The new species of Dactylobiotus (Parachela, Eutardigrada) from King George Island, Antarctica

Abstract

Phylum Tardigrada is a minute, hydrophilous animal group with a five segmented body which consists of a head and four trunk segments. This phylum is famous for the ability to survive the severe conditions such as cold, dry, or high radiation environments. The limno-terrestrial tardigrades are one of the dominant animal groups in the terrestrial ecosystem of Antarctica. However, due to their limited morphological characteristics and restricted access to the habitats, taxonomic study on Antarctic tardigrades is difficult to carry out. KOPRI ecology team collected several species of tardigrades from King George Island, Antarctica during 2014-2015 season expedition. Among the collected tardigrades, one species shows a bucco-pharyngeal apparatus with 10 peribuccal papillae reminiscent of Macrobiotus-type and the cuticular connection between claws, which are characteristics of the genus Dactylobiotus. This species is large in size (600-700 μm) with smooth cuticle and no conical papillae between 3rd and 4th limbs. Key morphological characters of bucco-pharyngeal apparatus and claws are being measured, and pt ratio (the ratio of the length of a given structure to the length of the buccal tube) are compared to that of other Dactylobiotus speciesto see whether the species is a previously reported Dactylobiotus species documented in other regions around the world, or a new species.