The Mesobiotus harmsworthi group has a global distribution, with localities in polar, temperate and tropical zones. Since the first species of the harmsworthi group was described in the beginning of the 20^th century, tens of new species within the group were found and named. However, the diagnosis of the nominal Mesobiotus harmsworthi is insufficient and enigmatic, thus it can be is a serious obstacle in solving the taxonomy of this group. Here, we integratively redescribe the nominal species for the genus Mesobiotus, i.e., Mesobiotus harmsworthi and clarify taxonomic statuses of the two subspecies: M. harmsworthi harmsworthi and M. harmsworthi obscurus that have been recognised as distinct taxa for more than three decades. Traditionally, egg chorion in M. harmsworthi was considered almost smooth and without any traces of areolation, however here we report many misunderstandings that accumulated across decades and we show that, in fact, the chorion in this species exhibits a partially developed areolation. We present an integrative (morphological, morphometric and molecular) diagnosis of the nominal taxon and we confirm that it differs from other species of the harmsworthi group by morphological characters of both animals and eggs. Additionally, we describe two new species of the genus Mesobiotus: M. skorackii sp. nov. from the Kyrgyz Republic (using classical morphological description) and M. occultatus sp. nov. from Svalbard Archipelago (by means of integrative taxonomy). Finally, we also provide the first genetic phylogeny of the genus Mesobiotus based on COI sequences which, together with molecular species delimitation, independently confirms the validity of the analysed taxa.

In a mixed moss and lichen sample collected in Esmeraldas Province in north-western Ecuador, 20 tardigrades and 11 eggs, belonging to a new species of the genus Mesobiotus, were found. In addition to the traditional taxonomic description with morphometrics, light and scanning microscopy imaging, we also provide nucleotide sequences of three nuclear (18S rRNA, 28S rRNA, ITS-2) and one mitochondrial (COI) DNA fragments of the new species. Based on the egg chorion morphology, Mesobiotus romani sp. nov. is the most similar to: M. binieki, M. coronatus, M. dimentmani, M. patiens, M. perfidus, M. philippinicusi, M. pseudoblocki, M. pseudocoronatus, M. pseudopatiens, M. radiatus, M. rigidus, M. simulans and M. wuzhishanensis, but differs mainly by some specific characters of both egg and adult morphology, and morphometrics.

Tardigrada in Antarctic regions are poorly known. The aim of this study was to examine for tardigrades the nests material of the kelp gull (Larus dominicanus Lichtenstein, 1823) in maritime Antarctic and discuss the possible ways of migration and dispersion of tardigrades by birds. We also discuss the influence of bird’s guano on the communities of microscopic invertebrates (mainly tardigrades). In the positive samples (mainly bryophytes and lichens) of seven Larus dominicanus nests, collected on Ardley Island (near Fildes Peninsula) and Argentine Islands, ca. 850 tardigrades and their eggs were found. In total, 13 taxa (including Ramajendas sp.) were identified, and four are new to science: Bryodelphax olszanowskii sp. nov., Diphascon puchalskii sp. nov., D. rudnickii sp. nov. and Hypsibius conwentzii sp. nov.. Bryodelphax olszanowskii sp. nov. differs from known Bryodelphax species in the weglarskae group mainly by having a different ventral plate configuration. Belonging to the pingue group, D. puchalskii sp. nov. differs from other species by some quantitative characters and D. rudnickii sp. nov. by having the first and second macroplacoids situated very close to each other. Hypsibius conwentzii sp. nov. differs from other species of the genus Hypsibius, with two macroplacoids and septulum, by some morphological and morphometric characters. Summarizing, Antarctic tardigrades are a very diverse group, and birds can be responsible for translocation of small invertebrates (including tardigrades) inside of various parts of plants and lichens. They also deposit large amounts of guano, which provides a lot of nutrients for poor tundra ecosystems and support small invertebrate communities.

Based on the original species descriptions, a review of the genus Paramacrobiotus was conducted. We divided the genus into two subgenera, Microplacoidus subgen. nov. and Paramacrobiotus subgen. nov., based on the presence or absence of a microplacoid, and characterized species within the genus based on seven different types of eggs. In a moss sample collected in Ecuador, Paramacrobiotus (Paramacrobiotus) spinosus sp. nov., was found. The new species differs from all species of the subgenus Parama crobiotus by the presence of richtersi type eggs and from other species by morphometric characters. Additionally, in the Ecuadorian material we found P. (Microplacoidus) magdalenae comb. nov., which is the first record of this species in Ecuador, and we provide the full set of measurements for this species, not included in the original description. An additional new record is P. (M.) alekseevi comb. nov. found in Vietnam for the first time. After examining microscope slides from the Iharos' collection d...