Oxyepoecus daguerrei

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Oxyepoecus daguerrei
Conservation status
Scientific classification
Kingdom: Animalia
Phylum: Arthropoda
Class: Insecta
Order: Hymenoptera
Family: Formicidae
Subfamily: Myrmicinae
Tribe: Solenopsidini
Genus: Oxyepoecus
Species: O. daguerrei
Binomial name
Oxyepoecus daguerrei
(Santschi, 1933)

Oxyepoecus daguerrei casent0913870 p 1 high.jpg

Oxyepoecus daguerrei casent0913870 d 1 high.jpg

Specimen Labels

Nothing is known about the biology of this species.

Identification

The exclusive character of O. daguerrei workers in relation to all other species in the genus is the straight costulae on the frontal carinae that prolong caudad, attaining the vertexal margin but failing to laterally reach the compound eye, also the postpetiole (d.v.) is relatively narrower than of others species of the genus (Albuquerque and Brandão 2009).

Keys including this Species

Distribution

Only known from three type specimens from Buenas Aires Province, Argentina.

Distribution based on Regional Taxon Lists

Neotropical Region: Argentina (type locality).

Distribution based on AntMaps

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Distribution based on AntWeb specimens

Check data from AntWeb

Biology

Only three specimens of O. daguerrei have been collected and all are from the same locality in Argentina.

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

Queens and 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.

  • daguerrei. Martia daguerrei Santschi, 1933e: 111 (w.) ARGENTINA. Combination in Oxyepoecus: Ettershank, 1966: 146. See also: Kempf, 1974b: 486; Albuquerque & Brandão, 2009: 294.

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) - O. daguerrei differs from Oxyepoecus crassinodus in the sculpture of the cephalic dorsum where the costulae attain posteriorly the occiput and are not separated into two patches by a median smooth stripe; the larger eyes with over 20 ommatidia in all and about 8 in a row across the greatest diameter; the more gently impressed metanotal groove; the rather inconspicuous propodeal armature, the teeth being rectangular and not obliquely raised upward when seen in profile; the weakly marginate and ecarinate lateral borders of declivous face of propodeum; the more compressed petiolar node.

The differences from Oxyepoecus rastratus are as follows: Sculpture on cephalic disc not attaining laterally the upper orbit of eyes which is separated from the sculptured area by a smooth stripe; shoulders scarcely marked; pronotum nearly continuously rounded in both directions; promesonotal disc smooth and shining; petiolar node not expanded laterad, decidedly narrower than postpetiole; the latter with weak transverse costulae on posterior surface of node.

Description

Worker

Kempf (1974) - (lectotype). Total length 2.6 mm; head length 0.63 mm; head width 0.52 mm; scape length 0.40 mm; maximum diameter of eyes 0.12 mm; Weber's length of thorax 0.72 mm; maximum width. of pronotum 0.36 mm; hind femur length 0.45 mm; petiole width.0.17 mm; postpetiole.width 0.23 mm; cephalic index 83. Fuscous brown to black; antennal scapes, thorax and pedicelar segments a bit lighter;

Kempf 1974 Oxyepoecus fig 11-22.jpg

mandibles and legs reddish brown. Mandibles, scapes, sides and gular face of head, pronotum, part of mesonotum, legs, petiole and most of the postpetiole, gaster smooth and shining throughout. Front and vertex densely longitudinally costate-striate, but the sculpture does not attain laterally the upper margin of the eyes, yet attains posteriorly the occipital border when head is seen in full-face view; costulae gently diverging caudad, the lateralmost costulae attaining the occipital corner; strong piligerous punctures both on sculptured and smooth parts of the cephalic dorsum. Mesonotum laterally longitudinally costulate, discally smooth except for a few weak and extremely short costulae arising from the metanotal groove. Propodeum densely and finely transversely striato-costulate. Meso- and metapleura horizontally costulate, the intervals practically smooth. Abundant erect or suberect hairs of variable length on thorax, pedicelar segments and gaster; on head, except for the long clypeal hairs, they are shorter, inclined mesad dorsally on disc, forward on sides. Scapes and legs with short, inclined to subappressed hairs.

Head a little elongate, the sides in full-face view very gently convex, the occipital corners rounded, the occiput straight. Mandibles subtriangular, the basal border not longer than the chewing border, the basal tooth strong, separated from the subbasal tooth by a deeply concave excision, the diastema rather broad. Median apron of clypeus projecting forward over the mandibles, clypeal carinae strong, slightly diverging cephalad, forming a pointed tooth which is flanked laterally and below by another small denticle. Frontal area smooth, scarcely impressed, ill-separated from the clypeus. Frontal carinae very short, closely approximated, the distance between their outer edges (interfrontal width) distinctly less than one third of head width, subparallel in front, slightly diverging behind, terminating at level of anterior orbit of eyes. Cheeks feebly costulate, costulae not attaining eyes. Eyes relatively larger, with about 8-9 facets in a row across the greatest diameter, and a total of nearly 30 ommatidia. Distance between anterior orbit of eyes and mandibular insertion subequal to maximum diameter of eyes. Antennal scape failing to attain the occipital corner by a distance equalling its maximum width. Funicular segment I longer than VIII and IX taken individually, as long as II-V combined; segments II-VII broader than long, VIII and IX as long as broad, subequal in length.

Thorax without marked shoulders, the pronotum gently convex in both directions, anteriorly and laterally immarginate; shoulders not marked. Metanotal groove very gently impressed but distinguishable in profile. Basal face of propodeum nearly twice as long as broad, the sides submarginate, slightly divergent caudad, posterior corners dentate, the propodeal teeth rectangular in profile. Declivous face of propodeum laterally marginate yet not carinate.

Petiole strongly pedunculate, subpetiolar tooth well developed, node high, antero-posteriorly compressed yet not strongly expanded laterad, not forming in dorsal aspect a broad scale. Postpetiole lower but much broader than petiole due to the laterally projecting blunt cones, the posterior surface with feeble transverse costulae.

Type Material

Kempf (1974) - Three workers, taken at Rosas, F.C. Sur, Buenos Aires province, Argentina, by Juan B. Daguerre, nn.. 1904 and 666. One worker (n. 1904, lectotype) seen, received from the Borgmeier collection (TB). The workers of collection n. 1904 were originally mounted on the same pin with Solenopsis metanotalis var. picturata Santschi, and the single worker of collection n. 666 with Solenopsis tetracantha Emery, a fact which suggested to Santschi that they were taken together and living in a symbiotic relationship of some sorts.

References

  • 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.
  • 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)
  • Kempf, W. W. 1974b. A review of the Neotropical ant genus Oxyepoecus Santschi (Hymenoptera: Formicidae). Stud. Entomol. 17: 471-512 (page 478, see also)
  • Santschi, F. 1933f. Fourmis de la République Argentine en particulier du territoire de Misiones. An. Soc. Cient. Argent. 116: 105-124 (page 111, worker described)