Acanthoponera

Acanthoponera is a rarely collected genus, less than a score of separate collections having reached myrmecologists to my knowledge. Nothing is known of its nesting habits or food, and the larva has never been seen, so far as I can learn. The genus is restricted to the New World, where it is known to range from Veracruz south into northwestern Argentina. Apparently it is restricted to forested country, although information on this is scanty. Probably an increase in night collecting in the tropics will give us more insight into the biology of this most interesting generalized ectatommine. (Brown 1958)

Identification
Brown (1958) - Medium-sized ants (workers ranging from 5 to 10 mm. in outstretched length), generally of a yellowish or tan color, with large, convex eyes and shallow antennal scrobes. The propodeum bears a pair of teeth or spines (long and slender in worker), and the apex of the petiolar node is produced dorsocaudad as a slender subconical spine with a more or less acute tip. The tarsal claws are very well developed, and each has not only a strong submedian tooth, but also a prominent, narrow lobe resembling a third tooth. The palpi of the female and worker are segmented maxillary 6, labial 4 (this seems to be the formula in the single male available, although the basalmost segment in each of the palps of this specimen is not properly visible under the partly-retracted maxillae and labrum); this formula is the primitive one for the Formicidae, and it is not known to hold in any other ectatommine genus. The palpi are long and slender as compared to those of other ectatommines. The characters above are those expected of an epigaeic, nocturnal forager that climbs trees or other vegetation, habits now confirmed by observations of Weber (1939) and Wilson (personal communication) on Acanthoponera minor.

The females of Acanthoponera, where known, are winged, slightly larger than workers from the same nest, and differ from the workers in the same ways that ponerines most often do. The female propodpal teeth are usually less well developed than in the worker. The color is the same or nearly the same as in the corresponding workers. The forewings have “complete” venation of the type of Ectatomma, but the hind wings differ from those of Ectatomma in that they lack the anal lobe. In the single Acanthoponera female available with wings, there is no trace of the first radial crossvein remaining, although such traces are present in the male specimen seen.

The male of this genus is known to me only from a single specimen sent by Father Borgmeier; I believe that this is the first true Acanthoponera male to be recorded. It will suffice here to describe this male as like a larger, more slender Heteroponera with tarsal claws as in worker-female Acanthoponera. A further notable character is the very extensive ventral excavation of the gaster; the cavity involves large parts of the second and following segments, and even the posteroventral border of the postpetiole. No such conformation exists in the few Heteroponera males I have seen, nor does it occur in other genera of ectatommines. More species must be examined in the male sex before we know whether or not this is a generic, or only a specific, character. The general color of this male is ferruginous yellow. The eyes are large, convex, and medially emarginate; the ocelli are large and clear. As already mentioned above, the male specimen seen has traces remaining of the first radial crossvein, visible in good light as tenuous veinlets extending downward from R toward Rs, but not reaching Rs before they fade out.

Worker Morphology
These characters are collated in the table "WorkerMorphology". View table.

Nomenclature

 *  ACANTHOPONERA [Heteroponerinae]
 * Acanthoponera Mayr, 1862: 732 [as subgenus of Ectatomma]. Type-species: Ponera mucronata, by subsequent designation of Wheeler, W.M. 1911f: 158.
 * Acanthoponera raised to genus: Emery, 1895g: 346; Emery, 1911d: 35.