Basiceros

Known only from Neotropical rainforests, the elusiveness of Basiceros is reinforced by an impressive form of crypsis exhibited by adult workers and queens, which accumulate soil and leaf litter particles on their integument with the aid of specialized setae. Little information is available regarding their natural history. Currently a member of the ‘Basiceros-genus group’ (Eurhopalothrix, Octostruma, Protalaridris, Rhopalothrix, Talaridris). For mouthparts, labral and mandibular morphologies present considerable variation in the Basiceros-genus group, likely a result of adaptive evolution. In Basiceros, those differences can be observed in the labrum shape and the various degrees of development of the labral cleft and the clypeomandibular space. Mouthpart traits indicate a strong correlated evolutionary history potentially associated with specialized feeding habits (Probst et al. 2019).

Biology
Probst et al. (2019) - Direct evidence of Basiceros preying on gastropods comes from photographic accounts - a larva of Basiceros singularis feeding on a gastropod with a rounded shell. For other Basiceros species, data on feeding preference are scarce. Part of a colony of Basiceros conjugans was collected in Peru, nesting in a rotten log, and the trash chamber included a gastropod shell, ant remains, and a cephalic capsule of Isoptera (Syntermitinae) (Probst 2015), suggesting that B. conjugans could have scavenger habits. Mandible shape is known to be a highly labile trait in ants; however, the labrum is often overlooked in the discussions of mouthpart evolution. This work provides the first step for examining ecological specialization of members of the Basiceros-genus group in the light of mouthpart traits, showing transitions in the mandible and labrum, probably due to prey specialization.

Worker Morphology
These characters are collated in the Worker Morphology table.

Nomenclature

 *  BASICEROS [Myrmicinae: Basicerotini]
 * Basiceros Schulz, W.A. 1906: 156. Replacement name for Ceratobasis Smith, F. 1860c: 78. [Junior homonym of Ceratobasis Lacordaire, 1848: 362 (Coleoptera).]
 * Basiceros senior synonym of Aspididris: Brown, 1974c: 132.
 * Basiceros senior synonym of Creightonidris: Fernández, 2003d: 314, 392; Feitosa, Brandão & Dietz, 2007: 17.
 * Basiceros senior synonym of Acanthidris, Eurhopalothrix, Heptastruma, Octostruma, Protalaridris, Rhopalothrix, Talaridris: Baroni Urbani & De Andrade, 2007: 88.
 * ASPIDIDRIS [junior synonym of Basiceros]
 * Aspididris Weber, 1950c: 3. Type-species: Aspididris militaris, by monotypy.
 * Aspididris junior synonym of Basiceros: Brown, 1974c: 132.
 * CERATOBASIS [junior homonym, see Basiceros]
 * Ceratobasis Smith, F. 1860c: 78. Type-species: Meranoplus singularis, by monotypy. [Junior homonym of Ceratobasis Lacordaire, 1848: 362 (Coleoptera).]
 * Basiceros Schulz, W.A. 1906: 156, replacement name for Ceratobasis Smith.
 * CREIGHTONIDRIS [junior synonym of Basiceros]
 * Creightonidris Brown, 1949f: 89. Type-species: Creightonidris scambognatha, by original designation.
 * Creightonidris junior synonym of Basiceros: Fernández, 2003d: 314, 392; Feitosa, Brandão & Dietz, 2007: 17.

Taxonomic Notes
All taxa of genera Eurhopalothrix, Octostruma, Protalaridris, Rhopalothrix and Talaridris were combined in Basiceros, sensu Baroni Urbani & De Andrade, 2007: 90-93. Synonymy of all basicerotine genera under Basiceros, by Baroni Urbani & De Andrade, 2007: 88, is incorrect procedure as Rhopalothrix has priority. Basicerotine genus-rank taxonomy documented in Bolton, 2003: 183-185, is retained.