Because fallax has a range enclosed by the more abundant jelskii and is so easily confused with it, natural history notes published in the past under the name of either species are generally unreliable. (Wilson 2003)
See the description in the nomenclature section.
Keys including this Species
A circum-Caribbean species, which I have verified from the Greater Antilles (Cuba, Jamaica, Puerto Rico), Central America, Colombia, and Venezuela. No certain records exist from the Lesser Antilles, where the closely related jelskii abounds. (Wilson 2003)
Distribution based on Regional Taxon Lists
Neotropical Region: Colombia, Costa Rica, Cuba (type locality), Grenada, Guadeloupe, Guatemala, Guyana, Honduras, Jamaica, Netherlands Antilles, Nicaragua, Puerto Rico, Trinidad and Tobago, Venezuela.
Distribution based on AntMaps
Distribution based on AntWeb specimens
Check data from AntWeb
Dominguez-Haydar et al. (2018) - Nest density was assessed in rehabilitated areas of “Cerrejón” coal mine (Colombia). We tested whether there is a relationship between spatial distribution pattern, age rehabilitation and temporal changes. Three sites with different ages of rehabilitation (1, 9 and 20 years) and a secondary forest were sampled during dry and rainy seasons. Within four plots (6 x 40m) per site, we located, counted and estimated the minimum distance among nests. Our results indicated that the number of active nests varied according to sites and sampling season, ranging between 125 and 625 nests ha-1 in the forest and the 20-y site, respectively, and at 1-year site ants were absent. Our results indicated that the nest distribution strongly depended on the scale of observation. A uniform distribution pattern was also found, mainly at the local scale (plot level), while an aggregated and random distribution was found at the site level. We conclude that ant density responded mostly to seasonal changes (dry versus wet season).
The following information is derived from Barry Bolton's New General Catalogue, a catalogue of the world's ants.
- fallax. Pheidole fallax Mayr, 1870b: 984 (s.) CUBA. Forel, 1881: 9 (w.); Goni, Zolessi & Imai, 1983: 365 (k.). Senior synonym of rubens: Forel, 1901e: 356; of britoi, columbica, fallacior, ovalis: Wilson, 2003: 290.
- columbica. Pheidole fallax r. columbica Forel, 1886b: xliv (s.) COLOMBIA. Raised to species: Dalla Torre, 1893: 89; Forel, 1899c: 66. Subspecies of fallax: Wheeler, W.M. 1908a: 133 (in key); Emery, 1922e: 101. Junior synonym of fallax: Wilson, 2003: 290.
- rubens. Pheidole fallax var. rubens Forel, 1899c: 66 (s.) COLOMBIA. Junior synonym of fallax: Forel, 1901e: 365.
- fallacior. Pheidole jelskii var. fallacior Forel, 1901e: 356 (s.) VENEZUELA. Subspecies of fallax: Bolton, 1995b: 321. Junior synonym of fallax: Wilson, 2003: 290.
- britoi. Pheidole fallax var. britoi Forel, 1912f: 221 (s.) COLOMBIA. Junior synonym of fallax: Wilson, 2003: 290.
- ovalis. Pheidole fallax var. ovalis Forel, 1912f: 221 (s.) JAMAICA. Junior synonym of fallax: Wilson, 2003: 290.
Cuba Naturhistorisches Museum Wien, Vienna - as reported in Wilson (2003) Unless otherwise noted the text for the remainder of this section is reported from the publication that includes the original description.
From Wilson (2003): A member of the fallax group, similar to Pheidole gigas, Pheidole jelskii, Pheidole obscurithorax, Pheidole puttemansi, Pheidole roushae, Pheidole tobini and Pheidole valens, and especially the very abundant and widespread Pheidole jelskii, with which it is easily confused.
Major: posterior half of dorsal surface of head primarily carinulate, with rugoreticulum extensive mesad of the eye most of the way to the occiput; pronotum transversely carinulate; anterior fourth to third of central strip of first gastral tergite shagreened; head tapered toward occiput in side view, as shown.
P. fallax differs from P. jelskii as follows and as depicted: in major, petiolar node higher and descending to peduncle by a much more concave curve, and scapes shorter (Scape Length/Head Width 0.50–0.59 as opposed to 0.60–0.70 in jelskii major); and in minor, occiput much broader and nuchal collar thinner than in jelskii.
MEASUREMENTS (mm) Lectotype major: HW 1.72, HL 1.84, SL 0.90, EL 0.24, PW 0.80. Paralectotype minor: HW 0.60, HL 0.72, SL 0.92, EL 0.18, PW 0.40.
COLOR Major and minor: body medium reddish brown, with gaster sometimes dark reddish brown.
Figure. Upper: major (compared with lectotype); variation in hypostomal teeth shown is with specimens from Puerto Rico (4 teeth)and Cuba (3 teeth). Lower: minor (compared with paralectotype, which shares the long, thin propodeal spine depicted; the very short spine at the top is of a Panama specimen, and the medium-length spine in the middle is of a syntype of the synonymous “var. columbica”). CUBA: Soledad, Las Villas. Scale bars = 1 mm.
- n = 10, 2n = 20, karyotype = 20M (Uruguay) (Goni et al., 1983).
L fallax, deceitful, false; allusion unknown. (Wilson 2003)
- Dominguez-Haydar, Y., B. Gutierrez-Rapalino, and J. J. Jimenez. 2018. Density and Spatial Distribution of Nests of Ectatomma ruidum and Pheidole fallax (Hymenoptera: Formicidae), as Response to the Recovery of Coal Mine Areas. Sociobiology. 65:415-421. doi:10.13102/sociobiology.v65i3.2880
- Forel, A. 1881. Die Ameisen der Antille St. Thomas. Mitt. Münch. Entomol. Ver. 5: 1-16 (page 9, worker described)
- Forel, A. 1901j. Variétés myrmécologiques. Ann. Soc. Entomol. Belg. 45: 334-382 (page 356, senior synonym of rubens)
- Goñi, B.; Zolessi, L. C. de; Imai, H. T. 1984 . Karyotypes of thirteen ant species from Uruguay (Hymenoptera, Formicidae). Caryologia 36: 363-371 (page 365, karyotype described)
- Mayr, G. 1870b. Neue Formiciden. Verh. K-K. Zool.-Bot. Ges. Wien 20: 939-996 (page 984, soldier described)
- Wilson, E. O. 2003. Pheidole in the New World: A dominant, hyperdiverse ant genus. Harvard University Press, Cambridge, MA. (page 290, fig. major, minor described; Senior synonym of columbica, fallacior, britoi, ovalis)