Oxyepoecus quadratus

Oxyepoecus quadratus
Scientific classification
Kingdom:	Animalia
Phylum:	Arthropoda
Class:	Insecta
Order:	Hymenoptera
Family:	Formicidae
Subfamily:	Myrmicinae
Tribe:	Solenopsidini
Genus:	Oxyepoecus
Species:	O. quadratus
Binomial name
Oxyepoecus quadratus Albuquerque & Brandão, 2004

The distribution of O. quadratus is represented by two localities in western Amazonian region, in Peru and Ecuador.

Identification

Albuquerque and Brandao (2004) - The exclusive character of the workers of O. quadratus is the subquadrate petiolar node (p.v.), but also the distribution of marked costulae on head and mesosoma are important.

Keys including this Species

• Key to Oxyepoecus species

Distribution

Latitudinal Distribution Pattern

Latitudinal Range: -0.0167° to -9.616666667°.

North Temperate	North Subtropical	Tropical	South Subtropical	South Temperate

• Source: AntMaps

Distribution based on Regional Taxon Lists

Neotropical Region: Brazil (type locality), Ecuador.

Distribution based on AntMaps

Distribution based on AntWeb specimens

Check data from AntWeb

Countries Occupied

Number of countries occupied by this species based on AntWiki Regional Taxon Lists. In general, fewer countries occupied indicates a narrower range, while more countries indicates a more widespread species.

Estimated Abundance

Relative abundance based on number of AntMaps records per species (this species within the purple bar). Fewer records (to the left) indicates a less abundant/encountered species while more records (to the right) indicates more abundant/encountered species.

Biology

Explore Overview of Oxyepoecus biology  The following account is modified from Kempf (1974) and Albuquerque & Brandão (2009). Our knowledge of Oxyepoecus ants still rests exclusively on chance discoveries. Since about 95% of the known specimens were taken as strays in berlesates of forest floor cover, very little may be said about the biology of Oxyepoecus species except for being denizens or at least foragers in this particular habitat. The minute size of Oxyepoecus, their color and cryptic habits hamper direct observation of their habits in natural conditions (especially inside shaded forest where light rarely reaches the ground). Oxyepoecus has been considered very rare in collections, but our studies show that they are rather common in the leaf litter of most localities where recent surveys have been conducted in the Mata Atlântica (see Comments in Albuquerque & Brandão, 2004). It is interesting to note that one of these localities we recently surveyed, Cunha, São Paulo state has four Oxyepoecus species (Oxyepoecus myops, Oxyepoecus rastratus, Oxyepoecus longicephalus and Oxyepoecus rosai), three of which were found in one square meter of leaf-litter (sample 48; all but O. rosai). In Salesópolis, SP, we recorded five of the 17 known Oxyepoecus species (O. myops, Oxyepoecus punctifrons, O. rastratus, O. rosai and Oxyepoecus vezenyii). Both Cunha and Salesópolis are localities circa 1000 m above sea level, covered by pristine evergreen dense forest. Although Oxyepoecus samples come mostly from forested localities, workers have been less frequently collected in places with more open vegetation, as open “cerrados” (savannas). Comparing the examined material of most species, one can see that the specimens mostly come from the same localities. This is because these localities we surveyed recently, extracting ants from the leaf-litter, or localities where careful collectors lived most of their lifes (Seara, SC, for instance, where F. Plaumann worked many years). Kusnezov (1952) put forward the hypothesis that Oxyepoecus ants are inquilines of Pheidole and Solenopsis nests. Evidence exists for their being symbiotic relationships between several Oxyepoecus species and other Myrmicinae ants (details provided here). Independent colonies seem to be vouched for by Oxyepoecus punctifrons and Oxyepoecus rastratus. The types of the former, collected at Rio Negro, Paraná State, Brazil, came from a nest that had over 60 workers living by themselves, but no further information is available. A few workers of the same species, at Campos do Jordão, São Paulo State, Brazil, were also found on a dead twig, between the bark and an overgrown cover consisting of lichens and mosses. The types of the var. luederwaldti (= rastratus) are from a very small colony nesting under the bark in a simple cavity within the alburnum of a tree (Luederwaldt, 1926: 275). Lenko's rastratus specimens from Caraça, Minas Gerais State, had their nest within a decaying log on the ground in a forest. A similar nesting situation was found from a more recent collection from Paraguay (col A. Wild). The fact that Oxyepoecus workers are relatively abundant in material extracted from leaf litter samples, while dealate gynes are seldom found in the litter and larvae have never been found in litter samples, suggests that they nest in the soil, where the gynes and larvae live, but workers leave the nest periodically to search for food. Oxyepoecus has been attracted to honey or sardine baits set over the ground in different habitats, which suggests they are generalist foragers. In just one case, a gyne and two workers of O. punctifrons (Vezenyii group) were found by Rogerio R. da Silva under the bark of a the canopy branch in a recently fallen Leguminoseae (Albuquerque & Brandão, 2004).

Nomenclature

The following information is derived from Barry Bolton's Online Catalogue of the Ants of the World.

• quadratus. Oxyepoecus quadratus Albuquerque & Brandão, 2004: 73, figs. 6a-c (w.) BRAZIL.

Unless otherwise noted the text for the remainder of this section is reported from the publication that includes the original description.

Description

Worker

Holotype and paratype within brackets t.l.= 2.32 (2.37); h.l.= 0.45 (0.46); h.w.= 0.46 (0.47); s.l.= 0.32 (0.36); m.l.e.= 0.09 (0.12); m.w.pr.= 0.32 (0.36); a.l.= 0.63 (0.68); h.f.l.= 0.38 (0.40); m.w.p.= 0.20 (0.24); m.w.pp.= 0. 23 (0.26); c.i. 97 (96). Color chestnut brown; mandibles, antennae, legs yellowish; and gaster fuscus, almost black. Integument smooth and shining, with the following exceptions: frontal carinae longitudinally costulate, prolonged posteriorly, reaching the level of the superior orbit of the compound eyes; genae with well marked longitudinal rugae that reach superiorly the inferior orbit of compound eyes and inferiorly the mandibular insertion; postero-lateral limit of disc of the pronotum, sides and anterior third of mesonotum, and metapleuron with longitudinal well marked costulae, of which one is prolonged posteriorly and curved over the bulla of the metapleural gland region, but specially on disc of pronotum and anterior third of mesonotum the costulae can be less marked; dorsal face of the propodeum with some well marked and curved costulae, 7-10 well formed, with ends over the sides of the propodeum; declivous face with two well formed costulae, the superior reaching the costulae of metapleuron and communicating with them; sides of the petiole with costulae in different orientations, but generally the penducle has many longitudinal costulae and the node has many transverse; posterior and dorsal surfaces of postpetiole with several small but well formed costulae. Hairs abundant, decumbent on cephalic disc, the majority turned to head median stripe; on cephalic border long, suberect without a regular orientation; long, suberect and relatively curved on pronotum, mesonotum with some long and erect; and metapleuron dorsum scarcely hairy, petiole node with some suberect and subdecumbent hairs; there are some decumbent on the postpetiole.

Head. Mandibles elongated, with a broad and relatively shallow diastema between the basal and subbasal tooth, also between the subbasal tooth and the other teeth. Anterior teeth of clypeus with small, blunt and lobe-like lateral denticles. Frontal carinae relatively short, subparallel, with a posterior moderate divergence and with a small constriction posteriorly, reaching the level of the straight line that passes through the inferior orbit of the compound eyes, the maximum width between their outer edges less than one third of the head width. Compound eyes small, with about 5-7 facets r.g.d.; total number of ommatidia about 16-18. Antennal scape failing to reach the occipital corner by a distance approximately equal to the maximum thickness of the scape. Funicular segment I as long as II-VI combined, segments II-VII distinctly broader than long, VIII and IX as long as broad.

Mesosoma. Promesonotum convex, marginate in front and laterally; shoulders marked, but without a defined angle. Metanotal groove not at all impressed (p.v.). Dorsal face of the propodeum posteriorly with two acute and prominent spines. Declivous face laterally marginate and weakly carinate. Propodeal lobes irregularly rounded.

Petiole node high and subquadrate at superior face (p.v.), antero-posteriorly compressed in a scale-like fashion, almost as broad as postpetiole; subpetiolar process as a sagital and undulate keel anteriorly ending in a prominent plate-shaped tooth. The postpetiole very broad, in a scalelike fashion, the level of the superior face lower than the petiole node is high; subpostpetiolar process small, almost imperceptible, extremely shallow.

Type Material

Holotype worker, Ecuador: Cuyabeno [0°16’S, 75°53’W], 27.i.1994, J.P. Caldwell [col.], deposited in Museu de Zoologia da Universidade de Sao Paulo. Paratype: worker. Peru: Panguana: Huanaca [9°37’S, 74°56’W], 26.xi.1983, M. Verhaagh [col.], deposited in MZSP.

Etymology

From the shape of the superior face of the petiolar node clearly subquadrate.

References

• Albuquerque, N.L.d., Brandão, C.R.F. 2004. A revision of the Neotropical Solenopsidini ant genus Oxyepoecus Santschi, 1926 (Hymenoptera: Formicidae: Myrmicinae). 1. The Vezenyii species-group. Papéis Avulsos de Zoologia (São Paulo). 44: 55-80 (doi:10.1590/S0031-10492004000400001).
• Albuquerque, N.L.d., Brandão, C.R.F. 2009. A revision of the Neotropical Solenopsidini ant genus Oxyepoecus Santschi, 1926 (Hymenoptera: Formicidae: Myrmicinae): 2. Final. Key for species and revision of the Rastratus species-group. Papéis Avulsos de Zoologia (São Paulo). 49: 289-309 (doi:10.1590/S0031-10492009002300001).

References based on Global Ant Biodiversity Informatics

• Albuquerque N. L. and Brandão, C. R. F. 2004. A revision of the Neotropical Solenopsidini ant genus Oxyepoecus Santschi, 1926 (Hymenoptera: Formicidae: Myrmicinae). 1. The Vezenyii species-group. Papeis Avulsos de Zoologia (São Paulo) 44: 55-80.
• Fernández, F. and S. Sendoya. 2004. Lista de las hormigas neotropicales. Biota Colombiana Volume 5, Number 1.
• Ulyssea M. A., C. R. F. Brandao. 2013. Catalogue of Dacetini and Solenopsidini ant type specimens (Hymenoptera, Formicidae, Myrmicinae) deposited in the Museu de Zoologia da Universidade de Sao Paulo, Brazil. Papies Avulsos de Zoologia 53(14): 187-209.