Temporal range: Burdigalian, Early Miocene Dominican amber, Dominican Republic
This species is considerably larger than all other Pseudomyrmex known from Dominican amber except P. avitus (q. v.). The head shape, mandibular dentition, marginate pronotum and petiole, and lack of metanotal groove are reminiscent of the extant Central American species P. rufomedius (F. Smith) and an undescribed Mexican species near P. rufomedius, but P. antiquus differs from these two in eye size, profemur shape, petiole shape, pilosity, and other details.
This taxon was described from Dominican amber, Dominican Republic (Burdigalian, Early Miocene).
The following information is derived from Barry Bolton's New General Catalogue, a catalogue of the world's ants.
- †antiquus. †Pseudomyrmex antiquus Ward, 1992: 57, figs. 1, 12 (w.) DOMINICAN AMBER (Miocene).
Large species (see measurements). Mandibles with about 6 rather robust teeth on the masticatory margin. Head somewhat quadrate, longer than broad or deep (CI 0.93, LCI 0.64), posterior margin slightly concave, rounding sharply into sides of head. In frontal view median clypeal lobe with a straight anterior margin, rounded laterally. Frontal carinae moderately well separated (MFC 0.03), fusing anterolaterally with antennal sclerites. Second and third funicular segments about 1.4 times longer than wide. Eyes elongate (REL ca. 0.52), not reaching the level of the median ocellus. Ocellar triangle small (OD 0.06). Vertex separated from side of head by a weak (broadly rounded) ridge between posterior margin of eye and posterolateral corner of head. Pronotum laterally marginate. Profemur broadened (FI 0.42). Metanotal groove essentially lacking (Figure 12); basal face of propodeum flattened, rounding into the shorter declivitous face (BF/DF 1.34). Petiole longer than high or wide (PLI 0.63, PWI ca. 0.57), laterally marginate, with a short anterior peduncle, prominent anteroventral tooth, and gradually rising anterodorsal face which rounds into a more steeply descending posterior face (Figure 12). In dorsal view petiole notably constricted anteriorly (PWI3 ca. 0.41), with concave posterodorsal margin. Postpetiole slightly broader than long (PPWI ca. 1.07). Integument apparently densely punctulate, opaque. Standing pilosity very sparse, present on pronotal humeri (1 pair), petiole (1 pair), postpetiole (2 pairs), and gaster; not seen on the mesonotum, propodeum, and extensor faces of tibiae. Color apparently medium brown, antennae and clypeus lighter.