Mycocepurus smithii is currently abundant and inhabits a large geographic range, making it a low conservation concern.
CITES: no special status
Aside from local competitors, Mycocepurus smithii does not seem to have any specialized predators. Members of Formicidae usually exhibit anti-predatory behaviors, such as swarming and biting. Some ants even have specialized jaw appendages for biting and stinging.
Mycocepurus smithii is roughly 3 mm long, and possess a fused mesonotum and pronotum, a promesonotum. A crown of spines on the promesonotum is unique to this genus and separates it from other ants. Mycocepurus smithii can be differentiated from other species in its genus by its lack of developed promesonotal spines in the center of its crown. Mycocepurus smithii can also be differentiated from other Mycocepurus ants by its sharp pronotal spines, which are generally shorter and more blunt in other species. This is an asexual species that is comprised of females only.
Average length: 3 mm.
Other Physical Features: ectothermic ; bilateral symmetry
Currently the lifespan of Mycocepurus smithii is unknown.
Mycocepurus smithii is a fungus cultivating ant species, and thus inhabits moist soil ideal for growing fungus. Its nests can be found an average of 0.325 m below ground and consist of multiple connected chambers. This species may be found in savannas or rain forests that provide suitable soil conditions.
Range depth: 0.20 to 0.85 m.
Average depth: 0.325 m.
Habitat Regions: tropical ; terrestrial
Terrestrial Biomes: savanna or grassland ; rainforest
Mycocepurus smithii inhabits the Neotropical region. This species is widely distributed throughout Central and South America, from Mexico through Argentina and also several islands in the Caribbean.
Biogeographic Regions: neotropical (Native )
The fungus cultivating behavior in this species appears to provide the sole food source for Mycocepurus smithii. The queen of the colony maintains a symbiosis with the fungus. The queen must transport, nourish, and cultivate fungi with which she will nourish her brood.
Other Foods: fungus
Primary Diet: mycophage
Mycocepurus smithii are most notably known for their fungal cultivating mutualistic relationship. The fungal colonies serve as a food source for the ants and the ants help cultivate and grow fungal colonies. Mycocepurus smithii and other fungus cultivating ants provide an important ecological function in cultivating fungus. Mycocepurus smithii may help spread fungal colonies to newer habitats.
Ecosystem Impact: creates habitat
Mutualist Species:
Currently there are no known positive effects of Mycocepurus smithii on humans.
Currently there are no known adverse effects of Mycocepurus smithii on humans.
Mycocepurus smithii undergoes a complete metamorphosis including egg, larva, pupa, and adult stages in that order. Due to the parthenogenic nature of M. smithii, the sex of all offspring is female.
Development - Life Cycle: metamorphosis
Ants typically rely on communication via pheromones. Even though ants have eyes and antenna, which can be used for some communication, in a mainly subterranean colonial world the most efficient mode of communication is through pheromones. It has been estimated that ant species generally use between 10 and 20 chemical "words" to convey a message. The most recognizable signals that biologists can detect are attraction, recruitment, alarm, identification of other castes, recognition of larvae and other life stages, and discrimination between nestmates and strangers.
Communication Channels: chemical
Other Communication Modes: pheromones ; scent marks
Perception Channels: visual ; acoustic ; chemical
Mycocepurus smithii appears to be a strictly asexual species of ant. Despite extensive testing no males have ever been discovered. All females in a given colony are clones of the queen, their mother. At this point, individuals of this species lack functional reproductive organs and thus the ability to reproduce.
Mating System: eusocial
Only queens reproduce; all other female workers are essentially sterile. In a related species, Mycocepurus goeldii, nests are prepared for reception of males and nuptial flights in late September, with mating occurring after the rains in early October. Such behaviors are not observed in M. smithii. Despite the lack of sexual activity in M. smithii, the peak production of alate females and nest founding occurs during the rainy season, July through September, similar to other species in its genus. Growth of M. smithii populations within a newly founded colony are markedly slower than in similar species, typically taking 2 to 5 months before the first workers are cited.
Breeding interval: Mycocepurus smithii reproduces once yearly.
Breeding season: Mycocepurus smithii reproduces during the rainy season, which occurs from July through September.
Key Reproductive Features: seasonal breeding ; parthenogenic ; asexual ; oviparous
All ant colonies show some degree of parental care. The initial brood in a colony is cared for by the queen. After a significant number of workers are born they then take over caring for the brood. The workers feed and protect the larvae for the remainder of their development.
Parental Investment: female parental care ; pre-hatching/birth (Provisioning: Female, Protecting: Female); pre-weaning/fledging (Provisioning: Female, Protecting: Female); pre-independence (Provisioning: Female, Protecting: Female)
Kempf (1963) summarized the biology of this species as follows:
"Bionomics. - The ensuing data have been compiled from papers by Forel (1893):371-372, 1912:187), Wheeler (1907:773-774), Wheeler & Mann (1914:42), Eidmann (1936:85-86), Borgmeier (1937:248) and Weber (1946:128-129). The contribution by Eidmann is by far the most complete.
The small and sluggish workers when foraging carry dry leaves and caterpillar droppings back to their nest. The nesting sites are either in open fields and woods or even in moist gullies. The nest proper is in the soil. On the surface it is marked by craters of earth crumbs, measuring not more than 8 cm in diameter. These superficial structures stand out by their color which is different from that of the top soil, indicating that the nest cavities are at some depth. According to Bondar (Borgmeier, 1937) nest chambers have been dug out at a depth varying from 80 to 100 cm. In Colombia, Forel (1912) found a rather shapeless fungus-garden of this species at very little profundity.
A fact reported by many observers and confirmed by my own field experience is that usually a small area contains many craters of the same species, whereas neighboring areas have none at all. H. H. Smith (Forel, 1893) who first called attention to the phenomenon, suggested that the craters of a given area represent the entrances of just one common formicarium (as happens with goeldii during the mating season, according to Luederwaldt). This, however, has not as yet been established conclusively.
The nest cavity, measuring 4-5 cm in width to 2.5-3 cm in height, possesses a flat ceiling and an excavated bottom. From the ceiling without the support of a framework of plant rootlets hang narrow clusters or threads of fungus material. These threads, which are quite consistent, are made up of finely cut up leaf material connected by the mycelium. The fungus itself has not as yet been identified. Eidmann states that superficially it resembles that of Atta sexdens, whereas Forel (1912) glibly states that it is not Pholiota (Rizotes) gongylophora. Away from the nest chamber lead several fine and threadlike tunnels barely giving passage to the tiny workers. Eidmann (1936, fig. 4) gives a photograph of a nest chamber with the suspended fungus garden.
While collecting in Puerto Rico, Wheeler (1907:774) made several attempts at excavation of the fungus garden of M. smithi but succeeded only once. In moist red clay under a stone he found a small irregular chamber with about 30 ants. The fungus garden, a small mass of approximately 2 cc in volume, consisted of caterpillar droppings studded with bromatia that scarcely differed from those of Cyphomyrmex rimosus and allies, the only Attine ants known to cultivate a yeast. Wheeler's discordant observation poses an interesting problem, but also needs further confirmation.
According to Eidmann, the colonies are polygynous. At any rate he found several dealated queens in a single nest chamber. The same author proclaims a lestobiotic relationship between M. smithi and Atta sexdens because he found a great many nest chambers of the former between the cavities made by the latter. However, if any such relationship exists, it is not obligatory since M. smithi also occurs in areas where no sign of an Atta sp. could be discovered. Perhaps this association, of which no details are known, dissolves itself in the loose relationship of facultative synoecetes.
In southeastern Brazil M. smithi lives occasionally side by side with M. goeldii under the same ecological conditions. Kerr (1961) even found 3 males of the former in a swarm of 150 males of the latter species at Rio Claro, Sao Paulo State, Brazil. None of the smithi males attempted to mate with goeldii queens."
Fern‡ndez-Mar’n et al. (2005) made observations on the biology of M. smithii in Puerto Rico as follows (abstract):
The genus Mycocepurus is a phylogenetically basal attine ant, so studies of its biology may provide insight into the evolution of behaviours associated with fungus-growing that characterize the tribe Attini. Mycocepurus smithii from Puerto Rico produces sexual females from July to September, but no males were observed in 2 years of observations, confirming previous observations elsewhere. Colonies were founded between July and August and most nests were haplometrotic (85% of 74 nests). After excavating a tunnel and small chamber, a foundress queen inserted her fore wings into the ceiling and used the wing surfaces as a platform on which the incipient fungal garden was grown. Foundresses foraged for substrate to grow the fungus garden. Growth of incipient colonies was slow: the first workers emerged 2-5 months after colony founding and, after 8 months, colonies contained on average only a single worker.
In Costa Rica this species inhabits disturbed and otherwise open habitats. I collected workers emerging from a nest in soil, in a lawn in front of a house at Tortuguero, on the Atlantic coast. Ulrich Mueller similarly collected a nest at a coastal site near Lim—n. I also collected smithii in a small patch of riparian forest at Finca La Pacifica in Guanacaste Province. Workers were in a Winkler sample of sifted leaf litter, together with a worker of M. curvispinosus.
Mycocepurus smithii appears to be a form that favors synanthropic habitats, while the very similar species M. tardus inhabits more forested habitats.
See also MacKay et al. (2004).
Central Mexico and the greater and lesser Antilles through Central America to southeastern Brazil and northwestern Argentina (Kempf 1963). Costa Rica: Atlantic lowlands, northern Pacific lowlands.
Taxonomic history
Kempf, 1963b PDF: 425 (q.).Combination in Mycocepurus: Wheeler & Mann, 1914 PDF: 42.Senior synonym of Mycocepurus attaxenus: Kempf, 1963b PDF: 425.Senior synonym of Mycocepurus bolivianus: Kempf, 1963b PDF: 425.Senior synonym of Mycocepurus smithii borinquenensis: Kempf, 1963b PDF: 425.Senior synonym of Mycocepurus smithii eucarnitae: Kempf, 1963b PDF: 425.Senior synonym of Mycocepurus manni: Kempf, 1963b PDF: 425.Senior synonym of Mycocepurus reconditus: Kempf, 1963b PDF: 425.Senior synonym of Mycocepurus smithii tolteca: Kempf, 1963b PDF: 425.Senior synonym of Mycocepurus smithii trinidadensis: Kempf, 1963b PDF: 425.
Mycocepurus smithii is a species of fungus-growing ant from Latin America. This species is widely distributed geographically and can be found from Mexico in the north to Argentina in the south, as well as on some Caribbean Islands.[1][2][3] It lives in a variety of forested habitats and associated open areas.[2] Two studies published in 2009 demonstrated that some populations of the species consist exclusively of females which reproduce via thelytokous parthenogenesis.[4][5] A detailed study found evidence of sexual reproduction in some populations in the Brazilian Amazon.[3] Accordingly, M. smithii consists of a mosaic of sexually and asexually reproducing populations.[3] In asexual populations all ants in a single colony are female clones of the queen.[3] Inside the colony, the ants cultivate a garden of fungus grown with pieces of dead vegetable matter, dead insects, and insect droppings.[6][7]
Ants of the genus Mycocepurus are distinctly recognizable for the crown-like cluster of spines on their promesonotum, the fused mesonotum and pronotum on the front of their mesosoma or midsection. Mycocepurus smithii has sharp, protruding propodeal (posterior of the alitrunk) spines unlike M. obsoletus whose propodeal spines are blunt. Workers also do not have developed promesonotal spines in the center of their crown, which separates M. smithii from M. goeldii and similar species.[1][2]
Initially, M. smithii was thought to only reproduce asexually because no evidence of male individuals had been found. This led to M. smithii being recognized as the first fungus-growing ant species to reproduce via thelytokous parthenogenesis, where females, the workers and reproductive queens, are produced asexually.[5][4] The cytogenetic mechanism of thelytoky is either apomixis (mitotic parthenogenesis) or automixis with central fusion and low recombination rates.[3] Automixis with central fusion is the cytogenetic mechanism that was recorded in other asexual ant species.[8] Nests with multiple dealated queens are often found, suggesting that M. smithii is a polygynous species.[5][6][7] This appears to be a case of secondary polygyny, and the queens may be daughters of the foundress.[6]
A detailed study of many M. smithii populations across their geographic distribution range (Mexico to Argentina) showed that some M. smithii populations in the Brazilian Amazon reproduce sexually. This was demonstrated using highly variable genetic markers. Sperm was also found stored in the spermathecas of queens. Sexual reproduction was suggested as a mechanism for maintaining the genetic diversity seen in this species.[3] In summary, M. smithii is not purely asexual, but instead consists of a "mosaic" of sexual and asexual populations. Phylogenetic reconstructions and the biology of the species suggest that these sexual populations gave rise to the asexual ones.[3] The mechanism behind the shift to asexuality is still unknown. However, antibiotic assays and genetic screenings suggest that it is not an endosymbiont such as Wolbachia causing the asexuality.[4] In fact, a comparative analysis showed that Wolbachia endosymbionts do not seem to cause asexuality in ants in general.[8]
The nests and colonies of M. smithii were studied in great detail in Puerto Rico and Brazil.[6][7][5] On the surface, M. smithii nests can be recognized by their nest mounds consisting of excavated soil and clay. A nest entrance of roughly 1.2 mm in diameter is located in the center of each nest mound. Large M. smithii nests, which are presumably older, can contain up to 7 or so chambers.[5][6][7] Some fungus chambers are shallow whereas others can be found in great depths, as deep as 2 meters.[7] The abandoned chambers are used to deposit waste from the fungus garden and loose soil from chamber construction. The number of nest chambers tends to increase as colonies grow older.[7] Because M. smithii queens are capable of asexual reproduction, it is believed that colonies can also grow by budding [7] in addition to independent colony foundation.[5] Colonies that grow by budding can result in large colony networks.[7]
Workers of M. smithii ants maintain narrow tunnels (diameter of 1.3 mm), which do not allow two ants to pass each other in the tunnel (head size is around 0.7 mm for workers and 0.9 mm for queens). The tunnels also have a number of slightly larger sections (about 3.6 mm diameter), which would allow passing while also facilitating information exchange. Narrow tunnels are presumably easier (energetically cheaper) to construct and may also aide in leveling the humidity or temperature of the colony or preventing predatory intrusions.[6][7] In general, M. smithii colonies are smaller than the colonies of M. goeldii.[5][7]
When founding a new colony, young queens either shed their wings prior to excavating the nest or just inside. They then excavate a tunnel to a depth of roughly 10 cm (4 in) and create a primary chamber. The dealate, or wingless, queen then carries the wings into the primary chamber and inserts them into the chamber ceiling where the surface of the wings is used as a platform for growing an incipient fungus garden. She will also forage around the nest entrance for caterpillar droppings to feed the fungus garden. The female fore wings of all so-called Paleoattini (the genera Mycocepurus, Apterostigma, and Myrmicocrypta) have a crescent-shaped spot lacking any veins, hairs, and pigmentation, and is thought to provide an "easy to clean" platform for the fungus garden.[6] Queens of the socially parasitic species Mycocepurus castrator do not found their colonies independently, and the clear spot is absent from their wings.[9] This indirectly supports the idea that the wing spot has a function during the early colony founding and fungus cultivation stage of independently founding Mycocepurus queens.[9] As the colony matures, workers develop and then tend to the fungus garden, feeding it dried leaves, caterpillar droppings, and other debris from the leaf-litter.[6][7]
One trait of M. smithii cultivation is that, unlike higher attines, they use a wide diversity of fungal lineages for their gardens.[10][11] Lineages of M. smithii have undergone many cultivar shifts over time. This tendency to shift cultivars is hypothesized to be a mechanism for helping to offset some of the costs of asexuality.[12] Also unlike other fungus-growing ants M. smithii has a microbiome that is distinct from the surrounding soil.[13] A Brazilian population of M. smithii has a fungal cultivar with gongylidia-like structures. This is unusual, because gongylidia are the nutrient rich food bodies produced by the fungi of leaf-cutting ants – and leaf-cutting ants are rather distant relatives of Mycocepurus.[14]
Mycocepurus smithii is a species of fungus-growing ant from Latin America. This species is widely distributed geographically and can be found from Mexico in the north to Argentina in the south, as well as on some Caribbean Islands. It lives in a variety of forested habitats and associated open areas. Two studies published in 2009 demonstrated that some populations of the species consist exclusively of females which reproduce via thelytokous parthenogenesis. A detailed study found evidence of sexual reproduction in some populations in the Brazilian Amazon. Accordingly, M. smithii consists of a mosaic of sexually and asexually reproducing populations. In asexual populations all ants in a single colony are female clones of the queen. Inside the colony, the ants cultivate a garden of fungus grown with pieces of dead vegetable matter, dead insects, and insect droppings.
