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2.1. Compilation of information about Kinorhyncha measurements A bibliographic search of taxonomic studies (descriptions of new taxa, redescriptions, et cetera) related to Kinorhyncha since the discovery of the phylum has been carried out. The keywords ‘Kinorhyncha’, ‘kinorhynch’ and ‘mud dragon’, followed by ‘measurement’, ‘measure’, ‘new species’ and ‘description’ were used in Google Scholar and the Web of Science™ for this survey. For each search, the title, material and methods, species description and morphometric tables of corresponding publications were screened to search for measurement definitions and details. The oldest publication that specified how to take a measurement was retained. All relevant papers were carefully consulted to extract all the information on Kinorhyncha measurements. Not all the information about the measurement uptake methods was included in these publications (e.g. preferred anatomical position to take trunk and segment lengths). Because of that, experts on the phylum, as well as attendees of the VI Scalidophora International Workshop (15–19th August, 2022; Helgoland, Germany) were consulted to compile this missing information., Published as part of González-Casarrubios, Alberto, Cepeda, Diego, Pardos, Fernando, Neuhaus, Birger, Yamasaki, Hiroshi, Herranz, María, Grzelak, Katarzyna, Maiorova, Anastassya, Adrianov, Andrey, Dal Zotto, Matteo, Di Domenico, Maikon, Landers, Stephen C. & Sánchez, Nuria, 2023, Towards a standardisation of morphological measurements in the phylum Kinorhyncha, pp. 217-223 in Zoologischer Anzeiger 302 on page 218, DOI: 10.1016/j.jcz.2022.11.015, http://zenodo.org/record/8164084

BackgroundWithin an evolutionary framework of Gastrotricha Marinellina flagellata and Redudasys fornerise bear special interest, as they are the only Macrodasyida that inhabit freshwater ecosystems. Notwithstanding, these rare animals are poorly known; found only once (Austria and Brazil), they are currently systematised as incertae sedis. Here we report on the rediscovery of Redudasys fornerise, provide an account on morphological novelties and present a hypothesis on its phylogenetic relationship based on molecular data.Methodology/principal findingsSpecimens were surveyed using DIC microscopy and SEM, and used to obtain the 18 S rRNA gene sequence; molecular data was analyzed cladistically in conjunction with data from 42 additional species belonging to the near complete Macrodasyida taxonomic spectrum. Morphological analysis, while providing new information on taxonomically relevant traits (adhesive tubes, protonephridia and sensorial bristles), failed to detect elements of the male system, thus stressing the parthenogenetic nature of the Brazilian species. Phylogenetic analysis, carried out with ML, MP and Bayesian approaches, yielded topologies with strong nodal support and highly congruent with each other. Among the supported groups is the previously undocumented clade showing the alliance between Redudasys fornerise and Dactylopodola agadasys; other strongly sustained clades include the densely sampled families Thaumastodermatidae and Turbanellidae and most genera.Conclusions/significanceA reconsideration of the morphological traits of Dactylopodola agadasys in light of the new information on Redudasys fornerise makes the alliance between these two taxa very likely. As a result, we create Anandrodasys gen. nov. to contain members of the previously described D. agadasys and erect Redudasyidae fam. nov. to reflect this novel relationship between Anandrodasys and Redudasys. From an ecological perspective, the derived position of Redudasys, which is deeply nested within the Macrodasyida clade, unequivocally demonstrates that invasion of freshwater by gastrotrichs has taken place at least twice, in contrast with the single event hypothesis recently put forward.

During a survey of the biota of the St. Lucia Estuary in the iSimangaliso Wetland Park, South Africa, a number of Gastrotricha were found among samples of meiofauna. Fresh, marine sediment yielded several specimens belonging to a total of seven species. Of these, two are already known from other regions (i.e., Dactylopodola australiensis and Heteroxenotrichula squamosa), one is described as new to science (Halichaetonotus sanctaeluciae sp. n.), while the remaining four (Pseudostomella sp., Halichaetonotus sp.1, Halichaetonotus sp. 2, Xenotrichula sp.) require further collections and analysis, in order to establish the extent of their affiliation to species already described. General appearance, shape of hydrofoil scale and the occurrence of three long spines on the dorsal side make the new species most closely related to H. australis and H. marivagus. The key differences from these taxa and between Halichaetonotus sanctaeluciae sp. n. and H. aculifer are discussed.

Oceanic islands, characterized by high levels of endemism and distinct faunas when compared to neighbouring continents, represent natural evolutionary laboratories for biologists to understand ecological and evolutionary processes. However, most studies on oceanic islands have focused on terrestrial and marine macrofaunal organisms, and ignored microscopic animals. We present here an inventory of all soft-bodied meiofaunal organisms collected during a two-weeks workshop on the oceanic island of Lanzarote, Canary Islands. Our checklist included 239 species, with 88 of them endemic to the archipelago. The number of endemic species was lower in groups with a higher proportion of parthenogenetic species, while it was not significantly affected by body size and percentage of species with dispersal stages. A higher percentage of endemic species was found in isolated habitats and environments, with only annelids showing significantly higher number of endemic species in anchialine caves. Our results might be biased by the high number of indeterminate species found in our samples and the lack of knowledge of the meiofaunal of the African coast. Our findings, however, provide the first insight of patterns of diversity in oceanic islands, suggesting that island endemic species might also exist amongst microscopic animals