto de Ecología A.C.-Instituto Nacional de Ecología (INE-SEMARNAT). P.107-121. ISBN 970-709-112-6.
 * Vasconcelos, H.L., J.M.S. Vilhena, W.E. Magnusson and A.L.K.M. Albernaz. 2006. Long-term effects of forest fragmentation on Amazonian ant communities. Journal of Biogeography 33:1348-1356
 * Vasquez-Bolanos M. 2011. Checklist of the ants (Hymenoptera: Formicidae) from Mexico. Dugesiana 18(1): 95-133.
 * Vásquez-Bolaños M. 2011. Lista de especies de hormigas (Hymenoptera: Formicidae) para México. Dugesiana 18: 95-133
 * da Silva de Oliveira A. B., and F. A. Schmidt. 2019. Ant assemblages of Brazil nut trees Bertholletia excelsa in forest and pasture habitats in the Southwestern Brazilian Amazon. Biodiversity and Conservation 28(2): 329-344.
 * da Silva, R.R., C.R.F. Brandao, and R. Silvestre. 2004. Similarity Between Cerrado Localities in Central and Southeastern Brazil Based on the Dry Season Bait Visitors Ant Fauna. Studies on Neotropical Fauna and Environment 39(3):191-199.