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Species: Cephalotes alfaroi   (Emery, 1890) 

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Taxonomic History (provided by Barry Bolton, 2019)

Cryptocerus alfaroi Emery, 1890c PDF: 76 (s.w.) COSTA RICA. Neotropic. AntCat AntWiki HOL

Taxonomic history

[Also described as new by Emery, 1894l PDF: 59.].
Combination in Cephalotes: Emery, 1914b PDF: 39.
See also: Kempf, 1951 PDF: 112.
Junior synonym of Cephalotes serraticeps: Kempf, 1963c PDF: 437.
Revived from synonymy: De Andrade & Baroni Urbani, 1999: 129.


  Geographic regions (According to curated Geolocale/Taxon lists):
    Americas: Brazil, Costa Rica
  Biogeographic regions (According to curated Bioregion/Taxon lists):

Distribution Notes:

Panama, Costa Rica. Costa Rica: in lowland rainforest sites throughout the country, to 500m elevation.


This species is found in mature lowland rainforest, where it is a resident of the high canopy. It is not common, but when workers are encountered they are conspicuous because of their large size and distinctive appearance. I most often encounter workers in treefalls.

I have seen one nest of this species. It was at Sirena in Corcovado National Park, in a 1-day old treefall. The tree was large, an Inga species with blood-red sap. Cephalotes workers were scattered thinly over the tree. Many workers were clustered around a nest entrance in a 30cm diameter branch, about half-way up the tree. I cut the branch open and collected the entire contents (alive) except for very small brood. This included minors, majors, a single dealate queen, an alate queen, and many males. The nest was a baseball-sized cavity in the center of a live branch. The entrance was through a rotten knot-hole. The entrance channel was plugged by a solid mass of ants, and the inside walls of the cavity were covered with a solid layer of ants. Water had collected in the bottom of the cavity, and it looked like there was much drowning brood in the bottom. I kept the colony alive for a while, in a plastic dish. The workers moved the brood into a petri dish covered with aluminum foil. They seemed to keep a lot of liquid around the brood.

The biology of alfaroi is probably similar to that of atratus, for which there are more published observations. See under atratus for additional natural history information.


Costa Rica:

Minor worker: eyes situated beneath the antennal scrobe, which extends above it to the vertex margin; frontal carinae not completely covering the genae; the entire border of the frontal carinae distinctly crenulated, with short, thick, somewhat clubbed setae projecting from the notches; the outer vertex spine, if present, with a laterally projecting denticule from its base, or without an outer spine, and the lateral denticule projecting from the sides of the head; CI less than or equal to 122 (CI = 100 x head width/head length. Head width = maximum head width behind the eyes, including the vertexal spines or lamellae if present. Head length = head length measured dorsally on the sagittal plane).

Major worker: eyes situated beneath the antennal scrobe, which extends above it to the vertex margin; anterior face of pronotum and remaining dorsal surface of mesosoma separated by a row of 4 stout spines, the two surfaces each flat and meeting at an obtuse angle.


A single nest series I collected in Corcovado National Park, on the Pacific side of Costa Rica, and scattered workers and one alate queen from La Selva Biological Station, on the Atlantic side of Costa Rica, differ in several characters. The Corcovado form has a large queen (HW across eyes 3.6mm), workers have a short stubble on the gaster that is relatively uniform over the surface, and on smaller workers the gastral dorsum has some light sculpture, especially medially. The La Selva form has smaller queen (HW 2.7mm on the one alate queen), workers have the stubble restricted to the posterior third or less of the first gastral tergite, and the gastral dorsum is smooth and shiny throughout, highly polished, even on smaller workers.

There is no doubt more material in collections, especially INBio. It would be good to evaluate the variability of these characters.


Andrade, M. L. de, and C. Baroni Urbani. 1999. Diversity and adaptation in the ant genus Cephalotes, past and present (Hymenoptera, Formicidae). Stuttgarter Beitrage zur Naturkunde Serie B (Geologie und Palaontologie) 271:1-889.

Emery, C. 1890. Studii sulle formiche della fauna neotropica. Bull. Soc. Entomol. Ital. 22:38-80.

Kempf, W. W. 1963. Nota sinonimica acerca de formigas da tribo Cephalotini (Hymenoptera, Formicidae). Rev. Bras. Biol. 23:435-438.

Specimen Habitat Summary

Found most commonly in these habitats: 1 times found in CC1500m., 1 times found in La Selva, 1 times found in lowland rainforest, 1 times found in montane wet forest, 1 times found in rainforest edge, 1 times found in wet forest.

Found most commonly in these microhabitats: 1 times One-day old clearing of young second growth forest, parcel along STR several hun, 1 times ex Sacoglottis trichogyna (Humiriaceae), 1 times Copa de arbol, 1 times Cephalotes; lone worker on sidewalk in lab clearing., 1 times lab clearing, 1 times in treefall.

Collected most commonly using these methods: 4 times Search, 2 times fogging, 1 times Foggin.

Elevations: collected from 5 - 500 meters, 78 meters average

Type specimens: syntype of Cephalotes alfaroi: casent0904899

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