Echiniscidae in the Mascarenes: the wonders of Mauritius

Abstract

Many regions of the world remain unexplored in terms of the tardigrade diversity, and the islands of the Indian Ocean are no exception. In this work, we report four species of the family Echiniscidae representing three genera from Mauritius, the second largest island in the Mascarene Archipelago. Two species belong in the genus Echiniscus: Echiniscus perarmatus Murray, 1907, a pantropical species, and one new species: Echiniscus insularissp. nov., one of the smallest members of the spinulosus group and the entire genus, being particularly interesting due to the presence of males and supernumerary teeth-like spicules along the margins of the dorsal plates. The new species most closely resembles Echiniscus tropicalis Binda & Pilato, 1995, for which we present extensive multipopulation data and greatly extend its distribution eastwards towards islands of Southeast Asia. Pseudechiniscus (Meridioniscus) mascarenensissp. nov. is a typical member of the subgenus with elongated (dactyloid) cephalic papillae and the pseudosegmental plate IV’ with reduced posterior projections in males. Finally, a Bryodelphax specimen is also recorded. The assemblage of both presumably endemic and widely distributed tardigrade species in Mauritius fits the recent emerging biogeographic patterns for this group of micrometazoans.

An integrative redescription of Echiniscus quadrispinosus quadrispinosus Richters, 1902 (Heterotardigrada, Echiniscidae) from the terra typica in Taunus Mountain Range (Europe; Germany)

“…Echiniscus q. cribrosus and E. q. fissispinosus differ from the nominal species by the absence of 'supplementary plates', which are in fact separated parts of paired plates I and II in E. q. quadrispinosus. Such pseudoplates are often present in other species of Echiniscus (see e.g., Claxton 1996;Kaczmarek & Michalczyk 2010;Claxton & Dastych 2017;Gąsiorek & Kristensen 2018;Bartylak et al 2019;Gąsiorek & Vončina 2019;Gąsiorek & Michalczyk 2020b;Gąsiorek et al 2020;Kiosya et al 2021). Additionally, some differences were also reported in chaetotaxy (e.g., lacking of appendages B, reduced or absent lateral or dorsal appendages).…”

Two new Bryodelphax Thulin, 1928 species (Heterotardigrada: Echiniscidae) from the Republic of Ireland with comments on the ‘weglarskae group’ and other heterotardigrade taxa, including the controversial genus Bryochoerus Marcus,1936

“…Schuster (1975) and some recent authors have mentioned the anus in species descriptions in general terms e.g. "large tripartite anus" (Gąsiorek et al, 2019b) or "trilobed anus" for diverse taxa (Gąsiorek et al, 2020b;Vončina et al, 2020;Kiosya et al, 2021;Gąsiorek et al, 2021c). Guidetti et al (2014) included an anus focused SEM micrograph of Mopsechiniscus franciscae Guidetti, Rebecchi, Cesari and McInnes, 2014 but analysis of the anal structures was not included in the description.…”