Crenubiotus yalini sp. nov. (Eutardigrada: Adorybiotidae) from China discovered through integrative taxonomy

Based on morphological and morphometric data (obtained with the use of light contrast and scanning electron microscopy) as well as on molecular phylogenetic analyses (based on nucleotide sequence data of 18S rRNA, 28S rRNA, ITS-2 and COI), this study reports a new tardigrade species, Crenubiotus yalini sp. nov., from the Zhejiang Qingliangfeng National Nature Reserve in south-eastern China. This description represents the second record of the genus Crenubiotus in the country. Morphological comparisons with the five known congeners revealed stable differentiating characteristics in both animals (buccal apparatus morphology) and eggs (pore ornamentation, egg process morphology, and egg size). Molecular phylogenetic (BI and ML) and species delimitation analyses methods (ASAP and ABGD) consistently support its status as a distinct evolutionary lineage. Furthermore, we discuss the potential confounding effect of mitochondrial introgression on species delimitation. This discovery enriches the known diversity of tardigrades in China and provides new material for studies on the biogeography and evolution of the genus Crenubiotus.