A freshwater shrimp, the genus Neocaridina has a land-locked life history and lives its entire life in freshwater. Two Neocaridina species are distributed in Honshu and the surrounding islands: Neocaridina denticulata and Neocaridina ikiensis, which is endemic to Iki Island. Recently, the invasive alien species Neocaridina davidi has become established in various sites in Japan, causing ecological problems.
We reported the first records of N.denticulata from Uku Island, Goto Islands, Nagasaki Prefecture, and N. ikiensis from mainland Kyushu, based on specimens. The results of mitochondrial DNA analysis suggest that these newly discovered populations are native. On the other hand, an invasive species, N. davidi was confirmed at eight sites in Fukuoka, Nagasaki, Oita, and Kumamoto prefectures. Our findings are useful for the conservation of native species and the management of invasive species.
Figure: Neocaridina denticulata collected from Uku Island. They would be a native population because they have a unique mitochondrial DNA haplotype. Photo by Jun Nakajima.
