Trachymyrmex carinatus

Trachymyrmex carinatus
Scientific classification
Kingdom:	Animalia
Phylum:	Arthropoda
Class:	Insecta
Order:	Hymenoptera
Family:	Formicidae
Subfamily:	Myrmicinae
Tribe:	Attini
Genus:	Trachymyrmex
Species:	T. carinatus
Binomial name
Trachymyrmex carinatus Mackay, W.P. & Mackay, E.E., 1997 Specimen labels

A ground nesting species that can be found in open exposed areas with sparse ground cover or in oak-juniper-pinyon woodlands.

Identification

In southern Arizona, T. carinatus co-occurs with Trachymyrmex arizonensis in mid elevation habitats. Workers and queens of these two species are easily distinguished by the distinctive frontal lobes of T. arizonensis and the preocular carinae nearly touching the frontal carinae in T. carinatus (not closely approaching the frontal carinae in T. arizonensis). T. carinatus also sometimes co-occurs with Trachymyrmex pomonae from which it may be separated by its larger size and symmetrical frontal lobes (lobes notably asymmetric in T. pomonae). In addition, workers of T. carinatus are superficially very similar to those of the allopatric Trachymyrmex septentrionalis, from which they may be separated by the characters given in the key. (Rabeling et al. 2007).

Keys including this Species

• Key to US Trachymyrmex

Distribution

Trachymyrmex carinatus was described by Mackay & Mackay (1997), based on specimens collected in Chihuahua, Mexico, and the Chiricahua Mountains of southeastern Arizona. T. carinatus occurs in central and southern Arizona, western New Mexico and the Mexican States of Sonora, Chihuahua and Coahuila, often in sympatry with Trachymyrmex arizonensis. A single collection from the Kofa Mountains in southwest Arizona marks its westernmost limit. (Rabeling et al. 2007).

Latitudinal Distribution Pattern

Latitudinal Range: 33.78166667° to 17.830278°.

North Temperate	North Subtropical	Tropical	South Subtropical	South Temperate

• Source: AntMaps

Distribution based on Regional Taxon Lists

Nearctic Region: United States.
Neotropical Region: Mexico (type locality).

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.

Habitat

T. carinatus has been encountered most commonly in the mountains of southern and central Arizona in mid elevation habitats (800–1800m). Colonies may be found in open exposed areas with sparse ground cover, such as washes or roadsides, but are especially abundant in oak-juniper-pinyon woodlands. (Rabeling et al. 2007).

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 (31 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 (56 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. ‎

From Rabeling et al. (2007): Specimens from the Kofa Mountains were collected from a nest next to a water seep shaded by palm trees on the wall of a canyon at ~800 m elevation (R. Snelling, personal communication). Nests are sometimes found under stones, but are more often encountered in open ground, where they can be recognized by the circular shape of the nest crater, which contrasts with the more amorphous nest excavations of T. arizonensis. Excavations by C. Rabeling reveal that nests in the Chiricahua Mountains of southern Arizona have one to three fungus garden chambers, with the shallowest chamber only 5 cm beneath the soil surface. Colonies have fewer than 100 workers. Mating flights occur near dawn on mornings following summer rains. (Mackay & Mackay 1997).

Castes

Images from AntWeb

Paratype of Trachymyrmex carinatus. Worker. Specimen code casent0103159. Photographer April Nobile, uploaded by California Academy of Sciences.	Owned by USNM, Washington, DC, USA.

Nomenclature

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

• carinatus. Trachymyrmex carinatus Mackay & Mackay, 1997a: 44, figs. 1, 2 (w.q.m.) MEXICO (Chihuahua).
  • Type-material: holotype worker, 29 paratype workers, 15 paratype queens, 3 paratype males.
  • Type-locality: holotype Mexico: Chihuahua, Municipio Riva Palacio, 15 km. W Bellavista, 16.viii.1981 (E. Mackay); paratypes with same data.
  • Type-depositories: MCZC (holotype); AMNH, LACM, LESM, MCZC, MZSP, USNM, WEMC (paratypes).
  • Combination in Trachymyrmex: Solomon, Rabeling, et al. 2019: 948
  • Status as species: Rabeling, et al. 2007: 8 (redescription).
  • Distribution: Mexico, U.S.A.

Type Material

• Holotype, worker, 15km W Bellavista, Municipio Riva Palacio, Chihuahua, Mexico, Museum of Comparative Zoology; see Rabeling et al. (2007).
• Paratype workers, paratype queens, and males American Museum of Natural History, William and Emma Mackay Collection, Los Angeles County Museum of Natural History, Museum of Comparative Zoology, National Museum of Natural History. Examined (Rabeling et al. 2007).

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

Description

Worker

Diagnosis from Rabeling et al. (2007): HL 0.8–1.0, HW 0.8–1.04, CI 96–108, SL 0.84–1.04, SI 100–105, ML 1.2–1.44. A relatively small species (HL 0.8–1, HW 0.8–1.04) with normally proportioned legs and antennal scapes (SI 100–105). Head more or less square (CI 96–108), sides subparallel posterior to the eyes, slightly tapering anteriorly between the eyes and mandibular insertions. Posterior margin weakly to moderately concave. Preocular carinae long, strongly curving mesially, and traversing nearly the entire distance between the eye and the frontal carinae, sometimes nearly touching the frontal carinae or appearing to do so. In full-face view, frontal lobes more or less symmetrical. Anterolateral promesonotal teeth moderate in size, pointed in dorsal view, projecting horizontally, not vertically. Anterior median pronotal tubercles small or reduced to denticles, or if tooth-like short and broadly pyramidal. Propodeal teeth usually acute, about as long as the distance between their bases. Dorsal surface of body moderately tuberculate, tuberculi generally moderate in size, bearing recurved setae. First gastric tergite coarsely and conspicuously tuberculate. Color brownish to yellow to medium reddish-brown.

Queen

Diagnosis from Rabeling et al. (2007): HL 1.1–1.25, HW 1.15–1.4, CI 105–112, SL 1.1–1.15, SI 82–96, ML 1.9–2.1. As in worker diagnosis, except for typical caste-specific morphology of the mesosoma related to wing-bearing and head with minute ocelli. Dorsolateral pronotal teeth well-developed, tuberculate, sharply triangulate in dorsal view, often blunt-tipped in anterior view. Mesoscutum coarsely and irregularly rugulose, sometimes with faint longitudinal pattern, minutely tuberculate, and with abundant short, suberect, slightly recurved setae.

Male

Diagnosis from Rabeling et al. (2007): HL 0.72–0.81, HW 0.75–0.84, CI 104, SL 0.81–0.9, SI 104–111, ML 1.6–1.8. Somewhat variable in size, but presenting the following characters: Dorsolateral pronotal tooth absent in dorsal view, ventrolateral pronotal tooth small, broadly to narrowly triangular. Mesoscutum irregularly rugulose, interrugal spaces coarsely granulose. Preocular carina a prominent vertical ridge, remaining strongly developed at least until it reaches the midpoint of the posterior border of the antennal scrobe. In full-face view, posterior corners of head more or less rounded, their outlines obscured by the presence of several conspicuous toothlike tuberculi on each corner.

Etymology

The species name “carinatus” refers to the well-developed carinae on the vertex of the workers’ and queens’ heads. (Rabeling et al. 2007).

References

• Alatorre-Bracamontes, C.E., Vásquez-Bolaños, M. 2010. Lista comentada de las hormigas (Hymenoptera: Formicidae) del norte de México. Dugesiana 17(1): 9-36.
• MacKay, W. P.; MacKay, E. E. 1997a. Una nueva especie de hormiga del género Trachymyrmex (Hymenoptera: Formicidae) del Estado de Chihuahua, México. Sociobiology 30: 43-49 (page 44, figs. 1, 2 worker, queen, male described)
• Prebus, M.M. 2021. Taxonomic revision of the Temnothorax salvini clade (Hymenoptera: Formicidae), with a key to the clades of New World Temnothorax. PeerJ 9, e11514 (doi:10.7717/peerj.11514).
• Rabeling C, Cover SP, Mueller UG and Johnson RA. 2007. A review of the North American species of the fungus-gardening ant genus Trachymyrmex (Hymenoptera: Formicidae). Zootaxa. 1664:1-54.
• 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

• Dattilo W. et al. 2019. MEXICO ANTS: incidence and abundance along the Nearctic-Neotropical interface. Ecology https://doi.org/10.1002/ecy.2944
• Franklin K. 2012. The remarkable resilience of ant assemblages following major vegetation change in an arid ecosystem. Biological Conservation 148(1): 96-105.
• Johnson R. Personnal Database. Accessed on February 5th 2014 at http://www.asu.edu/clas/sirgtools/resources.htm
• Rabeling C., S. P. Cover, R. A. Johnson, and U. G. Mueller. 2007. A review of the North American species of the fungus-gardening ant genus Trachymyrmex (Hymenoptera: Formicidae). Zootaxa 1664: 1-53
• 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.
• Vásquez-Bolaños M. 2011. Lista de especies de hormigas (Hymenoptera: Formicidae) para México. Dugesiana 18: 95-133