Oxyepoecus vezenyii

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Oxyepoecus vezenyii
Scientific classification
Kingdom: Animalia
Phylum: Arthropoda
Class: Insecta
Order: Hymenoptera
Family: Formicidae
Subfamily: Myrmicinae
Tribe: Solenopsidini
Genus: Oxyepoecus
Species: O. vezenyii
Binomial name
Oxyepoecus vezenyii
(Forel, 1907)

Oxyepoecus vezenyii casent0178102 profile 1.jpg

Oxyepoecus vezenyii casent0178102 dorsal 1.jpg

Specimen labels

A typical Oxyepoecus ant; rarely collected and little is known about its biology. Specimens have been collected in pitfall traps and in litter samples.

Identification

Workers of O. vezenyii are diagnosed by a combination of characters: the elongate mandible; the relatively small eyes with circa 20 ommatidia, and the pattern of microsculpture between the frontal carinae. The gyne runs near those of Oxyepoecus bruchi in Kempf ’s (1974) key, however it is differentiated by the pronotum, which is not declivous in the middle, and by the relatively small mesonotum (Albuquerque and Brandão 2004).

Keys including this Species

Distribution

Known from Brazil and Paraguay.

Distribution based on Regional Taxon Lists

Neotropical Region: Brazil, Paraguay (type locality).

Distribution based on AntMaps

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Distribution based on AntWeb specimens

Check data from AntWeb

Biology

Besides knowing this species has been collected in a number of ecosystems and biomes, little is known about its biology.

The following account of the biology of species within the genus is based on, and modified from, Kempf (1974) and Albuquerque and 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 not been collected.

Nomenclature

The following information is derived from Barry Bolton's New General Catalogue, a catalogue of the world's ants.

  • vezenyii. Monomorium (Martia) vezenyii Forel, 1907a: 20 (w.) PARAGUAY. Kempf, 1969: 277 (q.). Combination in Martia: Kusnezov, 1952h: 722; in Oxyepoecus: Ettershank, 1966: 145. See also: Kempf, 1974b: 505.

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

Kempf 1974 oxyepoecus fig. 1-10.jpg
Kempf (1974) - The closest relative of vezenyii, on account of the long, linear mandibles, the smooth integument and the antero-posteriorly compressed petiolar and postpetiolar nodes, is Oxyepoecus inquilinus, from which the worker of the former differs as follows: eyes much smaller, with only 6-7 facets across the greatest diameter which is inferior to the distance that separates the eye from the mandibular insertion, the total number of ommatidia not surpassing 20-25 in all; pronotum submarginate in front and on the sides, shoulders distinctly marked and subdentate; frontal carinae more approximated to each other, the maximum distance between their outer edges distinctly less than one third of head width; costulate-striate sculpture, although in part very faint and only vestigial, more extensive on frons and on sides of thorax; subpetiolar tooth with a foliaceous appendix.

The female, although conspicuously ergatomorphic on account of the poor development of the eyes, the ocelli and the pterothorax, and the total absence of wings, is nevertheless close to Oxyepoecus bruchi from which it has already been separated on a foregoing page.

Description

Worker

Kempf 1974 Oxyepoecus fig 11-22.jpg
Kempf (1974) - Total length 2.4-3.0 mm; head length 0.57-0.67 mm; head width 0.47-0.55 mm; scape length 0.36-0.41 mm; maximum diameter of eyes 0.08-0.09 mm; Weber's length of thorax 0.68-0.79 mm; maximum width of pronotum 0.36-0.44 mm; hind femur length 0.39-0.47 mm; petiole width 0.23-0.31 mm; postpetiole width 0.27-0.35 mm; cephalic index 79-84. Color light ferruginous; mandibles, antennae and legs lighter, more yellowish, gaster usually somewhat infuscated. Integument smooth and shining with the following exceptions: frontal carinae longitudinally costulate, the costulae prolonged caudad and obliquely laterad, reaching beyond level of posterior orbit of eyes where they become faint to vestigial; cheeks with a few longitudinal rugae that reach the anterior orbit of eyes; postero-lateral corner of dorsal disc of pronotum, sides and posterior third of mesonotum, mesopleura, metapleura and sides of propodeum with longitudinal costulae, which especially on pronotum, mesonotum and mesopleura vary in their degree of distinctness, from vestigial to well formed; basal face of propodeum with 10-15 costulae, 6-8 strong ones, the others weak; sides of petiolar node with a few, widely spaced horizontal rugulae; posterior surface of postpetiole with several rows of indistinct to well-expressed transverse rugae. Hairs abundant, long, standing on head, dorsum of thorax, petiole and postpetiole, and on gaster; on head, besides the scarcer standing hairs are inclined and shorter ones, inclined mesad dorsally on disc, forward on sides; gaster without these interspersed shorter and inclined hairs.

Head. Mandibles rather elongate than subtriangular, with a broad and relatively shallow diastema between the basal and subbasal tooth. Median apron of clypeus projecting above mandibles, with the usual posterior converging carinae and the anterior teeth; the lateral denticles blunt, lobe-like. Frontal carinae gently convex, slightly constricted posteriorly, the maximum width between their outer edges always less than one third of head width. Frontal area impressed, smooth and shining, ill-delimited. Eyes relatively small, with about 6-7 facets in a row across the greatest diameter which is less than the distance between the anterior orbit and the mandibular insertion: total number of ommatidia about 20. Antennal scapes failing to reach the occipital corner by a distance equalling the maximum thickness of the scape. Funicular segment I as long as II-V combined, segments II-VII distinctly broader than long, VIII and IX as long as broad.

Kempf 1974 Oxyepoecus fig 31-37.jpg
Thorax. Shoulders marked, somewhat tuberculate, sides of pronotum submarginate. Metanotal groove shallowly impressed, metanotal suture indistinct. Basal face of propodeum immarginate on sides, posteriorly with two small, pointed denticles. Declivous face laterally marginate and weakly carinate.

Petiole and postpetiole; the former strongly pedunculate, subpetiolar process elaborate and foliaceous, node strongly compressed antero-posteriorly and laterally expanded in a scalelike fashion, nearly as broad as postpetiole. The latter unusually broadened due to the drawn out lateral bulky lobes. Gaster shallowly excised at the postpetiolar insertion.

Queen

Kempf (1974) - (ergatomorphic). Total length 3.1 mm; head length 0.64 mm; head width 0.53 mm; scape length 0.43 mm; maximum diameter of eyes 0.11 mm; Weber's length of thorax 0.84 mm; maximum width of pronotum 0.43 mm; hind femur length 0.46 mm; petiole width 0.30 mm; postpetiole width 0.35 mm; cephalic index 82. Resembling the worker with the modification proper of the caste. Eyes surprisingly small, as in worker, with less than 30 ommatidia. Ocelli minute, their diameter less than the minimum thickness of scape. Thorax with bluntly marked shoulders, pronotum not entirely declivous in the middle, nearly one third of the maximum length is horizontal along the sagittal line, on anterior corners a few faint transverse to oblique rugae, the rest smooth and shining. Mesonotum (scutum and scutellum) relatively small, their combined length subequal to one half of Weber's length of thorax; scutum smooth and shining with heavier piligerous punctulae; scutellum entirely smooth. Basal face of propodeum transversely costate, with 8-10 costae, which continue downward and obliquely forward on the sides. Mesopleura smooth and shining. Propodeal spines short but pointed. Petiole and postpetiole as in worker, the subpetiolar process in the form of a small foliaceous lobe. Wings never developed.

Type Material

Kempf (1974) - The lone holotype in the Forel collection was not seen during this study.

References

  • Albuquerque, N. L. d. and C. R. F. Brandão. 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 (page 75, figs. 7a-c worker, queen (ergatomorph) descrided)
  • Albuquerque, N. L. d. and C. R. F. Brandão. 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.
  • Delsinne, T., W. Mackay, A. Wild, Y. Roisin, and M. Leponce. 2012. Distribution and Diversity of the Cryptic Ant Genus Oxyepoecus (Hymenoptera: Formicidae: Myrmicinae) in Paraguay with Descriptions of Two New Species. Psyche. 2012. DOI:10.1155/2012/594302
  • Ettershank, G. 1966. A generic revision of the world Myrmicinae related to Solenopsis and Pheidologeton (Hymenoptera: Formicidae). Aust. J. Zool. 14: 73-171 (page 146, Combination in Oxyepoecus)
  • Forel, A. 1907d. Formicides du Musée National Hongrois. Ann. Hist.-Nat. Mus. Natl. Hung. 5: 1-42 (page 20, worker described)
  • Kempf, W. W. 1969. Miscellaneous studies on Neotropical ants. V. (Hymenoptera, Formicidae). Stud. Entomol. 12: 273-296 (page 277, queen described)
  • Kempf, W. W. 1974b. A review of the Neotropical ant genus Oxyepoecus Santschi (Hymenoptera: Formicidae). Stud. Entomol. 17: 471-512 (page 505, see also)
  • Kusnezov, N. 1952k [1951]. Acerca de las hormigas simbióticas del género Martia Forel (Hymenoptera, Formicidae). Acta Zool. Lilloana 10: 717-722 (page 722, Combination in Martia)