Bathynomus vaderi Ng, Sidabalok & Nguyen, 2025: the senior synonym of B. paracelensis Huang & Kawai, 2025 (Crustacea, Isopoda, Cirolanidae)

<i>Bathynomus paracelensis</i> Huang & Kawai, 2025 was recently described based on four female specimens from the Paracel Islands in the South China Sea, and distinguished from <i>B. vaderi</i> Ng, Sidabalok & Nguyen, 2025 from Vietnam, by 14 morphological characters, with the primary ones being the body size and shape, pleotelson-size ratio and structure of the spines, as well as the numbers of uropod robust setae and their shape. Morphological comparisons of the type specimens of both species show that none of these characters are valid, with the two species also share nearly identical COI and 16S mitochondrial DNA sequences. As such, <i>B paracelensis</i> is here regarded as a junior synonym of <i>B vaderi</i>.