Acromyrmex lobicornis

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Acromyrmex lobicornis
Scientific classification
Kingdom: Animalia
Phylum: Arthropoda
Class: Insecta
Order: Hymenoptera
Family: Formicidae
Subfamily: Myrmicinae
Tribe: Attini
Genus: Acromyrmex
Species: A. lobicornis
Binomial name
Acromyrmex lobicornis
(Emery, 1888)

Acromyrmex lobicornis casent0217813 p 1 high.jpg

Acromyrmex lobicornis casent0217813 d 1 high.jpg

Specimen Labels

Subspecies
Synonyms

An inhabitant of desert areas, this fungus growing ant harvests vegetation from a large range of plants. Acromyrmex lobicorni form large colonies, ~10,000 workers in a mature colony, and forage in well defined columns.

Photo Gallery

  • Acromyrmex lobicornis nest, Río Negro Province, Argentina. Photo by Robert Fuentalba Ojeda.

Identification

Distribution

Latitudinal Distribution Pattern

Latitudinal Range: -22.809943° to -42.666°.

     
North
Temperate
North
Subtropical
Tropical South
Subtropical
South
Temperate

Distribution based on Regional Taxon Lists

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

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. ‎

Jofre et al. (2018) - Acromyrmex lobicornis is one of the most common leaf-cutting ant species in Argentina (Farji-Brener & Ruggiero, 1994). This species constructs nests with an external nest-mound (Farji-Brener, 2000; Bollazzi et al., 2008) that house about 10.000 workers (Jofré & Medina, 2012) and build well defined trails to forage. Acromyrmex lobicornis consumes a high percentage of species available in the environment (Armani & Quirán, 2007; Nobua-Behrmann, 2014), and their degree of selectivity or opportunism depends on the availability of resources within the proximity of their colonies (Farji-Brener & Protomastro, 1992; Pilati et al., 1997; Franzel & Farji-Brener, 2000; Armani & Quirán, 2007; Nobua-Behrmann, 2014).

Foraging

Nobua-Behrmann et al. (2017) studied temporal and thermal aspects of Acromyrmex lobicornis foraging behavior in the Monte Desert in Argentina where this species co-occurs with Amoimyrmex striatus. Acromyrmex lobicornis colonies actively foraged from spring to autumn, with occasional external activity during winter. Foraging intensity was highest during spring and summer, with up to 150 ants (foragers returning to the nest) / 5 minutes. During spring and summer, A. lobicornis foraged mostly during the night, starting at dusk and continuing for up to 16 hours until the next morning. Colonies switched to diurnal foraging in autumn, when temperatures are lower. During the hottest months, the overall daily foraging pattern appears to be complementary to its similar co-occurring congener: A. striatus daily foraging activity begins in the mornings when A. lobicornis colonies are ceasing their foraging activity cycle. Furthermore, the ending of A. striatus colonies foraging activity in the evenings also coincides with the beginning of A. lobicornis foraging. During autumn, colonies still showed considerably high foraging activity (up to 80 ants / 5 minutes). Daily and seasonal variations in nest maintenance activity were broadly similar to foraging activity patterns, though spanning larger time ranges than their foraging activity (starting earlier and finishing later).

The ants foraged within a particular temperature range that was relatively constant throughout the year and differed from its congener: A. striatus colonies foraged at higher temperatures than A. lobicornis in all seasons (26 - 45 °C vs. 16 - 35 °C, respectively).

Jofre et al. (2018) - Foraging behavior was studied in a natural reserve of San Luis, Argentina. The chaco vegetation found within the reserve had in the past been affected by overgrazing, fire, and logging. In addition to quantifying the plants selected by foragers, it was found that small and large nests showed similar feeding behavior.

Association with Other Organisms

Explore-icon.png Explore: Show all Associate data or Search these data. See also a list of all data tables or learn how data is managed.
  • This species is a host for the diapriid wasp Szelenyiopria pampeana (a parasite) in Argentina (Loiácono et al., 2000; Loiácono & Margaría, 2009; Loiacono et al., 2013; Loiacono, 2013; Gonzalez et al., 2016).
  • This species is a host for the diapriid wasp Trichopria formicans (a parasite) in Argentina (Loiacono et al., 2000; Loiacono, 2013; Gonzalez et al., 2016).
  • This species is a host for the diapriid wasp Trichopria sp. (a parasitoid) (Quevillon, 2018) (encounter mode independent; direct transmission; transmission outside nest).
  • This species is a host for the phorid fly Myrmosicarius cristobalensis (a parasitoid) (Quevillon, 2018) (encounter mode primary; direct transmission; transmission outside nest).

Castes

Nomenclature

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

  • lobicornis. Atta (Acromyrmex) lobicornis Emery, 1888c: 358 (w.) ARGENTINA (no province data).
    • [Misspelled as lobulicornis by Santschi, 1916b: 512.]
    • Emery, 1905c: 52 (q.m.); Santschi, 1916e: 388 (m.).
    • Combination in Acromyrmex: Bruch, 1914: 216.
    • Status as species: Dalla Torre, 1893: 153; von Jhering, 1894: 386; Forel, 1895b: 139; Emery, 1905c: 52; Emery, 1906c: 165; Forel, 1908c: 352; Forel, 1911c: 292; Santschi, 1912e: 530; Bruch, 1914: 216; Gallardo, 1915: 18; Gallardo, 1916d: 329; Santschi, 1916b: 512; Santschi, 1916e: 388; Bruch, 1917d: 431; Gallardo, 1919b: 244; Santschi, 1922b: 360; Emery, 1924d: 349; Santschi, 1925a: 390 (in key); Wheeler, W.M. 1925a: 36; Borgmeier, 1927c: 133; Santschi, 1927b: 128; Santschi, 1928f: 209; Kusnezov, 1953b: 338; Kusnezov, 1956: 34 (in key); Gonçalves, 1961: 148; Kempf, 1972a: 13; Zolessi & Abenante, 1977: 82; Zolessi, et al. 1988: 4; Cherrett & Cherrett, 1989: 51; Bolton, 1995b: 55; Wild, 2007b: 30.
    • Senior synonym of bucki: Gonçalves, 1961: 148; Kempf, 1972a: 13; Bolton, 1995b: 56.
    • Senior synonym of rufidens: Gonçalves, 1961: 148; Kempf, 1972a: 13; Bolton, 1995b: 56.
    • Current subspecies: nominal plus cochlearis, ferrugineus, pencosensis, pruinosior.
    • [Note: a record of this species from Ivory Coast by Santschi, 1927b: 128, Santschi, 1928f: 209, may have been a casual introduction, or the result of mislabelled material.]
  • bucki. Acromyrmex bucki Wasmann, 1931: 106 (w.) BRAZIL (Rio de Janeiro).
    • Junior synonym of lobicornis: Gonçalves, 1961: 148; Kempf, 1972a: 13; Bolton, 1995b: 54.
  • rufidens. Acromyrmex lobicornis var. rufidens Santschi, 1933e: 120 (w.) BRAZIL (Bahia, Amazonas).
    • Junior synonym of lobicornis: Gonçalves, 1961: 148; Kempf, 1972a: 13; Bolton, 1995b: 56.

Description

References

References based on Global Ant Biodiversity Informatics

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  • Cheli G. H., J. C. Corley, O. Bruzzone, M. Brío, F. Martínez, N. M. Roman, and I. Ríos. 2010. The ground-dwelling arthropod community of Península Valdés in Patagonia, Argentina. Journal of Insect Science 10:50 available online: insectsicence.org/10.50
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  • Santschi F. 1912. Quelques fourmis de l'Amérique australe. Revue Suisse de Zoologie 20: 519-534.
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  • Vittar, F. 2008. Hormigas (Hymenoptera: Formicidae) de la Mesopotamia Argentina. INSUGEO Miscelania 17(2):447-466
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  • 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.
  • Zolessi L. C. de; Y. P. de Abenante, and M. E. Philippi. 1989. Catálogo sistemático de las especies de Formícidos del Uruguay (Hymenoptera: Formicidae). Montevideo: ORCYT Unesco, 40 + ix pp.
  • de Zolessi, L.C., Y.P. de Abenante and M.E. Philippi. 1987. Lista sistemática de las especies de formícidos del Uruguay. Comunicaciones Zoologicas del Museo de Historia Natural de Montevideo 11(165):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