Systematic revision and cladistic and biogeographic analyses of the Tribe Nycteliini (Coleoptera: Tenebrionidae)

Gustavo E. Flores

The tribe Nycteliini (Pimeliinae) comprises 287 species and is one of the largest groups of Tenebrionidae endemic in South America. There are previous systematic revisions of its genera, but there are not studies dealing on the phylogenetic relationships among the genera nor on which tribe is closest to Nycteliini. To determine the group more closely related to the Nycteliini, a cladistic analysis of the Southamerican tribes Nycteliini, Praocini, and Physogasterini was performed. This analysis included 28 characteres of the external morphology, internal skeletal anatomy, and male and female genitalia, and the polarity of the characters was determined using the tribe Elenophorini. The analysis allowed to establish that Physogasterini is the sister group of Nycteliini.
    To establish the phylogenetic relationships among the genera of Nycteliini, a cladistic analysis of the genera of Nycteliini was performed using 75 characteres of the external morphology, internal skeletal anatomy, and male and female genitalia. The cladogram obtained shows that the monophyly of Nycteliini is justified by eight synapomorphies and the nine genera considered are monophyletic, with the exception of Mitragenius that constitutes a paraphyletic group, requiring removal of seven species formerly assigned to Mitragenius to a new genus, Patagonogenius, described herein. The relationships among the genera of Nycteliini are resolved, all the clades are justified by synapomorphies or reversals unique within the tribe and all the genera are supported by autapomorphies or a particular combination of the characteres.
    The tribe Nycteliini comprises ten genera: Nyctelia Latreille, Epipedonota Solier, Psectrascelis Solier, Scelidospecta Kulzer, Mitragenius Solier, Auladera Solier, Patagonogenius gen. n., Pilobalia Burmeister, Entomoderes Solier, and Gyriosomus Guérin. A systematic revision of the tribe Nycteliini was performed including characteres of the external morphology, internal skeletal anatomy, and male and female genitalia, most of these for the first time. The study shows that the characters of the internal skeletal anatomy (tentorium, meso and metendosternites, and elytral abdominal joint) and of the male and female genitalia offer good diagnostic characteres  to identify the genera of Nycteliini as well as the characteres of the external morphology. The systematic revision includes an historical review of the Nycteliini, a key for the recognition of the genera, redescriptions and description of the new genus, drawings of the characters of the male and female genitalia and the internal skeletal anatomy, and a checklist of the species for each genus.
    To perform a cladistic biogeographic analysis of the distribution area of Nycteliini, systematic revisions and cladistic analyses of four genera of the tribe were made using characteres of the external morphology, internal skeletal anatomy, and male and female genitalia, the last two for the first time. These revisions include keys for the recognition of the species, redescriptions and description of the new species, drawings of the characters of the male and female genitalia, and distribution maps.
The revision of Entomoderes allowed to recognize nine species: Entomoderes erebi (Lacordaire), E. cellulosus Waterhouse, E. draco Waterhouse, E. satanicus Waterhouse, E. borealis Peña, E. infernalis Burmeister, E. zupay Flores & Roig Juñent, E. subauratus Burmeister, and E. pustulosus Fairmaire. A cladistic analysis of Entomoderes was performed using 46 characteres and the polarity of the characters was determined with the genera Gyriosomus and Pilobalia. The four cladograms obtained show that the monophyly of Entomoderes is justified by 17 synapomorphies. The strict consensus tree reveals two trichotomies within Entomoderes. After applying the successive weighting procedure, the analysis yielded three most parsimoniuos, weighted trees that are three of the original ones, showing the basal trichotomy unresolved.
    A cladistic analysis of Auladera, Mitragenius and Patagonogenius was performed using 92 characteres and the polarity of the characters was determined with the genera Psectrascelis and Scelidospecta. The cladogram obtained revealed that Mitragenius is paraphyletic, requiring removal of seven species formerly assigned to Mitragenius to a new genus, described herein as Patagonogenius.
    Mitragenius comprises nine species: M. tristis Kulzer, M. costatus Kulzer, M. araneiformis Curtis, M. coarcticollis Fairmaire, M. nudus Berg, M. hirtulus Kulzer, M. planicollis sp. n., M. obscuratus Peña, and M. dejeanii Solier; Auladera includes four species: A. crenicosta (Guérin), A. andicola (Lacordaire), A. atronitens Kulzer, and A. rugicollis (Philippi & Philippi), which is elevated to species status; and Patagonogenius comprises seven species: P. breviangulus (Kulzer) comb. n., P. gentilii (Peña) comb. n., P. quadricollis (Fairmaire) comb. n. (type species), P. collaris (Kulzer) comb. n., P. acutangulus (Kulzer) comb. n., P. kulzeri (Marcuzzi) comb. n., and P. elegans (Peña) comb. n. Mitragenius pusillus Marcuzzi is synonymized with Patagonogenius collaris (Kulzer).
The phylogenetic analyses at different levels performed here within Nycteliini confirmed that the female genitalia offer more information than male genitalia for classification at tribal and generic levels within Tenebrionidae Pimeliinae, while the male genitalia are more useful at the specific level within Pimeliinae.
    A cladistic biogeographic analysis of the distribution area of Nycteliini was performed, defined in this study as southern arid lands of South America. Within this area, twelve areas of endemism were recognized on the basis of the distribution areas of arthropods. Known cladograms of five taxa belonging to the eremic component of South America were analyzed using the simplicity quantitative method. The cladogram obtained shows the sequence (Intermediate Desert, (Coquimbo, (Puna, (Southern Patagonian, (((Western Patagonian and Central Patagonian), (Central Valley and Maule)), (Pampa, (Northern Monte, (Chaco and Southern Monte)))))))) and allowed to propose a prossible biogeographic history to the eremic component inhabiting the southern arid lands of South America.