Integrative Descriptions of Two New Macrobiotidae Species (Tardigrada: Eutardigrada: Macrobiotoidea) from French Guiana and Malaysian Borneo

Macrobiotus naginae sp. nov., a New Xerophilous Tardigrade Species from Rokua Sand Dunes (Finland)

Animals that colonize soil show specific adaptations to soil. Compared to closely related species living on the surface, the limbs of soil-dwelling animals are often shortened, reduced, or absent to allow a less restricted passage through cavities between soil particles. This pattern of limb reduction has also been observed in tardigrades, where multiple lineages that colonized the below-ground habitat show independent reduction and/or loss of legs and claws. In the tardigrade superfamily Macrobiotoidea, leg and claw reductions are a common trait found in the Macrobiotus pseudohufelandi complex. This rarely found species complex currently contains four nominal taxa. Here we describe, with the use of integrative taxonomy, Macrobiotus naginae sp. nov., a new species in the Macrobiotus pseudohufelandi complex from inland sand dunes in Finland. We also provide a dichotomous key to the Macrobiotus pseudohufelandi complex to assist with their identification in future studies.

Reaching the Monophyly: Re-Evaluation of the Enigmatic Species Tenuibiotus hyperonyx (Maucci, 1983) and the Genus Tenuibiotus (Eutardigrada)

Revisions and redescriptions of taxa described in the past and that are now categorized as insufficiently diagnosed often play a crucial role in making further progress in modern taxonomy in many groups of organisms. Here we revised an enigmatic tardigrade species Tenuibiotus hyperonyx (Maucci, 1983) based on the newly discovered topotypic population from the Italian Alps. We performed an integrative analysis of morphological and genetic data in order to present an upgraded species description and elucidate its phylogenetic position. Our results enabled us to confidently place T.hyperonyx within the family Richtersiusidae, as a member of the genus Diaforobiotus. This change, together with a re-assessment of microphotographs of the Tenuibiotus willardi (Pilato, 1977) and Tenuibiotus bozhkae Pilato, Kiosya, Lisi, Inshina & Biserov, 2011 types, led to the discussion on species composition with narrative taxa amendments for the taxonomic parties involved in the proposed alteration.

Integrative descriptions of two new Macrobiotus species (Tardigrada, Eutardigrada, Macrobiotidae) from Mississippi (USA) and Crete (Greece)

In this paper, we describe two new Macrobiotus species from Mississippi (USA) and Crete (Greece) by means of integrative taxonomy. Detailed morphological data from light and scanning electron microscopy, as well as molecular data (sequences of four genetic markers: 18S rRNA, 28S rRNA, ITS-2 and COI), are provided in support of the descriptions of the new species. Macrobiotus annewintersaesp. nov. from Mississippi belongs to the Macrobiotus persimilis complex (Macrobiotus clade B) and exhibits a unique egg processes morphology, similar only to Macrobiotus anemone Meyer, Domingue & Hinton, 2014, but mainly differs from that species by the presence of eyes, granulation on all legs, dentate lunulae on legs IV, and of bubble-like structures within the tentacular arms that are present on the distal portion of the egg processes. Macrobiotus rybakisp. nov. from Crete belongs to the Macrobiotus clade A and is most similar to Macrobiotus dariae Pilato & Bertolani, 2004, Macrobiotus noemiae Roszkowska & Kaczmarek, 2019, Macrobiotus santoroi Pilato & D’Urso, 1976, and Macrobiotus serratus Bertolani, Guidi & Rebecchi, 1996, but differs from them mainly in the morphological details of its egg processes and chorion reticulation, but also by a number of morphometric characters. In light of the specific morphology of the egg processes of Macrobiotus annewintersaesp. nov. and Macrobiotus anemone, that are equipped with tentacular arms instead of proper terminal disc, we also provide an updated definition of the Macrobiotus persimilis complex.