Megalomyrmex foreli Emery 1890

Formicidae, Hymenoptera, Insecta, Arthropoda, Animalia

Identification

Mandibles with 5 distinct teeth, apical tooth largest, proximal tooth considerably smaller, remaining three teeth the smallest and subequal in size; mandibles shining, with large piligerous punctures; occipital carina visible in face view; promesonotal suture visible as a broad shallow depression; anteriomedial margin of mesonotum raised as a small triangular boss; propodeal suture not deeply impressed; propodeum with distinct dorsal and posterior faces, dorsal face with median longitudinal depression, posterodorsal margins vary from being strongly developed tubercles to mere bosses; ventral margin of postpetiole flat, sloping anteriorly, anterior margin often terminating in long, needle-like spine (figure: reduced, original) (variably developed; also easily broken off, and thus missing from some specimens); color orange to red brown, gaster darker than rest of body; HW 1.59; HL 1.82, SL 2.14; WL 2.62 (n=1).

Material I have examined from Costa Rica varies geographically in degree of development of propodeal tubercles (figure of propodeums, oblique view from top looking rearward), and color. A specimen from Limon province is strongly tuberculate, and red brown. Specimens from the San Vito area vary from strongly to weakly tuberculate, and are orange brown. Specimens from the Osa Peninsula are not at all tuberculate, and are red brown with strongly contrasting darker gaster.

Range

Peru, Ecuador, Colombia, Panama, Costa Rica (Brandão 1990, 2003). Costa Rica: scattered records from wet forest sites throughout the country.

Natural History

Specimens from Colombia bear labels "Cacao - associated with membracids Horiola picta (Coquebert)," and "arboles de cacao" (reported in Brandao 1990).

These large, conspicuous ants do not appear to be common in Costa Rica. I collected foreli several times in the San Vito area, and several times in Corcovado National Park. At San Vito, I encountered them as workers on the ground, during nocturnal collecting. In Corcovado, I encountered them in the hilly interior parts of the park, and not around Sirena on the coast. Workers occurred on the ground or on low vegetation. I once observed 15 workers together on one Costus inflorescence.

I observed a colony at the El Ceibo site on the Barva Transect in Braulio Carrillo National Park. It was in the understory of mature wet forest at night. I saw active workers on a large liana stem and discovered that there were cavities in the stem. I saw two entrance holes in the liana, with workers visible inside, and another entrance hole in the ground at the side of the liana where it was lying on the ground. The workers were aggressive, readily attacking my fingers when disturbed.

One of the upper entrance holes was concealed by a small aroid with basket roots. There was carton construction around the aroid roots, I assume made by the Megalomyrmex. The aroid also covered two giant margarodids. I sent the margarodids to Penny Gulan and she wrote "I mounted one of those 2 margarodids and, believe it or not, they are immature females (3rd instar). The one I mounted had pharate adult cuticle inside but not good enough to ID. However I can tell you that the species is a member of the subfamily Monophlebinae, probably tribe Llaveiini. There are several genera of this tribe in the Neotropics, but all poorly known. I'd be very interested in adult females and crawlers if you ever get a chance to collect more specimens."

Jones et al. (1999) studied the venom alkaloids of M. foreli (= M. latreillei) workers collected in Ecuador.

Literature Cited

Brandão, C. R. F. 1990. Systematic revision of the neotropical ant genus Megalomyrmex Forel (Hymenoptera: Formicidae: Myrmicinae), with the description of thirteen new species. Arquivos de Zoologia, São Paulo 31:411-481.

Brandão, C. R. F. 2003. Further revisionary studies on the ant genus Megalomyrmex Forel (Hymenoptera: Formicidae: Myrmicinae: Solenopsidini. Papéis Avulsos de Zoologia 43:145-159.

Jones, T. H., T. J. Wojciechowski, R. R. Snelling, J. A. Torres, P. Chacon, and P. J. DeVries. 1999. Dialkylpyrrolidines from the ants Megalomyrmex cyendyra Brandao and M. latreillei Emery. Caribbean Journal of Science 35:310-311.

Page author:

John T. Longino, The Evergreen State College, Olympia WA 98505 USA. longinoj@evergreen.edu

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