Oxyepoecus browni

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

O. browni is known from central and northeastern Brasil. Specimens have been collected in pitfall traps and in litter samples.

Identification

Albuquerque and Brandao (2004) - The exclusive character that separates workers of O. browni is the very modified shape of the dorsal face of the very convex propodeum.

Oxyepoecus striatus is most similar to O . browni. See the identification section of Oxyepoecus striatus for characters that can separate these two species.

Keys including this Species

Key to Oxyepoecus species

Distribution

Latitudinal Distribution Pattern

Latitudinal Range: -12.96444444° to -19.073°.


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

Queen


.

Nomenclature

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

browni. Oxyepoecus browni Albuquerque & Brandão, 2004: 60, figs. 1a-c (w.) BRAZIL. Ulysséa & Brandão, 2012: 172 (q.).

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

Description

Worker

Holotype, paratype within brackets t.l.= 2.29 (2.62); h.l.= 0.57 (0.58); h.w.= 0.46 (0.49); s.l.= 0.31 (0.40); m.l.e.= 0.09 (0.10); m.w.pr.= 0.42 (0.41); a.l.= 0.63 (0.74); h.f.l.= 0.38 (0.49); m.w.p.= 0.25 (0.32); m.w.pp.= 0.31 (0.34); c.i. 81 (84). Color reddish ferruginous. Integument smooth and shining, with the following exceptions: some moderately coarse costulae between the frontal carinae, obliquely prolonged caudad, surpassing the level of the superior margins of the compound eyes where the costulae become faint to vestigial, not reaching the occiput; the two patches of costulae separated by a smooth stripe; genae with few longitudinal rugae that do not reach the inferior orbit of the compound eyes; promesonotum with superficial, fine, and longitudinal costulae on disc, specially near the shoulders, reaching the sides of mesonotum; dorsal face of the propodeum with 10-12 transverse well marked costulae; meso and metapleuron covered by longitudinal irregular costulae, the costulae prolonged over the metapleural gland region. Hairs moderately abundant, short to long, suberect on head, dorsum of mesosoma, petiole, postpetiole and gaster; subdecumbent hairs also present on head disc; most hairs inclined mesad dorsally on discs, forwards on the sides; decumbent on the mandibles.

Head; mandibles elongate with a broad and relatively shallow diastema between the basal and subbasal tooth. Anterior teeth of the clypeus directed inwards with lateral external lobe-like denticles. Frontal carinae gently convex over the antennal sockets, posteriorly and obliquely prolonged laterad, the maximum width between their outer edges always less than one fourth of the head width. Compound eyes with 5-7 facets r.g.d., which is less than the distance between the anterior orbit and the mandibular insertion; total number of ommatidia not exceeding 20. Antennal scape failing to reach the occipital corner by a distance less than the scape maximum thickness. Funicular segment I longer than II-IV combined, segments II-VII distinctly broader than long, VIII and IX as long as broad.

Mesosoma. Dorsal disc of pronotum elevated and marginate, with the dorsal surface separated from the sides by well marked angles. Margination continuous until the metanotal groove. Metanotal groove shallowly to not at all impressed; distinct by a break in the sculpture before the transverse costulae of the propodeum (d.v.). Dorsal face of the propodeum immarginate on sides, curved and convex as seen from the side; posteriorly with two obliquely pointed and very small teeth. Small declivous face well marginate and carinate laterally.

Petiole, node high and convex, antero-posteriorly compressed and laterally expanded in a scalelike fashion (d.v.); subpetiolar process with the shape of a sinoidal curve in profile, in the form of a shallow sagital keel, with an anterior small blunt tooth pointing obliquely forwards (p.v.). The postpetiole is broad, a little broader than the petiole (d.v.); subpostpetiolar process in the shape of two parallel crests which when seen from the side appear as distinct swellings, with the two crests of equivalent size.

Queen

Ulysséa & Brandão (2012) - (dealate, N = 2): c.t. = 2.56‑2.57, l.c. = 0.48‑0.47, c.c. = 0.50‑0.52, c.o. = 0.16‑0.16, c.e. = 0.34‑0.34, c.m. = 0.16‑0.14, w.l. = 0.78‑0.78, m.w.pr. = 0.41‑0.41, m.w.p. = 0.27‑0.23, m.w.p.p. = 0.33‑0.31, h.f.l. = 0.41‑0.41, c.i. = 96‑90.38.

Resembling the con-specific worker with the modifications appropriate to the caste. Body color dark brown; mandibles, antennae, legs and posterior extremity of gaster yellowish. Integument, when observed under the stereomicroscope, smooth and shining, with the exceptions of frontal carinae with has regular and sub-parallel longitudinal costulae reaching the ocelli; these carinae diverge posteriorly separated by a smooth median region; genae with few longitudinal rugae that reaches the inferior margin of the compound eyes; promesonotum with superficial, fine and longitudinal costulae; scutellum with few fine and longitudinal rugae; propodeum with well marked transversal costulae, regularly and sub-parallel; metapleuron covered by longitudinal irregular costulae, the costulae prolonged over the metapleural gland region.

Hairs moderately abundant, long, suberect to subdecumbent with varied orientation on head, mesosoma, petiole, postpetiole and gaster; antennae and legs with short and decumbent hairs.

Head with relatively elongate mandibles, basal tooth not separated from the sub-basal by a broad or a relatively shallow diastema; frontal carinae gently convex over the antennal sockets, short and not surpassing the level of the superior margins of the compound eyes, prolonged posteriorly but diverging caudad – the maximum width between their outer edges always less than one fourth of the head width; compound eyes with about 11‑13 ommatidia in a row across the greatest diameter, length of compound eyes bigger than those of the workers, greater than the distance between the inferior margin of compound eye and the mandibular insertion; the three ocelli with similar size, their diameter equal to minimum antennal scape width; funicular segment I longer than II‑V together, segments II‑VIII combined, distinctly broader than long and segments IX and X longer than broad.

Mesosoma with promesonotum marginated laterally; scutum shining; propodeum with a well marked angle between the dorsal and slope faces in lateral view.

Petiolar node higher than that of the postpetiolar node, compressed antero-posteriorly and little expanded laterally; in lateral view, subpetiolar process with the shape of a sinusoid curve, with an expansion in the anterior extremity similar to a keel. Postpetiolar node broader than long, compressed antero-posteriorly and with a conspicuous subpostpetiolar process.

Type Material

Holotype worker, Brasil: Minas Gerais: Atalaia [18°03’S 41°06’W], 27.i.[19]94, I[van] Cardoso col., deposited in Museu de Zoologia da Universidade de Sao Paulo (coated with gold for SEM examination). Paratype: same data as holotype, deposited in Laboratório de Mirmecologia CEPEC / CPDC (coated with gold for SEM examination).

Etymology

In memory of the late myrmecologist William (Bill) L. Brown Jr.

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).
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, 167-173.
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).

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.
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.
Ulyssea M. A., and C. R. F. Brandao. 2012. A new ant species of Oxyepoecus (Hymenoptera: Formicida: Myrmicinae), with the description of Oxyepoecus browni gyne and new records for the genus. Papeis Avulsos de Zoologia 52(14): 167-173.