Romblonella

Most species have a very limited range, are rarely collected, and are known from only a few collections. Romblonella opaca is the exception. It is relatively widespread, known from small collections (1-5 workers) from four islands in the Philippines and its type locality in Indonesia.

Identification
Characterized by a robust, hard and compact body, stout propodeal spines, massive petiole and postpetiole, and gaster formed largely by the first tergite.

Taylor (1991) for the synonymized Willowsiella - Stereomyrmex and Romblonella share several features considered to indicate relationship between them. These include the general configuration of the mesosoma and nodes (despite the differences in the latter), and the fundamentally similar dental, fronto-clypeal, palpal and sting structures (the latter at least as visible without dissection). The two genera may be readily distinguished as follows:

Stereomyrmex - Antennae 11-jointed. Fronto-clypeal area strongly inflated. Antennal scrobes lacking. Petiole massively inflated (in S. dispar ), or somewhat scale-like and transverse (in S. anderseni). Postpetiole relatively small compared to petiole, transverse, and somewhat scale-like. Gaster emarginate at base, following the posterior outline of the postpetiole when viewed from above.

Romblonella - Antennae 12-jointed. Fronto-clypeal area unexceptionally inflated. Antenna scrobes strongly developed. Petiole somewhat globular but not unexceptionally inflated or transverse. Postpetiole of more normal proportions, subspherical, more-or-less as long as wide in dorsal view, at most only slightly smaller than petiole; usually larger. Gaster not basally emarginate.

Species by Region
Number of species within biogeographic regions, along with the total number of species for each region.

Nomenclature

 *  ROMBLONELLA [Myrmicinae: Formicoxenini]
 * Romblonella Wheeler, W.M. 1935a: 5. Type-species: Romblonella grandinodis (junior synonym of Myrmica opaca), by original designation.

Worker
Monomorphic, stout and thickset; integument hard, thick, very coarsely sculptured. Head subrectangular, with moderately large, convex eyes at the middle of the sides. Ocelli absent. Mandibles short, subtriangular, with strong, subequal teeth. Clypeus short and depressed on the sides, with broad, antero-posteriorly convex median portion, extending back between the frontal carinae, the anterior border without teeth. Frontal carinae widely separated, somewhat lobular and horizontal anteriorly, continued back to within a short distance of the posterior corners of the head as a pair of sharp, diverging ridges which form the mesial borders of distinct but shallow scrobes. Frontal area distinct but shallow; frontal groove absent. Antennae short, 12-jointed; funiculi enlarged toward the tip, forming a very distinct 3-jointed club which is as long as the remainder of the funiculus, first funicular joint enlarged, nearly twice as long as broad, joints 2-8 short and transverse. Thorax stout, evenly convex above, without promesonotal and mesoepinotal sutures. Epinotum armed with a pair of long spines, which are placed rather low. Petiole and post-petiole very large, nodiform, the former narrowed and subpedunculate anteriorly. Gaster broadly elliptical, formed very largely by the first segment. Sting small. Coxae small, legs stout, middle and hind tibiae spurless; tarsal claws simple.