Systematics of Cylloepus Erichson, 1847 (Insecta: Coleoptera: Elmidae)

• Ano de defesa: 2024
• Autor(a) principal: Polizei, Thiago Tadeu Silva
• Tipo de documento: Tese
• Tipo de acesso: Acesso aberto
• Idioma: eng
• Instituição de defesa: Biblioteca Digitais de Teses e Dissertações da USP
• Palavras-chave em Português: Besouros de correnteza; DNA barcoding.; DNA barcoding; Filogenia; Neotropical region; Phylogeny; Região neotropical; Riffle beetles; Taxonomia; Taxonomy
• Link de acesso: https://www.teses.usp.br/teses/disponiveis/38/38131/tde-21082024-150548/

Elmidae is the fourth biggest family of aquatic beetles, despite their cosmopolitan distribution, the family is usually found in running waters in mountain streams, in tropical and subtropical climates. The family includes approximately 1550 species described in 155 genera, and Brazil has the biggest diversity in the world with almost 200 species under 27 genera. The New World Cylloepus includes 57 species and two subspecies, recorded in sixteen countries. A family comprehensive relationship hypothesis has never been proposed, thus, the relationships between the genera are misunderstood, especially those related to Neotropical fauna. Three genera, Hexacylloepus, Huleechius, and Neocylloepus, were erected from species originally described into Cylloepus without any cladistic analysis or even a detailed morphological study. This project aims to evaluate the monophyly of Cylloepus and to hypothesize the relationship between the species of the genus based on morphological and molecular phylogenetic analysis in addition to a taxonomic review. The specimens studied were obtained in expeditions for all Brazilian geographical regions, visits to national and international collections, loan requests, and the types examination. The morphological study was carried out based on pinned and wet specimens and the dissection of the mouthparts, thoracic segments, metathoracic wing, abdominal segments, and male and female genitalia was done. A total of 8.466 specimens were analyzed, also 282 habitus images from almost all species, 284 SEM images, and 790 drawings were accomplished. The morphological cladistic analysis under implied weights resulted in a single tree with 982 steps, based on 95 terminals (57 described species, 24 undescribed, and 14 of external groups). Cylloepus is recognized as monophyletic with the inclusion of the new species, the synonymy of Huleechius species, and the establishment of two new genera: Tupielmis and Antillelmis to house species previously placed in Cylloepus. The maximum likelihood phylogenetic analysis using the mitochondrial COI gene, from 45 taxa, representing 25 species of Cylloepus, 12 new species, and eight outgroup species, also recovered Cylloepus as monophyletic. Fourteen well-morphologically recognized species groups were established; from this, ten were also recovered based on molecular data. Cylloepus was redescribed and the diagnosis was amended, providing new morphological information, also, a dichotomic taxonomic key was provided. All species were redescribed, based on types and/or additional material, synonymies and new rank status were proposed, also lectotypes were designated for eight species. Cylloepus is now recorded in 20 countries, including the first record for five countries. Additionally, 32 species expanded their distribution, and Brazil presents the greatest diversity of Cylloepus with 35 species, followed by Peru and Ecuador with thirteen and twelve species respectively. This study elucidates that taxonomic studies using morphological and molecular data are very useful and can improve our understanding of evolutionary relationships, and help to discover new taxa or correct previous hypotheses. This is the first systematic study in Elmidae to use morphological and molecular data. Now Cylloepus corresponds to the fourth biggest genus of Elmidae in the world and the biggest in the Neotropical and New World region, with 74 species.