Phylogenetic relationships within the Terebellidae (Polychaeta : Terebellida) based on morphological characters André R. S. Garraffoni A,B,C and Paulo C. Lana A A Centro de Estudos do Mar, Universidade Federal do Paraná, Av. Beira Mar s/n, CP 50002, Pontal do Paraná, PR 83255-000, Brazil. B Present address: Universidade Federal dos Vales do Jequitinhonha e Mucuri, Departamento de Ciências Biológicas, Campus II, Rodovia BR-367, CEP: 39.100-000, Diamantina, MG, Brazil. C Corresponding author. Email: garrafoni@gmail.com Abstract. Most of the recognised genera in Terebellidae lack phylogenetic support because their current diagnoses are based on homoplastic or plesiomorphic features. To address this problem, the phylogenetic relationships of terebellid genera were studied using a morphology-based parsimony analysis of 94 species, with members of the Ampharetidae and Alvinellidae as outgroups. The monophyly of the Terebellidae is supported by the presence of a prostomium shaped as a dorsal ridge-like structure, the prostomial buccal tentacles not retractable into the mouth and the ventral glandular areas having distinct pads. The subfamilies Polycirrinae, Terebellinae and Trichobranchinae are monophyletic. Species of Trichobranchinae form a clade within the Terebellidae, which provides further evidence to support its subfamily status. The lack of evidence to support Thelepodinae reinforces previous statements that this group is not monophyletic. Introduction Terebellids are tubicolous polychaetes found worldwide in shallow and deep waters (McHugh 1995; Hutchings 2000a, 2000b; Garraffoni et al. 2006). They are selective deposit feeders (Fauchald and Jumars 1979), using their long, grooved and ciliated buccal tentacles to collect sediments and organic matter (Hutchings 2000a, 2000b). Terebella lapidaria Linnaeus, 1767 was the first-described terebellid. Subsequently, Müller (1771) described Amphitrite cirrata and Amphitrite reniformis under the name Amphitritae. Grube (1850) was the first to assign a family name, Terebellacea, to the group, which included the genera Terebella, Terebellides Sars, 1830, Sabellides Milne-Edwards in Lamarck, 1838, Polycirrus Grube, 1850, Pectinaria Savigny in Lamarck, 1818, Amphicteis Grube, 1850 and Scalis Grube, 1846. The first revision of Terebellacea was undertaken by Malmgren (1866), who recognised the subfamilies Amphi- tritea, Polycirridea, Artacamacea, Trichobranchidea and Canephoridea, established 18 new genera and described 19 new species. As pointed out by Londoño-Mesa (2003), Malmgren (1867) was also the first to correct the spelling of the subfamilies to ‘inae’. Hessle (1917) erected four new genera, one new subfamily (Thelepinae), synonymised the genera Eureutho Malmgren, 1866 and Leucariste Malmgren, 1866 with Polycirrus, the subfamily Artacamacea with Amphitritinae, and the subfamily Canephoridea with Trichobranchidea, besides proposing the family rank for this last taxon, as Trichobranchidae. Hessle (1917) referred Octobranchus Marion & Bobretzsky, 1875 to Trichobranchidae. Fauvel (1927) again divided the family Trichobranchidae into two distinct subfamilies, Trichobran- chinae and Canephorinae, and revalidated the subfamily Artacaminae. Caullery (1944: 189) described a new species of Terebellides, without indicating to which subfamily this new species was allocated. Caullery (1944) described 40 new species and two new genera, Paralanice and Opisthopista, and designated Leucariste and Ereutho as subgenera of Polycirrus. The first worldwide catalogue of polychaetes (Hartman 1959) reported 46 valid genera with 318 species, changed the name of Amaea Malmgren, 1866 (preoccupied by a mollusk genus) to Amaeana and Polymnia Malmgren, 1867 to Eupolymnia, and again conferred a family status to Trichobranchidae. Day (1967) transferred the abranchiate genera of Amphitritinae (Leaena Malmgren, 1866, Spinosphaera Hessle, 1917, Lanassa Malmgren, 1866, Phisidia Saint-Joseph, 1894, Proclea Saint- Joseph, 1894 and Laphania Malmgren, 1866) to Polycirrinae, changed the subfamily name Amphitritinae to Terebellinae, considered the family Trichobranchidae as a subfamily (Trichobranchinae), and synonymised Artacaminae with Terebellinae, and the genus Pseudothelepus Augener, 1918 with Streblosoma Sars, 1872. Hartmann-Schröder (1971) revalidated the subfamily Artacaminae, considering it distinct from Amphitritinae, and again assigned a family status to Trichobranchidae. Holthe (1976) described the new genus Paramphitrite and corrected the name of the subfamily Thelepinae to Thelepodinae. Fauchald (1977) reported some genera that were not included in the family before, such as Pseudoampharete Hartmann- Schröder, 1960, Spiroverma Uchida, 1968, Terebellanice Hartmann-Schröder, 1962, Paraxionice Fauchald, 1972, Ó CSIRO 2008 10.1071/IS07006 1445-5226/08/060605 CSIRO PUBLISHING www.publish.csiro.au/journals/is Invertebrate Systematics, 2008, 22, 605–626