Marine tardigrades of Princess Alice Bank (Azores, Northeast Atlantic) with a description of a new species of Quisarctus Fujimoto, 2015.

A new marine tardigrade, Quisarctus armatus sp. nov., found in samples from 151306 m depths at the Princess Alice Bank (PAB), south of the Azores archipelago, is described in this study. It is the second species in the genus and differs from its putative sister species Q. yasumurai by the shape of leg IV sensory organ, the presence of lipoid eyes, a partially folded cuticle of the digits and an elongated mouth cone. Quisarctus armatus sp. nov. shows sexual dimorphism with the length of primary clavae, the shape of leg IV sensory organ, and with differently shaped cirri E in females and males. The associated marine tardigrade fauna of PAB consists of Neostygarctus oceanopolis, Chrysoarctus briandi and representatives of Halechiniscidae. The known marine tardigrade fauna from the Azores now covers six genera with four identified species plus records of Halechiniscidae.