No abstract

Habitat shift is a key innovation that has contributed to the extreme diversification of insects. Most groups are well-adapted to more or less specific environments and shifts usually only happen between similar habitats. To colonize a profoundly different habitat type does not only present ecological opportunities but also great challenges. We used Hydrophiloidea (water scavenger beetles) as a system to study transitions between terrestrial and aquatic environments. We estimated the diversification rate of different clades using phylogenetic trees based on a representative taxon sampling and six genes. We also investigated possible evolutionary changes in candidate genes following habitat shifts. Our results suggest that the diversification rate is relatively slow (0.039-0.050 sp/My) in the aquatic lineage, whereas it is distinctly increased in the secondarily terrestrial clade (0.055-0.075 sp/My). Our results also show that aquatic species have a G (Glycine) or S (Serine) amino acid at a given site of COI, while terrestrial species share an A (Alanine) amino acid with terrestrial outgroups. This indicates that habitat factors may create selection pressure on the evolution of functional genes and cause homoplasy in molecular evolution [Current Zoology 60 (5): [561][562][563][564][565][566][567][568][569][570] 2014 ].

Helochares (Hydrobaticus) MacLeay, 1871 is the largest subgenus of Helochares Mulsant, 1844. The Chinese fauna of Helochares (Hydrobaticus) is still poorly known. Five species are recognized, including three herein described as new: Helochares (Hydrobaticus) hainanensis sp. n. (Hainan); H. wuzhifengensis sp. n. (Jiangxi); H. tengchongensis sp. n. (Yunnan). Helochares minor d’Orchymont, 1925 and H. nipponicus Hebauer, 1995 are recorded from China for the first time. Descriptions, diagnoses, and illustrations of the new species are given. Habitus and aedeagus photos of the new record species are provided.