Abstract
AbstractInsects have invaded marine habitats only rarely and secondarily. Recently, we discovered a flightless dipteran species skating rapidly on the surface of seawater ponds at the Pacific coast of eastern China. Morphological analyses initially suggested an isolated position of the non‐biting midge, suggesting the erection of a new genus within Chironomini (Diptera: Chironomidae). However, an analysis of molecular data revealed that the marine species is in fact nested within the species‐rich genus Dicrotendipes. The apparent conflict between molecular and morphological data can be easily explained. It is likely that the new species has evolved a series of autapomorphic adaptations. These traits clearly distinguish the taxon from other species of the genus but do not justify the erection of a new supraspecific taxon, which would render Dicrotendipes paraphyletic. The switch to marine environments was likely a trigger for various morphological modifications resulting from increased selective pressure. Molecular data suggest that the potential speciation event occurred around 19–29 Ma, linked with a migration from freshwater to seawater ponds along the Pacific Ocean. Considering the results of our analysis, we place the flightless marine skater in the genus Dicrotendipes. All life stages of Dicrotendipes sinicus Qi & Lin sp. n. are described and illustrated, associated with larvae obtained by rearing or confirmed through association with DNA barcodes. The biology and ecology of the species are outlined based on collection data and in situ observations. Evolutionary patterns linked with repeated invasions of marine habitats are discussed.
Highlights
| INTRODUCTIONDespite the recently documented decline in insect diversity (Costello, May, & Stork, 2013) and biomass (Hallmann et al, 2017), insects are still by far the most diverse group of animals
Despite the recently documented decline in insect diversity (Costello, May, & Stork, 2013) and biomass (Hallmann et al, 2017), insects are still by far the most diverse group of animals (Stork, McBroom, Gely, & Hamilton, 2015), often occurring in immense densities
Few insect species have evolved morphological and physiological adaptations to a glide on the water surface (Cheng, 1976). They are arguably most pronounced in the water skaters, for example, the marine Halobates Eschscholtz, 1822 (Heteroptera) and in a number of non‐biting midges such as the marine Pontomyia Edwards, 1926 (Diptera)
Summary
Despite the recently documented decline in insect diversity (Costello, May, & Stork, 2013) and biomass (Hallmann et al, 2017), insects are still by far the most diverse group of animals. The group can be found in a multitude of terrestrial and freshwater habitats and play an integrative role in these environments, forming an essential part of food chains Despite their remarkable ecological versatility and pancrustacean ancestry (Misof et al, 2014), only few insects inhabit marine habitats, and only peripherally and secondarily. Few insect species have evolved morphological and physiological adaptations to a glide on the water surface (Cheng, 1976) They are arguably most pronounced in the water skaters, for example, the marine Halobates Eschscholtz, 1822 (Heteroptera) and in a number of non‐biting midges such as the marine Pontomyia Edwards, 1926 (Diptera). Evolutionary and phylogenetic links between freshwater and marine chironomid taxa are insufficiently understood at present It remains unclear why species of some clades can occur in extremely different habitats and which forces drive allopatric speciation in natural populations. The biology and ecology of the hitherto unknown marine species are outlined based on collection data and in situ observations
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