Phalacromyrmex

The only species in the genus, Phalacromyrmex fugax, has been collected in forest habitats. The genus is endemic to Brazil and little is known about the biology of these ants.

Identification
Although quite distinct in its own right, this new genus seems at least superficially related with the ants of the tribe Dacetini in the subfamily Myrmicinae. As regards the number of antennal segments, it agrees with the Daceton-complex, but is otherwise completely different in head shape, short triangular mandibles, position of eyes and development of antennal scrobe. By its general habitus Phalacrornyrmex seemingly imitates the short-mandibulate members of the strumigenys-complex, especially Codiomyrmex and Glamyromyrmex (=Strumigenys). However, many important characters, such as the number of antennal segments, the unarmed petiolar and postpetiolar nodes, lacking any trace of spongiform appendages, the normally ovate gaster, lacking an anterior truncation and transverse crest, separate it also from this group. The peculiar palpal formula - maxillary palps with 3, labial palps with 2 segments - removes Phalacrornyrmex from all known Dacetine genera. As long as the sexual forms and the larvae are unknown, it seems best not to include the present genus in the Dacetini, although it seems even farther removed from all other Myrmecine tribes. (Kempf 1960)

Nomenclature

 *  PHALACROMYRMEX [Myrmicinae: Phalacromyrmecini]
 * Phalacromyrmex Kempf, 1960b: 89. Type-species: Phalacromyrmex fugax, by original designation.

Worker - Mandibles short, broadly triangular, strongly curved laterad and apicad; chewing border serially dentate, larger teeth alternating with smaller ones. Labrum bilobed. Palpal formula 3:2. Antennae 11-segmented, funiculus with a 2-segmented apical club. Frontal carinae broadly expanded laterad and foreward, covering cheeks and eyes in full-face view. Clypeus flanked by the frontal carinae, its anterior border scarcely convex. Eyes small, situated ventrolaterally below the deeply excavate antennal scrobe. Thorax dorsally flattened, laterally marginate; mesoepinotum conspicuously compressed. Epinotum with a pair of upright triangular lamellae. Middle and hind legs without a tibial spur. Petiole strongly pedunculate. Both petiolar and postpetiolar nodes little broader than long, unarmed, lacking spongiform appendages. Gaster ovate, its anterior end not truncate, lacking a transverse crest. Body integument mostly smooth and shining. Erect hairs simple, short, very scarce, absent on dorsum of head. Appressed pilosity scarce and inconspicuous.

Baroni Urbani & De Andrade (2007) - Only one unequivocal synapomorphy for this genus results from our data, the presence of mesopleural costulation. CI 1.00, RI 0.00. We doubt, however the generic rank of this character. Other apomorphic characters resulting from our analysis are:

Worker (and gyne?) presence of a cuticular process of the mesonotum. CI 0.86, RI 0.75. Cuticular projections of the mesonotum are known also in Epopostruma and Strumigenys.

Worker (and gyne?) metapleaural gland bulla close to the annulus. CI 0.62, RI 0.40. The same character state is encountered in a number of non-related Dacetini genera like Protalaridris, Microdaceton, Epopostruma, a. o.

Worker (and gyne?) antennae 11-jointed. CI 0.20, RI 0.50. A character state shared with several outgroups and with Daceton and Acanthognathus.

The pretended generic apomorphies above are likely to be a by-product of the clustering together of the three "Phalacromyrmecini" genera, a clustering that is based on weak characters. We suspect that all the former Phalacromyrmecini genera might be better understood as atypical Strumigenys species.

Etymology
phalacros - bald-headed; myrmex - an ant