A new species of the genus Lepechinella Stebbing, 1908 (Crustacea: Amphipoda: Lepechinellidae) from Japan.

A new species of lepechinellid amphipod, Lepechinella macrospinosa sp. nov., is described from off Yakushima Island, Japan.

First record of the genus Cymadusa Savigny, 1816 (Crustacea: Amphipoda: Ampithoidae) from Japan, with redescription and DNA barcoding for C. imbroglio Rabindranath, 1972.

The ampithoid amphipod Cymadusa imbroglio Rabindranath, 1972 was collected from Ishigaki Island, southwest Japan, as the first Japanese record of the genus. The specimens collected from Ishigaki Island also represent the northernmost record of the species. We herein provide a detailed description and illustration of the specimens from Ishigaki Island.

Plate reduction in southern Japanese freshwater populations of threespine stickleback ().

Adaptation to similar environments can lead to the evolution of similar phenotypes in phylogenetically independent lineages. However, the extent of parallel evolution often varies. Because such variations can be due to environmental heterogeneity among seemingly similar habitats, identification of the environmental factors that cause non-parallel patterns can provide valuable insight into the ecological factors associated with phenotypic diversification.

Multiple waves of freshwater colonization of the three-spined stickleback in the Japanese Archipelago.

Background: The three-spined stickleback (Gasterosteus aculeatus) is a remarkable system to study the genetic mechanisms underlying parallel evolution during the transition from marine to freshwater habitats. Although the majority of previous studies on the parallel evolution of sticklebacks have mainly focused on postglacial freshwater populations in the Pacific Northwest of North America and northern Europe, we recently use Japanese stickleback populations for investigating shared and unique features of adaptation and speciation between geographically distant populations. However, we currently lack a comprehensive phylogeny of the Japanese three-spined sticklebacks, despite the fact that a good phylogeny is essential for any evolutionary and ecological studies.