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Many diadromous fishes such as salmon and eels that move between freshwater and the ocean have evolved semelparous reproductive strategies, but both groups display considerable plasticity in characteristics. Factors such as population density and growth, predation risk or reproduction cost have been found to influence timing of maturation. We investigated the relationship between female size at maturity and individual growth trajectories of the long-lived semelparous European eel, Anguilla anguilla A Bayesian model was applied to 338 individual growth trajectories of maturing migration-stage female silver eels from France, Ireland, the Netherlands and Hungary. The results clearly showed that when growth rates declined, the onset of maturation was triggered, and the eels left their growth habitats and migrated to the spawning area. Therefore, female eels tended to attain larger body size when the growth conditions were good enough to risk spending extra time in their growth habitats. This flexible maturation strategy is likely related to the ability to use diverse habitats with widely ranging growth and survival potentials in the catadromous life-history across its wide species range., (© 2018 The Author(s).)

Poisonous Entoloma rhodopolium and other similar species including edible E. sarcopum are morphologically diverse. People mistake poisonous species for edible species. Classification and the detection method of these species need to be defined. The morphological and phylogenetic studies have been reported in northern Europe. In Japan, the genetic study remains unsolved. Thus, phylogenetic analysis of E. rhodopolium was conducted using ITS and RPB2 sequences, and the result was compared with that of European species. Japanese E. rhodopolium was classified into three clades, none of which belonged to the true European E. rhodopolium and other known species. Three species were defined as new species. Entoloma rhodopolium clade-I (named E. lacus) was genetically close to but morphologically separated from E. majaloides. Clade-II (E. subrhodopolium) was classified to the same group as E. sinuatum and E. subsinuatum, but distinct from these species. Clade-III was segregated from known Entoloma species including E. lupinum, and named E. pseudorhodopolium. Based on the classification, a simple identification method PCR-RFLP was developed to discriminate between poisonous species and edible E. sarcopum, which is very similar in morphology. The study can help to clarify the taxonomy of complex E. rhodopolium-related species, and to prevent food poisoning.