New Records of Tardigrades from the Republic of South Africa with Integrative Description of a New Mesobiotus Species (Tardigrada: Eutardigrada: Macrobiotidae)

In this study, we provide a comprehensive description of a newly identified eutardigrade species, Mesobiotus longiconicus sp. nov., based on an integrative approach combining morphological and genetic data. The species was discovered at Lajuma Research Centre, Republic of South Africa, and is classified within the harmsworthi group. It can be differentiated from its closest relatives—Meb. barabanovi, Meb. ethiopicus, Meb. harmsworthi, Meb. reinhardti, and Meb. skorackii—by distinct morphological and morphometric characteristics of the bucco-pharyngeal apparatus, claws, and eggs. These morphological differences are further validated by genetic analyses using four molecular markers: 28S rRNA, 18S rRNA, COI, and ITS2. Additionally, two other tardigrade species were identified in the same locality, including Minibiotus pentannulatus, which is now recorded for the second time outside its type locality. With this discovery, the total number of tardigrade taxa reported from South Africa reaches 101, including Meb. longiconicus sp. nov.