A NEW GENUS AND SPECIES OF DORVILLEIDAE (ANNELIDA, POLYCHAETA) FROM BERMUDA, WITH A PHYLOGENETIC ANALYSIS OF DORVILLEIDAE, IPHITIMIDAE AND DINOPHILIDAE

Neotenotrocha sterreri gen. et sp. n. is described from Bermuda. It is a gonochoristic, interstitial polychaete exhibiting sexual dimorphism . The maximum length of males is only 140 mum, while females may be up to 255 mum long. They are thus the smallest polychaetes known to cont ain a mature ovary. The new species is referred to the polychaete fami ly Dorvilleidae, primarily due to the presence of a ctenognath jaw app aratus. In almost all external characters the new form is strongly red uced, lacking parapodia, setae, antennae, and palps, whereas larval ch aracters such as trochae and a neurotroch are retained in adults. In t he light of earlier literature on phylogeny within Dorvilleidae and th e likelihood that Iphitimidae and Dinophilidae are closely affiliated with the latter family, the unique combination of characters in Neoten otrocha is of special interest. A phylogenetic analysis of all apparen tly valid genera in the three families leads to the hypothesis that Di nophilidae and Iphitimidae represent monophyletic and paraphyletic sub groups, respectively, within Dorvilleidae. Accordingly, the definition of Dorvilleidae is emended and a key to the genera provided. The spec ies Ougia macilenta (Oug, 1978) is referred to Parougia Wolf, 1986 and the generic status of Meiodorvillea apalpata Jumars, 1974 and Protodo rvillea gaspeensis Pettibone, 1961 is discussed. Some remarks on the a pplicability of concepts such as neoteny and progenesis in the charact erization of interstitial dorvilleids are included. On the basis of th e cladogram and these considerations, it is hypothesized that this gro up may have originated in a single evolutionary event.