Pseudomyrmex fasciatus

Pseudomyrmex fasciatus occurs from Chiapas, Mexico to Costa Rica. Recorded habitats include montane rainforest edge, montane wet forest, montane moist forest, and second-growth forest edge, at elevations ranging from 750 m to 1,600 m (mean 1,115 m; n = 28). Nests have been collected in dead twigs of various woody plants, including vines and orchids. Two series of specimens intercepted in quarantine at San Francisco, from Guatemala, are labeled ‘ex Oncidium wentworthianum’ and ‘ex Epidendrum atropurpurium’, respectively. A third interception, at Hoboken, New Jersey was from an Oncidium stem.

Identification
Small to medium-sized species (HW 0.84–0.94) with moderately elongate head (CI 0.79–0.86) (Fig. 15) and relatively large eyes (REL 0.45–0.48); frontal carinae separated by less than basal scape width; metanotal groove weakly impressed, in proﬁle barely discernable; dorsal face of propodeum ﬂat, rounding into declivitous face, and the two subequal in length; petiole relatively slender (PLI 0.46–0.58, PL/HL 0.54–0.60); in proﬁle, anterodorsal face of petiole ﬂat to convex, ascending gradually to summit in posterior half of node, then rounding into more steeply descending posterior face; profemur generally slender (FI 0.41–0.47); hind leg relatively short (LHT/HL 0.67-0.76). Head subopaque to sublucid, densely punctulate-coriarious, the punctulae on vertex separated by less than their diameters. Standing pilosity sparse, absent from propodeum and mesonotum (MSC 2–5). Light yellow- to orange-brown, with dark brown anterolateral patches on abdominal tergite 4 (ﬁrst gastric tergite), sometimes joined medially, and conspicuous transverse bands on abdominal tergites 5 and 6 (gastric tergites 2 and 3); distal half of metafemur weakly (and variably) infuscated.

Among species in the P. elongatulus group that are predominantly yellow-orange to light orange-brown in color, this species can be recognized by the combination of relatively large eyes (worker REL 0.45–0.48, queen REL 0.45–0.46), moderately elongate head (worker CI 0.79–0.86, queen CI 0.72–0.76), weakly developed metanotal groove in the worker, and conspicuous transverse maculation on abdominal tergites 4–6 (gastric tergites 1–3). Our phylogenomic data reveal that Pseudomyrmex fasciatus is sister to Pseudomyrmex cognatus (including its phylogenetically embedded inquiline, Pseudomyrmex comitator) (Fig. 1). Pseudomyrmex fasciatus and P. cognatus are broadly sympatric and quite different in appearance, with workers and queens of P. cognatus being brown to brownish-black in color.

Distribution based on Regional Taxon Lists
Neotropical Region: El Salvador, Costa Rica, Guatemala, Honduras, Mexico, Nicaragua.

Nomenclature

 * . Pseudomyrmex fasciatus Ward & Branstetter, 2022: 24, figs. 15, 20 (w.dq.) COSTA RICA.

Type Material

 * Holotype Worker. COSTA RICA Puntarenas: 2 km SSE Monteverde, 1,230 m, 10.28906 −84.80304  ± 3 m, 5 Jan 2018, ex dead twig of vine, montane rainforest edge, P.  S. Ward PSW18011 (MUCR) (CASENT0863540).
 * Paratypes: series of workers, 1 dealate queen, same data as holotype (CASC, JTLC, LACM, MCZC, PSWC, UCDC, UNAM, USNM).