Back after 43 years: a new species of Actinarctus (Heterotardigrada, Tanarctidae) from the northeast coast of India

Abstract

Marine tardigrades from the Indian waters offer an important but largely overlooked component of regional biodiversity, and every new record contributes significantly to understanding their distribution and taxonomy. Expanding knowledge of this group, the present study describes a new species of Actinarctus Schulz, 1935 discovered nearly half a century after the last known addition to the genus, from the coastal region of Odisha along the northeast coast of India. This highlights the hidden diversity of marine meiofauna in the Indian subcontinent. The new species, Actinarctus odissi sp. nov., can be easily distinguished from its congeners by the structure and ornamentation of the dorsal body cuticle, shape and arrangements of lateral epicuticular alae, structure and length of leg IV sensory organ and primary clava, presence of Van der Land’s organ in the cephalic and leg sensory organs, occurrence of two small, circular, cushion-like structures between the bases of the internal and external digits.