Natural History:

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).

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 )

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.

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.

Alto Paraná , Amambay, Canindeyú , Central, Concepción , Misiones, Ñeembucú (ALWC, BMNH, LACM, MHNG, MZSP, USNM). Literature records: Misiones (Fowler 1981).

(No. 38 a et 38 b). [[ worker ]].

 

L. 2,2 a 2,5 mill. Caracteres du sous-genre. Mandibules armees de 5 dents obtuses, tres etroites, a bord terminal tres oblique. Elles sont densement striees et subopaques. Tete plus ou moins carree, un peu plus etroite derriere que devant, largement et faiblement echancree derriere, dentee aux angles pos. terieurs. Les yeux sont situes a peine en arriere du milieu des cotes. En arriere, les aretes frontales divergent comme chez loa Acromyrmex , laissant entre elles deux aretes medianes, paralleles, obtuses. Une arete laterale de chaque cote du dessous de la tete, allant rejoindre la dent de l'occiput. Le pronotum et le devant du mesonotum ont chacun quatre epines obtuses, non denticulees, dont les laterales sont les plus longues. Colles du premier sont disposees eu demi-cercle concave derriere, celles du second ou demi-cercle concave devant; a elles huit, elles forment un cercle, ru milieu duquel sont encore deux tubercules obtus. Derriere ce corola d'epines, le mesonotum a une forte impression transversale, et derriere celle la une portion elevee et pourvue de deux dents en avant et de deux petites epines en arriere. La face basale du meta- notum est bordee lateralement et terminee de chaque cote, devant, pur uno tres petite dent, et derriere par une assez longue epine subverticale. Deux petites dents metasternales obtusos. Premier article du pedicule assez longuement petiole et lateralement borde devant, et surmonte derriere d'un n oe ud eleve, cubique, a pans verticaux, quadridente en haut. Second article du pediculo presque 4 fois large comme le premier, presque aussi large quo le devant do l´abdomen, avec quatre cotes longitudinales elevees et trois sillons outro elles. Abdomen petit; son premier segment qui en recouvre plus des 2 / 3 est d´1 / 3 plus long quo large et a los cotes subparalleles et bordes d'une forte cote.

 

Entierement mat. La sculpture est densement, profondement et irregulierement reticulee (les mailles sont irregulieres, surtout sur la tete). Le fond des mailles est microscopiquement granuleux. Sur la tete, les reticulations sont moins fines et s'elevent en partie sous forme de rides ou rugosites tres irregulieres qui portent ca et la dos asperites tuberiformes et piligeres. Sur le thorax, les retieu- latious sont tres accentuees, plus fines et plus regulieres, visibles jusqu'a l'extremite des epines. Sur l'abdomen, les scapes et les pattes elles sont d'une finesse et d'une densite extreme, assez regulieres. Quelques poils dresses, courts sur la tete. Sur le resto du corps, les scapes et les pattes il n'y a qu'une pubescence espacee et recourbee plutot qu'adjacente, d'un jaune assez brillant.

 

D'un roux plus ou moins jaunatre. Dessus de la tete et de l'abdomen plus fonces. Pattes testacees.

 

(38). I have found this species only at Belleisle (leeward, 1000 ft.), in open woods, very hard clay soil; and another locality noted below. They were taken at the mouths of little tunnels, from which they were bringing out grains of earth. Twenty or more of these tunnels were found scattered over a space several yards long and wide; this was noticed in three localities some distance apart, without, so far as I observed, any intermediate tunnel-mouths. I judge therefore that the tunnels in each locality belong to a common large formicarium, which may be at a considerable distance below the surface. I followed some of the tunnels for several inches perpendicularly down, but the clay was so hard that a pickaxe would have been required to dig further. The ants are sluggish, and have a kind of staggering gait, that reminds one of the S. American Oecodomas.

 

(N. B. - I am told that a large leaf-carrying ant is found in the forest, but I have not yet seen it (found later; see below). I did not see any indication that this small species carried leaves, but the grains of earth it brings up and piles about the mouth of the tunnel have the same irregularly rounded form as those brought up by the South American leaf-carriers; only they are much smaller).

 

(38 a). Nov. 8 th. Belleisle, as noted above.

 

(38 b). Nov. 18 th. Near Brighton (south end of island), 300 ft.; hard road in scrubby forest; at the mouths of tunnels like those of 38 a. In the same ground were tunnels of No. 51.

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

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:

• cultivated fungus Basidiomycota

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.

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 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

Currently the lifespan of Mycocepurus smithii is unknown.

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)

Barcode of Life Data Systems (BOLDS) Stats
Public Records: 0
Species: 5
Species With Barcodes: 1

Mycocepurus smithii is currently abundant and inhabits a large geographic range, making it a low conservation concern.

CITES: no special status

Currently there are no known adverse effects of Mycocepurus smithii on humans.

Currently there are no known positive effects of Mycocepurus smithii on humans.