Colonies have been collected from Acacia hindsii and A. collinsii, but little more has been recorded about their biology. Janzen's field notes indicate that this species is monogynous. (Ward 1993)
Ward (1993) - P. mixtecus is distinguished from all other species, except Pseudomyrmex veneficus and Pseudomyrmex flavicornis, by its laterally rounded median clypeal lobe, broad head, and black (or very dark brown) body. It differs from P. veneficus by the fully opaque head, absence of conspicuous suberect pubescence on the petiole, and larger size. P. mixtecus is evidently closely related to P. flavicornis but averages smaller in size (compare worker HW and LHT values), a difference which is absolute in queens (queen HW 0.96-1.01 (n=8), whereas queen HW > 1.11 in P.flavicornis). In addition the petiole is relatively longer and higher, for a given head width, in both workers and queens of P. mixtecus.
Known only from the Mexican states of Guerrero and Oaxaca.
Distribution based on Regional Taxon Lists
Distribution based on AntMaps
Distribution based on AntWeb specimens
Check data from AntWeb
The following information is derived from Barry Bolton's New General Catalogue, a catalogue of the world's ants.
- mixtecus. Pseudomyrmex mixtecus Ward, 1993: 144, figs. 15, 26, 55, 61, 69 (w.q.m.) MEXICO.
Unless otherwise noted the text for the remainder of this section is reported from the publication that includes the original description.
Worker measurements (n=13). —HL 0.94-1.19, HW 0.89-1.03, MFC 0.054-0.073, CI 0.86-0.95, REL 0.42-0.47, REL2 0.46-0.52 OOI 1.22-2.28, VI 0.61-0.73, FCI 0.056-0.073, SI 0.43-0.45, SI2 0.86-0.97, NI 0.60-0.65, PLI 0.60-0.68, PWI 0.60-0.68, PPWI 1.40-1.73.
Similar to P. ferrugineus (q.v.) except as follows. Size smaller (HW < 1.04, LHT < 0.90), head broad (CI > 0.85); frontal carinae separated by about basal scape width or less (FCI2 0.45-0.54). Basal and declivitous faces of propodeum forming a less obtuse angle in profile than typical for P. ferrugineus. Head densely punctulate, opaque. Standing pilosity rather common, usually some setae exceeding 0.12 mm and 0.20 mm in length on mesosoma dorsum and petiole, respectively. Pubescence dense but appressed. Very dark brown to black, appendages lighter.
Holotype worker. MEXICO, Guerrero: 25.4 mi. S. Chilpancingo, 10.viii.1966, D. H. Janzen #M008810966 (LACM). HW 0.97, HL 1.07, EL 0.48, PL 0.55, PH 0.35.
Paratypes. Same data as holotype, and three other accession numbers (M007810966, M009810966, M010810966) with same locality, date, and collector: series of 43 workers, 34 queens and 17 males (American Museum of Natural History, The Natural History Museum, California Academy of Sciences, Estacion de Biologia Chamela, Graham B. Fairchild Museo de Invertebrados, Instituto Nacional de Biodiversidad, Los Angeles County Museum of Natural History, Museum of Comparative Zoology, Museu de Zoologia da Universidade de Sao Paulo, Philip S. Ward Collection, University of California, Davis, National Museum of Natural History).
- Ward, P. S. 1993. Systematic studies on Pseudomyrmex acacia-ants (Hymenoptera: Formicidae: Pseudomyrmecinae). J. Hym. Res. 2: 117-168 (page 144, figs. 15, 26, 55, 61, 69 worker, queen, male described)
- Ward, P.S. 2017. A review of the Pseudomyrmex ferrugineus and Pseudomyrmex goeldii species groups: acacia-ants and relatives (Hymenoptera: Formicidae). Zootaxa 4227: 524–542 (doi: 10.11646/zootaxa.4227.4.3).