Abstract
A new genus of Sabellidae (Annelida, Polychaeta), collected in the soft bottoms off the Antarctic Peninsula (Antarctica) in January 2006 is described. The new genus Euchoneira is included in the most plesiomorphic area in the sub-family Sabellinae. Similar to the genus Euchone, this new taxon presents a well developed anal depression with lateral wings, but the shape of abdominal uncini resembles that of Jasmineira. The new species Euchoneira knoxi gen. sp. nov., very abundant in the investigated area, is a gonochoric form (sex-ratio close 1:1). Females contained eggs ranging from 100 to 250 µm in diameter (modal class 175 µm) either in the abdomen or thorax. Males with mature sperm had spermatozoa with a characteristic cylindrical shape of the nucleus with a pointed, “nip-like” acrosome, a morphology similar to that already observed in Euchone pallida Ehlers, 1908, a second species collected together with the new taxon and already known for the Antarctic area. Additions to the description of E. pallida concerning internal structure of the crown, is also given. To define the relationships between the newly described genus and the genera present in the plesiomorphic area of the Sabellinae subfamily, a cladistic analysis was performed utilizing a previous data set after adding the new taxon. The consensus tree confirmed Amphicorina armandi (Claparéde, 1868) as the most plesiomorphic taxon separated from all the others. The new genus is located in an intermediate position between Jasmineira - Claviramus and the clade containing Chone and Euchone species, close to Fabrisabella vasculosa.References
Banse, K. (1972) Redescription of some species of Chone Kröyer and Euchone Malmgren, and three new species (Sabellidae, Polychaeta). Fishery Bulletin, 70, 459–495.
Bick.A., & Randel, N. (2005) Ontogenetic variations in characters of Euchone analis (Krøyer, 1856) (Polychaeta, Sabellidae, Sabellinae) from Spitsbergen, and new assignments of Oriopsis ingelorae Plate, 1995 and O. liefdefjordensis Plate, 1995. Acta Zoologica, 86, 145–157.
Cochrane, S.J. (2003) Snowflakes and feather-dusters – some challenges for soft-bottom fanworm systematics. Hydrobiologia, 496, 49–62.
Fitzhugh, K. (1989) A systematic revision of the Sabellidae-Caobangidae-Sabellongidae complex (Annelida: Polychaeta). Bulletin of the American Museum of Natural History, 192, 1–104.
Fitzhugh, K. (2002) Fan worm polychaetes (Sabellidae: Sabellinae) collected during the Thai-Danish BIOSHELF Project. Phuket Marine Biological Center Special Publication, 24, 353–424.
Fitzhugh, K. (2003) A new species of Megalomma Johansson, 1927 (Polychaeta: Sabellidae: Sabellinae) from Taiwan, with comments on sabellid dorsal lip classification. Zoological Studies, 42(1), 106–134.
Gambi, M.C., Patti, F., Micaletto, G., & Giangrande, A. (2001) Diversity of reproductive features in some antarctic polynoid and sabellid polychaetes, with the description of Demonax polarsterni n.sp. (Polychaeta: Sabellidae). Polar Biology, 24, 883–891.
Giangrande, A. (1992) The genus Chone (Polychaeta, Sabellidae) in the Mediterranean Sea with description of C. longiseta n. sp. Bollettino di Zoologia, 59, 517–529.
Giangrande, A. & Licciano, M. (2006) The genus Euchone (Polychaeta, Sabellidae) in the Mediterranean Sea, addition of two new species and discussion on some closely related taxa. Journal of Natural History, 40(21), 1301–1330.
Hofsommer, A. (1913) Die Sabellidien-ausbeute der Poseidon-Fahrten und die Sabellidien der Kieler Bucht. Wissenschaftliche Meeresunters. Abteilung Kiel, 15, 305-364.
Krøyer, H. (1856) Meddelelser af en Afhandling om Ormelslaegten Sabella Linn., isaer med Hensyn till dens nordiske Arter. Oversigt over det Kongelige Danske Videnskabernes Selskabs Forhandlinger, 1856, 1–36.
Maddison, W.P. & Maddison, D.R. (1999) MacClade Version 3,08. Sinaur Associates, Sunderland, Massachussets.
Malmgren, A.J. (1866) Nordiska Hafs-Annulater. Öfversigt af Kongliga Vetenskaps-Akademiens Förhandlingar Stockholm, 22, 355–410.
Orrhage, L. (1980) On the structure and homologues of the anterior end of the polychaete families Sabellidae and Serpulidae. Zoomorphology, 96, 113–168.
Patti, F.P., Gambi, M.C. & Giangrande, A. (2003) Preliminary study on the systematic relationships of Sabellinae (Polychaeta: Sabellidae), based on the C1 domain of the 28S rDNA, with discussion of reproductive features. Italian Journal of Zoology, 70, 269–278.
Rouse, G.W. (1999) Polychaete sperm: phylogenetic and functional considerations. Hydrobiologia, 402, 215–224.
Saiz–Salinas, J.I., García, F.J., Manjón-Cabeza, M.E., Parapar, J., Peña-Cantero, A., Saucède, T., Troncoso, J.S. & Ramos, A. (2008) Community structure and spatial distribution of benthic fauna in the Bellingshausen Sea (West Antarctica). Polar Biology, 31, 735–743.
Swofford, D.L. (1999) PAUP*. Phylogenetic analysis using parsimony (* and other methods). Version 4. Sinaur Associates, Sunderland, Massachusets, USA.
Tovar-Hernández, M.A. & Sosa-Rodríguez, T. (2006) Redescription of Chone infundibuliformis Krøyer, 1856 (Polychaeta: Sabellidae) and histology of the branchial crown appendages, collar and glandular ridge. Zootaxa, 1115, 31–59.
Tovar-Hernández, M.A., Licciano, M., & Giangrande, A. (2007) Revision of Chone (Polychaeta: Sabellidae) from the Eastern Central Atlantic and Mediterranean Sea with description of two new species. Scientia Marina, 71(2), 315–338.
Tovar-Hernández, M.A. (2008) Phylogeny of Chone Krøyer, 1856 (Polychaeta: Sabellidae) and related genera. Journal of Natural History, 42(33–34), 2193–2226.