Abstract
Morphological and molecular data based on the COI gene were used to describe a new species of the colonial ascidian genus Pycnoclavella. The new species, P. stolonialis, is widespread sublittorally in the Irish Sea and also occurs on the western Irish coast, Wales and eastern England and may be locally common. It has been commonly known as the ‘pin head’ sea squirt since first recorded from Northern Ireland in 1984 but has not yet been formally described. P. stolonialis is the only described species of Pycnoclavella combining the presence of stolons, peribranchial incubation mode and a larva lacking an otolith. In addition, it features ca. 10% sequence divergence with the closest species of the genus in our phylogenetic trees. P. stolonialis showed intermediate characters between two groups of Pycnoclavella; the stanleyi and the aurilucens groups. Larval morphology and molecular data supported the inclusion of P. stolonialis within the aurilucens group, but the stolonial colony structure is characteristic of the stanleyi group. This implies that colony structure may not be a good character for separating these two groups. New information on distribution is given for P. atlantica, P. aurilucens and P. communis.References
Berrill, N.J. (1947) The structure, tadpole and budding of the ascidian Pycnoclavella aurilucens Garstang. Journal of the Marine Biological Association of UK, 27, 245–251.
Berrill, N.J. & Abbott, D.P. (1947) The structure or the ascidian, Pycnoclavella stanleyi n. sp., and the nature of its tadpole larva. Canadian Journal of Research 27: 43–49
Berrill, N.J. (1950) The Tunicata. Ray Society Publs. 133, 1–354
Brunetti, R. (1991) Pycnoclavella taureanensis n.sp. (Ascidiacea) from the Mediterranean Sea. Vie et Milieu, 41, 245–248.
Bunker, F.StP.D. & Holt, R.H.F. (2003) Survey of Sea Caves in Welsh Special Areas of Conservation 2000 to 2002. A report to the Countryside Council for Wales by MarineSeen, Pembrokeshire. CCW Marine Monitoring Report No: 6, 184pp.
Bunker, F.StP.D., Mercer, T., & Howson, C. (2004) Isle of Wight European Marine Site Sublittoral Monitoring 2003–2004. English Nature Contract FST20-46-16. English Nature, Peterborough, 56pp
Bunker, F. StP.D., Picton, B.E. & Morrow, C. (1992) New information on species and habitats in the Skomer Marine Nature Reserve (and other sites off the Pembrokeshire coast. A report to the Countryside Council for Wales from MarineSeen and the Ulster Museum. MarineSeen, Pembrokeshire, Wales.
Delsuc, F., Brinkmann, H., Chourrout, D. & Philippe, H. (2006) Tunicates and not cephalochordates are the closest living relatives of vertebrates. Nature, 439, 965–968.
Erwin, D.G., Picton, B.E., Connor, D.W., Howson, C.M., Gilleece & P. Bogues, M.J. (1986) The Northern Ireland Sublittoral Survey. Ulster Museum. Belfast.
Felsenstein, J. (1981) Evolutionary trees from DNA sequences: a maximum likelihood approach. Journal of Molecular Evolution, 17, 368–376.
Folmer, O., Black, M., Hoeh, W., Lutz, R. & Vrijenhoek, R. (1994) DNA primers for amplification of mitochondrial cytochrome c oxidase subunit I from diverse metazoan invertebrates. Molecular Marine Biology Biotechnology, 3, 294–299.
Garstang, W. (1891) Report on the Tunicata of Plymouth. 1. Clavelinidae, Perophoridae, Diazonidae. Journal of the Marine Biological Association of UK, 2, 47–67.
Goodbody, I. (1996) Pycnoclavella belizeana, a new species of ascidian from the Caribbean. Bulletin of Marine Science, 58, 590–597.
Goodwin, C.E., Picton, B.E., Breen, J. & Edwards, H. (2008). Sublittoral Survey Northern Ireland: A review of the status of Northern Ireland Priority Species of marine invertebrates. National Museums Northern Ireland/Northern Ireland Environment Agency, Belfast, 142pp.
Goodwin, C.E., Picton, B.E., Breen, J. & Edwards, H. (2009). The Maidens. Reports from the Sublittoral Survey Northern Ireland project 2006–2009. National Museums Northern Ireland/Northern Ireland Environment Agency, Belfast, 67pp.
Hall, T.A. (1999) BioEdit: a user-friendly biological sequence alignment editor and analysis program for Windows 95/ 98/NT. Nucleic Acids Symposium Series, 41, 95–98.
Huelsenbeck, J.P. & Ronquist, F. (2001) MRBAYES: Bayesian inference of phylogenetic trees. Bioinformatics,17, 754–755.
Kott, P. (1990) The Australian Ascidiacea. Part 2, Aplousobranchia (1). Memoirs of the Queensland Museum, 29, 299 pp.
Kott, P. (2003) New syntheses and new species in the Australian Ascidiacea. Journal of Natural History, 37, 1611–1653.
Kott, P. (2005) Pycnoclavella (Tunicata: Ascidiacea) species from the West Indian Ocean. African Zoology, 40, 205–212.
Millar, R.H. (1953) On a collection of ascidians from the Gold Coast. Proceedings of the Zoological Society of London, 123, 277–325.
Millar, R.H. (1960) Ascidiacea. Discovery Reports, 30, 1–160.
Monniot, C. (1997) Les genres Archidistoma et Clavelina (Ascidiacea, Clavelinidae) dans le canal du Mozambique. Zoosystema, 19, 193–209.
Monniot, F. (1988) Ascidies de Nouvelle-Caledonie. V. Polycitoridae du lagon. Bulletin du Museum national d’Histoire naturelle, Paris, ser. 4, 10, 197–235.
Monniot, F. & Monniot, C. (1996) New collection of ascidians from the Western Pacific and Southeastern Asia. Micronesica, 29, 133–279.
Pérès, J.M. (1953) Remarques systématiques et biologiques sur deux espèces de Clavelinidae (Ascidiacea, Aplousobranchia) de la région de Marseille. Reccueil des Travaux de la Station marine d’Endoume, 9, 67–71.
Pérez-Portela, R., Duran, S., Palacín, C. & Turon X (2007a) The Genus Pycnoclavella (Ascidiacea) in the Atlanto-Mediterranean region: a combined molecular and morphological approach. Invertebrate Systematics, 21, 187–205.
Pérez-Portela, R., Duran, S., Palacín, C. & Turon, X. (2007b) Biological traits of three closely related species of Pycnoclavella (Ascidiacea) in the Western Mediterranean. Marine Biology, 152, 1031–1038
Pérez-Portela, R. & Turon, X. (2008) Phylogeny of the Clavelinidae, Ascidiacea, inferred from mtDNA data. Invertebrate Biology, 127, 108–120.
Pérez-Portela R, Bishop J, Davis A & Turon X. (2009) Phylogeny of the families Pyuridae and Styelidae (Stolidobranchiata, Ascidiacea) inferred from mitochondrial and nuclear DNA sequences. Molecular Phylogenetics and Evolution, 50, 560–570
Picton, B.E. & Costello, M.J. (1998) BioMar biotope viewer: a guide to marine habitats, fauna and flora of Britain and Ireland, Dublin: Environmental Sciences Unit, Trinity College
Posada, D. & Crandall, K.A. (1998) MODELTEST: testing the model of DNA substitution. Bioinformatics, 14, 817–818.
Rostron, D.M. & Bunker, F.StP.D. (1997) An assessment of Sublittoral epibenthic rock communities and species following the Sea Empress oil spill. A report to the Countryside Council for Wales by MarineSeen, Pembrokeshire. 32pp
Swalla, B.J., Cameron, C.B., Corley, L.S. & Garey, J.R. (2000) Urochordates are monophyletic within the deuterostomes. Systematics Biology, 49, 52–64
Swofford, D.L. (2002) ‘PAUP*´, Phylogenetic Analysis Using Parsimony (*and Other Methods).’ Version 4, Sinauer Associates: Sunderland, MA, USA.
Trason, W.B. (1963) The life cycle and affinities of the colonial ascidian Pycnoclavella stanleyi. University of California Publications in Zoology, 65, 283–326.
Turbeville, J.M., Schulz, J.R. & Raff, R.A. (1994) Deuterostome phylogeny and the sister group of the chordates: evidence from molecules and morphology. Molecular Biology and Evolution, 11, 648–655.
Turon, X. (1987) Estudio de las ascidias de las costas de Cataluña e Islas Baleares. Ph.D. Thesis, University of Barcelona, Spain, 353pp
Turon, X. (1988) The ascidians of Tossa de Mar (NE Spain). II. Biological cycles of the colonial species. Cahiers de Biologie Marine, 29, 407–418
Turon, X. & López-Legentil, S. (2004) Ascidian molecular phylogeny inferred from mtDNA data with emphasis on the Aplousobranchiata. Molecular Phylogenetics and Evolution, 33, 309–320.
Wada, H. (1998) Evolutionary history of free-swimming and sessile lifestyles in Urochordates as deduced from 18SrDNA molecular phylogeny. Molecular Biology and Evolution, 15, 1189–1194
Zeng, L. & Swalla, B.J. (2005) Molecular phylogeny of the protochordates: chordate evolution. Canadian Journal of Zoology, 83, 24–33.
Zeng, L., Jacobs, M.W. & Swalla, B.J. (2006) Coloniality has evolved once in Stolidobranch Ascidians. Integrative and Comparative Biology, 46, 255–268.