Rhopalothrix plaumanni

Specimens were collected from ground litter. Little else is known about the biology of .

Identification
Key to Rhopalothrix workers

Distribution based on Regional Taxon Lists
Neotropical Region: Brazil.

Nomenclature

 *  plaumanni. Rhopalothrix plaumanni Brown & Kempf, 1960: 235, fig. 58 (w.) BRAZIL. Senior synonym of acutipilis: Longino & Boudinot, 2013: 315.
 * acutipilis. Rhopalothrix acutipilis Kempf, 1962b: 28, fig. 28 (q.) BRAZIL. Junior synonym of plaumanni: Longino & Boudinot, 2013: 315.

Longino and Boudinot (2013) - In this study queens were associated with workers for three Central American species. The queens differed from the workers in pilosity and the shape of the face. The queens bore numerous short bristles, which are lacking on the workers, and the worker faces had much stronger grooves and gibbosities. The characteristics of the mandible and labrum were shared between queens and workers. Examination of the figures for R. plaumanni and R. acutipilis, the types of which are from the same locality and by the same collector, suggest that R. acutipilis is the queen of R. plaumanni.

Worker
Holotype. TL 1.85, HL 0.43, HW 0.47 (CI 108), ML 0.13, WL 0.51 mm.

Form of head and mandibles shown. This is a close relative of weberi and isthmica. Note the small, single-facetted eyes and the deeply notched bilobed labral shield. Following are the main distinctive characters:

1. Dorsum of head lacking the pair of well-defined and moderately arched transverse ridges and sulci of weberi; instead only a feeble, blunt and strongly arched posterior ridge is present. Disc in front of this ridge flattened to weakly concave.

2. Mandibles relatively short, at their bases only about half as wide as the labral shield. Dentition of masticatory margin, from base to apex, as follows: 2 blunt and indistinct denticles, 1 smaller acute tooth, a indistinctly denticulate diastema, 2 longer acute teeth, the basal slightly longer than the distal, 1 very long spiniform subapical tooth with a small reclinate denticle at its base, 2 small intercalary teeth on apical fork, the first usually rudimentary, 1 spiniform long apical tooth, subequal in length to subapical tooth, the latter slightly longer than width of mandibles at base.

3. Anterior clypeal margin feebly concave as in weberi, the lateral condylar gibbosities not as prominent as in isthmica.

4. Thoracic dorsum rather flat. Promesonotal suture vestigial. Metanotal groove extremely shallow and scarcely impressed. Propodeal spines subrectangular, not acute as in isthmica nor blunt as in weberi; infradental lamella, as seen in profile, weakly but evenly concave. Petiole with a rather short peduncle.

5. Erect pilosity extremely scarce, apparently confined to gastric apex (exposed portions of tergites and sternites II-IV each bearing a transverse row of several spatulate hairs), and leading edge of scape (with 2 reclinate spatulate setae basad, 6 standing spatulate setae apicad of elbow). Extensor surfaces of tibiae at apices and of the tarsi their length with conspicuous, short, inclined, paddle-shaped hairs. Clypeus and adjoining areas of front with conspicuous oval or round subappressed setae. Ground pilosity consisting in minute, sparse, thickened standing setulae, arising from the punctures on head, thorax, and tergites and sternites of gaster.

6. Sculpture as in isthmica, normally exposed surfaces opaque, punctulate-granulose with minute tuberculae. Color fuscous-brown; mandibles, clypeus, antennae, legs rather sordid testaceous.

Paratype has the following measurements: TL 1.75, HL 0.42, HW 0.47 (CI 113), WL 0.49 mm, but is otherwise identical with the holotype.

Type Material
Holotype a worker taken from sifted soil cover at Nova Teutonia, Santa Catarina, Brazil (F. Plaumann leg.), deposited in WWK (from CTB). Another worker paratype from the same collection.

Longino and Boudinot (2013):

Holotype, worker: Brazil, Santa Catarina: Nova Teutônia (F. Plaumann), paratype worker at (not examined).

Rhopalothrix acutipilis Holotype, queen: Brazil, Santa Catarina: Nova Teutônia, V-1960 (F. Plaumann) (not examined).