First record of Triops strenuus Wolf, 1911 (Branchiopoda, Notostraca), a tadpole shrimp of Australian origin, from Japan

Abstract

Three species of tadpole shrimp, i.e.,Triops granarius(Lucas, 1864),Triops longicaudatus(LeConte, 1846) andTriops cancriformis(Bosc, 1801-1802), have been known from Japan. In this paper the author describes a fourthTriopsspecies (= Triops strenuusWolf, 1911) living in the rice paddies of a southern area of Honshu, the largest of the four main islands of Japan. This species was probably endemic to the Australian continent, and no habitat distribution outside Australia has been reported so far. The impact on the existing ecosystem of Japan is quite unknown, and therefore, it is necessary to announce this intrusion into Japan in order to clarify the invasion route, habitat ecology, and the future measures against this new alien species. This invasion is considered to be caused by the resting eggs brought together with silica sand (imported from Western Australia into Japan for the large-scale beach improvement). The results presented here also describe the phylogenetic relationship with all the Australian species described so far, but also all the knownTriopsspecies of the world, based on the nucleotide sequences of mitochondrial DNA.