Echiniscus quasiporus sp. nov. reveals a new type of cuticular plate puncturing in Echiniscoidea (Heterotardigrada)
摘要
Chaetotaxy (morphology and the arrangement of body appendages) and cuticular sculpturing provide key taxonomic traits in Echiniscidae, the most diverse limnoterrestrial heterotardigrade family. Historically, more attention was given to chaetotaxy, but with time cuticular sculpturing proved to bear a stronger phylogenetic signal. To date, two types of cuticular puncturing have been recognised: pseudopores (shallow exocuticular pits which appear in phase contrast microscopy, PCM, as blurred bright dots) and pores (canals that connect the environment with mesocuticular cavity network and which appear as sharp bright dots in PCM). In this study, we integratively describe Echiniscus quasiporus sp. nov. exhibiting a new type of cuticular puncturing, quasipores, which are deep cavities in exocuticle indistinguishable from pores neither under PCM nor via scanning electron microscopy (SEM) imaging of the cuticle surface, yet they do not connect the environment with mesocuticular cavity network. The morphology of quasipores became apparent only using a 3D analysis of cuticular structure in SEM. The new species was found in the Western Ghats of India, a global biodiversity hotspot, of which tardigrade fauna is extremely poorly known.