Pseudomyrmex leptosus

A workless parasite of Pseudomyrmex ejectus.

Identification
Ward (1985) - P. leptosus queens are readily distinguishable from those of Pseudomyrmex apache and Pseudomyrmex seminole on the basis of size alone (HL > 1.25 in P. apache and P. seminole, HL < 0.95 in P. leptosus). P. leptosus queens differ from those of Pseudomyrmex simplex by the possession of a wider, more broadly rounded head (CI ≥ 0.77 VI ≤ 0.75, in P. leptosus; CI ≤ 0.77, VI ≥ 0.80, in P. simplex), shorter eyes (REL2 ≤ 0.63 in P. leptosus; REL2 ≥ 0.65 in P. simplex), more divergent frontal carinae, and narrower forefemur (FI 0.42-0.47 in P. leptosus, FI 0.49-0.55 in P. simplex). The differences between P. leptosus and Pseudomyrmex pallidus queens are more subtle. All of their measurements and indices overlap, although P. leptosus tends to be smaller and (more importantly) to possess a more broadly rounded head, so that VI 0.68-0.75 (VI 0.71-0.88 in P. pallidus). The most important distinction between the two species lies in the sculpture of the frons and vertex: finely punctate on a predominantly smooth, shiny background in P. leptosus; more coarsely punctate on a sublucid, coriarious background in P. pallidus. Despite some size-related sculptural variation in P. pallidus even the smallest P. pallidus queens possess more strongly developed coriarious sculpture on the head than P. leptosus queens. The postpetiole and gaster of P. leptosus also tend to be shinier than those of P. pallidus.

Distribution
Known from the state of Florida, USA.

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

Biology
This species is known from queens and males collected in, or reared from, two mixed nests of P. leptosus and Pseudomyrmex ejectus from the vicinity of Gainesville, Florida (R. W. Klein, leg.) and a subsequent collection in Munroe Co, FL. The original colonies each contained two dealate queens of P. leptosus (together with P. ejectus workers, and brood of both species), and Klein subsequently reared P. leptosus alates in the laboratory (Ward 1985).

This species is apparently a workerless, social parasite of 'P. ejectus. Details on the life history and behavior of P. leptosus will appear elsewhere (R. W. Klein. in prep.).

Castes
A workerless parasite.

Nomenclature

 *  leptosus. Pseudomyrmex leptosus Ward, 1985b: 233, figs. 19, 26, 34, 35, 38 (q.m.) U.S.A.

Queen
Measurements (n = 11): HL 0.83-0.91, HW 0.67-0.70, MFC 0.019-0.027, CI 0.77-0.82, OI 0.53-0.59, REL 0.47-0.51, REL2 0.59-0.63, OOI 0.92-1.58, VI 0.68-0.75, FCI 0.028-D.039, CDI 0.047-0.057, SI 0.45-0.48, SI2 0.75-0.77, FI 0.42-0.47. NI 0.60-0.68, PLI 0.47-0.51, PLI2 0.72-0.84, PHI 0.59-0.68, PWI 0.43-0.51, PWI2 0.50-0.57, PPWI 1.02-1.18, PPWI2 0.61-0.67.

Queen Diagnosis. —A small orange species with broadly rounded, shiny head (HW 0.67-0.70, VI 0.68-0.75); anterior clypeal margin medially straight or slightly convex, laterally angulate: distance between frontal carinae less than basal width of scape; occipital margin convex, flat, or weakly concave, in full-face, dorsal view; lateral margins of pronotum rounded; basal face of propodeum rounding into declivitous face; petiole relatively slender, twice as long as high; anterior face of petiole convex, in lateral view: postpetiole as wide or wider than long. Front of head finely but densely punctulate, on a more or less smooth, shining, background; fine punctures becoming less dense towards the occiput, which is also smooth and shining; petiole and most of mesosoma sublucid, finely or obscurely punctulate on a weak coriarious background; propleuron subopaque, coriarious-imbricate; postpetiole and gaster weakly shining, the sheen partially obscured by numerous, fine piligerous punctures. Erect pilosity very sparse; several erect setae on dorsum of head, pronotum, mesonotum, metanotum, petiole, postpetiole and gaster; erect pilosity essentially absent from propodeum, scapes, and mid and hind femora. Fine appressed pubescence present, but not obscuring sculpture on most parts of body; appressed pubescence moderately dense on abdominal tergite IV, only partially obscuring the shiny integument. Body light orange-brown; a conspicuous pair of anterolateral, dark fuscous patches on abdominal tergite IV.

Type Material
Ward (1985):

Holotype queen. Payne's Prairie. 8 mi S Gainesville. Alachua Co., Florida. 5.viii.1982. R. W. Klein (ex lab colony established from a mixed nest of P. leptosus and P. ejectus originally collected 16.v.1982). HW 0.70. HL 0.86, EL 0.41. PL 0.53. PH 0.27

Paratype queens, males. Payne's Prairie. 8 mi S Gainesville. R.W. Klein (ex lab colony established from mixed nest of 'P. leptosus' and P. ejectus originally collected 16.v.1982); Gainesville. Alachua Co., Florida. R. W. Klein (ex lab colony established from mixed nest of 'P. leptosus' and P. ejectus originally collected 15.v.I982) (,, MCZ, , ,  ).

Additional References

 * Klein, R. W. 1987. A workerless inquiline in Pseudomyrmex (Hymenoptera: Formicidae: Pseudomyrmecinae). Pages 623-624 in J. Eder and H. Rembold, editors. Chemistry and biology of social insects. Verlag J. Peperny, München. 757 p.