Pheidole andersoni

This species occurs in cloud forest habitats of Mexico and Guatemala. Minor and major workers recruit to baits on the forest floor and occur in Winkler samples. Two nests have been observed. One was in a vertical clay bank at a trail edge. A small cylindrical clay turret extended horizontally from the bank, 5-10 mm long and 3-4 mm wide. A major worker was at the entrance. A partial excavation revealed a chamber a few cm deep with many minor and major workers. A second nest was in bare soil of a road in a coffee farm (no further observation details).

Identification
Minor: face and mesosoma foveolate, with foveolation faint to absent on lower half of katepisternum; promesonotal groove absent; propodeal spines one fourth to one fifth length of posterior face of propodeum; gaster smooth and shining; abundant erect setae on mesosomal dorsum and gaster; tibiae with 2-3 erect setae; color orange.

Major: inner hypostomal teeth distinct, closely spaced; scape base terete; face with distinct scrobes, delimited dorsally by frontal carinae and forming concave trough below them, ventral and posterior margins less delimited, surface of scrobe smooth and shiny; head weakly depressed posteriorly; face surface generally shiny, space between frontal carinae smooth, space between eye and antennal fossa and vertex lobes with widely separated, subparallel, longitudinal carinae; propodeal spines one half length of posterior face of propodeum; gastral dorsum smooth and shining; sides of head with abundant erect setae; abundant flexuous erect setae on mesosomal dorsum, tibiae, and gaster.

Measurements, minor worker: HW 0.45, HL 0.49, SL 0.41, EL 0.10, WL 0.56, PSL 0.03, PTW 0.08, PPW 0.14, CI 91, SI 93, PSLI 6, PPI 168 (n=5).

Measurements, major worker: HW 0.81, HL 0.98, SL 0.44, EL 0.14, WL 0.82, PSL 0.07, PTW 0.19, PPW 0.33, CI 83, SI 54, PSLI 8, PPI 176 (n=5).

A set of species occurs from the southern U.S.A. to Costa Rica that share a habitus. The minor workers of most species are similar to the common Pheidole flavens and thus easily escape detection in mixed samples and samples without major workers. The major workers have subrectangular heads, HW is in the 0.7-1.0 range, the antennae are short (SI 40-55), the antennal scrobes are well marked, the frontal carinae are expanded to form the pronounced dorsal margin of the scrobes, the face is generally shiny with widely separated longitudinal carinae distributed in various ways, the vertex lobes are pronounced and with a deep posterior sinus separating them, and in profile the posterior part of the head is often compressed. Most species are orange, but Pheidole zannia in Honduras appears to be in a mimicry complex and has divergent harlequin color, with black head and gaster and sharply contrasting orange mesosoma. This species also has the minor worker face smooth and shiny rather than foveolate. All of the species appear to nest in soil.

The species are distributed in a mosaic across Middle America, with various degrees of allopatry, parapatry, and narrow sympatry. Pheidole mera is known from south Texas in the U.S.A. Pheidole andersoni is a cloud forest species in the Sierra Madre de Chiapas and adjacent parts of Guatemala. Pheidole tikal is in the Petén region of Guatemala. Pheidole zannia occurs in cloud forests of central Honduras. Pheidole natalie has a somewhat disjointed distribution, with morphologically very similar populations in cloud forests of southern Mexico (Oaxaca), northern Honduras (Cusuco), and Nicaragua. Pheidole corniclypeus occurs in lowland rainforests in eastern Honduras, Nicaragua, and possibly into northeastern Costa Rica. Pheidole costaricensis occurs in lowland to lower montane wet forest in Costa Rica, and there is the potential for another lowland Pacific slope species in Costa Rica. The one well-documented case of sympatry is the co-occurrence of P. natalie and P. corniclypeus on one mountainside in central Nicaragua.

Distribution based on Regional Taxon Lists
Neotropical Region: Mexico, Guatemala.

Nomenclature

 *  andersoni. Pheidole andersoni Longino, 2019: 22, fig. 12 (w.) MEXICO.

Type Material

 * HOLOTYPE: 1 major worker, Mexico, Chiapas: 19km ENE Tonalá, 16.15630 -93.59920 ±100 m, 1250 m, 15-Jul-2007, second growth wet forest, nest in clay soil (J. Longino, JTL6054) [UNAM, unique specimen identifier CASENT0645179].
 * PARATYPES: major, minor workers: same data as holotype [CAS, DZUP, JTLC, MCZC, UNAM, USNM].

Etymology
In honor of Bob Anderson, Coleopterist, who has contributed so much to Neotropical myrmecology.