Oxyepoecus rosai

Oxyepoecus rosai
Scientific classification
Kingdom:	Animalia
Phylum:	Arthropoda
Class:	Insecta
Order:	Hymenoptera
Family:	Formicidae
Subfamily:	Myrmicinae
Tribe:	Solenopsidini
Genus:	Oxyepoecus
Species:	O. rosai
Binomial name
Oxyepoecus rosai Albuquerque & Brandão, 2009 Specimen Labels

Specimens were attracted to sardine baits or recovered from the leaf-litter using Winkler extractors.

Identification

Albuquerque & Brandão (2009) - In the Rastratus species-group, O. rosai workers present the integument of mesopleuron and lateral pronotum irregularly sculptured, as in Oxyepoecus myops, but differs from the later by the larger compound eyes, and by the smooth integument on the head vertex and lateral portions of the pronotum, petiolar node, and postpetiole.

Keys including this Species

• Key to Oxyepoecus species

Distribution

The distribution of O. rosai includes only localities at South and Southeastern Brazil, between São Paulo and Santa Catarina States.

Latitudinal Distribution Pattern

Latitudinal Range: -21.969° to -27.817°.

North Temperate	North Subtropical	Tropical	South Subtropical	South Temperate

• Source: AntMaps

Distribution based on Regional Taxon Lists

Neotropical Region: Brazil (type locality).

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).

Castes

Males are unknown.

Nomenclature

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

• rosai. Oxyepoecus rosai Albuquerque & Brandão, 2009: 304, figs. 5a-c, 8 (w.q.) 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 paratypes (N = 33) variation within brackets): t.l. = 2.33 (2.30‑2,40); h.l. = 0.60 (0.60‑0.63); h.w. = 0.45 (0.43‑0.48); s.l. = 0.35 (0.35‑0.38); m.l.e. = 0.10 (0.10‑0.13); m.w.pr. = 0.33 (0.30‑0.35); a.l. = 0.65 (0.65‑0.68); h.f.l. = 0.35 (0.35‑0.38); m.w.p. = 0.20 (0.20‑0.23); m.w.pp. = 0.25 (0.25‑0.28); c.i. 75 (72‑76). Color chestnut brown, gaster fuscous. Irregularly costulae and rugulate sculpture covering almost all head dorsum integument, except by clypeus, around antennal insertions and vertex; almost all mesosoma irregularly reticulate, except antero-lateral portion of pronotum, area around propodeal spiracle, petiolar peduncle dorsum, node of petiole and postpetiole smooth and shining. Hairs moderately abundant, short and subdecumbent, on head dorsum mesad oriented, anteriorly curved on head sides; dorsum of mesosoma with suberect hairs, backwards oriented on petiolar and postpetiole nodes; gaster without interspersed shorter and decumbent hairs.

Head (f.f.v.): Mandible with basal border slightly shorter than chewing border, basal tooth separated from subbasal tooth by shallow diastema. Anterior tooth of clypeus mesially directed with smaller lateral denticle. Frontal carinae gently convex and subparallel over antennal sockets, maximum width between outer edges always less than one fourth head width. Compound eye with 4‑5 facets r.g.d., height less than oculomalar; total number of ommatidia not exceeding 13. Antennal scape fails to reach vertexal corner by distance approximately equal to maximum scape width. Funnicular segment I longer than II‑V combined, segments II‑VII distinctly broader than long, VIII and IX as long as broad. Vertexal margin straight.

Mesosoma with promesonotum gently rounded on shoulders. Metanotal groove almost indistinct (p.v.). Basal face of propodeum immarginate on sides, posteriorly with a small tooth. Declivous face laterally weakly carinate.

Petiole pedunculate, node scarcely compressed antero-posteriorly (d.v.) club shaped; subpetiolar process with a small, blunt and obliquely oriented denticle anteriorly. Postpetiole very broad, not as high as petiolar node; subpostpetiolar process shaped as small, transversal crest.

Queen

(variation of gynes paratypes, N = 2): t.l. = (2.80‑2.93); h.l. = (0.60‑0.63); h.w. = (0.50‑0.53); s.l. = (0.40‑0.43); m.l.e. = (0.25‑0.30); m.w.pr. = (0.43‑0.45); a.l. = (0.70‑0.73); h.f.l. = (0.38‑0.40); m.w.p. = (0.18‑0.20); m.w.pp. = (0.33‑0.35); c.i. (83‑85). Almost same workers character states, with caste differences of: three ocelli very small, with same diameter, approximately half minimum thickness of antennal scape, compound eye with 8 facets r.g.d., and circa 40 in whole eye.

Type Material

Holotype: worker. Brazil: São Paulo: Salesópolis [23°39’S, 45°53’W], 20‑26.x.1997, C. Klingenberg & C.I. Yamamoto col., attracted to sardine baits; deposited in Museu de Zoologia da Universidade de Sao Paulo. Paratypes (all from Brazil): São Paulo: forty one workers and two gynes from Salesópolis (Same locality of the Holotype, but collected in different dates and by different collectors); 33 workers and 2 gynes deposited in MZSP, one worker deposited in American Museum of Natural History, one worker deposited in California Academy of Sciences, one worker deposited in Instituto de Biologia Universidade Federal Rural do Rio de Janeiro, one worker deposited in Laboratório de Mirmecologia CEPEC / CPDC, one worker deposited in Museo de Historia Natural, Bogata, one worker deposited in Los Angeles County Museum of Natural History, one worker deposited in Instituto de Zoologia Agricola, one worker deposited in National Museum of Natural History.

Etymology

We are pleased to dedicate this species to our friend and colleague, Rogério Rosa da Silva, the most efficient collector in our team.

References

• 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 C.R.F. Brandao. 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(23): 289-309.
• Silva R.R., and C. R. F. Brandao. 2014. Ecosystem-Wide Morphological Structure of Leaf-Litter Ant Communities along a Tropical Latitudinal Gradient. PLoSONE 9(3): e93049. doi:10.1371/journal.pone.0093049
• 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.