Cryptic diversity, intraspecific phenetic plasticity and recent geographical translocations inBranchiomma(Sabellidae, Annelida)

Abstract

The importance of identifying biological diversity accurately and efficiently is becoming more evident. It is therefore critical to determine the species boundaries between closely related taxa and to establish diagnostic characters that allow us to define species. This is not an easy task when species exhibit high intraspecific phenotypic plasticity or when distinct evolutionary lineages with an unusually large amount of genetic distinctiveness show no apparent morphological diversity (cryptic species). These phenomena appear to be common in the genus of fan worms Branchiomma (Sabellidae, Annelida) and consequently taxonomic errors are widespread in the group. Moreover, some Branchiomma species have been unintentionally translocated outside the area where natural range extension is expected, increasing the taxonomic problems. We have performed a range of analytical methods including genetic distances, Bayesian Interference, maximum likelihood, maximum parsimony, statistical parsimony analyses and general mixed Yule coalescent model to clarify the taxonomic status and asses the species boundaries of Branchiomma in Australia. This study shows that the traditional diagnostic morphological features are greatly homoplastic. Results also indicate that the diversity of Branchiomma in Australia is Capa 2 higher than previously reported and evidence some cases of high phenetic plasticity (in features previously considered as stable within species), high intraspecific genetic variability, cryptic species and several unexpected cases of translocations. Corresponding author: María Capa, Museum of Natural History and Archaeology,Norwegian University of Sciences and Technology, maria.capa@ntnu.no.María Capa, Australian Museum, Sydney NSW 2010, Australia. E-mail: maria.capa@ntnu.no. Avanzados, 21, Balearic Islands, Pat Hutchings, Australian Museum, Sydney NSW 2010, Australia. E-mail: pat.hutchings@austmus.gov.au. Joan Pons, IMEDEA (CSIC-UIB), Instituto Mediterráneo de Estudios Capa 3 IntroductionThe genus Branchiomma is a homogeneous group of fan worms (Sabellidae, Annelida) characterised by the presence of paired compound eyes and stylodes alternating along the radioles ( Figs 1A-B, 2). The stylodes are epithelial appendages directed outwards of the radiolar crown, unique amongst members of Sabellidae and their shape and relative length between the radioles (Fig. 1A-G) is considered to be one of the main specific diagnostic features (Knight-Jones, 1994;Tovar-Hernández & Knight-Jones, 2006). There are currently around 30 nominal species of Branchiomma (Tovar-Hernández & Dean, 2010) described from a variety of shallow water environments, ranging from fine sediments to hard substrates and from many localities around the world. Some of these nominal species are well defined morphologically with precise data about their reproductive strategies, ecology and geographic distribution being available (e.g. Sordino & Gambi, 1992;Licciano et al., 2002;Tovar-Hernández & Knight-Jones, 2006;Licciano & Giangrande, 2008; TovarHernán...

A taxonomic guide to the fanworms (Sabellidae, Annelida) of Lizard Island, Great Barrier Reef, Australia, including new species and new records

“…This species was characterised and defined by molecular markers as Branchiomma sp. D (in Capa et al 2013). Some of the diagnostic morphological features of this species are the presence of a posterior peristomial ring collar with wide separated dorsal margins, the digitiform stylodes along radioles, with one or two pairs that are about twice as long as their neighbours and flattened and thoracic uncini with two rows of small teeth over the main fang.…”

“…Branchiomma bairdi is distinguished from other congeners by the presence of strap-like and long macrostylodes (up to four times the length of the neighbouring digitiform stylodes, not so large in small specimens), and the colour pattern, with olive-green bodies and conspicuous bright orange spots alternating with radiolar eyes. This species was originally described from the Caribbean but has recently been reported is other biogeographical areas as an invasive species (Tovar-Hernández et al 2009Arias et al 2013;Capa et al 2013;Capa 2014). First record from Lizard Island.…”

“…Of course, many other species were known to inhabit the archipelago waters but had not been recorded in the literature. Other taxonomic or faunistic studies reporting sabellids from nearby localities within the Great Barrier Reef include Rouse (1990), Hartmann-Schröder (1991), Knight-Jones & Mackie (2003), Capa (2007) and Capa et al (2011Capa et al ( , 2013, increasing the total number of sabellid species documented for this area to 12.…”

Kimberley marine biota. Historical data: polychaetes (Annelida)

“…Some widespread polychaetes are being shown to represent suites of cryptic species (Carlton 2009;Capa et al 2013). For example, some current work on nereidids has shown that using both morphological and molecular data to redefine species boundaries considerably reduces the distributional ranges (Glasby et al 2013).…”

“…While polychaete collections were historically preserved in formalin, contemporary collection practice now routinely preserves material in ethanol to enable subsequent genetic studies, which are changing our taxonomic concepts -see for example Capa et al (2010Capa et al ( , 2013 and Wei et al (2013). Such studies are expected to continue and the contemporary surveys underway (2009)(2010)(2011)(2012)(2013)(2014) in the Project Area are undertaking such practices.…”