Pseudomyrmex leptosus

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Pseudomyrmex leptosus
Conservation status
Scientific classification
Kingdom: Animalia
Phylum: Arthropoda
Class: Insecta
Order: Hymenoptera
Family: Formicidae
Subfamily: Pseudomyrmecinae
Genus: Pseudomyrmex
Species: P. leptosus
Binomial name
Pseudomyrmex leptosus
Ward, 1985

Pseudomyrmex leptosus casent0103909 dorsal 1.jpg

Specimen Label

This workerless parasite is known from queens and males collected in mixed nests of P. leptosus and its host Pseudomyrmex ejectus from Florida. The original colonies each contained two dealate queens of P. leptosus together with P. ejectus workers and brood of both species (Ward 1985).

At a Glance • Workerless Inquiline  



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.

Keys including this Species


Known from the state of Florida, USA.

Latitudinal Distribution Pattern

Latitudinal Range: 29.683° to 27.15°.

Tropical South

Distribution based on Regional Taxon Lists

Nearctic Region: United States (type locality).

Distribution based on AntMaps


Distribution based on AntWeb specimens

Check data from AntWeb

Countries Occupied

Number of countries occupied by this species based on AntWiki Regional Taxon Lists. In general, fewer countries occupied indicates a narrower range, while more countries indicates a more widespread species.


Estimated Abundance

Relative abundance based on number of AntMaps records per species (this species within the purple bar). Fewer records (to the left) indicates a less abundant/encountered species while more records (to the right) indicates more abundant/encountered species.



This species is apparently a workerless, social parasite of P. ejectus. Details on the life history and behavior of P. leptosus are discussed by Klein (1987).


A workerless parasite.


The following information is derived from Barry Bolton's Online Catalogue of the Ants of the World.

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

Unless otherwise noted the text for the remainder of this section is reported from the publication that includes the original description.



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 (Museum of Comparative Zoology) (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) (The Natural History Museum, Los Angeles County Museum of Natural History, MCZ, Philip S. Ward Collection, University of California, Davis, National Museum of Natural History).


  • 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.
  • Ward, P. S. 1985b. The Nearctic species of the genus Pseudomyrmex (Hymenoptera: Formicidae). Quaest. Entomol. 21: 209-246 (page 233, figs. 19, 26, 34, 35, 38 queen, male described)

References based on Global Ant Biodiversity Informatics

  • Brandao C. R. F., F. A. Esteves, and L. P. Prado. 2010. A catalogue of the Pseudomyrmecinae ant type specimens (Hymenoptera, Formicidae) deposited in the Museu de Zoologia da Universidade de Sao paulo, Brazil. Papeis Avulsos de Zoologia 50(45): 693-699.
  • Deyrup M., C. Johnson, G. C. Wheeler, J. Wheeler. 1989. A preliminary list of the ants of Florida. Florida Entomologist 72: 91-101
  • Deyrup, M. 2003. An updated list of Florida ants (Hymenoptera: Formicidae). Florida Entomologist 86(1):43-48.
  • Johnson C. 1986. A north Florida ant fauna (Hymenoptera: Formicidae). Insecta Mundi 1: 243-246
  • Ward P. S. 1985. The Nearctic species of the genus Pseudomyrmex (Hymenoptera: Formicidae). Quaestiones Entomologicae 21: 209-246