Oxyepoecus species groups

The species of Oxyepoecus can be split into two species groups, as detailed by Albuquerque and Brandão (2004, 2009).

Vezenyii species group

These species share a smooth and shining cephalic dorsum and a head sculpture that, if present, is restricted to the anterior portion of genae and to the insides of the frontal carinae, from where it may be prolonged caudad into two patches always separated by a smooth median frontal stripe.

Description

Color: integument shading from lighter yellowish to dark brown, with mandibles, the antennal club and scape, and the legs usually yellowish. In O. punctifrons the whole body and appendages share the same color. The integument can be almost smooth and shining when observed under the stereomicroscope, or present the following microsculpture types: costulae, straight, curved or sinuous, short or covering large areas of the body (some could be arranged in a network, we then describe the sculpture as irregularly reticulate); rugae straight or curved; striae usually thinner than rugae; piligerous punctuations. The longitudinal costulate sculpture between the frontal carinae can either surpass the level of a virtual line crossing the inferior margins of the compound eyes, or reach, or even surpass the level of a line that crosses the superior margins of the compound eyes. Accordingly we will refer to this as the level of inferior or superior margins of the compound eyes. The hairs can appear as a ground-pilosity or be described individually, showing decumbent to erect inclinations; in general we find a fine pubescence on antennal clubs, coxae and tarsomera; gaster without pubescence. The occipital border of the head has a straight margin or is gently convex; except for O. crassinodus workers that show a brief median concavity. The mandibles are subtriangular, but range from elongate to short. The posterior region of the frontal carinae, above the antennal sockets, can be subparallel or convex externally with a posterior constriction (f.f.v.). The maximum width between their outer edges (always taken in the median region of the carinae) can range from one fifth to one third of the head width. The compound eyes can have as few as 3 facets (r.g.d.) and as many as 12. The total number of ommatidia can range from 6 to 50; and the size of the compound eyes greatest diameter in relation to the malar area can be equal, bigger or smaller. The shoulders can be marked or rounded; also the lateral margins of the pronotum could form an angle or be rounded. The metanotal groove can be somewhat impressed, at maximum equal to the greatest diameter of the metapleural spiracle. The dorsal face of the propodeum can be smooth or present transverse costulae; their margins either marginate or not. The declivous face of the propodeum can be smooth or present some transversal rugae or striae and be marginate or not. The petiole can be pedunculate, antero-posteriorly compressed forming a node, or not compressed and club-like. The postpetiole can be as high as the petiolar node (p.v.), and its width larger than that of the petiolar node (d.v.).

Rastratus species group

The species included in the Rastratus group are characterized by the cephalic dorsum entirely costulate or, in the case the sculpture covers only partially the head dorsum, the area between the frontal carinae is always sculptured, while in species of the Vezenyii group this area is always smooth.

Description

Color: varies from reddish-yellow to almost black; mandible, antennal club and scape, and yellowish legs are usually lighter than other body parts. The integument can be almost totally smooth and shining when observed under the stereomicroscope; when the integument presents microsculpture it appears as short or long, straight, curved or undulate costulae (sometimes set in a net, called then irregularly reticulate), straight or curved rugae, striae (thinner than rugae), and piligerous punctuations. The longitudinal costulae between the frontal carinae, when present, surpass the level of a virtual line that crosses the superior margins of the compound eyes (referred from now on as the level of the superior margins of the compound eyes; we adopt the same terminology for the inferior margins), and can reach posteriorly the vertex margin; laterally the costulae can reach the margin above the compound eyes. The hairs can appear as background pubescence or individually, decumbent to erect; generally the antennal club presents a fine pubescence, while the coxae, tarsomeres and gaster are smooth and free of pubescence. The head vertexal margin in frontal view can be straight, gently convex, or present a small central concavity. Mandible subtriangular, ranging from elongate to short. Posterior region of the frontal carinae, posterior to the antennal sockets, subparallel or convex, externally with a posterior constriction (f.f.v.); the maximum width between their outer edges (always taken in the midlength of the carinae) ranges from one fifth to one third of the head width. The compound eyes have as few as 3 facets r.g.d. and as many as 10 r.g.d. The total number of ommatidia ranges from 5‑6 to 30; the greatest diameter can be equal or shorter than the virtual straight line linking the anterior margin of the compound eye and the mandibular insertion, (oculomalar distance). The anterodorsal corner of the pronotum (called hereafter shoulders) can be gently marked, as an angle between the superior and the lateral surfaces, or rounded. The metanotal groove is visible or not at all perceptible. The basal face of the propodeum is smooth or presents transversal costulae. The declivous face of the propodeum is smooth or presents some oblique rugae or striae, and may present a margin separating the posterior and lateral faces. The peduncle of the petiole can be relatively long; in dorsal view, the petiolar node width can be almost the double of the peduncle width. The postpetiole can be as high as the petiolar node (p.v.), and its width can be equal to or greater than that of the petiolar node (d.v.).

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
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).