Pseudomyrmex ferrugineus

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Pseudomyrmex ferrugineus
Scientific classification
Kingdom: Animalia
Phylum: Arthropoda
Class: Insecta
Order: Hymenoptera
Family: Formicidae
Subfamily: Pseudomyrmecinae
Genus: Pseudomyrmex
Species group: ferrugineus
Species: P. ferrugineus
Binomial name
Pseudomyrmex ferrugineus
(Smith, F., 1877)

Pseudomyrmex ferrugineus casent0005785 profile 1.jpg

Pseudomyrmex ferrugineus casent0005785 dorsal 1.jpg

Specimen labels


A common species, these ants live in swollen-thorn acacias (=Vachella).


Ward (1993) - Workers and queens of P. ferrugineus can be recognized by features of head morphology (laterally rounded median clypeal lobe, well separated frontal carinae and correspondingly limited exposure of the median lobes of the antennal sclerites, and moderately broad worker head), head sculpture (densely punctulate and (sub)opaque, but weakly shining on upper third of head between the ocelli and compound eye), and coloration (variably brown, not black or orange-brown). This species is most likely to be confused with the allopatric Pseudomyrmex janzeni and the partly sympatric Pseudomyrmex flavicornis. See under those species for more specific discussion.


Eastern and southern Mexico, Guatemala, Belize, El Salvador and Honduras.

Distribution based on Regional Taxon Lists

Neotropical Region: Belize, Costa Rica, El Salvador, Guatemala, Honduras, Mexico (type locality), Nicaragua.

Distribution based on AntMaps


Distribution based on AntWeb specimens

Check data from AntWeb


A common species, its colonies have been recorded from all swollen-thorn acacia species growing within its range, i.e. Acacia chiapensis (this and the following Acacia species are now classified as Vachellia), A. collinsii, A. cookii, A. cornigera, A. gentlei, A. globulifera, A. hindsii, A. janzenii, A. mayana and A. sphaerocephala. Pseudomyrmex ferrugineus is usually monogynous (Janzen 1967b, 1973) but a few alcohol nest series from Guatemala, belonging to apparently mature colonies (as judged by the presence of alates), contained more than one dealate queen. Janzen (1966, 1967b) conducted a series of experimental and observational studies of the symbiosis between P. ferrugineus and Vachellia cornigera in Mexico (also see Chapter 14 of the The Ants). The results of this work demonstrated the ants protect their host from herbivores and competing plants. The plants, in turn, provide specialized food and nesting resources to the ants.

Pseudomyrmex ferrugineus was the subject of a study of worker kinship and nestmate recognition (Mintzer 1982; Mintzer et al. 1985). This demonstrated a worker-based and likely genetic component of colony odor.

Pseudomyrmex ferrugineus inhabit a majority of Turnera velutina (previously Acacia hindsii) plants (citations given in Fonseca-Romero et al. 2019), serving the role of a dominant, aggressive ant species that defends the plant. The plant in turn provides nesting space (hollow thorns) and food (extrafloral nectaries and beltian bodies) to the ants.

Life History Traits

  • Queen number: monogynous



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

  • ferrugineus. Pseudomyrma ferruginea Smith, F. 1877b: 64 (w.) MEXICO. Combination in Pseudomyrmex: Kempf, 1972a: 218. Senior synonym of bequaerti Wheeler (and its junior synony bequaerti Enzmann), fulvescens, hondurana, saffordi Wheeler, vesana, wasmanni: Ward, 1989: 437. See also: Ward, 1993: 136.
  • fulvescens. Pseudomyrma belti r. fulvescens Emery, 1890b: 64 (w.) GUATEMALA. Forel, 1907e: 7 (m.); Wheeler, W.M. 1942: 160 (q.). Combination in Pseudomyrmex: Kempf, 1972a: 216. Raised to species: Dalla Torre, 1893: 57. Subspecies of belti: Forel, 1899c: 87. Junior synonym of ferrugineus: Ward, 1989: 437.
  • canescens. Pseudomyrma canescens Wasmann, 1915a: 321, pl. 14, figs. 1-4 (w.q.m.) MEXICO. [Junior primary homonym of canescens Smith, above.] Replacement name: wasmanni Wheeler, W.M. 1921b: 92 (footnote).
  • wasmanni. Pseudomyrma wasmanni Wheeler, W.M. 1921b: 92 (footnote). Replacement name for canescens Wasmann, 1915a: 321. [Junior primary homonym of canescens Smith, F. 1877b: 66.] Subspecies of belti: Stitz, 1937: 133; Wheeler, W.M. 1942: 164. Junior synonym of ferrugineus: Ward, 1989: 437.
  • bequaerti. Pseudomyrma belti subsp. bequaerti Wheeler, W.M. 1942: 164 (w.) HONDURAS. Combination in Pseudomyrmex: Kempf, 1972a: 216. Senior synonym of bequaerti Enzmann: Brown, 1949a: 42. Junior synonym of ferrugineus: Ward, 1989: 437.
  • saffordi. Pseudomyrma belti subsp. saffordi Wheeler, W.M. 1942: 162 (w.) MEXICO. Combination in Pseudomyrmex: Kempf, 1972a: 216. Junior synonym of ferrugineus: Ward, 1989: 437.
  • vesana. Pseudomyrma belti subsp. vesana Wheeler, W.M. 1942: 163 (w.) MEXICO. Combination in Pseudomyrmex: Kempf, 1972a: 216. Junior synonym of ferrugineus: Ward, 1989: 437.
  • bequaerti. Pseudomyrma belti subsp. bequaerti Enzmann, E.V. 1944: 80, pl. 2, fig. 17 (w.) HONDURAS. [Unresolved junior primary homonym of bequaerti Wheeler, above.] Junior synonym of bequaerti Wheeler: Brown, 1949a: 42.
  • hondurana. Pseudomyrma kuenckeli var. hondurana Enzmann, E.V. 1944: 87 (w.) HONDURAS. Junior synonym of kuenckeli: Kempf, 1961a: 402; of ferrugineus: Ward, 1989: 437.

Type Material

Ward (1993):

  • Lectotype worker, Mexico (The Natural History Museum) [Examined].
  • Pseudomyrma belti race fulvescens Emery 1 890:64. Lectotype worker, Guatemala (Beccari) (Museo Civico di Storia Naturale, Genoa) [Examined].
  • Pseudomyrma canescens Wasmann 1915:321. Syntype workers, Tampico, Mexico (Brakhoven) (MCSN, Museum of Comparative Zoology) [Examined].
  • Pseudomyrma belti subsp. bequaerti Wheeler 1942:164. Lectotype worker, Puerto Castilla, Honduras (J. Bequaert) (MCZC) [Examined].
  • Pseudomyrma belti subsp. saffordi Wheeler 1942:162. Lectotype worker, Chicoasen, Chiapas, Mexico (G.N. Collins) (MCZC) [Examined].
  • Pseudomyrma belti subsp. vesana Wheeler 1942:163. Holotype (unique syntype) worker, Cordoba, Mexico (F. Knab) (MCZC) [Examined].
  • Pseudomyrma belti subsp. bequaerti Enzmann 1945:80. Syntype workers, Puerto Castilla, Honduras (J. Bequaert) (MCZC) [Examined].
  • Pseudomyrma kuenckeli var. hondurana Enzmann 1945:87. Lectotype worker, Honduras (Bates) (MCZC) [Examined].

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



Ward (1993) - Worker measurements (n = 69). —HL 0.99-1.33, HW 0.92-1.15, MFC 0.054-0.108, CI 0.81-0.94, REL 0.42-0.48, REL2 0.48-0.54, OOI 1.39-3.16, VI 0.60-0.78, FCI 0.054-0.101, SI 0.41-0.46, SI2 0.79-0.91, NI 0.61-0.72, PLI 0.54-0.69, PWI 0.56-0.73, PPWI 1.34-1.70.

Medium-sized species (HW > 0.91; LHT 0.75-1.06) with broad head (CI > 0.80); anterior margin of median clypeal lobe straight or weakly concave, rounded laterally; palp formula 5,3; frontal carinae well separated (FCI > O.O5) and median lobe of antennal sclerite not strongly exposed (FCI2 0.45-0.69); mesonotum notably inclined and with basal face of propodeum rounding gradually into declivitous face, but deviations from this pattern occur; petiole relatively short, high and wide (see relevant metrics: PLI, PWI), with a distinct anterior peduncle (PWI3 0.36-0.50); posterolateral angles of petiole moderately developed but not as pronounced as in P. peperi; postpetiole broad. Head densely punctulate, predominantly opaque or subopaque but at least weakly shining on upper third of head between ocelli and compound eye; mesosoma punctulate to punctulate-coriarious, subopaque to sublucid; posterior portions of propodeum opaque to subopaque and usually overlain by larger but weak, irregular punctures or rugulae. Petiole, postpetiole and gaster with fine piligerous punctures, sublucid. Standing pilosity common; pubescence dense but fine and appressed on most surfaces. Color variable, from light reddish- or yellowish-brown to very dark brown, gaster (and usually head) somewhat darker than the mesosoma; mandibles, scapes, frontoclypeal complex, and apices of legs usually lighter.

Worker Morphology

  • Caste: monomorphic


  • Kempf, W. W. 1972b. Catálogo abreviado das formigas da regia~o Neotropical. Stud. Entomol. 15: 3-344 (page 218, Combination in Pseudomyrmex)
  • Fonseca-Romero, M. A., J. Fornoni, E. del-Val, and K. Boege. 2019. Ontogenetic trajectories of direct and indirect defenses of myrmecophytic plants colonized either by mutualistic or opportunistic ant species. Oecologia. 190:857-865. doi:10.1007/s00442-019-04469-y
  • Smith, F. 1877b. Descriptions of new species of the genera Pseudomyrma and Tetraponera, belonging to the family Myrmicidae. Trans. Entomol. Soc. Lond. 1877: 57-72 (page 64, worker described)
  • Ward, P. S. 1989a. Systematic studies on pseudomyrmecine ants: revision of the Pseudomyrmex oculatus and P. subtilissimus species groups, with taxonomic comments on other species. Quaest. Entomol. 25: 393-468 (page 437, Senior synonym of bequaerti Wheeler (and its junior synony bequaerti Enzmann), fulvescens, hondurana, saffordi Wheeler, vesana and wasmanni:)
  • Ward, P. S. 1993. Systematic studies on Pseudomyrmex acacia-ants (Hymenoptera: Formicidae: Pseudomyrmecinae). J. Hym. Res. 2: 117-168 (page 136, see also)
  • Ward, P.S. 2017. A review of the Pseudomyrmex ferrugineus and Pseudomyrmex goeldii species groups: acacia-ants and relatives (Hymenoptera: Formicidae). Zootaxa 4227: 524–542 (doi: 10.11646/zootaxa.4227.4.3).

References based on Global Ant Biodiversity Informatics

  • Brandao, C.R.F. 1991. Adendos ao catalogo abreviado das formigas da regiao neotropical (Hymenoptera: Formicidae). Rev. Bras. Entomol. 35: 319-412.
  • Castano-Meneses, G., M. Vasquez-Bolanos, J. L. Navarrete-Heredia, G. A. Quiroz-Rocha, and I. Alcala-Martinez. 2015. Avances de Formicidae de Mexico. Universidad Nacional Autonoma de Mexico.
  • Dattilo W. et al. 2019. MEXICO ANTS: incidence and abundance along the Nearctic-Neotropical interface. Ecology
  • 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.
  • Eubanks, M. D., Nesci, K. A., Petersen, M. K., Liu, Z., and Sanchez, H. B. (1997). The exploitation of an ant-defended host plant by a shelter-building herbivore. Oecologia 109: 454-460.
  • Fernández, F. and S. Sendoya. 2004. Lista de las hormigas neotropicales. Biota Colombiana Volume 5, Number 1.
  • Heil, M. 2013. Let the best one stay: screening of ant defenders by Acacia host plants functions independently of partner choice or host sanctions. Journal of Ecology 101: 684-688.
  • Ibarra-Manriquez, G., and R. Dirzo. 1990. Plantas mirmecofilas arboreas de la estacion de biologia Los Tuxtlas, Veracruz, Mexico. Revista de Biologia Tropical 38: 79-82.
  • Janzen, D. H. 1973. Evolution of polygynous obligate acacia-ants in western Mexico. Journal of Animal Ecology 42:727-750.
  • Kautz, S., D. J. Ballhorn, J. Kroiss, S. U. Pauls, C. S, Moreau, S. Eilmus, and M. Heil. 2012. Host plant use by competing acacia-ants: mutualists monopolize while parasites share hosts. Plos One 7, e37691.
  • Kempf, W.W. 1972. Catalago abreviado das formigas da regiao Neotropical (Hym. Formicidae) Studia Entomologica 15(1-4).
  • Maes, J.-M. and W.P. MacKay. 1993. Catalogo de las hormigas (Hymenoptera: Formicidae) de Nicaragua. Revista Nicaraguense de Entomologia 23.
  • Mintzer, A. 1982. Nestmate recognition and incompatibility between colonies of the acacia-ant Pseudomyrmex ferruginea. Behavioral Ecology and Sociobiology 10: 165-168.
  • Novais, S. M., W. D. DaRocha, N. Calderon-Cortes, and M. Quesada. 2017. Wood-boring beetles promote ant nest cavities: extended effects of a twig-girdler ecosystem engineer. Basic and Applied Ecology 24: 53-59.
  • Quiroz Robledo L. N., and J. E. Valenzuela Gonzalez. 1993. Contribucion al conocimiento de la mirmecofauna del estado de Hidalgo, Mexico (Hymenoptera: Formicidae). En: Villavicencio-Nieto (ed) Flora y Fauna del Estado de Hidalgo. Universidad Autónoma de Hidalgo. p. 340-393. ISBN 968-63 40-36-X
  • Rico-Gray, V. 1993. Use of plant-derived food resources by ants in the dry tropical lowlands of coastal Veracruz, Mexico. Biotropica 25(3):301-315.
  • Rico-Gray,V., J.G. Garcia-Franco, M. Palacios-Rios, C. Diaz-Castelazo, V. Parra-Tabla and J.A. Navarro. 1998. Geographical and Seasonal Variation in the Richness of Ant-Plant Interactions in Mexico. Biotropica 30(2):190-200.
  • 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.
  • 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
  • Ward, P. S. 1989. Systematic Studies on Pseudomyrmecine Ants: Revision of the Pseudomyrmex Oculatus and P. Subtilissimus Species Groups with Taxonomic Comments on Other Species. Questiones Entomologicae 25: 393-468
  • Ward, P.S. 1993. Systematic studies on Pseudomyrmex acacia-ants (Hymenoptera: Formicidae) Journal of Hymenoptera Research 2(1):117-168
  • Wheeler W. M. 1907. A collection of ants from British Honduras. Bulletin of the American Museum of Natural History 23: 271-277.
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