First non-feeding Sericini beetles (Coleoptera, Scarabaeidae): new genus from Amazonia and phylogenetic position

摘要

Two unusual scarab species discovered from two localities in the Amazonian Basin are described. We used comparative morphology and phylogenetic analysis to infer their systematic placement. A parsimony-based phylogenetic analysis was performed using 108 morphological characters from adults and larvae. Taxon sampling represented most 'traditional' subfamilies of coprophagous and phytophagous Scarabaeidae. Given the apparent presence of some morphological key characters, we emphasized Sericini and other Melolonthinae lineages in order to assess as accurately as possible their systematic placement. Phylogenetic analysis revealed them to be part of the Glade of South American Sericini and to represent a new genus (Parasymmela gen. n.) which was distinctive in several apomorphies. We were able to distinguish two separate species, Parasymmela amazonica sp. n. and P. howdeni sp. n. The strong reduction of mouthparts in Parasymmela led us to believe that it represents the first non-feeding taxon among the megadiverse tribe Sericini, which is discussed in the light of the evolutionary biology and feeding behavior of all phytophagous scarab lineages. For the South American Sericini, repeatedly retrieved as sister to all other Sericini, the subtribe Astaenina Burmeister, 1855 (type genus: Astaena Erichson, 1847) is re-established (currently in synonymy with Sericina Kirby, 1837).