Oxyepoecus regularis

Oxyepoecus regularis
Scientific classification
Kingdom:	Animalia
Phylum:	Arthropoda
Class:	Insecta
Order:	Hymenoptera
Family:	Formicidae
Subfamily:	Myrmicinae
Tribe:	Solenopsidini
Genus:	Oxyepoecus
Species:	O. regularis
Binomial name
Oxyepoecus regularis Ulysséa & Brandão, 2012

Oxyepoecus regularis is known from three localities in Northeastern Brazil, all in the state of Bahia – Milagres, Boa Vista do Tupim and Vitória da Conquista. The sampled place in Milagres is covered by “Caatinga Arbórea”, while in Boa Vista do Tupim it corresponds to a “Mata Seca”, both areas are located within the “Caatinga” biome. The specimens sampled in Vitória da Conquista were collected in areas covered by Atlantic Forest (M.L. Oliveira, personal communication).

Identification

Ulysséa & Brandão (2012) - The exclusive character of Oxyepoecus regularis workers in relation to the other species of the Rastratus group is the presence of sub-parallel longitudinal, regularly spaced costulae, which are thick and well marked on the dorsum and lateral areas of the head, extending until the vertexal margin, on the gena and on the ventral face of the head.

Keys including this Species

• Key to Oxyepoecus species

Distribution

Latitudinal Distribution Pattern

Latitudinal Range: -12.66° to -13.77555556°.

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 have yet to be collected.

Nomenclature

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

• regularis. Oxyepoecus regularis Ulysséa & Brandão, 2012: 169, figs. 1, 2 (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 variation of 70 paratypes within brackets): t.l. = 2.06 (1.99‑2.23), h.w. = 0.46 (0.43‑0.48), h.l. = 0.51 (0.49‑0.55), e.l. = 0.05 (0.05‑0.08), s.l. = 0.30 (0.28‑0.34), m.l. = 0.09 (0.06‑0.11), w.l. = 0.60 (0.52‑0.65), m.w.pr. = 0.35 (0.30‑0.36), m.w.p. = 0.15 (0.14‑0.18), m.w.p.p. = 0.21 (0.19‑0.24), h.f.l. = 0.30 (0.28‑0.33), c.i. = 90.20 (82.93‑95).

With characters and states present in other Oxyepoecus species of the Rastratus group (Albuquerque & Brandão, 2009:293) and body color black, mandibles, antennae and legs yellowish, gaster dark brown. Integument, when observed under the stereomicroscope, sculptured with thick, well marked, regularly spaced and sub-parallel costulae, with the exceptions of the nuchal region and gaster, which are smooth; dorsum of head with longitudinal costulae, prolonged posteriorly, reaching the occipital margin and laterally surpassing the compound eyes region, covering the ventral face of the head; genae, dorsum and laterals of pronotum, mesonotum, mesopleura and metapleuron (including bulla) with longitudinal costulae; in the genae the costulae reach the superior margin of the lateral portion of clypeus; anterior inclination of pronotum, propodeum, petiole (including the ventral face) and postpetiole with well marked transversal costulae.

Long, suberect to subdecumbent hairs with varied orientations on head, mesosoma, petiole, postpetiole and gaster; antennae and legs with short and decumbent hairs.

Mandibles relatively short and striate in its basal portion, basal tooth not separated from the sub-basal by a broad or a relatively shallow diastema; frontal carinae short, not surpassing the level of the superior margins of the compound eyes, gently convex and sub-parallel, the maximum width between their outer edges always less than one third of the head width; compound eyes convex, with about 3‑4 ommatidia in a row across the greatest diameter, total number of ommatidia less than 12.

Mesosoma with convex promesonotum in lateral view and weakly marginate in front and laterally in dorsal view; well marked shoulders; metanotal groove absent; metanotal suture indistinct; propodeal spines long, acute and oriented backwards.

Petiolar node higher than that of the postpetiole in lateral view, subquadrate in dorsal view, not compressed antero-posteriorly neither laterally expanded; in lateral view, subpetiolar process in the form of a subquadrate denticle whose height is approximately equivalent to the half of the height of the anterior region of the peduncle. Postpetiolar node broader than long, antero-posteriorly compressed and laterally expanded; subpostpetiolar process conspicuous and developed as two small and transverse crests when seen from the side.

Queen

(dealate, N = 1): t.l. = 2.47, h.w. = 0.50, h.l. = 0.55, e.l. = 0.13, s.l. = 0.34, m.l. = 0.15, w.l. = 0.70, m.w.pr. = 0.38, m.w.p. = 0.19, m.w.p.p. = 0.25, h.f.l. = 0.35, c.i. = 90.91.

Resembling worker, with the appropriate caste modifications. Integument, when observed under the stereomicroscope, sculptured with thick, well marked, regularly spaced and sub-parallel costulae, with the exceptions of the nuchal region and gaster, which are smooth; dorsum of pronotum and propodeum with transversal costulae; sides of pronotum and bulla covered by oblique costulae; mesopleura, metapleuron and sides of propodeum with longitudinal costulae in the inferior region and oblique costulae in the superior region; scutum and scutellum longitudinally costulate. Compound eyes with about 10‑12 ommatidia in a row across the greatest diameter. Three ocelli equal in size, diameter equal to minimum antennal scape width. Remaining characters as in workers.

Type Material

Holotype: Worker, Brazil: Bahia: Milagres [12°54.542’S, 39°51.279’W], 23.x.2010, M.A. Ulysséa, A.M. Medina & E.M. Campos leg., extracted from 1 m2 samples of Caatinga leaf litter submitted to the Winkler extractor for 48 hours (Museu de Zoologia da Universidade de Sao Paulo).

Paratypes: seventy workers and one gyne extracted from 1 m2 leaf litter samples submitted to Winkler apparatus, from Brazil: Bahia: Milagres: 68 workers and 01 gyne sampled in different dates and areas in the municipality of Milagres: 06 workers, 29.vii.2010 (Museu de Zoologia da Universidade Estadual de Feira de Santana), 07 workers, 09.xi.2010 (MZSP), 19 workers, 17.i.2011 (MZSP) [12°54.411’S, 39°50.863’W]; 09 workers, 13.vii.2010 (03 in Laboratório de Mirmecologia CEPEC / CPDC, 03 in The Natural History Museum and 03 in Museum of Comparative Zoology), 07 workers, 23.x.2010 (MZFS) and 12 workers, 10.i.2011 (MZSP) [12°54.542’S, 39°51.279’W]; 03 workers, 24.x.2010 (USNM), 05 workers and 01 gyne (MZSP), 10.i.2011 [12°54.294’S, 39°52.083’W]; M.A. Ulysséa, A.M. Medina & E.M. Campos leg.; Boa Vista do Tupim: 02 workers sampled in different dates and areas: 01 worker, 25.i.2011 (MZSP) [12°39’36”S, 40°36’32”W], L.S.S.R. Macêdo, J.J. Resende, C.B.S. Galheigo & E. da C. Menezes leg.; 01 worker, 27.i.2011 (MZFS) [12°39’36”S, 40°36’32”W], L.S.S.R. Macêdo & E. da C. Menezes leg.

Etymology

The specific name refers to the regular sculpture covering the whole body, which is mostly re-covered by sub-parallel longitudinal costulae. This combination of sculpture is not found in any another Oxyepoecus species described until now.

References

• [[Media:Ulyssea Brandao 2012.pdf|Ulysséa, M.A. & Brandão, C.R.F. 2012. A new ant species of Oxyepoecus (Hymenoptera: Formicidae: Myrmicinae), with the description of Oxyepoecus browni gyne and new records for the genus. Papeis Avulsos de Zoologia 52, 1*Ulysséa, M.A., Brandão, C.R.F. 2013. Ant species (Hymenoptera, Formicidae) from the seasonally dry tropical forest of northeastern Brazil: a compilation from field surveys in Bahia and literature records. Revista Brasileira de Entomologia 57, 217–224 (doi:10.1590/s0085-56262013005000002).

67-173.]]