Dolopomyrmex pilatus

Identification
A monotypic genus within the Solenopsidini, Dolopomyrmex appears to be closer to two exclusively Old World solenopsidine genera, Anillomyrma and Bondroitia. A comparison of the workers is instructive and striking. All three genera share a closely similar structure of the clypeus, frontal lobes, and antennae, strongly oblique mandibular cutting margins with 4 teeth (3 teeth in one Anillomyrma species), and similar petiolar structures, most notably having the spiracle located anterolaterally on the side of the node, reduced palpal counts, and vestigial or absent compound eyes. The only truly discordant note is the absence of a median clypeal seta in Dolopomyrmex, present in Anillomyrma, Bondroitia, and most other Solenopsidine genera. The presence of a median clypeal seta was once thought to be a diagnostic character for the Solenopsidini (Bolton, 1987), but is presently seen to be more variable and less important than previously thought. Bolton’s (2003) recent redefinition of the tribe reflects this change. (Cover and Deyrup 2007)

Distribution
United States: Arizona, California and New Mexico.

Distribution based on Regional Taxon Lists
Nearctic Region: United States.

Biology
Cover and Deyrup (2007) - The type locality is a desert wash with highly compacted, sandy soil located at the border between relatively flat desert and the foothills of the Chiricahua Mountains. It is a very arid, sunbaked habitat for most of the year. Ant species found at the site include: Crematogaster opuntiae, Aphaenogaster albisetosa, Pogonomyrmex barbatus, Pogonomyrmex imberbiculus, Pheidole desertorum, Pheidole rugulosa, Dorymyrmex insanus, Forelius mccooki, and Camponotus fragilis, all desert or desert foothills ants common throughout much of the American Southwest. The following notes summarize the circumstances of each collection at the type locality. SPC 1441 was collected when a single worker was seen entering a minute, nearly invisible hole with a trace of excavated soil around it, in bare soil between mesquite clumps a day after rain. Chambers containing winged queens, males, some brood, and workers were found between 30-50 cm. deep. SPC 1454 was found in soil “while excavating a nest of another species” and included winged queens as well as workers. SPC 2173, 2174 and 2530 are all small series of workers taken 15-25 cm deep in soil when excavating nests of Pogonomyrmex imberbiculus after rain at the type locality. The Pogonomyrmex nests were all located in bare soil between mesquite clumps. SPC 1441 was maintained alive for about a week in a large plastic petri dish with a plaster bottom and moist cotton in it. The workers fed intermittently on fresh ant brood and termite nymphs, but ignored other dead insects and sweet substances. Mackay & Mackay (2002) report this ant (as Tranopelta sp.) from “Creosotebush scrub and mesquite dominant zones, often near desert playas or arroyos, sometimes in open desert or in forest meadows. Occasionally they are found in salt flats or saltbush communities.”

Nomenclature

 *  pilatus. Dolopomyrmex pilatus Cover & Deyrup, 2007: 92, figs. 1  3 (w.q.m.) U.S.A. [D. pilatus Fisher & Cover, 2007: 83. Unavailable name.]

Etymology
“Pilum” is Latin for the short, but powerful throwing spear of the Roman legionaries. So Dolopomyrmex pilatus is the “spear-bearing ambush ant.”