Subfamilies
Links
Jack Longino's Ants of Costa Rica
American Museum Social Insects website
William and Emma Mackay Ants of North America site
sF Ectatomminae Ectatomma
Ectatomma are common, large ants of the litter. The differences between ruidum and gibbum have always been, to my mind, rather subtle. As usual, Jack Longino's Ectatomma pages are very useful, and I have borrowed both text and images.
Male, but not female, alates are exceptionally common in BCI malaise traps.
Species are sorted by size, and a useful composite picture of head and mesosoma structure is appended at the end. Note that one key way to separate ruidum from its congeners is a symmetric, parallel petiolar node, that looks like it has been squeezed between thumb and index finger.
Pronotum with median eminence not or only very feebly differentiated; dorsolateral tubercles or angles obsolete.
Pronotum with a well-differentiated median eminence and a pair of dorsolateral (humeral) teeth; petiolar node as seen from the side high and thin, at least the upper half with anterior and posterior faces vertical and subparallel; head in perfect full-face view with posterior outline arcuate from eye to eye; color reddish brown to nearly black. Ectatomma gibbum is difficult to distinguish from E. ruidum.
Pronotum with a well-differentiated median eminence and a pair of dorsolateral (humeral) teeth; petiolar node as seen from the side high and thin, at least the upper half with anterior and posterior faces vertical and subparallel; head in perfect full-face view with posterior outline transverse, nearly stright over most of the distance between eyes; color reddish brown to nearly black.
Pronotum with a well-differentiated median eminence and a pair of dorsolateral (humeral) teeth; petiolar node as seen from the side low and thick, subtriangular, with broadly rounded summit, and anterior and posterior slopes strongly converging upward; color orange brown.
Last Updated: 23Dec2004