Pheidole fallax

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)

Identification
See the description in the nomenclature section.

Distribution
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, Grenada, Guadeloupe, Guatemala, Guyana, Honduras, Jamaica, Nicaragua, Puerto Rico, Trinidad and Tobago, Venezuela.

Biology
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).

Nomenclature

 *  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.

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.'''

Type Material
Cuba - as reported in Wilson (2003)

Etymology
L fallax, deceitful, false; allusion unknown. (Wilson 2003)