New record of <italic>Munidopsis taiwanica</italic> (Decapoda, Anomura) from a mud volcano field in the Mariana Trench, with in-situ observations on habitat.

Squat lobsters are prevalent in chemosynthetic environments but have been insufficiently studied in mud volcano habitats. An abyssal species, <italic>Munidopsis taiwanica</italic> Osawa, Lin & Chan, 2008 was recently collected in a mud volcano field in the Mariana Trench at a depth greater than 5000 m, which represents a new distributional record. Its diagnostic characters are presented in this study. In-situ observation suggested that <italic>M. taiwanica</italic> was closely associated with this chemosynthetic environment and probably exhibited camouflage behaviour by attaching seafloor sediments onto its body. <italic>Munidopsis taiwanica</italic> is the first confirmed species of squat lobster found in the mud volcano environment, and currently represents the deepest record (5491 m) of squat lobsters in the world. [ABSTRACT FROM AUTHOR]