Pheidole tristis

Nothing is known about the biology of tristis.

Identification
See the description in the nomenclature section.

Distribution
Kempf (1972): southeastern Brazil (Santa Catarina, Sao Paulo, Rio de Janeiro, Parana) and north central Argentina (Misiones).

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

Nomenclature

 * fumipennis. Atta fumipennis Smith, F. 1858b: 169 (w.q.) BRAZIL. Combination in Aphaenogaster: Forel, 1895b: 129; in Pheidole: Donisthorpe, 1932c: 474. Junior synonym of tristis: Brown, 1981: 527.
 * rubra. Atta rubra Smith, F. 1858b: 168 (q.) BRAZIL. Combination in Pheidole: Mayr, 1886c: 360. Junior synonym of tristis: Kempf, 1965: 183.
 *  tristis. Myrmica tristis Smith, F. 1858b: 132 (w.) BRAZIL. Combination in Pheidole: Mayr, 1886c: 360. Senior synonym of emeryi, rubra: Kempf, 1965: 183; of fumipennis: Brown, 1981: 527; of alsia, crassipes: Wilson, 2003: 769.
 * crassipes. Pheidole crassipes Mayr, 1887: 590 (s.), 600 (w.) BRAZIL. Junior synonym of tristis: Wilson, 2003: 769.
 * emeryi. Pheidole emeryi Mayr, 1887: 589 (s.), 599 (w.) BRAZIL. Junior synonym of tristis: Kempf, 1965: 183.
 * alsia. Pheidole emeryi var. alsia Santschi, 1923d: 58 (s.w.) BRAZIL. Subspecies of tristis: Bolton, 1995b: 316. Junior synonym of tristis: Wilson, 2003: 769.

Description
From Wilson (2003): DIAGNOSIS A medium-sized reddish-yellow (major) or yellowish brown (minor) member of the tristis group whose major has very prominent subangulate pronotal humerus, swollen hind femora, diamond-shaped postpetiolar node with subangulate margins, small rounded subpostpetiolar process, and foveolate and opaque gastral tergite.

Minor: large ovoid postpetiolar node, prominent convex subpostpetiolar process, and foveolate and opaque gastral tergites. Similar to Pheidole balzani, Pheidole fabricator and Pheidole nigella, and less so to Pheidole brunnescens, Pheidole exarata, Pheidole excubitor, Pheidole germaini, Pheidole grandinodus, Pheidole hispaniolae, Pheidole obrima, Pheidole prattorum, Pheidole rogeri, Pheidole sabina, Pheidole sarpedon, Pheidole stulta, Pheidole tristops, Pheidole unicornis and Pheidole zoster, differing in many details of body form, sculpturing, and pilosity, as illustrated, and in color.

MEASUREMENTS (mm) Major (Boraceia Biological Station, Sao Paulo state): HW 1.66, HL 1.76, SL 0.82, EL 0.20, PW 0.84. Holotype minor: HW 0.80, HL 0.84, SL 0.84, EL 0.12, PW 0.52.

COLOR Major: body and appendages clear light reddish yellow ("orange"), with gaster a shade darker.

Minor: concolorous medium yellow brown, in both the Boraceia Biological Station series and holotype minor.



'''Figure. Upper: major (Boraceia Biological Station, Mun. Salesopolis, Sao Paulo state, Brazil, col. William L. Brown), associated with minors compared by E. O. Wilson with holotype minor from Tijuca, Rio de Janeiro, Brazil. At the bottom the right hind femur is depicted. Lower: holotype, minor. Scale bars = 1 mm.'''

Type Material
- as reported in Wilson (2003)

Type Locality Information
Tijuca, Brazil. (Wilson 2003)

Etymology
L tristis, sad, allusion unknown. (Wilson 2003)

Additional References
Kempf, W. W. 1972. Catálogo abreviado das formigas da região Neotropical. Stud. Entomol. 15: 3–344.

Smith, F. 1858. Catalogue of hymenopterous insects in the collection of the British Museum, Part VI: Formicidae. London: British Museum, 216 pp.

Text and images from this publication used by permission of the author.