Integrative taxonomy in Syllis prolifera (Annelida, Syllidae): from a unique cosmopolitan species to a complex of pseudocryptic species.

Syllis prolifera (Syllidae, Syllinae) is an abundant species of marine annelids commonly found in warm to temperate waters worldwide. Although morphological variability occurs among populations, S. prolifera has long been considered a cosmopolitan species, widely distributed in coastal environments, including acidified and polluted areas. However, the increasing number of cases of cryptic and pseudocryptic speciation in several polychaete families in recent years has led us to question whether S. prolifera represents a single globally distributed taxon or is a species complex. To address this question, we conducted an integrative study, combining morphological, ecological and molecular data of 52 S. prolifera specimens collected in different localities across the western Mediterranean Sea and the Gulf of Cadiz. Our phylogenetic and species delimitation analyses that included two mitochondrial DNA markers (COI and 16S rRNA ) were congruent in not considering S. prolifera a unique entity. Five distinct lineages that can also be recognised by certain morphological and ecological traits were identified from these analyses instead. Overall, our study does not support the homogeneity of S. prolifera across the Mediterranean Sea, providing a new example of pseudocrypticism in marine invertebrates.

New mitogenomes of Runcinidae and Facelinidae: two understudied heterobranch families (Mollusca: Gastropoda).

Here, we present the mitochondrial sequences of two sea slugs (Heterobranchia): Runcina aurata and Facelina auriculata, the latter being the type species of the family. The mitochondrial genomes are 14,282 and 14,171bp in length, respectively, with a complete set of 13 PCGs, 2 rRNAs, and 22 tRNAs. None of the mitogenomes show gene reorganization, keeping the standard mitogenomic structure of Heterobranchia. Nucleotide composition differs significantly between them, with R. aurata showing the most AT-rich mitogenome (25.7% GC content) reported to date in Heterobranchia, and F. auriculata showing a rich GC content (35%) compared with other heterobranch mitochondrial genomes.

Attack on crypsis: Molecular and morphological study of Dendrodoris Ehrenberg, 1831 (Mollusca: Gastropoda: Nudibranchia) from the Mediterranean Sea and Northern Atlantic Ocean reinstates Dendrodoris temarana Pruvot-Fol, 1953.

The genus Dendrodoris is ascribed to the family Dendrodorididae, whose members are characterized lacking spicules in the dorsum as well as a radula, one of the most important taxonomic traits to distinguish and define nudibranch species. The absence of this taxonomic character makes difficult to delineate species based on morphologic traits, and consequently, several cryptic species may remain unreported resulting in a potential underestimation of the real diversity of the genus. Species delimitation analyses based on molecular data constitute an important tool to unveil cryptic species, especially when morphology may be misleading. However, for the genus Dendrodoris, only two molecular studies have been performed to date, both based on Indo-pacific species and the molecular marker COI. In the present study, we performed a multilocus approach using the molecular markers COI, 16S and H3 based on 47 Dendrodoris specimens from the North Atlantic Ocean and Mediterranean Sea. As a result, we detected monophyly for five of the previously accepted species plus the presence of an unidentified one. Using morphological and anatomical data from 14 additional individuals and a review of the literature, we verified this unidentified species is the previously synonymized species Dendrodoris temarana Pruvot-Fol, 1953, and we redescribe it morphologically (chromatic pattern, gills, rhinophores and anal papilla), anatomically (neural, circulatory, digestive and reproductive systems), and biologically herein. D. temarana is differentiated by its chromatic pattern, previously thought to be intraspecific variation of D. grandiflora (Rapp, 1827), D. limbata (Cuvier, 1804) and D. herytra Valds Ortea in Valds, Ortea, Avila Ballesteros, 1996, and therefore it is considered a pseudocryptic species. This study increases the number of valid species in the North Atlantic and Mediterranean to nine and confirms the importance of integrative taxonomic approaches to resolve the identification of cryptic species in complex groups.

A molecular phylogeny of Thuridilla Bergh, 1872 sea slugs (Gastropoda, Sacoglossa) reveals a case of flamboyant and cryptic radiation in the marine realm.

The genus Thuridilla Bergh, 1872 comprises mostly tropical sap-sucking sea slugs species with flamboyantly coloured forms. However, the potential for cryptic or pseudocryptic species masked by convergent or polymorphic colour patterns has not been tested using molecular characters. In this study, we sampled 20 of the 23 recognized worldwide species and performed the most comprehensive molecular phylogenetic analysis of the genus to date using a multi-locus approach combining two mitochondrial (cytochrome c oxidase subunit I, 16S rRNA) and two nuclear (Histone H3, 28S rRNA) genes using maximum likelihood, maximum-parsimony and Bayesian criteria. Three molecular species delimitation methods (ABGD, GMYC, bPTP) and the morphology of radular teeth were additionally used to aid in species delimitation. Our analyses supported 35 species within Thuridilla, of which more than one-third (13) are part of a single radiation here named the Thuridilla gracilis (Risbec, 1928) species-complex. This complex includes T. gracilis, T. splendens (Baba, 1949), T. bayeri (Er. Marcus, 1965), and T. ratna (Er. Marcus, 1965), plus nine additional undescribed species. All 13 species are distinguishable by radular characters, external morphology and their DNA. The detection of this radiation led diversity of Thuridilla to be underestimated by about 25% and provides a new comparative system for studying the role of colour patterns in marine diversification.

Redescription of a forgotten nudibranch Miamira striata (Eliot, 1904) and review of the taxonomic status of the genus Orodoris (Nudibranchia: Chromodorididae: Miamirinae).

The genus Orodoris Bergh, 1875 is a small genus that together with Miamira Bergh, 1875, was considered as a junior synonym of Ceratosoma A. Adams Reeve, 1850. This decision was based on a morphological phylogenetic study conducted in 1999 that recovered the monophyly of the Ceratosoma. However, in 2012, molecular evidences led to the resurrection of Miamira, while Orodoris was retained as a junior synonym of Miamira with no further details. Here we revise the status of the genus Orodoris in light of the rediscovery of M. striata (syn. Orodoris striata Eliot, 1904). Our phylogenetic analysis revealed a close sister relationship between Miamira striata and Miamira miamirana Bergh, 1875 which nested within the Miamira clade. Therefore, to retain the monophyly of Miamira, the genus Orodoris should be maintained as a junior synonym of the former. This study proposes a neotype for M. striata and underscores the importance of reviewing historical taxonomic changes and investigating ancient descriptions prior to describing new taxa. Our study also confirms that Miamira magnifica Eliot, 1910 from the Indian Ocean and Miamira flavicostata Baba, 1940 from the Pacific Ocean represent two distinct, sister species.

Astonishing diversity revealed: an annotated and illustrated inventory of Nudipleura (Gastropoda: Heterobranchia) from Mozambique.

This paper provides the first comprehensive annotated and illustrated inventory of Nudipleura from Mozambique. A total of 267 species are recorded, including 61 putative new species, documented over a period of seven years from several localities along the coast. At least 20 species need further investigation through molecular and taxomic analysis. Of the 186 confirmed described species, 118 are new records for the Mozambican fauna. Sampling was carried in tidal reefs and depths up to 60m on the subtropical and tropical coast of Mozambique. The most representative families were Chromodorididae (69 species), Discodorididae (30 species), Facelinidae (23 species) and Phyllididae (16 species). Nevertheless, a vast area of Mozambique remains unexplored, thus it is likely that the species documented here represent only a fraction of the true Nudipleura diversity of the country.

A test of color-based taxonomy in nudibranchs: Molecular phylogeny and species delimitation of the Felimida clenchi (Mollusca: Chromodorididae) species complex.

Traditionally, species identification in nudibranch gastropods relies heavily on body color pattern. The Felimida clenchi species complex, a group of brightly colored Atlantic and Mediterranean species in the family Chromodorididae, has a history of exceptional controversy and discussion among taxonomists. The most widely accepted hypothesis is that the complex includes four species (Felimida clenchi, F. neona, F. binza and F. britoi), each with a characteristic body color pattern. In this study, we investigated the taxonomic value of coloration in the Felimida clenchi complex, using molecular phylogenetics, species-delimitation analyses (ABGD, GMYC, PTP), haplotype-network methods, and the anatomy of the reproductive system. None of our analyses recovered the traditional separation into four species. Our results indicated the existence of three species, a result inconsistent with previous taxonomic hypotheses. We distinguished an undescribed species of Felimida and redefined the concepts of F. clenchi and F. binza, both highly polychromatic species. For the first time, molecular data support the existence of extreme color polymorphism in chromatic nudibranch species, with direct implications for the taxonomy of the group and its diversity. The polychromatism observed in the F. clenchi complex apparently correlates with the regional occurrence of similar color patterns in congeneric species, suggesting different mimicry circles. This may represent a parallel in the marine environment to the mechanisms that play a major role in the diversification of color in terrestrial and fresh-water chromatic groups, such as heliconian butterflies.

Review of Baeolidia, the largest genus of Aeolidiidae (Mollusca: Nudibranchia), with the description of five new species.

This paper discusses the systematics of the aeolid genus Baeolidia Bergh, 1888. To date, this monophyletic genus is the most diverse within Aeolidiidae with sixteen valid species. Excluding Baeolidia cryoporos Bouchet, 1977, the genus is restricted to the Indo-Pacific and Eastern Pacific. Species of Baeolidia show a huge intrageneric variability in several morphological characters. Only oral glands, if present, may distinguish Baeolidia from other aeolidiids genera. Aeolidiella occidentalis Bergh, 1875, Aeolidiella faustina Bergh, 1900 and Spurilla orientalis Bergh, 1905 are transferred to Baeolidia but they are considered nomina dubia. Five new species, Baeolidia rieae sp. nov., Baeolidia variabilis sp. nov., Baeolidia lunaris sp. nov., Baeolidia gracilis sp. nov. and Baeolidia scottjohnsoni sp. nov. are described.

Going further on an intricate and challenging group of nudibranchs: description of five novel species and a more complete molecular phylogeny of the subfamily Nembrothinae (Polyceridae).

Nembrothinae is a colourful subfamily of nudibranch polycerids, which despite its large size and striking appearance, needs to be more thoroughly studied. The available scientific information about this subfamily is very recent, and pictures of living undescribed species become available every day. Nevertheless, the lack of associated material for morphological, anatomical, and molecular analysis results in scarce additional studies. In this paper, five novel species are described: Roboastra ernsti sp. nov., Roboastra nikolasi sp. nov., Tambja brasiliensis sp. nov., Tambja crioula sp. nov., and Tambja kava sp. nov. In addition, Tambja divae (Marcus, 1958), a species previously known only from the original description, is redescribed and additional data and comments on Tambja cf. amakusana Baba, 1987 and Tambja marbellensis Schick and Cervera, 1998 are provided. Molecular data (H3, COI and 16S genes) for all these novel species and some additional ones were obtained and included in a previous molecular database. Maximum-likelihood, maximum-parsimony and Bayesian analyses were carried out. The phylogeny presented here has revealed Nembrothinae to be an intricate and challenging group of nudibranchs to study. Intermediate missing species seem to be critical to understanding the evolutionary relationships within this group.

A tale that morphology fails to tell: a molecular phylogeny of Aeolidiidae (Aeolidida, Nudibranchia, Gastropoda).

Aeolidida is one of the largest clades of nudibranchs with at least 560 known species. However, its systematics has not been studied in a comprehensive manner. Phylogenetic analyses of larger clades such as Nudibranchia or Cladobranchia have usually included a poor sample of aeolids. Furthermore, phylogenetic studies at the family or generic level in Aeolidida are a few and far between. The first molecular phylogeny of the aeolid family Aeolidiidae is presented here. This study, the most comprehensive for Aeolidida to date, uses new sequences of two mitochondrial (COI and 16S) genes and one nuclear gene (H3). 251 specimens from members of seven families of Aeolidida, including 39 species of Aeolidiidae were studied. Excluding Pleurolidia juliae, Aeolidiidae is monophyletic. Our results resolve the systematic relationships within the Aeolidiidae at a generic level, requiring changes in the systematics of this family. Spurilla, Anteaeolidiella, Limenandra and Aeolidia are well-supported and monophyletic clades. Aeolidiella stephanieae is transferred to Berghia and Aeolidiopsis ransoni and Spurilla salaamica to Baeolidia, to maintain the monophyletic lineages reflected in this study. The systematics of Cerberilla remains unclear. Some species earlier attributed to Aeolidiella are now grouped in a previously unnamed clade that we designate as Bulbaeolidia gen. nov.