Formicidae, Hymenoptera, Insecta, Arthropoda, Animalia
Major dorsal view (reduced, original).
Line drawing of major and minor worker, dorsal view, from Kempf (1958).
Costa Rica, Panama, Colombia. Costa Rica: throughout the country, coextensive with Cordia alliodora.
Minor worker: eyes situated behind the scrobe, which terminates in front of the eye; lateral border of head convex and upturned above eye, without a rounded excision; petiole with distinct anterior and dorsal faces; lateral margins of mesosoma, including propodeal margins, denticulate, concolorous with rest of mesosoma; ventral surface of head largely punctate, at most weakly rugose; anterior face of petiole flat or convex, meeting dorsal face at obtuse angle; silvery hairs covering half or less of mesopleuron; lateral postpetiolar lobes short and blunt; postpetiole with differentiated anteroventral projection; compared to peruviensis, postpetiole relatively broader in dorsal view.
Major worker: eyes situated behind the scrobe, which terminates in front of the eye; head with complete and strongly developed cephalic disk; cephalic disk continuous anteriorly, frontal carinae meet anteriorly at a linear incision, mandibles completely hidden beneath frontal carinae; color largely black, with anterolateral margins of gaster yellow; cephalic disk subcircular, only slightly longer than wide.
Cephalotes setulifer is an obligate inhabitant of the ant-plant Cordia alliodora (Carroll 1983, Longino and Hanson 1995, Longino 1996). The first published record of a nest was from C. alliodora (Menozzi 1927), as was the second (Wheeler 1942) and the third (Kempf 1958). Wheeler considered the species to be a facultative inquiline, and assumed that it could be found nesting elsewhere. Kempf was more circumspect, stating "We need more factual evidence in order to decide whether setulifer is an obligatory or only a facultative inquiline of this ant plant." Andrade and Baroni Urbani (1999) follow Kempf in this regard. Carroll (1983) was the first to report on extensive collections from C. alliodora. He found C. setulifer to be a common and widespread inhabitant of C. alliodora, and he suggested that C. setulifer was an obligate plant-ant. In my experience, C. setulifer is perhaps the most ubiquitous inhabitant of C. alliodora in Costa Rica, occurring in most trees in the various populations I have surveyed. Despite extensive faunal surveys throughout Costa Rica, I have never found C. setulifer nesting anywhere other than in C. alliodora. C. setulifer is clearly an obligate plant-ant in C. alliodora.
Domatia inhabited by C. setulifer are easy to identify because the head of a soldier appears as a perfectly circular brown dot between the projecting stems. Poking this dot with a grass stem will cause the soldier to retreat into the domatium, but the soldier will quickly return when the stem is removed.
This species demonstrates that not all host specialists are "dominant" ants in the sense of exclusively occupying most of a hostplant and having large colonies. Cephalotes setulifer is an inconspicuous and timid ant, capable of coexisting in the same tree with any of the dominant ants that inhabit C. alliodora: Azteca pittieri complex, Azteca JTL-003, Azteca beltii, and Pseudomyrmex viduus. Hence, it may best be called an obligate inquiline.
The species appears to be monogynous. I have observed hundreds of nodes with founding queens, and all have been solitary.
Cryptocerus setulifer Emery 1894:211. Syntype worker, queen: Costa Rica, Jimenez [MCSN].
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.
Carroll, C. R. 1983. Azteca (hormiga Azteca, Azteca ants, Cecropia ants). In D. H. Janzen (Ed.). Costa Rican Natural History, pp. 691-693. University of Chicago Press, Chicago.
Emery, C. 1894. Studi sulle formiche della fauna neotropica. VI-XVI. Bull. Soc. Entomol. Ital. 26:137-241.
Kempf, W. W. 1958. New studies of the ant tribe Cephalotini (Hym. Formicidae). Stud. Entomol. (n.s.)1:1-168.
Longino, J. T. 1996. Taxonomic characterization of some live-stem inhabiting Azteca (Hymenoptera: Formicidae) in Costa Rica, with special reference to the ants of Cordia (Boraginaceae) and Triplaris (Polygonaceae). Journal of Hymenoptera Research 5:131-156.
Longino, J. T., and P. Hanson. 1995. The ants (Formicidae). In P. Hanson and I. Gauld (Ed.). The Hymenoptera of Costa Rica, pp. 588-620. Oxford University Press, Oxford, U.K.
Menozzi, C. 1927. Formiche raccolte dal Sig. H. Schmidt nei dintorni di San Jose di Costa Rica. Entomol. Mitt. 16:266-277, 336-345.
Wheeler, W. M. 1942. Studies of neotropical ant-plants and their ants. Bul. Mus. Comp. Zool., Harvard 90:1-262.
John T. Longino, The Evergreen State College, Olympia WA 98505 USA.firstname.lastname@example.org
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