Odontomachus bradleyi

Brown (1976) - O. bradleyi is an interesting species. Though in its habitus it is a thoroughly ordinary neotropical Odontomachus, the 4-merous labial palpi indicate that it cannot even belong to the O. haematodus group. It will be interesting to see how restricted its geographical distribution actually is; right now, it is known only from the type locality.

Distribution based on Regional Taxon Lists
Neotropical Region: Ecuador, Peru.

Nomenclature

 *  bradleyi. Odontomachus bradleyi Brown, 1976a: 133 (w.) PERU.

Worker
Holotype: TL 14.8, HL 3.56, HW (across vertex) 2.20, HW (across ocular prominences) 2.53, ML 1.92, scape L 3.46, eye L 0.52, WL 4.14 mm; CI 62, MI 54, SI 157. Paratypes, 4 workers from type locality: TL 14.1-14.8, HL 3.42-3.54, HW 2.09-2.17, ML 1.84-1.88, scape L 3.40-3.44, eye L 0.49-0.51, WL 4.00-4.10 mm; CI 61-62, MI 53-54, SI 159-164.

A large, brown species near the upper size range of Odontomachus laticeps, Odontomachus biumbonatus and Odontomachus caelatus, but with relatively narrower head, particular form of petiolar node, and with labial palpi 4-merous as well as maxillary palpi.

Mandibles massive, as in the 3 species just mentioned; dorsal subapical tooth worn round-ended, or ground down to its base in old specimens; truncate or with an emarginate apex in younger ones. Head nearly parallel-sided behind ocular prominences, sides feebly converging caudad, posterior margin biconvex, concave in the middle. Antennal fossae confluent; extraocular furrows and temporal ridges developed.

Trunk robust; mesonotum strongly convex, especially anteriorly, sloping downward behind to mesometanotal suture, which is broad and with more or less distinct longitudinal ribs. Metanotum short, transverse, usually bounded in front by a cross-carina; outline of surface variable, sloping upward caudad. Propodeum slightly convex in lateral-view outline, with a shallow but distinct saddle centered just behind midlength. Mesepisternum with a distinctly defined margin along its whole dorsal length.

Petiole (of holotype 0.80 mm long) anterior face steep and convex for about the first 0.1 mm above anterior collar, then concave (for about 0.3 mm) to beginning of slender apical spine, into which the node tapers gradually above. Apical spine straight, or very feebly curved posteriad, its axis inclined slightly posteriad. Posterior outline of node generally concave from posterior collar to apical spine, but with a feebly convex middle section; posterior face of node mostly flat, with a faint impression about halfway up.

Striation of head and trunk moderately coarse (5 striae per 0.1 mm sample square in middle of left half of vertex), on sides of head extending laterad only to level of eye, and beyond this smooth and shining, with only scattered fine punctures and some faint bluish iridescence. A similar but narrow smooth zone extends across the back of each lobe of the vertex along the nuchal carina, but these smooth zones do not quite reach the midline at the V. Pronotum longitudinally striate mesad, but concentrically around the disc, so that cervix and anterior face of pronotum are transversely striate, and its sides are obliquely striate fanwise. Mesonotum, metanotum and propodeum striate transversely as seen from above. Petiolar node indistinctly striate around front, sides and basal strip of rear face, the striae on the sides horizontal above, but sloping downward caudad below mid-height. Apex and spine of node, also lowest part of sides, and most of posterior face, nearly or quite smooth and shining. Mesepisternum finely vertically striate over anterior quarter or third, and with a few coarse vertical striae in posterior corner, otherwise smooth and shining. Propodeal spiracle small, subelliptical to reniform, not much longer than broad.

First gastric tergum smooth and shining, with a few coarse piligerous punctures and spaced fine ones associated with the pubescence. Second gastric tergum alutaceous (finely reticulate) and with coarse but ill-defined punctures, the latter especially numerous anteriad; surface moderately shining. Third and fourth gastric terga partly alutaceous and with some coarse punctures ; fifth (last exposed) tergum mostly smooth and shining, with fine spaced punctures.

Pilosity only moderately well developed; standing hairs on dorsal surface mostly 0.3-0.4 mm long, gradually tapered to apex: the usual pair on the center of cephalic dorsum, 2-6 or so on pronotal disc, 35-50 or so inclined caudad on gastric dorsum, some smaller ones on ventral surfaces of mandibles and gaster, and a few on coxae.

Pubescence fine and short, but fairly abundant and visible even at magnifications as low as 10 X ; mostly appressed and decumbent, sparse on mandibles, more abundant on antennal scapes and legs, where some of the individual tiny hairs are erect or suberect. Dorsum of head and trunk with hairs of pubescence generally running across the striation, rather than along with it. Anterior upper face of petiolar node with fine decumbent pubescence; on gastric tergum I fine, appressed, individual pubescence hairs averaging about twice as long as average distance between them ; pubescence longer and danser on terga I I-IV. On underside of gaster, pubescence is appressed to suberect.

Color medium reddish brown, gaster darker brown above; smooth areas of sides of head, mesepisterna, and gastric dorsum with a more or less distinct bluish iridescence; mandibles dark brownish; legs sordid yellow to castaneous.

Type Material
The type series consists of 4 workers from Huacapistana, Dept. Junin, Peru, 3 June 1920 (J. C. Bradley), and a single additional worker with the same data, but «1-2 June I 920». The series of 3 June also has «#535», but I have been unable to find an entry corresponding to this number in Prof. Bradley's notes in the Cornell Lot Book. The lot number for the collection is 569, covering the Cornell University Expedition. Huacapistana is on the Rio Tarma, a tributary of the Rio Chanchamayo, on the trail or road between Tarma (elev. about 3050 m) and San Ramon, at the confluence of R. Tarma and R. Chanchamayo (elev. about 825 m ). The elevation of Huacapistana is given by Prof. Bradley in the Lot Book as «5000 ft.» (1524 m), which is doubtless a rough approximation.