Solenopsis pythia

It has been suggested this ant may be a social parasite. This is based on morphological evidence as nothing is known about the biology of this species.

Identification
Pitts et. al. (2018) - A member of the Solenopsis saevissima species-group. The major workers of S. pythia look like small workers of Solenopsis saevissima. The gynes, however, are easily recognized by having acute occipital angles, large piligerous foveolae of the head and mesosoma, coarse costulae on the mandibles, a small OI, a distinct median furrow on the posterior 0.33 to 0.50 of the mesonotum, and a thick coarsely sculptured petiolar node. Trager (1991) lists piligerous foveolae size as 0.01–0.15 mm: this must be a misprint and should read “0.010–0.015 mm.” The petiolar node is shorter and subquadrate and the posterior angles of propodeum are more defined than in S. saevissima. This is the only species in the S. saevissima species-group that lacks the bidentate metasternal process.

Solenopsis pythia has been suggested by some (e.g., Trager 1991) to be so unique that it is suspected to be a social parasite. Many of the gyne characters may actually be sympleisomorphic, as they are shared with the gynes in the Solenopsis molesta species-group. These characters include a quadrate first flagellomere, large and conspicuous piligerous foveolae on the head and mesosoma, coarse costulae of the mandibles, thick and coarsely sculptured petiolar node, short and subquadrate petiolar node, well demarcated posterior angles of propodeum, and absent bidentate process of the metasternum. There are obvious synapomorphic S. saevissima species-group characters in S. pythia, however, such as the lack of a ventral petiolar process in gynes and workers

Distribution based on Regional Taxon Lists
Neotropical Region: Argentina.

Nomenclature

 *  pythia. Solenopsis (Solenopsis) pythia Santschi, 1934c: 30 (q.) ARGENTINA. Trager, 1991: 182 (w.). See also: Wilson, 1952b: 50.

Pitts et. al. (2018):

Worker
Head weakly ovate to subquadrate. Head sculpture with small piligerous foveolae, approximately 0.01 mm in diameter. Median frontal streak absent. Median ocellus absent in largest major workers. Mandibular costulae present throughout. Mesonotum with 20–25 setae. Promesonotal suture in largest major workers gently curved medially. Mesonotum weakly convex in lateral view. Propodeum sculpture glabrous posteroventral to spiracle. Postpetiole shape as high as or higher than broad. Postpetiole sculpture in posterior view with lower 0.33–0.50 transversely rugose, upper surface glabrous and shiny. Color generally orange brown, with frons, clypeus and venter yellow brown.

Queen
Head. Slightly broader than long, quadrate, sides of head convex from eyes to occipital angles, straight to nearly straight ventral to eyes. Eye normally with 2–4 several short setae protruding from between ommatidia, setal length ≤ 3X width of ommatidium. Ocelli large, prominent. Median ocellus circular, lateral ocelli slightly ovate. Clypeus projecting, carinal teeth stout and sharp, carinae weakly to moderately defined, less so dorsally, slightly divergent ventrally. Paracarinal teeth usually absent, or more rarely poorly defined. Median clypeal tooth poorly developed, usually absent. Approximately 0.50 of eye dorsal to midpoint of head. Antenna usually 11-segmented, sometimes 10-segmented.

Mesosoma. Parapsidal lines present on posterior half of disk. Mesonotum with distinct, median furrow on posterior 0.50 to 0.33 on disk. Posterior margin of mesonotum angulate medially, bent anteriorly. Posterior margin of scutellum sometimes angulate medially. Metasternum lacking median bidentate process. Wings not examined.

Metasoma. Lateral faces of postpetiole strongly to slightly concave. Petiolar spiracle weakly tuberculate. Postpetiolar spiracle not tuberculate.

Coloration, Sculpturing, and Pilosity. Piligerous foveolae large, conspicuous, width 0.010–0.020 mm in diameter, slightly larger on head than on thorax and abdomen. Dorsum of mesosoma with distinctly piligerous foveolae. Pubescence simple, golden and erect, of uniform length (0.15–0.20 mm), longer and denser on head than elsewhere, longest on anterior edge of clypeus. Mandible with several coarse, distinct costulae present throughout. Propodeum and petiole postpetiole striato-rugulose throughout. Postpetiole striatorugulose throughout, sometimes extreme dorsum glabrous. In some cases, sculpture of postpetiole tuberculate and dorsum finely granulate. Interfoveolar spaces of head and pronotum finely striate; striae distinct to indistinct. Remaining interfoveolar spaces smooth and polished. Color yellow orange with medial area of mesonotum, parapsidal lines, lateral margins of T1 and preapical transverse areas on gaster segments brown. Internal margins of ocelli sometimes brown.

L ~5.3–6.2, HW 1.3, VW 0.7–0.8, HL 1.0–1.1, EL 0.4–0.5, OD 0.1–0.15, OOD 0.15–0.25, LOW 0.08–0.12, MOW 0.10–0.12, CD 0.14–0.16, MFC 0.15–0.18, EW 0.35–0.40, SL 0.69–0.82, PDL 0.16–0.18, LF1 0.1, LF2 0.1, LF3 0.1, WF1 0.06–0.07, FL 0.91–1.02, FW 0.19–0.25, MW 1.18–1.32, DLM 2.28–2.44, PRH 0.90–1.03, PL 0.72–0.83, PND 0.61–0.73, PH 0.62–0.72, PPL 0.32–0.43, DPW 0.49–0.84, PPW 0.48–0.61, PHB 0.58–0.71, N=7.

MISC Several dealated (wingless) gynes were collected from a single nest, suggesting that polygyny may occur in this species.

Type Material
Holotype gyne. Argentina. Misiones Province. Lorento. A. A. Oglobin. .

References based on Global Ant Biodiversity Informatics

 * Cuezzo, F. 1998. Formicidae. Chapter 42 in Morrone J.J., and S. Coscaron (dirs) Biodiversidad de artropodos argentinos: una perspectiva biotaxonomica Ediciones Sur, La Plata. Pages 452-462.
 * Kempf, W.W. 1972. Catalago abreviado das formigas da regiao Neotropical (Hym. Formicidae) Studia Entomologica 15(1-4).
 * Kusnezov N. 1978. Hormigas argentinas: clave para su identificación. Miscelánea. Instituto Miguel Lillo 61:1-147 + 28 pl.
 * Santschi F. 1934. Fourmis de Misiones et du Chaco argentin. Revista de la Sociedad Entomológica Argentina. 6: 23-34.
 * Trager J. C. 1991. A revision of the fire ants, Solenopsis geminata group (Hymenoptera: Formicidae: Myrmicinae). Journal of the New York Entomological Society 99: 141-198
 * Vittar, F. 2008. Hormigas (Hymenoptera: Formicidae) de la Mesopotamia Argentina. INSUGEO Miscelania 17(2):447-466
 * Wilson E. O. 1952. The Solenopsis saevissima complex in South America (Hymenoptera: Formicidae). Memórias do Instituto Oswaldo Cruz. Rio de Janeiro 50: 60-68.