A trans-isthmus survey of marine tardigrades from Costa Rica (Central America) with descriptions of seven new species

The Central American Isthmus has had profound effects on the evolution and distribution of larger marine organisms, but the impacts on meiobenthic animals have received little attention. Tardigrades are microscopic metazoan lobopodians that are ubiquitous in benthic communities worldwide, but little is known about marine tardigrades in Central America. Only two marine tardigrades have been identified to species level in all of Central America, and these came from a single sample of barnacles from El Salvador collected in 1953. Additionally, multiple haplotypes of <i>Echiniscoides</i> were reported from Costa Rica and Panama, but species names were not assigned. Here we report an extensive survey of both intertidal and subtidal marine tardigrades from both the Caribbean and Pacific coasts of Costa Rica. We found 701 individuals in 65 samples. There was a total of 19 taxa, including seven species with a sufficient quality and quantity of specimens to describe here as new to science. The new species are <i>Archechiniscus murilloi</i> sp. nov., <i>Batillipes homocercus</i> sp. nov., <i>Batillipes ichthyocercus</i> sp. nov., <i>Echiniscoides costaricensis</i> sp. nov., <i>Echiniscoides ritavargasae</i> sp. nov., <i>Styraconyx vargasi</i> sp. nov. and <i>Tanarctus breedyae</i> sp. nov. Ten taxa were found only in the Caribbean, six were found only in the Pacific, and three were found on both coasts. We discuss the three species with trans-isthmus distributions and note two additional candidate geminate species pairs that warrant further investigation.