Pheidole oculata

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Pheidole oculata
Conservation status
Scientific classification
Kingdom: Animalia
Phylum: Arthropoda
Class: Insecta
Order: Hymenoptera
Family: Formicidae
Subfamily: Myrmicinae
Tribe: Attini
Genus: Pheidole
Species: P. oculata
Binomial name
Pheidole oculata
(Emery, 1899)

Pheidole oculata casent0102052 profile 1.jpg

Pheidole oculata casent0102052 dorsal 1.jpg

Specimen labels

Fischer et al. (2020) found 13 unusual species, which they call the Pheidole lucida group (for the first of its two described species, Pheidole lucida, Pheidole oculata being the other), all of which are associated with other Pheidole species in Madagascar. Although the full biology of these species is not yet known, multiple lines of evidence suggest that they are inquilines (residing inside the nest of another species), and likely social parasites. First, they were frequently observed and collected as part of a nest series of other Pheidole species (i.e., the putative hosts). Second, they have a suite of morphological traits that are typically observed in other inquiline species. The minor worker caste has reduced mandibles and loss of cuticular pigmentation, whereas the queens show modifications found in many other inquiline species that are often referred to as part of a ‘‘parasitic syndrome’’ (e.g., rounded head shape, elongated antennae, broadened postpetiole, etc. (Wilson, 1971; Wilson, 1984)). Third, the major worker subcaste, a hallmark of the genus and present in all 1,000+ non-parasitic Pheidole species, is entirely absent in the P. lucida group. In this genus, the partial loss of the worker caste is a strong indication of a socially parasitic lifestyle, where reproductive allocation to the worker caste is often reduced or lost entirely (Buschinger, 2009; Wilson, 1971; Wilson, 1984; Hoelldobler & Wilson, 1990; Maschwitz et al., 2000; Sumner et al., 2003). Only one of the 13 inquiline species (an undescribed species, Pheidole gf010) seems to be entirely workerless, with the queen itself showing a very reduced, worker-like morphology. Sumner et al. (2003) suggested that workers of incipient social parasites (inquilines) may help the parasitic queen suppress host reproduction and redirect host resources toward the production of parasite queens and males. We refer to this group as ‘‘social parasites’’ because of the evidence above but, without direct observation, the strength of this parasitism in the P. lucida group is uncertain and we cannot rule out weak or even no costs to the host (i.e., commensalism). However, the important point for the following study is that if the workers in the P. lucida group are symbiotic with the host colonies, we should expect their phenotypes to be subject to scrutiny by the host workers in everyday social interactions.



Distribution based on Regional Taxon Lists

Malagasy Region: Madagascar (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.


Association with Other Organisms

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This species is a inquiline for the ant Pheidole veteratrix (a host) in Madagascar (Fischer et al., 2020).


Images from AntWeb

Pheidole oculata casent0102052 head 2.jpg
Syntype of Aphaenogaster oculataQueen (alate/dealate). Specimen code casent0102052. Photographer April Nobile, uploaded by California Academy of Sciences. Owned by MSNG, Genoa, Italy.

PheidoleEconomo-header (  X-ray micro-CT scan 3D model of Pheidole oculata (worker) prepared by the Economo lab at OIST.

See on Sketchfab. See list of 3D images.


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

  • oculata. Aphaenogaster oculata Emery, 1899f: 276 (q.) MADAGASCAR. Combination in Parapheidole: Emery, 1915d: 68; in Pheidole: Smith, D.R. 1979: 1366.



  • Brown, W. L., Jr. 1973b. A comparison of the Hylean and Congo-West African rain forest ant faunas. Pp. 161-185 in: Meggers, B. J., Ayensu, E. S., Duckworth, W. D. (eds.) Tropical forest ecosystems in Africa and South America: a comparative review. Washington, D.C.: Smithsonian Institution Press, viii + 350 pp. (Parapheidole synonymy)
  • Buschinger, A. (2009). Social parasitism among ants: a review (Hymenoptera: Formicidae). Myrmecol. News 12, 219–235.

References based on Global Ant Biodiversity Informatics

  • Fisher B. L. 1997. Biogeography and ecology of the ant fauna of Madagascar (Hymenoptera: Formicidae). Journal of Natural History 31: 269-302.
  • Fisher B. L. 2003. Formicidae, ants. Pp. 811-819 in: Goodman, S. M.; Benstead, J. P. (eds.) 2003. The natural history of Madagascar. Chicago: University of Chicago Press, xxi + 1709 pp.
  • Wheeler W. M. 1922. Ants of the American Museum Congo expedition. A contribution to the myrmecology of Africa. IX. A synonymic list of the ants of the Malagasy region. Bulletin of the American Museum of Natural History 45: 1005-1055