title: Jaw morphology and ontogeny in five species of Ophryotrocha.
abstract: Detailed scanning electron microscopy of jaws within the genus Ophryotrocha (Dorvilleidae, Annelida) was performed on 871 jaw parts. The investigations resulted in new understandings of the ontogeny and jaw morphology and have systematic implications for the family. Five species in the genus (Ophryotrocha alborana, O. diadema, O. gracilis, O. hartmanni, and O. labronica pacifica) were kept in culture, and the development of the jaws was studied by sampling throughout their life history. Ophryotrocha species have mandibular plates that remain the same throughout ontogeny, whereas the posterior shafts elongate. Both mandibular plate morphology and shaft ontogeny have species-specific distinctions. In Ophryotrocha, the maxillae can be assigned to three to four distinct types, which are replaced by moulting. The maxillary morphology and developmental stages at which moults occur are species specific, although with broad intervals. A redefinition is given for some of the basic jaw elements, and new homologies are proposed for structures that are also present across other dorvilleid taxa.
authors.affiliation: Marine Biological Laboratory, University of Copenhagen, DK-3000 Helsingør, Denmark. momacnaughton@snm.ku.dk
authors.forename: Martin Oliver
authors.initials: MO
authors.lastname: Macnaughton
authors.forename: Katrine
authors.initials: K
authors.lastname: Worsaae
authors.forename: Danny
authors.initials: D
authors.lastname: Eibye-Jacobsen
mesh_terms: D000818:Animals; D007568:Jaw / Q000033:anatomy & histology* / Q000648:ultrastructure; D008334:Mandible / Q000033:anatomy & histology / Q000254:growth & development; D008437:Maxilla / Q000033:anatomy & histology / Q000254:growth & development; D011077:Polychaeta / Q000033:anatomy & histology* / Q000254:growth & development* / Q000648:ultrastructure