Oxyepoecus punctifrons

One of the few Oxyepoecus that has been collected from a nest that is not associated with another ant species.

Identification
Kempf (1974) - As regards mandibular shape, i. e. the basal tooth stout and separated from the remaining teeth by a deep cleft, punctifrons resembles Oxyepoecus mandibularis, which differs in having the entire cephalic and thoracic dorsum sculptured and opaque. The predominantly smooth and shining integument and the large eyes remind of Oxyepoecus inquilinus, the latter having, however, long, subfalcate mandibles, more sharply denticulate clypeus, a heavier, thick-set thorax, a well developed propodeal armature with prominent spines, strongly antero-posteriorly compressed and laterally expanded petiolar node, and the posterior surface of postpetiole heavily transversely costulate.

Finally, punctifrons diverges from Oxyepoecus crassinodus by lighter color, larger eyes, longer scape, the only shallowly impressed metanotal groove, the weak to often obsolete sculpture on sides of thorax and basal face of propodeum, the lack of transverse costulae on posterior surface of postpetiole.

Distribution
Known from several localities within southeast and south Brazil, all in the “Mata Atlântica” Domain (Albuquerque and Brandão 2004).

Distribution based on Regional Taxon Lists
Neotropical Region: Brazil.

Biology
While scant, the biological information about this species has been helpful in revealing that species within the genus, as noted below, can exist in their own nests.

Known O. punctifrons specimens were collected mainly in the leaf litter, however two workers and one gyne were founded interestingly in the canopy of an “Angico” tree Anandenanthera (Leguminosae) (Albuquerque and Brandão 2004).

Castes
Males have not been collected.

Nomenclature

 *  punctifrons. Monomorium punctifrons Borgmeier, 1927b: 63 (w.) BRAZIL. [Also described as new by Borgmeier, 1928a: 39.] Wheeler, G.C. & Wheeler, J. 1977: 586 (l.). Albuquerque & Brandão, 2004: 71 (q.). Combination in Martia: Kusnezov, 1952h: 722; in Oxyepoecus: Ettershank, 1966: 146. See also: Kempf, 1974b: 495.

Worker
Kempf (1974) - (lectotype). Total length 3.2 (2.7-3.4) mm; head length 0.73 (0.64-0.79) mm; head width 0.59 (0.49-0.67) mm; scape length 0.53 (0.48-0.57) mm; maximum diameter of eyes 0.14 (0.11-0.15) mm; Weber's length of thorax 0.89 (0.77-0.98) mm; maximum width of pronotum 0.40 (0.36-0.47) mm; hind femur length 0.63 (0.55-0.68) mm; petiole width 0.20 (0.16-0.21) mm; postpetiole width 0.27 (0.23-0:32) mm; cephalic index 80 (77-85). Color reddish yellow. Integument smooth and shining with the following exceptions: frontal carinae laterad of posteromedian extension of clypeus finally costulate, the costulae not extending posteriorly beyond the frontal carinae; cheeks finely costulate, the costulae not attaining the anterior border of the eyes; mesopleura and inferior half of metapleura finely and superficially horizontally costulate; basal face of propodeum superficially, nearly indistinctly, transversely costulate. Piligerous punctures quite conspicuous on dorsum of head. Hairs abundant, long standing hairs on dorsum of head, thorax, petiole, postpetiole and on gaster; shorter, inclined hairs interspersed with the long hairs principally on head and on gaster; short, oblique hairs on sides of head, on antennae and legs.

Head. Mandibles subtriangular, the basal border as long as chewing border; basal tooth stout, separated from the subbasal tooth by a deep cleft. Antero-median apron of clypeus protruding, laterally carinate, the carinae diverging cephalad, terminating in front in a short, relatively little projecting tooth which is flanked laterally by a minute, obtuse, lobelike denticle. Frontal area impressed, smooth and shining, well delimited from clypeus. Frontal carinae little expanded laterad, short, terminating at level of anterior orbit of eyes, the distance between the subparallel outer edges subequal to one fourth of the maximum head width. Eyes relatively large, moderately convex, their distance from the mandibular insertion equal to thejr greatest diameter which has approximately 11 facets in a row, the total number being about 50 ommatidia in all. Antennal scapes relatively long, their apex attaining the occipital corner when laid back-over the head as much as possible. Funicular segment I longer than VIII and IX taken individually, as long as II-IV combined, segment II as long as broad, segment III-VII nearly as long as broad, segments VIII and IX slightly longer than broad.

Thorax. Shoulders absolutely rounded, not marked, dorsum of pronotum not marginate on sides, promesonotal suture absent. Metanotal groove slightly impressed in profile, metanotal suture present. Basal face of propodeum about twice as long as broad, laterally immarginate, posterior corner with a small, not prominent, rectangular tooth; sides of declivous face submarginate, not carinate. The costulae and striae on metapleura extend over the distinct bulla of the metasternal gland.

Petiole and postpetiole. Petiole briefly pedunculate, club-shaped in dorsal view, the node proper not compressed antero-posteriorly nor laterally expanded, anterior surface of node strictly oblique in profile. Subpetiolar carina sharp, terminating in front in a small tooth. Postpetiole likewise scarcely compressed antero-posteriorly and little expanded laterad, the lateral projections short, blunt and bulky, the posterior surface nearly devoid of transverse costulae or rugae, except for one or two vestigial ones just above the articular collar. Gaster scarcely excised in front.

Variation. The divergence in size is noticeable as borne out by the measurements of the type series already given above. The additional specimens keep themselves more or less within the same limits, as shown by the range of the following measurements: head length 0.60-0.81 mm; head width 0.48-0.67 mm; scape length 0.44-0.55 mm; thorax length 0.76-0.96 mm; hind femur length 0.49-0.63 mm.

The development of the propodeal armature varies from merely obtuse or feebly tuberculate propodeal corners (smaller specimens) to neatly denticulate ones (larger specimens). The longitudinal costulae inside of the frontal carinae are quite constant with the exception of the Campos do Jordão (São Paulo State) specimens, which have them extended further back, in the fashion of crassinodus. The sculpture on the sides of thorax may be nearly absent (especially on mesopleura), or as in the description, or even stronger, as in the Campos do Jordão series. The same applies to the transverse costulae on basal face of propodeum, which vary between sharply expressed and nearly absent, the condition being to some extent dependent on overall size.

Queen
Albuquerque and Brandao (2004) - (ergatomorphic): t.l.= 3.32; h.l.= 0.67; h.w.= 0.55; s.l.= 0.55; m.l.e.= 0.15; m.w.pr.= 0.50; a.l.= 0.95; h.f.l.= 0.46; m.w.p.= 0.18; m.w.pp.= 0.35; c.i. 82. Resembling worker, with the head similar except for the presence of minute occelli, their diameter less than the minimum thickness of the antennal scape. Compound eyes almost equal to the worker, somewhat convex, with some 13 facets r.g.d., total number of ommatidia circa 60. Antennal segments (scape and funiculus) equal to the workers. Mesosoma with blunt marked shoulders; pronotum smooth and shining. Mesonotum (scutum and scutellum) relatively large, 2/3 of the mesosoma; scutum smooth and shining with some piligerous punctulae; scutellum entirely smooth. Mesopleuron with the anepisternum and katepisternum separated by a shallow groove, both with some very fine, almost imperceptible and oblique costulae. Dorsal face of the propodeum transversely costate, with 13-15 fine costulae, which continue downwards and obliquely forwards on the sides. Propodeal teeth short and blunt. Petiole not much compressed, almost club shaped, the subpetiolar process straight, ending anteriorly as a blunt and small denticle. Postpetiole twice broader than the petiole node, subpostpetiolar process somewhat developed as two small and transverse crests.

Type Material
Kempf (1974) - 64 workers from the same colony, taken by the late Father Miguel Witte, O.F.M., at Rio Negro, Paraná State, Brazil, in April 1925 (TB n. 424, lectotype and paratypes).

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.
 * Albuquerque, N.L. and C.R.F. Brandao. 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(23): 289-309.
 * Brandao, C.R.F. 1991. Adendos ao catalogo abreviado das formigas da regiao neotropical (Hymenoptera: Formicidae). Rev. Bras. Entomol. 35: 319-412.
 * Favretto M. A., E. Bortolon dos Santos, and C. J. Geuster. 2013. Entomofauna from West of Santa Catarina State, South of Brazil. EntomoBrasilis 6 (1): 42-63.
 * Fernandes T. T., W. Dattilo, R. R. Silva, P. Luna, C. M. Oliveira, and M. Santina de Castro Morini. 2019. Ant occupation of twigs in the leaf litter of the Atlantic Forest: influence of the environment and external twig structure. Tropical Conservation Science 12: 1-9.
 * Kempf W. W. 1974. A review of the Neotropical ant genus Oxyepoecus Santschi (Hymenoptera: Formicidae). Studia Entomologica 17: 471-512.
 * Kempf W. W. 1978. A preliminary zoogeographical analysis of a regional ant fauna in Latin America. 114. Studia Entomologica 20: 43-62.
 * Kempf, W.W. 1972. Catalago abreviado das formigas da regiao Neotropical (Hym. Formicidae) Studia Entomologica 15(1-4).
 * Rosa da Silva R. 1999. Formigas (Hymenoptera: Formicidae) do oeste de Santa Catarina: historico das coletas e lista atualizada das especies do Estado de Santa Catarina. Biotemas 12(2): 75-100.
 * 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. E. Cereto, F. B. Rosumek, R. R. Silva, and B. C. Lopes. 2011. Updated list of ant species (Hymenoptera, Formicidae) recorded in Santa Catarina State, southern Brazil, with a discussion of research advances and priorities. Revista Brasileira de Entomologia 55(4): 603-611.
 * da Silva, R.R. and R. Silvestre. 2004. Riqueza da fauna de formigas (Hymenoptera: Formicidae) que habita as camadas superficiais do solo em Seara, Santa Catarina. Papéis Avulsos de Zoologia (São Paulo) 44(1): 1-11