Strumigenys myllorhapha

A common inhabitant of moist tropical forest habitats across a wide range of elevation, from lowland rainforest through to cloud forest. It is a denizen of the litter as evidenced by the many hundreds of samples obtained from forest litter sampling but may also opportunistically nest in the canopy under epiphytes. Nests are presently known from in or under dead wood on ground. (Longino, Ants of Costa Rica)

Identification
Bolton (2000) - A member of the crassicornis-complex in the Strumigenys gundlachi group. The very long mandibles of myllorhapha (MI 61 - 67) are not matched by any other species of the crassicornis-complex, but several species of the gundlachi-complex have the MI approaching or exceeding 60. None of these have the dentition or the extremely elongated labral lobes of Strumigenys myllorhapha.

Longino (Ants of Costa Rica) - Mandibles in full-face view linear, elongate and narrow; at full closure engaging only at apex; ventral surface of petiole without spongiform tissue; leading edge of scape with freely projecting hairs; inner margin of mandible with a clearly defined submedian tooth near the midlength; labral lobes long, trigger hairs at apices of lobes short; middle preapical denticle distinctly larger than flanking denticles, similar in size to submedian tooth; mandibles relatively long (MI 61-67); mesosomal dorsum evenly convex, propodeal suture not impressed; total head length greater than 0.90mm. Also see Bolton (2000:190).

Specimens from the lowlands are light ferruginous and relatively smaller, while those from montane regions are dark brown and relatively larger (see Costa Rican Ants and Elevation). In the case of myllorhapha I have been able to detect neither morphological discontinuity between light and dark forms, nor zones of sympatry. Therefore I treat the light and dark forms as intraspecific variation in this case.

Distribution based on Regional Taxon Lists
Neotropical Region: Belize, Costa Rica, Honduras, Mexico, Panama.

Nomenclature

 *  myllorhapha. Neostruma myllorhapha Brown, 1959b: 12, fig. 4 (w.) COSTA RICA. Combination in Pyramica: Bolton, 1999: 1672; in Strumigenys: Baroni Urbani & De Andrade, 2007: 124. See also: Bolton, 2000: 190.

Worker
Bolton (2000) - TL 2.3-2.8, HL 0.58-0.67, HW 0.40-0.49, CI 72-75, ML 0.37-0.44, MI 61-67, SL 0.23-0.28, SI 55-59, PW 0.28-0.34, AL 0.60-0.74 (20 measured). Characters of crassicornis complex but with mandibles and labral lobes very long. Enlarged submedian tooth shifted distally so that it is between one-half and two-thirds the mandible length from the base. Between it and the apicodorsal tooth with 4 - 6 denticles of varying size, proximal to it with 5 - 8 denticles; generally there are more denticles proximal of the sub median tooth than distal to it. Apex of mandible with 3 minute intercalary denticles between apicodorsal and apicoventral teeth. Vertical inner face of mandible below masticatory margin with an elongate pale apparently glandular area close to the base. In shape it is an elongate tear-drop, pointed anteriorly and twice longer than broad; its margins are sharply defined and it is much paler in colour than the surrounding cuticle. The structure is visible even when the mandibles are fully closed. The basal mandibular gland described above is also discernible in Strumigenys auctidens, Strumigenys pasisops and Strumigenys stenotes but in all of these it is shorter, broader and by no means as sharply defined nor obviously paler than the surrounding cuticle. Colour is variable in myllorhapha, ranging from brownish yellow to almost black. Individual colour appears to be altitude linked, with darker specimens from higher altitudes.

Type Material
Bolton (2000) - Holotype worker, COSTA RICA: no locality data (F. Nevermann) (examined).