Commentary: Integrative Taxonomy Reveals Freshwater Shrimp Diversity (Decapoda: Atyidae: Neocaridina) from Kyushu and Southern Honshu of Japan, with a Discussion on Introduced Species.

Shih et al. (2024) reported on the detection of Neocaridina species in Japan and their morphological characteristics in Zoological Studies. Eleven taxa were identified based on mitochondrial DNA (mtDNA) analysis and morphological examination. Among these, they identified two taxa that formed sister groups: N. denticulata and N. davidi, which are primarily found in Japan and China. In this commentary, I argue that both species are actually N. davidi. This conclusion was previously drawn by Onuki and Fuke (2022) based on their examination of genome-wide SNPs, mtDNA, and morphological data. The doubts raised about this identification represent a serious issue in terms of conservation, as N. denticulata is a native species, whereas N. davidi is considered an invasive alien species in Japan. Two likely reasons for this misidentification are the oversight of previous studies and the inability to account for the effects of interspecific and intraspecific hybridization. Inaccurate or unsubstantiated identifications pose significant challenges to taxonomy and conservation, underscoring the need for research grounded in reliable methods and well-characterized specimens.