|Based on Ward et al. (2014) and Blaimer et al. (2018).|
The species of Xenomyrmex form rather small colonies and nest in plant-cavities, such as those of oak-galls, twigs, Acacia thorns, epiphytic Bromeliads (Tillandsias). In the field the various forms are easily mistaken for minute species of Solenopsis, like Solenopsis picta and Monomorium, especially Monomorium floricola and Monomorium ebeninum, which nest in the same situations. From the fact that the types of Xenomyrmex stollii were found in a huge oak gall, which also contained a colony of Camponotus abscisus, Forel concluded that Xenomyrmex was probably a parasitic or symbiotic genus like Formicoxenus, but this opinion has received no support from subsequent observations. The generic name is therefore a misnomer. (Wheeler 1931)
Keys including this Genus
Distribution and Richness based on AntMaps
• Antennal segment count 11 • Antennal club 2-3 • Palp formula 4,2 • Total dental count 5-6 • Spur formula 0, 0 • Sting present
• Antennal segment count 12 • Antennal club 0 • Total dental count 3-4 • Spur formula 0, 0 (from literature)
The following information is derived from Barry Bolton's New General Catalogue, a catalogue of the world's ants.
- XENOMYRMEX [Myrmicinae: Formicoxenini]
- Xenomyrmex Forel, 1885a: 369. Type-species: Xenomyrmex stollii, by monotypy.
- Xenomyrmex senior synonym of Myrmecinella: Wheeler, W.M. 1931a: 129.
- MYRMECINELLA [junior synonym of Xenomyrmex]
- Myrmecinella Wheeler, W.M. 1922d: 1. Type-species: Myrmecinella panamana, by original designation.
- Myrmecinella junior synonym of Xenomyrmex: Wheeler, W.M. 1931a: 129.
Small, monomorphic, with rather thick, smooth or delicately sculptured integument. Head rather large, subrectangular, with feebly rounded sides and slightly concave posterior border. Eyes small, flattened, at the anterior third of the head; ocelli absent. Mandibles triangular, with strongly convex external border, the terminal border provided with three stout apical and a few indistinct basal denticJes. Maxillary palpi 4-jointed; labial palpi 2-jointed. Antennre ll-jointed, the basal funicular joint elongate; joints 2-7 small and transverse, the last three joints forming a club, the last joint swollen and longer than the two basal joints· which are unequal and scarcely longer than broad. Clypeus short and convex, in the middle extending backward between the frontal carinre, and projecting anteriorly as a broad lobe with a concave median border and on each side a stout, somewhat outwardly curved tooth. Frontal carinre short, somewhat diverging posteriorly and rather widely separated. Frontal area and groove obsolete. Thorax slender, much narrower than the head, shaped much as in Monomorium, broadest through the pronotum, with pronounced mesoepinotal constriction; epinotum small, sub cuboidal, unarmed. Petiole small, subcylindrical, non pedunculate, parallel-sided, feebly convex above and below, but without a distinct node, anterodorsally with a tooth or angle on each side. Postpetiole small and short, scarcely broader than the petiole, convex above. Gaster about the size of the head, oval, somewhat flattened dorsoventrally, narrowed anteriorly towards the petiole. Legs with distinctly incrassate femora and stout, clavate tibie; claws simple.
Much larger than the worker. Head longer and more rectangular. Eyes flattened as in the worker but larger; ocelli small. Frontal area and anterior portion of frontal groove distinct. Thorax elongate-elliptical, as in Monomorium, nearly three times as long as broad, narrower than the head, with elongate mesonotum and small scutellum. Petiole, postpetiole and appendages like those of the worker, gaster much more voluminous, elongate-elliptical. Fore wings with open submarginal and discal cells and a single long cubital cell; hind wings without veins.
As small as the worker. Head rather large, through the eyes somewhat broader than long, convex above, broader behind than in front, with broadly rounded posterior corners and short, straight cheeks. Eyes placed anteriorly, large and convex, nearly half as long as the sides of the head; ocelli small, prominent and widely separated. Clypeus convex, its anterior border narrowly concave in the middle, with a vestigial denticle on each side. Mandibles small and narrow, their truncated terminal border with three or four subequal denticles. Antennae rather long, 12-jointed; scapes cylindrical, as long as the two basal funicular joints together, first funicular joint not enlarged but the second distinctly thicker than the more apical joints; last joint as long as the two preceding joints together. Thorax proportionally shorter than in the female, narrower than the head, with large pro-mesonotum and small epinotum; mesonotum as broad as long, with distinct notauli ("Mayrian furrows"); scutellum and mesosterna large and convex. Petiole above with a rounded, distinct, but low node. Postpetiole and gaster shaped as in the worker. Genitalia somewhat retracted; stipes rounded triangular; volsella: biramous and pecuJiarJy contorted; sagitta: long and slender. Legs not incrassated. Venation of forewings much reduced, only the subcostal and median cells, the base of the radial vein and the pterostigma remaining, or in some cases only the pterostigma and base of the subcostal vein; hind wings veinless as in the female.
- Ashmead, W. H. 1905c. A skeleton of a new arrangement of the families, subfamilies, tribes and genera of the ants, or the superfamily Formicoidea. Can. Entomol. 37: 381-384 (page 383, Xenomyrmex in Myrmicinae, Stenammini)
- Bolton, B. 1994. Identification guide to the ant genera of the world. Cambridge, Mass.: Harvard University Press, 222 pp. (page 105, Xenomyrmex in Myrmicinae, Metaponini?)
- Bolton, B. 2003. Synopsis and Classification of Formicidae. Mem. Am. Entomol. Inst. 71: 370pp (page 254, Xenomyrmex in Myrmicinae, Formicoxenini)
- Brandão, C. R. F. 1991. Adendos ao catálogo abreviado das formigas da região Neotropical (Hymenoptera: Formicidae). Rev. Bras. Entomol. 35: 319-412 (page 391, Xenomyrmex in Myrmicinae, Archaeomyrmecinii?)
- Creighton, W. S. 1957c. A study of the genus Xenomyrmex (Hymenoptera, Formicidae). Am. Mus. Novit. 1843: 1-14 (page 6, Key to species)
- Dalla Torre, K. W. von. 1893. Catalogus Hymenopterorum hucusque descriptorum systematicus et synonymicus. Vol. 7. Formicidae (Heterogyna). Leipzig: W. Engelmann, 289 pp. (page 64, Xenomyrmex in Myrmicinae)
- Dlussky, G. M.; Fedoseeva, E. B. 1988. Origin and early stages of evolution in ants. Pp. 70-144 in: Ponomarenko, A. G. (ed.) Cretaceous biocenotic crisis and insect evolution. Moskva: Nauka, 232 pp. (page 79, Xenomyrmex in Myrmicinae, Myrmecinini)
- Emery, C. 1895l. Die Gattung Dorylus Fab. und die systematische Eintheilung der Formiciden. Zool. Jahrb. Abt. Syst. Geogr. Biol. Tiere 8: 685-778 (page 769, Xenomyrmex in Myrmicinae, Myrmicini)
- Emery, C. 1914e. Intorno alla classificazione dei Myrmicinae. Rend. Sess. R. Accad. Sci. Ist. Bologna Cl. Sci. Fis. (n.s.) 18: 29-42 (page 41, Xenomyrmex in Myrmicinae, Solenopsidini [subtribe Monomoriini])
- Emery, C. 1922c. Hymenoptera. Fam. Formicidae. Subfam. Myrmicinae. [part]. Genera Insectorum 174B: 95-206 (page 188, Xenomyrmex in Myrmicinae, Solenopsidini)
- Ettershank, G. 1966. A generic revision of the world Myrmicinae related to Solenopsis and Pheidologeton (Hymenoptera: Formicidae). Aust. J. Zool. 14: 73-171 (page 81, 150, Review of genus; Xenomyrmex incertae sedis in Myrmicinae)
- Forel, A. 1885a . Études myrmécologiques en 1884 avec une description des organes sensoriels des antennes. Bull. Soc. Vaudoise Sci. Nat. 20: 316-380 (page 369, Xenomyrmex as genus)
- Forel, A. 1893b. Sur la classification de la famille des Formicides, avec remarques synonymiques. Ann. Soc. Entomol. Belg. 37: 161-167 (page 165, Xenomyrmex in Myrmicinae, Formicoxenini)
- Forel, A. 1899d. Formicidae. [part]. Biol. Cent.-Am. Hym. 3: 25-56 (page 52, Xenomyrmex in Myrmicinae, Myrmicini)
- Forel, A. 1917. Cadre synoptique actuel de la faune universelle des fourmis. Bull. Soc. Vaudoise Sci. Nat. 51: 229-253 (page 243, Xenomyrmex in Myrmicinae, Solenopsidini)
- Hölldobler, B.; Wilson, E. O. 1990. The ants. Cambridge, Mass.: Harvard University Press, xii + 732 pp. (page 16, Xenomyrmex in Myrmicinae, Metaponini?)
- Jaffe, K. 1993. El mundo de las hormigas. Baruta, Venezuela: Equinoccio (Ediciones de la Universidad Simón Bolívar), 188 pp. (page 11, Xenomyrmex in Myrmicinae, Myrmecinini)
- Kempf, W. W. 1972b. Catálogo abreviado das formigas da regia~o Neotropical. Stud. Entomol. 15: 3-344 (page 259, Xenomyrmex in Myrmicinae, Myrmecinini)
- Smith, D. R. 1979. Superfamily Formicoidea. Pp. 1323-1467 in: Krombein, K. V., Hurd, P. D., Smith, D. R., Burks, B. D. (eds.) Catalog of Hymenoptera in America north of Mexico. Volume 2. Apocrita (Aculeata). Washington, D.C.: Smithsonian Institution Pr (page 1384, Xenomyrmex in Myrmicinae, Solenopsidini)
- Wheeler, W. M. 1910b. Ants: their structure, development and behavior. New York: Columbia University Press, xxv + 663 pp. (page 139, Xenomyrmex in Myrmicinae, Myrmicini)
- Wheeler, W. M. 1922i. Ants of the American Museum Congo expedition. A contribution to the myrmecology of Africa. VII. Keys to the genera and subgenera of ants. Bull. Am. Mus. Nat. Hist. 45: 631-710 (page 663, Xenomyrmex in Myrmicinae, Solenopsidini)
- Wheeler, W. M. 1931a. Neotropical ants of the genus Xenomyrmex Forel. Rev. Entomol. (Rio J.) 1: 129-139 (page 129, 131, Xenomyrmex senior synonym of Myrmecinella, and revision of genus; Xenomyrmex in Myrmicinae, Solenopsidini)