An interesting new gastrotrich from littoral meiobenthos (Long Beach Island, USA), with a key to species of Tetranchyroderma (Gastrotricha: Macrodasyida)

Abstract

Marine representatives of the phylum Gastrotricha are reported for the first time from the State of New Jersey, USA. Littoral and shallow sublittoral sediment collected at Ship Bottom on Long Beach Island, near Atlantic City, yielded 11 species belonging to eight genera in six families in the orders Macrodasyida (four genera in three families) and Chaetonotida (four genera in three families). Littoral samples were richer than the one sublittoral sample (7 vs 4 spp.). Among the taxa was a large, undescribed species of Tetranchyroderma characterized by the following key traits: total body length up to 605 μm; cuticular covering complete, made up of pentancres; a pair of cephalic tentacles; dorsal adhesive tubes arranged in dorsal and dorsolateral columns; a pair of ventral adhesive tubes arising from a common base, near the perigenital area only on the right side; peculiar cuticular openings ‘stomata’ along the ventrolateral margins of the body; protogynous hermaphroditism. Tetranchyroderma weissi sp. nov. is, at least in the investigated location, restricted to the sediment layers below 20 cm of the intertidal zone, and is able to live in thiobiotic sediment. A key to the described species of the world based on easily discernible traits, visible in both living and formalin-fixed specimens is provided.