Loweriella

A monotypic genus that is only known from the workers of Loweriella boltoni from Borneo. The few collections that have been made are from the rainforest.

Identification
The worker of Loweriella boltoni (this is a monotypic genus) is similar to Bothriomyrmex in having a broadly convex anterior clypeal margin, elongate anterior clypeal setae, an anteriorly-placed posterior clypeal margin, relatively small compound eyes, and in the overall shapes of the mesosomal profile, petiole and first gastral segment. However, Loweriella differs from Bothriomyrmex in having well developed frontal carina; the medial hypostoma notched rather than completely absent; the mandible with a greater number of teeth, a relatively larger apical tooth and a more poorly defined basal mandibular angle; a 6:4 palp formula; and having a keel-shaped fourth gastral sternite. These differences allow ready separation of Loweriella and Bothriomyrmex and suggest that each is distinct from the other.

Distribution
Only known from northwestern Borneo.

Nomenclature

 *  LOWERIELLA [Dolichoderinae: Bothriomyrmecini]
 * Loweriella Shattuck, 1992c: 126. Type-species: Loweriella boltoni, by original designation.

Shattuck (1992):

Worker: Medial hypostoma notch-like, absent posteromedially and weakly developed anterolaterally near the anterior corners of the notch; anterior clypeal setae 8-10, straight or slightly curved ventrally, the central pair about the same length as the closed mandibles, the lateral setae shorter; compound eyes small, with about 35-40 ommitidia; palp formula 6:4; apical mandibular tooth elongate, noticeably longer than the subapical tooth; dorsal face of propodeum shorter than the declivitousface and separated from it by a distinct ridge or carina.

Worker
HEAD. Vertex convex (with a very slight central concavity). Compound eyes present, approximately round; small, with about 35-40 ommitidia; relatively anterior on head. Ocelli absent. Antennae 12 segmented. Scape short, at most surpassing the vertex by less than one-third its length. Anterolateral clypeal margin even with the mediolateral region. Anteromedial clypeal margin entire and with a slight, shallow medial concavity. Anterior clypeal setae 8-1 0; the central pair about the same length as the closed mandibles, the lateral setae shorter; straight or slightly curved ventrally. Posterior clypeal margin even with or anterior to the anterior surfaces of the antennal socket cavities. Anterior tentorial pit nearer the antennal socket than the mandibular insertion. Frontal carina present. Anterolateral hypostoma reduced to a thin sclerite. Medial hypostoma notch-like, absent posteromedially and weakly developed anterolaterally near the anterior corners ofthe notch. Psammophore absent. MOUTHPARTS. Palp formula 6:4. Third maxillary palp segment subequal in length to segment 4. Fifth maxillary palp segment at the apical extreme of segment 4. Mandible with 7-8 teeth and 2-5 denticles. Apical tooth elongate, noticeably longer than the subapical tooth. Basal angle weakly defined by a denticle. Basal margin smooth and without teeth or denticles. MESOSOMA. Posteroventral pronotum lateral, rounded orangled. Mesopleural process absent. Anteromedial mesosternum even with the lateral regions. Declivitous and dorsal faces of propodeum flat; dorsal face shorter than the declivitous face. Propodeal angle a distinct ridge or carina. Mesosomal spines and tooth absent. Erect pronotal hairs absent. Dorsal pro-mesonotal junction with the pronotum and mesonotum even. Metanotal groove forming a distinct angle between the mesonotum and propodeum. Metanotal spiracle dorsal and lying on the dorsal surface when viewed in lateral profile. propodeal spiracle lateral and ventral ofthe propodeal dorsum (although located posteriorly near the declivitous face). Hind tibial spur with well developed barbules along entire inner surface (except extreme base). PETIOLE. Scale present; ridged and with a distinct angle dorsally; strongly inclined anteriorly and with the anterior face much shorter than the posterior face. Venter with a well developed lobe. GASTER. First tergite projecting anteriorly, concealing all but the extreme anterior region of the petiole in dorsal view; with a groove or indentation for the reception of the entire height of the petiole. Anterior tergosternal suture of the first segment extending laterally from the helcium in a distinct arch which extends dorsal of the dorsal helcial surface. Fifth tergite ventral, gaster with 4 apparent tergites. Gastral compression absent (gaster circular in cross section). Fourth stemite keel-shaped posteriorly. GENERAL CHARACTERS. Worker caste monomorphic. Chromosome number unknown. Integument thin and flexible, weakly sculptured.

See the Loweriella boltoni species page for additional details.