Traditional Taxonomic Groupings Mask Evolutionary History: A Molecular Phylogeny and New Classification of the Chromodorid Nudibranchs

Abstract

Chromodorid nudibranchs (16 genera, 300+ species) are beautiful, brightly colored sea slugs found primarily in tropical coral reef habitats and subtropical coastal waters. The chromodorids are the most speciose family of opisthobranchs and one of the most diverse heterobranch clades. Chromodorids have the potential to be a model group with which to study diversification, color pattern evolution, are important source organisms in natural products chemistry and represent a stunning and widely compelling example of marine biodiversity. Here, we present the most complete molecular phylogeny of the chromodorid nudibranchs to date, with a broad sample of 244 specimens (142 new), representing 157 (106 new) chromodorid species, four actinocylcid species and four additional dorid species utilizing two mitochondrial markers (16s and COI). We confirmed the monophyly of the Chromodorididae and its sister group relationship with the Actinocyclidae. We were also able to, for the first time, test generic monophyly by including more than one member of all 14 of the non-monotypic chromodorid genera. Every one of these 14 traditional chromodorid genera are either non-monophyletic, or render another genus paraphyletic. Additionally, both the monotypic genera Verconia and Diversidoris are nested within clades. Based on data shown here, there are three individual species and five clades limited to the eastern Pacific and Atlantic Oceans (or just one of these ocean regions), while the majority of chromodorid clades and species are strictly Indo-Pacific in distribution. We present a new classification of the chromodorid nudibranchs. We use molecular data to untangle evolutionary relationships and retain a historical connection to traditional systematics by using generic names attached to type species as clade names.

Flashback and foreshadowing—a review of the taxon Opisthobranchia

“…Subsequently, multilocus analyses appeared utilizing a variety of nuclear and mitochondrial markers to unravel phylogenetic relationships within Opisthobranchia and subgroups (e.g. Wägele et al 2003;Grande et al 2004a, b;Vonnemann et al 2005;KlussmannKolb and Dinapoli 2006;Händeler and Wägele 2007;Händeler et al 2009;Malaquias et al 2009;Klussmann-Kolb 2010a, b, 2011;Maeda et al 2010;Pola and Gosliner 2010;Moore and Gosliner 2011;Johnson and Gosliner 2012;Pola et al 2012;Corse et al 2013;Carmona et al 2013, and many more) (Fig. 3a, b) or phylogenetic relationships of opisthobranch taxa within Euthyneura (Grande et al 2004b;Klussmann-Kolb et al 2008;Jörger et al 2010;Göbbeler and Klussmann-Kolb 2011;Dayrat et al 2011;Schrödl et al 2011a; (Fig.…”

The end of a long controversy: systematics of the genus Limenandra (Mollusca: Nudibranchia: Aeolidiidae)

“…However, Carmona et al (2013) found genetic differences between these two species (minimum uncorrected p-distance = 7.3 % for COI between L. nodosa and L. confusa, see Table 2 of that contribution). Recent studies supported by molecular phylogenies are starting to separate taxa with ecological or geographical differences (Claremont et al 2011;Johnson and Gosliner 2012). Clearly, both species have distinct geographical patterns (Atlantic-Mediterranean for L. nodosa and Pacific for L. confusa).…”

A new <em>Felimare</em> (Mollusca: Heterobranchia: Nudibranchia) of the Atlantic blue chromodorid chromatic group from Cape Verde

“…Marcus, 1967; Glossodoris Ehrenberg, 1831 and Chromodoris Alder and Hancock, 1855, both as part of the provisional genus 'Felimida' Ev. Marcus, 1971;and Risbecia Odhner, 1934, synonymized by Johnson and Gosliner (2012) with Hypselodoris. Ortea's et al (1996) review, however, did not include in this group other Atlantic species clearly belonging to the blue chromatic group, such as Felimare zebra (Heilprin, 1889) from Bermuda.…”

“…The Felimare genus was re-erected by Johnson and Gosliner (2012). According to these authors, Felimare should include all the eastern Pacific, Atlantic and Mediterranean species previously attributed to Hypselodoris as well as two species of Mexichromis (one from the eastern Pacific and one from the Caribbean).…”

“…According to these authors, Felimare should include all the eastern Pacific, Atlantic and Mediterranean species previously attributed to Hypselodoris as well as two species of Mexichromis (one from the eastern Pacific and one from the Caribbean). To date, there are 39 described species within the genus: 36 valid species of the genus Felimare sensu WORMS (Bouchet and Caballer 2015), and three species described as Hypselodoris sensu WORMS, but that according to the Johnson and Gosliner's (2012) hypothesis should be included in Felimare: Hypselodoris samueli Caballer and Ortea, 2012, Hypselodoris alaini Ortea, Espinosa and Buske, 2013, and Hypselodoris fregona Ortea and Caballer, 2013(Caballer and Ortea 2012, Ortea et al 2013. Recently, Furfaro et al (2016) raised a subspecies from the Atlantic blue chromodorid chromatic group, Felimare picta verdensis (Ortea, Valdés and García-Gómez, 1996), to species rank.…”