Eciton lucanoides

Identification
Jack Longino:

Minor worker: head, mesosoma, and metasoma evenly orange yellow or with some degree of reddish infuscation on mesosoma; occipital tooth present; petiolar teeth in the form of short, acute flanges, joined medially and forming a single median carina descending onto the posterior face, when viewed from the rear appearing as a Y-shaped structure; petiole long and low, subrectangular, or somewhat shortened and approaching the shape of burchellii; petiole never with anterodorsal elevated flange; fourth abdominal tergite with short, sparse appressed pubescence beneath erect setae.

Major worker: face densely micropunctate, matte; long sickle-shaped mandibles with broad tooth on inner margin at midlength; other characters as in minor.

Similar species: Eciton hamatum.

Distribution based on Regional Taxon Lists
Neotropical Region: Bolivia, Brazil, Colombia, Costa Rica, Nicaragua, Peru.

Biology
Jack Longino: This species occurs in mature wet forest throughout the Atlantic slope. Its highest density seems to be mid-elevation sites, but it can still be relatively abundant in the lowlands. At La Selva Biological Station it has a density similar to Eciton hamatum, with which it is often confused.

Raiding is always in columns, never in a carpet like Eciton burchellii. Raiding can be during the day or at night.

Brown & Fenner (1998) report this species conducting raids on the nests of Neoponera obscuricornis at La Selva, Costa Rica.

Castes

 * Worker

Nomenclature

 * . Eciton lucanoides Emery, 1894c: 176, pl. 2, fig. 1 (s.) PERU.
 * Type-material: 2 syntype workers.
 * Type-locality: Peru: Cumbase (no collector’s name).
 * Type-depository: MSNG.
 * Combination in E. (Eciton): Emery, 1910b: 21.
 * Status as species: Emery, 1900a: 186; Emery, 1910b: 21; Mann, 1916: 420; Borgmeier, 1923: 38; Borgmeier, 1936: 52; Borgmeier, 1955: 262 (redescription); Kempf, 1972a: 102; Watkins, 1976: 9 (in key); Bolton, 1995b: 185; Palacio, 1999: 152 (in key); Bezděčková, et al. 2015: 109; Palacio, 2019: 601.
 * Distribution: Bolivia, Brazil, Colombia, Costa Rica, Nicaragua, Panama, Peru.
 * Current subspecies: nominal plus conquistador.

Taxonomic Notes
Jack Longino:

Eciton lucanoides was described by Emery (1894) based on a soldier from Peru. Weber (1949) described Eciton lucanoides conquistador based on workers from Panama. Borgmeier (1955) made lucanoides conquistador a subspecies of lucanoides. Kempf (1972) listed the range of lucanoides as Peru, Bolivia, Brazil (Rondonia and Acre), Colombia, and the range of conquistador as Panama, Costa Rica, and Nicaragua. The males of these forms are unknown. Eciton jansoni was described by Forel (1912) based on a male from Nicaragua, and Kempf (1972) gives the range as Nicaragua, Costa Rica, Panama, Colombia, Ecuador.

By a process of elimination and geographic correspondence in Costa Rica, Eciton jansoni has to be the male of lucanoides conquistador. The males of the other Eciton species are known. Eciton jansoni males are very common in primary forest areas of the Atlantic slope, which is where E. l. conquistador is also common. Morphologically, there is a slight boss on the inner margin of the male mandible, perhaps corresponding to the pronounced tooth in the same position on the soldier.

Thus, if E. l. conquistador is distinct from E. lucanoides sensu stricto, then the Costa Rican species should be called E. jansoni, with E. l. conquistador a junior synonym. If it is not, then both are junior synonyms of E. lucanoides. Is E. l. conquistador really different from E. lucanoides senso stricto?

Borgmeier (1955) stated (my translation) "Eciton conquistador (the name is tacky) I regard as a subspecies of lucanoides. The differences from lucanoides are the following: the soldier of conquistador differs by the smaller head, the broad tooth on the inside of the mandible, the longer scape, the longer funiculus, the more raised and approximated lateral carinae of the propodeum, and the narrower petiole and postpetiole. The worker differs in the longer scape, the more raised and approximated lateral carinae of the propodeum, the strong central keel on the posterior face of the propodeum, and the narrower petiole." (I enjoyed Borgmeier's little editorial comment on Weber's name.) The range of E. jansoni approximately covers the range of both E. l. conquistador and E. lucanoides senso stricto, which suggests either that there is no difference in the males that corresponds to the worker subspecies or the differences are subtle and have not been discovered. More work is needed on character variation across the range of this lineage.

I have chosen to refer to the Costa Rican material as E. lucanoides, with the possibility that it may later change to E. jansoni.

References based on Global Ant Biodiversity Informatics

 * Borgmeier T. 1953. Vorarbeiten zu einer Revision der neotropischen Wanderameisen. Studia Entomologica 2: 1-51.
 * Borgmeier T. 1955. Die Wanderameisen der neotropischen Region. Studia Entomologica 3: 1-720.
 * Borowiec M. L. 2016. Generic revision of the ant subfamily Dorylinae (Hymenoptera, Formicidae). ZooKeys 608: 1–280.
 * Emery C. 1894. Studi sulle formiche della fauna neotropica. VI-XVI. Bullettino della Società Entomologica Italiana 26: 137-241.
 * Emery C. 1900. Nuovi studi sul genere Eciton. Memorie della Reale Accademia delle Scienze dell'Istituto di Bologna (5)8: 173-188
 * Emery C. 1910. Hymenoptera. Fam. Formicidae. Subfam. Dorylinae. Genera Insectorum 102: 1-34.
 * Fernández F., E. E. Palacio, W. P. Mackay, and E. S. MacKay. 1996. Introducción al estudio de las hormigas (Hymenoptera: Formicidae) de Colombia. Pp. 349-412 in: Andrade M. G., G. Amat García, and F. Fernández. (eds.) 1996. Insectos de Colombia. Estudios escogidos. Bogotá: Academia Colombiana de Ciencias Exactas, Físicas y Naturales, 541 pp
 * Fernández, F. and S. Sendoya. 2004. Lista de las hormigas neotropicales. Biota Colombiana Volume 5, Number 1.
 * INBio Collection (via Gbif)
 * Kempf, W.W. 1972. Catalago abreviado das formigas da regiao Neotropical (Hym. Formicidae) Studia Entomologica 15(1-4).
 * Longino J. T. L., and M. G. Branstetter. 2018. The truncated bell: an enigmatic but pervasive elevational diversity pattern in Middle American ants. Ecography 41: 1-12.
 * Longino J. et al. ADMAC project. Accessed on March 24th 2017 at https://sites.google.com/site/admacsite/
 * Maes, J.-M. and W.P. MacKay. 1993. Catalogo de las hormigas (Hymenoptera: Formicidae) de Nicaragua. Revista Nicaraguense de Entomologia 23.
 * Mann W. M. 1916. The Stanford Expedition to Brazil, 1911, John C. Branner, Director. The ants of Brazil. Bulletin of the Museum of Comparative Zoology 60: 399-490
 * O'Donnell S., J. Lattke, S. Powell, and M. Kaspari. 2007. Army ants in four forests: geographic variation in raid rates and species composition. Journal of Animal Ecology 76: 580-589.
 * Watkins J. F., II 1976. The identification and distribution of New World army ants (Dorylinae: Formicidae). Waco, Texas: Baylor University Press, 102 pp