Oxyepoecus ephippiatus

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

With the exception of a specimen label that includes "lowland rainforest", nothing is known about the biology of Oxyepoecus ephippiatus.

Identification

Albuquerque and Brandao (2004) - The exclusive character of the workers of O. ephippiatus is the very modified shape of the dorsal face of the propodeum (saddle shaped) with its level elevated in regard to the rest of mesosoma. O. ephippiatus gyne runs near those of Oxyepoecus vezenyii in Kempf ’s key (1974), however its propodeum is different, as discussed in the description.

Keys including this Species

Distribution

Latitudinal Distribution Pattern

Latitudinal Range: -0.631944444° to -64.36°.

     
North
Temperate 		North
Subtropical 		Tropical South
Subtropical 		South
Temperate

Distribution based on Regional Taxon Lists

Neotropical Region: Brazil (type locality), Ecuador.

Distribution based on AntMaps

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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.
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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.
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Biology

Explore-icon.png 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.

  • ephippiatus. Oxyepoecus ephippiatus Albuquerque & Brandão, 2004: 64, figs. 2a-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.= 2.62 (2.57); h.l.= 0.58 (0.58); h.w.= 0.49 (0.49); s.l.= 0.40 (0.38); m.l.e.= 0.10 (0.10); m.w.pr.= 0.41 (0.41); a.l.= 0.74 (0.74); h.f.l.= 0.49 (0.48); m.w.p.= 0.32 (0.31); m.w.pp.= 0. 34 (0. 31); c.i. 84 (84). Color ferruginous brown. Integument smooth and shining, with the following exceptions: frontal carinae with 4-6 short but well formed costulae that are not prolonged posteriorly, ending before the level of the inferior orbits of the compound eyes; genae with few longitudinal short rugae that do not reach the inferior orbit of the compound eyes; promesonotum smooth and shining; dorsal face of the propodeum with 6-8 well marked transverse costulae that cover the metapleural region; declivous face smooth and shining. Hairs abundant, long, but without a regular orientation on head, suberect and relatively curved anteriorly on pronotal dorsum, mesonotum and petiolar node; suberect, but curved backwards on the postpetiole.

Head. Mandibles relatively elongated, with a broad and shallow diastema between the basal and subbasal teeth. Anterior teeth of clypeus with lateral blunt and scarcely developed denticles. Frontal carinae gently convex, with the posterior ends at the level of the middle of the compound eyes, the maximum width between their outer edges approximately two fifths of the head width. Compound eyes medium sized, with about 6-8 facets r.g.d., which is almost equal to the distance between the anterior orbit and the mandibular insertion: total number of ommatidia about 30. 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-V combined, segments II-VII distinctly broader than long, VIII and IX as long as broad.

Mesosoma. Pronotum shoulders not at all marked, sides of the pronotum completely rounded. Metanotal groove not at all impressed with the mesosoma in profile. Propodeum very modified, with the shape of a pronounced horse saddle, the level of the dorsal face much higher than the level of the rest of the mesosoma, dorsal face of the propodeum immarginate on sides; posteriorly with two medium sized teeth. Declivous face laterally weakly marginate and carinate.

Petiole node high and round, antero-posteriorly compressed and laterally expanded in a scalelike fashion, almost with the same width as the postpetiole (d.v.); subpetiolar process with an anterior end as a prominent and blunt tooth directed obliquely forwards (p.v.). The postpetiole very broad, antero-posteriorly compressed, the subpostpetiolar process forming a small and continuous plate with its ventral margin bearing three regularly spaced minute notches.

Queen

t.l.= 3.32; h.l.= 0.69; h.w.= 0.58; s.l.= 0.35; m.l.e.= 0.21; m.w.pr.= 0.55; a.l.= 0.88; h.f.l.= 0.61; m.w.p.= 0.35; m.w.pp.= 0.34; c.i. 84. Color chestnut ferruginous brown. Integument almost as in the conspecific workers, with the following exceptions: genae rugae almost reaching the inferior orbit of the compound eyes; scutellum weakly marginate and smooth and shining; Propodeum as in the workers, although the level of the dorsal face is similar to the level of the scutellum. Hairs as in the workers.

Head (f.f.v.) more elongate than in the workers, occipital corners broadly rounded. Compound eyes with 12-14 ommatidia r.g.d. and a total of approximately 70 ommatidia. Ocelli equally developed, very small, with the same diameter of the thinnest part of the antennal scape. The antennal scapes when laid back over the head as much as possible, almost attaining the occipital border. Funicular segment as in the workers.

Petiolar node, in relation to that of the workers, more antero-posteriorly compressed.

Type Material

Holotype worker, Brasil: Amazonas: Manaus, Rs 1301 [01°30’S 46°11’W], 16.xii.[19]93, A.B. Casimiro [col.] # H-49, deposited in Instituto Nacional de Pesquisas da Amazonia. Paratypes: worker. Brasil: Amazonas: Manaus, 29.ix.[19]93, A.B. Casimiro [col.] # 2306, deposited in Museu de Zoologia da Universidade de Sao Paulo (coated with gold for SEM examination) paratype incomplete, just the mesosoma and petiole]. Gyne. Brasil: AM: Manaus, Rs 1104, 16.xii.[19]93, A.B. Casimiro [col.] # L-9, deposited in MZSP.

Etymology

Refering to the saddle shape of the propodeum (Latin: ephippium = saddle).

References

References based on Global Ant Biodiversity Informatics

  • Fernandes I., and J. de Souza. 2018. Dataset of long-term monitoring of ground-dwelling ants (Hymenoptera: Formicidae) in the influence areas of a hydroelectric power plant on the Madeira River in the Amazon Basin. Biodiversity Data Journal 6: e24375.
  • Franco W., N. Ladino, J. H. C. Delabie, A. Dejean, J. Orivel, M. Fichaux, S. Groc, M. Leponce, and R. M. Feitosa. 2019. First checklist of the ants (Hymenoptera: Formicidae) of French Guiana. Zootaxa 4674(5): 509-543.
  • Mertl A. L., J. F. A. Traniello, K. Ryder Wilkie, and R. Constantino. 2012. Associations of two ecologically significant social insect taxa in the litter of an amazonian rainforest: is there a relationship between ant and termite species richness? Psyche doi:10.1155/2012/312054
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