2026-05-20 東北大学
図1. 愛知県新豊根ダムで発見されたDaphnia retrocurva. A）成熟個体、B, C）幼若個体、 D）後腹部突起、E）尾爪にある櫛列（赤矢印）。第二触覚の遊泳剛毛（写真Aの赤矢印）や、後腹部突起、尾爪の櫛列などの形態は、Daphnia 属の種判別に重要な形質であり、いずれもDaphnia retrocurvaの特徴を示している。
＜関連情報＞
- https://www.tohoku.ac.jp/japanese/2026/05/press20260520-03-daphnia.html
- https://checklist.pensoft.net/article/185312/
北米原産地以外でのDaphnia retrocurva Forbes, 1882（甲殻類、枝角類、ミジンコ科）の初記録（日本、新豊根貯水池） First record of Daphnia retrocurva Forbes, 1882 (Crustacea, Cladocera, Daphniidae) outside its native North America (Shin Toyone Reservoir, Japan)
Wataru Makino, Jotaro Urabe
Check List Published:28 Apr 2026
DOI:https://doi.org/10.15560/22.2.402
Abstract
Daphnia retrocurva Forbes, 1882 (Crustacea, Cladocera, Daphniidae), a North American freshwater zooplankton species, was found in an artificial reservoir in central Japan. This represents the first record of D. retrocurva not only in Japanese and Asian freshwaters but also from outside North America. Our phylogenetic analysis based on mitochondrial DNA sequences revealed little differentiation between Japanese and North American populations. By combining geographical isolation and the lack of genetic differentiation, we consider Japanese D. retrocurva to be non-indigenous and relatively recently introduced.
