New Indomalayan Nebularmis species (Heterotardigrada: Echiniscidae) provoke a discussion on its intrageneric diversity

Patterns of sexual dimorphism in the armoured tardigrades

Sexual dimorphism is widespread among animals, with diverse patterns and proposed explanations observed across the Tree of Life. Here we present the first formal analysis of the patterns of sexual dimorphism in body size and cephalic sensory appendages across 40 species (from 10 genera) of armoured tardigrades (Echiniscidae). Phylogenetic signal was found for body size traits and the cephalic papilla relative size, indicating that the association between these traits between the sexes has high evolutionary persistence. The Echiniscidae body size dimorphism is generally female-biased, which would be in accordance with the fecundity hypothesis. No strong evidence of allometric patterns of body size sexual dimorphism was found. In contrast, some of the cephalic appendages show male-biased sexual dimorphism, particularly those that, by being more innervated, are thought to function as chemodetection organs used by males during mate search. The latter is consistent with the sexual selection hypothesis. As the first systematic quantification and analysis of the patterns of sexual dimorphism in the phylum Tardigrada, this study provides important insights into their ecology and evolution, such as corroborating the suggestion that cephalic appendages evolved for mate searching.

Atlas of the Echiniscidae (Heterotardigrada) of the Worldpart I: West Palaearctic Echiniscus species

Traditionally Eurocentric tardigrade taxonomy has started to dissect endemics from very few truly cosmopolitan or widely distributed species, originally described mostly from the West Palaearctic, in the last decade. Obviously, the most problematic for taxonomic identification are species in large genera containing over 100 species in the case of Tardigrada. In limno-terrestrial heterotardigrades, only Echiniscus C.A.S. Schultze, 1840 fulfils this criterion, being a perfect example of taxonomic inflation. In Echiniscidae, this phenomenon results predominantly from the historical fallacy of attaching more importance to chaetotaxy than to the analysis of dorsal plate sculpturing. In this paper, the first of a series on echiniscids of the World, we review the current state of knowledge on the West Palaearctic Echiniscus species. Echiniscus granulatus (Doyre, 1840) and E. spinulosus (Doyre, 1840) are re-described based on multiple population data. Echiniscus lapponicus Thulin, 1911 and E. militaris Murray, 1911 are provided with the first SEM and molecular data, respectively. Following synonymies are made based on analyses of ample comparative material, type series, and redescriptions: E. blumi schizofilus Barto, 1941 syn. nov. and E. trojanus Maucci, 1973 syn. nov. of E. blumi blumi Richters, 1903; E. inocelatus Miheli, 1938 syn. nov., E. heterospinosus Maucci, 1954 syn. nov. and E. egnatiae Durante Pasa & Maucci, 1979 syn. nov. of E. granulatus; Echiniscus merokensis suecicus Thulin, 1911 syn. nov., E. columinis Murray, 1911 syn. nov., E. batramiae Iharos, 1936 syn. nov., E. jagodici Miheli, 1951 syn. nov. and E. laterospinosus Rudescu, 1964 syn. nov. of E. merokensis merokensis Richters, 1904; E. hexacanthus Maucci, 1973 syn. nov. of E. militaris Murray, 1911; E. carusoi Pilato, 1972 syn. nov. of E. spinulosus; E. osellai Maucci, 1974 syn. nov. of E. trisetosus Cunot, 1932. Two new nomina dubia are proposed: E. apuanus M. Bertolani, 1946 sp. dub. (and a probable synonymy with E. merokensis suggested) and E. pajstunensis Barto, 1941 sp. dub. Two new nomina inquirenda are established: E. marleyi Li, 2007 sp. inq. (another chaetotaxy-based morphotype of the Echiniscus blumi-canadensis complex) and E. punctus McInnes, 1995 sp. inq. (the lack of reliable morphological criteria separating it from E. granulatus). We summarise the morphological, phylogenetic and biogeographic information for the West Palaearctic Echiniscus species, and conclude with a total of 21 valid and identifiable taxa. We predict this number will decrease further with solving the species delimitation issues within the Echiniscus blumi-canadensis complex. Among these 21 taxa, 13 species (62%) are to be found solely in the Western Palaearctic and/or entire Holarctic regions. This augments the many recent findings that tardigrades are typically biogeographically structured and form clearly defined faunae.

High Mountain Echiniscid (Heterotardigrada) Fauna of Taiwan

Taiwan lies at the transitional zone between the East Palaearctic and Oriental regions, which translates into both Palaearctic and Indomalayan taxa being present on the island. Furthermore, large habitat heterogeneity and high mountains contributed to the rise of conditions favouring allopatric speciation and the emergence of endemic species. The tardigrade fauna of Taiwan is poorly studied, and the aim of this contribution is to provide new data on the members of the family Echiniscidae, the largest limno-terrestrial group of the class Heterotardigrada, found at high elevations in central Taiwan. We report 11 species grouped in 5 genera: Claxtonia (1 species), Echiniscus (3 species), Hypechiniscus (1 species), Nebularmis (2 species), and Pseudechiniscus (4 species). All are new to Taiwan, including 5 species that are new to science, 4 or which are described herein by means of integrative taxonomy: Hypechiniscus crassus sp. nov. (the exarmatus morphogroup), Pseudechiniscus (Meridioniscus) dreyeri sp. nov., Pseudechiniscus (Pseudechiniscus) formosus sp. nov., and Pseudechiniscus (Pseudechiniscus) totoro sp. nov. The new findings also help to clarify the description of Echiniscus clevelandi Beasley, 1999, and supplement the phylogenies of the Echiniscus virginicus complex and of the genera Hypechiniscus, Nebularmis and Pseudechiniscus.