Cyphomyrmex bicornis

This species is known from two widely separated collection sites, one in southern Brazil, the other in Amazonian Colombia. The Colombian material was found in a 100mm deep soil sample in a primary forest (Castro et al., 2018).

Identification
See description section below.

Distribution based on Regional Taxon Lists
Neotropical Region: Brazil, Colombia.

Castes
The queen and male are unknown.

Nomenclature

 * . Cyphomyrmex bicornis Forel, 1895j: 179 (w.) BRAZIL (Rio se Janeiro).
 * Type-material: syntype workers (number not stated).
 * Type-locality: Brazil: Rio de Janeiro, Colonia Alpina, nr Theresopolis (E.A. Göldi).
 * Type-depository: MHNG.
 * Status as species: Emery, 1924d: 341; Borgmeier, 1927c: 125; Weber, 1940a: 409 (in key); Kempf, 1966: 177 (redescription); Weber, 1966: 167; Kempf, 1972a: 92; Snelling, R.R. & Longino, 1992: 481 (in key); Bolton, 1995b: 167.
 * Distribution: Brazil.

Description
Kempf (1966) - This rare and cryptic species, which so far has been collected only twice, is apparently confined to the woodlands in the Mantiqueira Mountains in Rio de Janeiro State. The specimen described above agrees well with the description of the type. Only the epinotum and postpetiolar dorsum are even smoother than in the type, lacking the vestigial tumuli mentioned by Forel. According to the original description, the mandibles are 5-6 toothed. My specimen has the tips of the mandibles broken off, but it seems that the basic dental number is five, there being a minute intercalary tooth in the diastema between the 2nd and 3rd tooth.

The present species is quite distinct, chiefly in the peculiarly auriculate occipital lobes of head, which occur only in Cyphomyrmex laevigatus. The latter, however, differs conspicuously from bicornis, from which it is differentiated clearly here.

Worker
Kempf (1966) - Total length 3.2 mm; head length 0.83 mm; head width 0.76 mm; thorax length 1.04 mm; hind femur length 0.83 mm. Brown; head and gaster somewhat darker. Integument densely granular, opaque, including the antennal scrobe.

Head (fig 5). Clypeus: anterior border feebly convex with a faint mesial notch, flanked on each side by a small tooth next to origin of frontal lobes. A median tumulus behind frontal area, flanked by a broad circular depression in the frontal lobes, above the antennal sockets. Carinae on vertex short but strong, diverging cephalad. Eyes with about 8 facets across greatest diameter. Preocular carinae curving mesad in front of eyes. Postocular carinae forming the strongly lamellate border the huge, auriculate, occipital lobes, continuing foreward and obliquely downward beneath the eyes, fading out just in front of the anterior orbit of eyes. Lower border of sides of head strongly but irregularly carinate. Scape rather thin at base, gradually thickening in a club-like fashion toward apex; its upper and lower border of leading face finely carinulate. Funicular segments II-VIII scarcely longer than broad.

Thorax (fig 23). Pronotum without dorsal projections, dorso-laterally marginate by a blunt and feeble longitudinal welt; antero-inferior corner subdentate and rectangular. Mesonotum: a pair of anterior, conical, bluntly tipped spines; a posterior pair of more approximate longitudinal welts, which are obtusely carinate, anteriorly diverging and rounded in profile. Mesoepinotal constriction strong. Epinotum completely unarmed and convex in both directions. Legs somewhat compressed, femora ventrally with a lamellate carinule. Hind femora ventrally dilated at basal third into an obtuse triangular lobe (fig 41).

Pedicel as shown in Figs. 23 and 33. Petiolar node broader than long, its anterior corners rounded in dorsal view, its dorsum without ridges, its postero-superior border without a projecting laminule. Postpetiole still broader than petiole, strikingly transverse, lacking conspicuous dorsal and lateral impressions and tumuli. Anterior border of tergum I of gaster carinulate above the postpetiolar insertion; laterally immarginate.

Hairs decumbent or appressed on body and appendages, rather fine and not scale-like, somewhat glistening, more conspicuous on scapes and legs.

Type Material
Kempf (1966) - Worker(s) collected by E. A. Goeldi, presumably deposited in the Forel collection; not seen.

References based on Global Ant Biodiversity Informatics

 * Lapola D. M., and H. G. Fowler. 2008. Questioning the implementation of habitat corridors: a case study in interior São Paulo using ants as bioindicators. Braz. J. Biol., 68(1): 11-20.