Pheidole risii

Rosumek (2017) assessed trophic resource use and period of activity within the ant community in a southern Brazil Atlantic forest. He found this species was a quintessential generalist.

Identification
See the description in the nomenclature section.

Distribution
From Wilson (2003): In addition to the type locality, risii has been recorded from São Paulo, Brazil (Kempf 1972b).

Distribution based on Regional Taxon Lists
Neotropical Region: Argentina, Brazil.

Worker
Minor

Nomenclature

 *  risii. Pheidole risii Forel, 1892a: 38 (s.w.q.m.) ARGENTINA. See also: Wilson, 2003: 740.

Description
From Wilson (2003): DIAGNOSIS Similar in various traits to Pheidole aper, Pheidole bambusarum, Pheidole brevicona, Pheidole dyctiota, Pheidole laeviventris, Pheidole lutzi, Pheidole rugatula, Pheidole senilis, Pheidole sigillata, Pheidole trachyderma and Pheidole traini, differing as follows.

Major: shallow antennal scrobes; pilosity along dorsal profile of head dense, with uniform short hairs about as long as Eye Length along the posterior half and much longer hairs along the anterior half; occipital cleft deep; occipital lobes smooth and subangulate; pronotum sparsely carinulate, mostly smooth; propodeal spine very stout, equilaterally triangular; postpetiolar node very broad, 2X broader than petiolar node, and spinose.

Minor: occiput, humeri, and propodeal dorsum rugoreticulate; almost all of head and mesosoma foveolate; occiput broad, concave, and lacking nuchal collar.

MEASUREMENTS (mm) Syntype major: HW 0.96, HL 1.02, SL 0.44, EL 0.12, PW 0.54. Syntype minor: HW 0.66, HL 0.66, SL 0.62, EL 0.12, PW 0.44.

COLOR Major: body reddish yellow except for gaster, which is yellowish brown.

Minor: concolorous dark yellow.



'''Figure. Upper: syntype, major. Lower: syntype, minor. Scale bars = 1 mm.'''

Type Material
ARGENTINA: Buenos Aires, col. Fr. Ris. and  - as reported in Wilson (2003)

Etymology
Named after the collector, Fr. Ris. (Wilson 2003)