Polychaeturidae Kielan−Jaworowska, 1966

Hints, Olle & Eriksson, Mats E., 2010, Ordovician polychaeturid polychaetes: Taxonomy, distribution and palaeoecology, Acta Palaeontologica Polonica 55 (2), pp. 309-320 : 310

Family Polychaeturidae Kielan−Jaworowska, 1966 Type genus: Polychaetura Kozłowski, 1956 , younger synonym of Pteropelta Eisenack, 1939 .

Discussion.—The family−level classification of Palaeozoic eunicidans was delineated by Kielan−Jaworowska (1966). The monotypic family Polychaeturidae was established particularly on the basis of the distinct carriers, left MI, the basal plate and anterior maxillae ( Kielan−Jaworowska 1966: 102). The general labidognath apparatus architecture of polychaeturids is nevertheless similar to that of polychaetaspids and ramphoprionids. Therefore, Kozur (1970) regarded Polychaeturidae as a synonym of Polychaetaspidae , and placed Pteropelta as a genus of the latter family. Edgar (1984) emended the diagnosis of the Polychaetaspidae to incorporate four genera (from three families sensu Kielan−Jaworowska 1966); Ramphoprion , Oenonites (= Polychaetaspis ), Kozlowskiprion , and Pteropelta (= Polychaetura ). Later Orensanz (1990) also supported that idea and used Polychaetaspidae sensu lato in his jaw−based phylogenetic analysis of extant and fossil eunicemorph polychaetes.

In our opinion polychaetaspids and ramphoprionids represent well−constrained phylogenetical groupings, each possessing distinct morphological characteristics. Moreover, since Kielan−Jaworowska’s (1966) monograph and the amendments subsequently suggested by Kozur (1970), Edgar (1984), and Orensanz (1990), additional genera have been described and assigned to both the Ramphoprionidae : “ Pararamphoprion ” Männil and Zaslavskaya, 1985, Protarabellites Stauffer, 1933 , and Megaramphoprion Eriksson, 2001 ; and the Polychaetaspidae : Dubichaetaspis Eriksson, 1998 and Incisiprion Hints, 1998 . If we now follow the amendments proposed by Kozur (1970), Edgar (1984), and Orensanz (1990) and lump all these genera—including Pteropelta —into Polychaetaspidae sensu lato, we would loose natural groupings of polychaetaspids and ramphoprionids and a useful rank in the classification hierarchy of fossil polychaetes would also become lost. A possible solution to the problem would be the application of an additional taxonomic rank, either subgenus or subfamily. Subgenera of fossil eunicidans have already been used by Bergman (1989) for paulinitids. His subgenus concept was, however, much narrower than would be in case of e.g., Dubichaetaspis , Incisiprion , or Megaramphoprion . Introduction of a subfamilial level (i.e., Polychaetaspinae, Ramphoprioninae, Polychaeturinae) could be more suitable. However, only a fraction of the early Palaeozoic jaw−bearing polychaetes is currently described and although Ordovician and Silurian faunas of Baltica and Laurentia are relatively well studied, those of other terranes are poorly known (see details in Hints and Eriksson 2007a). Therefore, many new genera and probably also families will be identified and described in the future. This may, in turn, considerably alter our view on the higher−level classification of early Palaeozoic jaw−bearing polychaetes. For these reasons we consider changing the classification of Kielan−Jaworowska (1966) premature and prefer, for the time being, to retain using Polychaeturidae at the family level.