Pseudomyrmex veneficus

An acacia nesting species of western Mexico.

Identification
Ward (1993) - The small size (worker HW < 0.96; queen HW 0.84-0.96, n=12), conspicuous suberect pubescence on the propodeum and petiole, and black coloration of the head and gaster distinguish workers and queens of P. veneficus. The related species, Pseudomyrmex flavicornis, is larger (worker HW > 0.98, queen HW 1.12-1.19) with a broader and more robust petiole. Workers and queens of P. flavicornis also lack the sublucid head and conspicuous suberect pubescence characteristic of P. veneficus. Pseudomyrmex mixtecus is somewhat intermediate between these two - it has the head sculpture and pubescence typical of P. flavicornis but approaches P. veneficus in size (worker and queen head widths overlapping, although only slighter in the queens where HW 0.96-l.01 (n=8) in P. mixtecus) and petiolar dimensions.

Distribution based on Regional Taxon Lists
Neotropical Region: Mexico.

Biology
Ward (1993) - P. veneficus has a limited distribution in western Mexico (Sinaloa to Michoacan) where colonies occupy Acacia hindsii and, at one locality, A. collinsii. Janzen (1973) gives a detailed description of the ecology and behavior of this highly polygynous, effectively unicolonial, species whose colonies are among the largest of all social insects (containing millions of workers and several hundred thousand queens).

Nomenclature

 *  veneficus. Pseudomyrma belti subsp. venefica Wheeler, W.M. 1942: 162 (w.q.m.) MEXICO. Combination in Pseudomyrmex: Kempf, 1972a: 216. Senior synonym of venifica Enzmann: Brown, 1949a: 42. Raised to species: Ward, 1989: 439. See also: Ward, 1993: 152.
 * venifica. Pseudomyrma belti subsp. venifica Enzmann, E.V. 1944: 81 (w.q.) MEXICO. Junior synonym of venefica: Brown, 1949a: 42.

Worker
Ward (1993) - measurements (n=12). HL 0.95-1.04, HW 0.85-0.95, MFC 0.045-0.073, CI 0.88-0.95, REL 0.44-0.47, REL2 0.47-0.52, OOI 1.26-2.30, VI 0.66-0.75, FCI 0.051-0.081, SI 0.43-0.46, SI2 0.85-0.94, NI 0.58-0.65, PLI 0.60-0.67, PWI 0.58-0.67, PPWI 1.35-1.73.

Similar to Pseudomyrmex ferrugineus (q.v.) except as follows. Smaller (LHT 0.69-0.80), with broad head (Cl > 0.87); frontal carinae separated by basal scape width or less (FCI2 0.40-0.60); petiole short (PL 0.43-0.54) and relatively narrow (see PWI values) with somewhat rounded posterolateral angles. Head densely punctulate, subopaque to sublucid, with weak silvery reflectance. Overlying rugulo-punctate sculpture on propodeum weak and ill-defined. Standing pilosity variable in abundance, becoming rather short (0.10 mm) and sparse in southern populations. Pubescence thick and conspicuous, suberect on some surfaces especially the propodeum and petiole; suberect pubescence on petiolar dorsum contrasting with the appressed pubescence on the postpetiole. Very dark greyish-brown to black, parts of the mesosoma and petiole sometimes with lighter yellowish brown (more consistently so in the queen).

Type Material
Ward (1993):

Syntype workers, males, queens, Escuinapa, Sinaloa, Mexico (J. H. Batty) [Examined]. One syntype worker here designed LECTOTYPE.

Pseudomyrma belti subsp. venifica Enzmann 1945:81. Syntype workers, queens, Manzanillo, Colima, Mexico (C. H. T. Townsend) [Examined].