Oxyepoecus regularis, Ulysséa & Brandão, 2012

Ulysséa, Mônica A. & Brandão, Carlos R. F., 2012, A New Ant Species Of Oxyepoecus (Hymenoptera: Formicidae: Myrmicinae), With The Description Of Oxyepoecus browni Gyne And New Records For The Genus, Papéis Avulsos de Zoologia 52 (14), pp. 167-173 : 167-173

Oxyepoecus regularis sp. nov. Ulysséa & Brandão

Holotype: Worker, Brazil: Bahia: Milagres [12°54.542’S, 39°51.279’W], 23.x.2010, M.A. Ulysséa, A.M. Medina & E.M. Campos leg., extracted from 1 m 2 samples of Caatinga leaf litter submitted to the Winkler extractor for 48 hours ( MZSP).

Paratypes: seventy workers and one gyne extracted from 1 m 2 leaf litter samples submitted to Winkler apparatus, from Brazil: Bahia: Milagres: 68 workers and 01 gyne sampled in different dates and areas in the municipality of Milagres : 06 workers, 29.vii.2010 ( MZFS) , 07 workers, 09.xi.2010 ( MZSP) , 19 workers, 17.i.2011 ( MZSP) [12°54.411’S, 39°50.863’W]; 09 workers, 13.vii.2010 (03 in CPDC, 03 in BMNH and 03 in MCZC) , 07 workers, 23.x.2010 ( MZFS) and 12 workers, 10.i.2011 ( MZSP) [12°54.542’S, 39°51.279’W]; 03 workers, 24.x.2010 ( USNM) , 05 workers and 01 gyne ( MZSP), 10.i.2011 [12°54.294’S, 39°52.083’W]; M.A. Ulysséa, A.M. Medina & E.M. Campos leg.; Boa Vista do Tupim : 02 workers sampled in different dates and areas: 01 worker, 25.i.2011 ( MZSP) [12°39’36”S, 40°36’32”W], L.S.S.R. Macêdo, J.J. Resende, C.B.S. Galheigo & E. da C. Menezes leg. ; 01 worker, 27.i.2011 ( MZFS) [12°39’36”S, 40°36’32”W], L.S.S.R. Macêdo & E. da C. Menezes leg.

Etymology: The specific name refers to the regular sculpture covering the whole body, which is mostly re-covered by sub-parallel longitudinal costulae. This combination of sculpture is not found in any another Oxyepoecus species described until now.

Diagnosis: The exclusive character of Oxyepoecus regularis sp. nov. workers in relation to the other species of the Rastratus group is the presence of sub-parallel longitudinal, regularly spaced costulae, which are thick and well marked on the dorsum and lateral areas of the head, extending until the vertexal margin, on the gena and on the ventral face of the head.

Workers (holotype and variation of 70 paratypes within brackets): t.l. = 2.06 (1.99-2.23), h.w.= 0.46 (0.43-0.48), h.l. = 0.51 (0.49-0.55), e.l. = 0.05 (0.05-0.08), s.l. = 0.30 (0.28-0.34), m.l. = 0.09 (0.06-0.11), w.l. = 0.60 (0.52-0.65), m.w.pr. = 0.35 (0.30-0.36), m.w.p. = 0.15 (0.14-0.18), m.w.p.p. = 0.21 (0.19-0.24), h.f.l. = 0.30 (0.28-0.33), c.i. = 90.20 (82.93-95).

Description: With characters and states present in other Oxyepoecus species of the Rastratus group (Albuquerque & Brandão, 2009:293) and body color black, mandibles, antennae and legs yellowish, gaster dark brown. Integument, when observed under the stereomicroscope, sculptured with thick, well marked, regularly spaced and sub-parallel costulae, with the exceptions of the nuchal region and gaster, which are smooth; dorsum of head with longitudinal costulae, prolonged posteriorly, reaching the occipital margin and laterally surpassing the compound eyes region, covering the ventral face of the head; genae, dorsum and laterals of pronotum, mesonotum, mesopleura and metapleuron (including bulla) with longitudinal costulae; in the genae the costulae reach the superior margin of the lateral portion of clypeus; anterior inclination of pronotum, propodeum, petiole (including the ventral face) and postpetiole with well marked transversal costulae.

Long, suberect to subdecumbent hairs with varied orientations on head, mesosoma, petiole, postpetiole and gaster; antennae and legs with short and decumbent hairs.

Mandibles ( Fig. 1a ) relatively short and striate in its basal portion, basal tooth not separated from the sub-basal by a broad or a relatively shallow diastema; frontal carinae short, not surpassing the level of the superior margins of the compound eyes, gently convex and sub-parallel, the maximum width between their outer edges always less than one third of the head width; compound eyes convex, with about 3-4 ommatidia in a row across the greatest diameter, total number of ommatidia less than 12.

Mesosoma with convex promesonotum in lateral view ( Fig. 1b ) and weakly marginate in front and laterally in dorsal view ( Fig. 1c ); well marked shoulders; metanotal groove absent; metanotal suture indistinct; propodeal spines long, acute and oriented backwards.

Petiolar node higher than that of the postpetiole in lateral view ( Fig. 1b ), subquadrate in dorsal view ( Fig. 1c ), not compressed antero-posteriorly neither laterally expanded; in lateral view, subpetiolar process in the form of a subquadrate denticle whose height is approximately equivalent to the half of the height of the anterior region of the peduncle. Postpetiolar node broader than long, antero-posteriorly compressed and laterally expanded; subpostpetiolar process conspicuous and developed as two small and transverse crests when seen from the side.

Gyne (dealate, N = 1): t.l. = 2.47, h.w. = 0.50, h.l. = 0.55, e.l. = 0.13, s.l. = 0.34, m.l. = 0.15, w.l. = 0.70, m.w.pr. = 0.38, m.w.p. = 0.19, m.w.p.p. = 0.25, h.f.l. = 0.35, c.i. = 90.91. Resembling worker, with the appropriate caste modifications. Integument, when observed under the stereomicroscope, sculptured with thick, well marked, regularly spaced and sub-parallel costulae, with the exceptions of the nuchal region and gaster ( Fig. 2c ), which are smooth; dorsum of pronotum and propodeum with transversal costulae; sides of pronotum and bulla covered by oblique costulae ( Fig. 2b ); mesopleura, metapleuron and sides of propodeum with longitudinal costulae in the inferior region and oblique costulae in the superior region; scutum and scutellum longitudinally costulate. Compound eyes with about 10-12 ommatidia in a row across the greatest diameter ( Fig. 2a ). Three ocelli equal in size, diameter equal to minimum antennal scape width. Remaining characters as in workers.

Male: Unknown.

Comments: O. regularis is known from three localities in Northeastern Brazil, all in the state of Bahia – Milagres, Boa Vista do Tupim and Vitória da Conquista. The sampled place in Milagres is covered by “Caatinga Arbórea”, while in Boa Vista do Tupim it corresponds to a “Mata Seca”, both areas are located within the “Caatinga” biome. The specimens sampled in Vitória da Conquista were collected in areas covered by Atlantic Forest (M.L. Oliveira, personal communication). As we had no opportunity to actually study these latter specimens, only by photographs, they were not considered as paratypes .

Oxyepoecus regularis will run with O. rastratus in couplet 15 of the identification key for Oxyepoecus workers published by Albuquerque and Brandão (2009). As said before, it can be easily distinct from O. rastratus by the presence of thick, sub-parallel, regularly spaced and well marked costulae; laterals of pronotum longitudinally costulate and anterior pronotal inclination transversally costulate.

Figures

FIGURE 1: Worker of Oxyepoecus regularis sp. nov.: a) head in full-face view; b) body in lateral view; c) body in dorsal view.

FIGURE 2: Gyne of Oxyepoecus regularis sp. nov.: a) head in full-face view; b) body in lateral view; c) body in dorsal view.