A NEW SPECIES OF URODASYS (GASTROTRICHA, MACRODASYIDA) FROM DYSOXIC SEDIMENTS OF THE SANTA BARBARA BASIN (CALIFORNIA, U.S.A)

摘要

Numerous specimens belonging to an undescribed macrodasyid gastrotrich species were recovered during a survey of the biota associated with the severely dysoxic sedi- ments of the Santa Barbara Basin, off California, U.S.A. Densities of this species reach 10 specimens cm~-2. Urodasys anorektoxys sp. Nov. Is described and figured. Specimens of this taxon attain the largest size within the genus; body, excluding the motile tail, is up to 1100μm in length. Adults are protandric, then simultaneous hermaphrodites and lack a stylet-like sexual structure; the main morphological traits include (1) a unitary ventral ciliary field, and (2) a pharyngeal region that bears a total of 14 pairs of adhesive tubes, 12 pairs ventrolaterally and two pairs dorsolaterally. The systematic position of the new species is discussed.