title: Phylogenetic relationships within the Phyllidiidae (Opisthobranchia, Nudibranchia).
abstract: The Phyllidiidae (Gastropoda, Heterobranchia, Nudibranchia) is a family of colourful nudibranchs found on Indo-Pacific coral reefs. Despite the abundant and widespread occurrence of many species, their phylogenetic relationships are not well known. The present study is the first contribution to fill the gap in our knowledge on their phylogeny by combining morphological and molecular data. For that purpose 99 specimens belonging to 16 species were collected at two localities in Indonesia. They were photographed and used to make a phylogeny reconstruction based on newly obtained cytochrome oxidase subunit (COI) sequences as well as sequence data from GenBank. All mitochondrial 16S sequence data available from GenBank were used in a separate phylogeny reconstruction to obtain information for species we did not collect. COI data allowed the distinction of the genera and species, whereas the 16S data gave a mixed result with respect to the genera Phyllidia and Phyllidiella. Specimens which could be ascribed to species level based on their external morphology and colour patterns showed low variation in COI sequences, but there were two exceptions: three specimens identified as Phyllidia cf. babai represent two to three different species, while Phyllidiella pustulosa showed highly supported subclades. The barcoding marker COI also confirms that the species boundaries in morphologically highly variable species such as Phyllidia elegans, Phyllidia varicosa, and Phyllidiopsis krempfi, are correct as presently understood. In the COI as well as the 16S cladogram Phyllidiopsis cardinalis was located separately from all other Phyllidiidae, whereas Phyllidiopsis fissuratus was positioned alone from the Phyllidiella species by COI data only. Future studies on phyllidiid systematics should continue to combine morphological information with DNA sequences to obtain a clearer insight in their phylogeny.
authors.affiliation: Radboud University Nijmegen, Institute for Water and Wetland Research, Heyendaalseweg 135, 6525 AJ Nijmegen, The Netherlands; Naturalis Biodiversity Center, PO Box 9517, 2300 RA Leiden, The Netherlands.
authors.forename: Bart E M W
authors.initials: BE
authors.lastname: Stoffels
authors.affiliation: Naturalis Biodiversity Center, PO Box 9517, 2300 RA Leiden, The Netherlands; Oxford University Museum of Natural History, Parks Road, Oxford OX1 3PW, United Kingdom.
authors.forename: Sancia E T
authors.initials: SE
authors.lastname: van der Meij
authors.affiliation: Naturalis Biodiversity Center, PO Box 9517, 2300 RA Leiden, The Netherlands.
authors.forename: Bert W
authors.initials: BW
authors.lastname: Hoeksema
authors.affiliation: Naturalis Biodiversity Center, PO Box 9517, 2300 RA Leiden, The Netherlands.
authors.forename: Joris
authors.initials: J
authors.lastname: van Alphen
authors.affiliation: Radboud University Nijmegen, Institute for Water and Wetland Research, Heyendaalseweg 135, 6525 AJ Nijmegen, The Netherlands.
authors.forename: Theo
authors.initials: T
authors.lastname: van Alen
authors.affiliation: Radboud University Nijmegen, Institute for Water and Wetland Research, Heyendaalseweg 135, 6525 AJ Nijmegen, The Netherlands.
authors.forename: Maria Angelica
authors.initials: MA
authors.lastname: Meyers-Muñoz
authors.affiliation: Naturalis Biodiversity Center, PO Box 9517, 2300 RA Leiden, The Netherlands.
authors.forename: Nicole J
authors.initials: NJ
authors.lastname: de Voogd
authors.affiliation: Research Center for Oceanography (RCO), Indonesian Institute of Science (LIPI), Jl. Pasir Putih I, Ancol Timur, Jakarta 14430, Indonesia.
authors.forename: Yosephine
authors.initials: Y
authors.lastname: Tuti
authors.affiliation: Radboud University Nijmegen, Institute for Water and Wetland Research, Heyendaalseweg 135, 6525 AJ Nijmegen, The Netherlands; Naturalis Biodiversity Center, PO Box 9517, 2300 RA Leiden, The Netherlands.
authors.forename: Gerard
authors.initials: G
authors.lastname: van der Velde
keywords: 16S; COI; Indonesia; mtDNA; nudibranch; phylogenetic relations