Phylogenetic relationships of tropical western Atlantic snappers in subfamily Lutjaninae (Lutjanidae: Perciformes) inferred from mitochondrial DNA sequences

Phylogenetic relationships among 20 nominal species of tropical lutjanine snappers (Lutjanidae) (12 from the western Atlantic, one from the eastern Pacific, and seven from the Indo‐Pacific) were inferred based on 2206 bp (712 variable, 614 parsimony informative) from three protein‐coding mitochondrial genes. Also included in the analysis were DNA sequences from two individuals, identified initially as Lutjanus apodus, which were sampled off the coast of Bahia State in Brazil (western Atlantic), and from three individuals labelled as ‘red snapper’ in the fish market in Puerto Armuelles, Panama (eastern Pacific). Bayesian posterior probabilities and maximum‐likelihood bootstrap percentages strongly supported monophyly of all lutjanines sampled and the hypothesis that western Atlantic lutjanines are derived from an Indo‐Pacific lutjanine lineage. The phylogenetic hypothesis also indicated that oceans where lutjanines are distributed (western Atlantic, eastern Pacific, and Indo‐Pacific) are not reciprocally monophyletic for the species distributed within them. There were three strongly supported clades that included all western Atlantic lutjanines: one included six species of Lutjanus from the western Atlantic, two species of Lutjanus from the eastern Pacific, and the monotypic genera Rhomboplites and Ocyurus (western Atlantic); one that included three, probably four, species of Lutjanus in the western Atlantic; and one that included Lutjanus cyanopterus (western Atlantic), an unknown species of Lutjanus from the eastern Pacific, and three species of Lutjanus from the Indo‐Pacific. Molecular‐clock calibrations supported an early Miocene diversification of an Indo‐Pacific lutjanine lineage that dispersed into the western Atlantic via the Panamanian Gateway. Divergent evolution among these lutjanines appears to have occurred both by vicariant and ecological speciation: the former following significant geographic or geological events, including both shoaling and closure of the Panamanian Gateway and tectonic upheavals, whereas the latter occurred via phenotypic diversification inferred to indicate adaptation to life in different habitats. Taxonomic revision of western Atlantic lutjanines appears warranted in that monotypic Ocyurus and Rhomboplites should be subsumed within the genus Lutjanus. Finally, it appears that retail mislabelling of ‘red snapper’ in commercial markets extends beyond the USA. © 2011 The Linnean Society of London, Biological Journal of the Linnean Society, 2011, 102 , 915–929.     

Systematic revision of the living species of Bullidae (Mollusca: Gastropoda: Cephalaspidea), with a molecular phylogenetic analysis

Bullidae are a worldwide family of marine shelled cephalaspidean gastropods with a mainly tropical distribution, but also with some representatives in temperate waters. The taxonomy of the group has in the past been based only on shell characters, and the few anatomical accounts available have not addressed more than one to three species, so there has been no agreement about the number of valid species. Seventy‐two specific names and 16 varietal names have been proposed worldwide. The systematics of the family Bullidae are revised, based not only on shells but also on anatomy of all extant species and on DNA sequence data. Twelve species are recognized worldwide, including one new species here described, and all are assigned to the genus Bulla. Two species occur in the eastern Atlantic, B. striata and B. mabillei; two in the western Atlantic, B. occidentalis and B. solida; two in the eastern Pacific, B. gouldiana and B. punctulata; and six in the Indo‐West Pacific, B. ampulla, B. arabica sp. nov. , B. orientalis, B. peasiana, B. quoyii and B. vernicosa. Full synonymies and taxonomic histories are provided for each species. In order to promote taxonomic stability, neotypes are designated for B. striata, B. solida, B. nebulosa (valid name B. gouldiana) and B. vernicosa, and lectotypes for B. occidentalis, B. mabillei, B. punctulata, B. ampulla and B. quoyii. The type locality of B. ampulla is restricted to Mauritius. Bullidae show a general morphological stasis, with anatomy being very similar between species. However, there are high levels of intraspecific variability in the shell, radula and male genital system. In some cases species could only be separated based on molecular data . After defining the characters and geographical range of each species it became clear that sympatric species (a maximum of three) show distinctive shells and reproductive structures, which makes identification straightforward. This study employs an integrative approach, combining information on shells, anatomy, DNA and geographical distribution, in order to resolve the systematics of a difficult taxonomic group. © 2008 The Linnean Society of London, Zoological Journal of the Linnean Society, 2008, 153 , 453–543.     

BIODIVERSITY RESEARCH: Genetic diversity in two introduced biofouling amphipods (Ampithoe valida & Jassa marmorata) along the Pacific North American coast: investigation into molecular identification and cryptic diversity

Aim We investigated patterns of genetic diversity among invasive populations of Ampithoe valida and Jassa marmorata from the Pacific North American coast to assess the accuracy of morphological identification and determine whether or not cryptic diversity and multiple introductions contribute to the contemporary distribution of these species in the region. Location Native range: Atlantic North American coast; Invaded range: Pacific North American coast. Methods We assessed indices of genetic diversity based on DNA sequence data from the mitochondrial cytochrome c oxidase subunit I (COI) gene, determined the distribution of COI haplotypes among populations in both the invasive and putative native ranges of A. valida and J. marmorata and reconstructed phylogenetic relationships among COI haplotypes using both maximum parsimony and Bayesian approaches. Results Phylogenetic inference indicates that inaccurate species‐level identifications by morphological criteria are common among Jassa specimens. In addition, our data reveal the presence of three well supported but previously unrecognized clades of A. valida among specimens in the north‐eastern Pacific. Different species of Jassa and different genetic lineages of Ampithoe exhibit striking disparity in geographic distribution across the region as well as substantial differences in genetic diversity indices. Main conclusions Molecular genetic methods greatly improve the accuracy and resolution of identifications for invasive benthic marine amphipods at the species level and below. Our data suggest that multiple cryptic introductions of Ampithoe have occurred in the north‐eastern Pacific and highlight uncertainty regarding the origin and invasion histories of both Jassa and Ampithoe species. Additional morphological and genetic analyses are necessary to clarify the taxonomy and native biogeography of both amphipod genera.     

Trans‐Pacific and trans‐Arctic pathways of the intertidal macroalga Fucus distichus L. reveal multiple glacial refugia and colonizations from the North Pacific to the North Atlantic

Aim We examined the phylogeography of the cold‐temperate macroalgal species Fucus distichus L., a key foundation species in rocky intertidal shores and the only Fucus species to occur naturally in both the North Pacific and the North Atlantic. Location North Pacific and North Atlantic oceans (42° to 77° N). Methods We genotyped individuals from 23 populations for a mitochondrial DNA (mtDNA) intergenic spacer (IGS) (n = 608) and the cytochrome c oxidase subunit I (COI) region (n = 276), as well as for six nuclear microsatellite loci (n = 592). Phylogeographic structure and connectivity were assessed using population genetic and phylogenetic network analyses. Results IGS mtDNA haplotype diversity was highest in the North Pacific, and divergence between Pacific haplotypes was much older than that of the single cluster of Atlantic haplotypes. Two ancestral Pacific IGS/COI clusters led to a widespread Atlantic cluster. High mtDNA and microsatellite diversities were observed in Prince William Sound, Alaska, 11 years after severe disturbance by the 1989 Exxon Valdez oil spill. Main conclusions At least two colonizations occurred from the older North Pacific populations to the North Atlantic between the opening of the Bering Strait and the onset of the Last Glacial Maximum. One colonization event was from the Japanese Archipelago/eastern Aleutians, and a second was from the Alaskan mainland around the Gulf of Alaska. Japanese populations probably arose from a single recolonization event from the eastern Aleutian Islands before the North Pacific–North Atlantic colonization. In the North Atlantic, the Last Glacial Maximum forced the species into at least two known glacial refugia: the Nova Scotia/Newfoundland (Canada) region and Andøya (northern Norway). The presence of two private haplotypes in the central Atlantic suggests the possibility of colonization from other refugia that are now too warm to support F. distichus. With the continuing decline in Arctic ice cover as a result of global climate change, renewed contact between North Pacific and North Atlantic populations of Fucus species is expected.     

No longer a circumtropical species: revision of the lizardfishes in the Trachinocephalus myops species complex,with description of a new species from the Marquesas Islands

Trachinocephalus, a formerly monotypic and nearly circumtropical genus of lizardfishes, is split into three valid species. Trachinocephalus gauguini n. sp. is described from the Marquesas Islands and is distinguished from the two other species in the genus by having a shorter snout, a narrower interorbital space, larger eye and modally fewer anal‐fin and pectoral‐fin rays. The distribution of Trachinocephalus myops (type species) is restricted to the Atlantic Ocean and the name Trachinocephalus trachinus is resurrected for populations from the Indo‐West Pacific Ocean. Principal component analyses and bivariate plots based on the morphometric data differentiated T. gauguini from the other two species, but a substantial overlap between T. myops and T. trachinus exists. Phylogenetic evidence based on mtDNA COI sequences unambiguously supports the recognition of at least three species in Trachinocephalus, revealing deep divergences between the Atlantic Ocean, Indo‐West Pacific Ocean and Marquesas entities. Additional analyses of species delimitations using the generalized mixed Yule coalescent model and the Poisson tree processes model provide a more liberal assessment of species in Trachinocephalus, indicating that many more cryptic species may exist. Finally, a taxonomic key to identify the three species recognized here is provided.     

Tethyan vicariance, relictualism and speciation: evidence from a global molecular phylogeny of the opisthobranch genus Bulla

Aim Our aims were: (1) to reconstruct a molecular phylogeny of the cephalaspidean opisthobranch genus Bulla, an inhabitant of shallow sedimentary environments; (2) to test if divergence times are consistent with Miocene and later vicariance among the four tropical marine biogeographical provinces; (3) to examine the phylogenetic status of possible Tethyan relict species; and (4) to infer the timing and causes of speciation events. Location Tropical and warm‐temperate regions of the Atlantic, Indo‐West Pacific, Australasia and eastern Pacific. Methods Ten of the 12 nominal species of Bulla were sampled, in a total sample of 65 individuals, together with cephalaspidean outgroups. Phylogenetic relationships were inferred by Bayesian analysis of partial sequences of the mitochondrial cytochrome c oxidase I (COI) and 16S rRNA and nuclear 28S rRNA genes. Divergence times and rates of evolution were estimated using uncorrelated relaxed‐clock Bayesian methods with fossil calibrations (based on literature review and examination of fossil specimens), implemented in beast . The geographical pattern of speciation was assessed by estimating the degree of overlap between sister lineages. Results Four clades were supported: Indo‐West Pacific (four species), Australasia (one species), Atlantic plus eastern Pacific (three species) and Atlantic (two species), with estimated mean ages of 35–46 Ma. Nominal species were monophyletic, but deep divergences were found within one Indo‐West Pacific and one West Atlantic species. Species‐level divergences occurred in the Miocene or earlier. The age of a sister relationship across the Isthmus of Panama was estimated at 7.9–32.1 Ma, and the divergence of a pair of sister species on either side of the Atlantic Ocean occurred 20.4–27.2 Ma. Main conclusions Fossils suggest that Bulla originated in the Tethys realm during the Middle Eocene. Average ages of the four main clades fall in the Eocene, and far pre‐date the 18–19 Ma closure of the Tethys Seaway. This discrepancy could indicate earlier vicariant events, selective extinction or errors of calibration. Similarly, the transisthmian divergence estimate far pre‐dates the uplift of the Panamanian Isthmus at about 3 Ma. Speciation events occurred in the Miocene, consistent with tectonic events in the central Indo‐West Pacific, isolation of the Arabian Sea by upwelling and westward trans‐Atlantic dispersal. Differences in habitat between sister species suggest that ecological speciation may also have played a role. The basal position of the Australasian species supports its interpretation as a Tethyan relict.     

Global distribution of cryptic native,introduced and hybrid lineages in the widespread estuarine amphipod Ampithoe valida

Biological invasions can pose a severe threat to coastal ecosystems, but are difficult to track due to inaccurate species identifications and cryptic diversity. Here, we clarified the cryptic diversity and introduction history of the marine amphipod Ampithoe valida by sequencing a mtDNA locus from 683 individuals and genotyping 10,295 single-nucleotide polymorphisms (SNPs) for 349 individuals from Japan, North America and Argentina. The species complex consists of three cryptic lineages: two native Pacific and one native Atlantic mitochondrial lineage. It is likely that the complex originated in the North Pacific and dispersed to the north Atlantic via a trans-arctic exchange approximately 3 MYA. Non-native A. valida in Argentina have both Atlantic mitochondrial and nuclear genotypes, strongly indicating an introduction from eastern North America. In two eastern Pacific estuaries, San Francisco Bay and Humboldt Bay, California, genetic data indicate human-mediated hybridization of Atlantic and Pacific sources, and possible adaptive introgression of mitochondrial loci, nuclear loci, or both. The San Francisco Bay hybrid population periodically undergoes population outbreaks and profoundly damages eelgrass Zostera marina thalli via direct consumption, and these ecological impacts have not been documented elsewhere. We speculate that novel combinations of Atlantic and Pacific lineages could play a role in A. valida’s unique ecology in San Francisco Bay. Our results reinforce the notion that we can over-estimate the number of non-native invasions when there is cryptic native structure. Moreover, inference of demographic and evolutionary history from mitochondrial loci may be misleading without simultaneous survey of the nuclear genome.

     

Observations on torquaratorid acorn worms (Hemichordata,Enteropneusta) from the North Atlantic with descriptions of a new genus and three new species

Enteropneusts in the family Torquaratoridae were imaged using still and video cameras in the deep North Atlantic and then collected by remotely operated vehicles. From this material, we describe Yoda purpurata n. gen, n. sp., Tergivelum cinnabarinum n. sp., and Allapasus isidis n. sp. Individuals of the first two species were browsing completely exposed on the sea floor, whereas the specimen of the last species was encountered floating ~1 m above the sea floor. Living specimens of Y. purpurata were 12–19 cm long and had a dark reddish‐purple proboscis, collar, and genital wings (folded dorsally over the anterior region of the trunk). Members of this species were hermaphrodites (the first ever discovered in the phylum Hemichordata), with numerous separate testes and ovaries in the genital wings. Living specimens of T. cinnabarinum were 12–26 cm long and had a cinnabar‐colored proboscis, collar, and back veils (arising from the anterior region of the trunk); sexes were separate, and body shape and internal morphology closely resemble those of its brown congener, T. baldwinae, from the eastern Pacific. The only specimen of A. isidis collected was a male 13 cm long and pale yellow when alive. Its body shape was proportionally shorter and broader than that of its orange congener, A. aurantiacus, from the eastern Pacific, but the internal anatomy of the two species is virtually identical. [Correction made after online publication August 21, 2012 to correct species name in preceding sentence.]     

Y‐chromosome evidence supports widespread signatures of three‐species Canis hybridization in eastern North America

There has been considerable discussion on the origin of the red wolf and eastern wolf and their evolution independent of the gray wolf. We analyzed mitochondrial DNA (mtDNA) and a Y‐chromosome intron sequence in combination with Y‐chromosome microsatellites from wolves and coyotes within the range of extensive wolf–coyote hybridization, that is, eastern North America. The detection of divergent Y‐chromosome haplotypes in the historic range of the eastern wolf is concordant with earlier mtDNA findings, and the absence of these haplotypes in western coyotes supports the existence of the North American evolved eastern wolf (Canis lycaon). Having haplotypes observed exclusively in eastern North America as a result of insufficient sampling in the historic range of the coyote or that these lineages subsequently went extinct in western geographies is unlikely given that eastern‐specific mtDNA and Y‐chromosome haplotypes represent lineages divergent from those observed in extant western coyotes. By combining Y‐chromosome and mtDNA distributional patterns, we identified hybrid genomes of eastern wolf, coyote, gray wolf, and potentially dog origin in Canis populations of central and eastern North America. The natural contemporary eastern Canis populations represent an important example of widespread introgression resulting in hybrid genomes across the original C. lycaon range that appears to be facilitated by the eastern wolf acting as a conduit for hybridization. Applying conventional taxonomic nomenclature and species‐based conservation initiatives, particularly in human‐modified landscapes, may be counterproductive to the effective management of these hybrids and fails to consider their evolutionary potential.     

Phylogeny and biogeography of Muusoctopus (Cephalopoda: Enteroctopodidae)

Deep‐sea octopuses of the genus Muusoctopus are thought to have originated in the Pacific Northern Hemisphere and then diversified throughout the Pacific and into the rest of the World Ocean. However, this hypothesis was inferred only from molecular divergence times. Here, the ancestral distribution and dispersal routes are estimated by Bayesian analysis based on a new phylogeny including 38 specimens from the south‐eastern Pacific Ocean. Morphological data and molecular sequences of three mitochondrial genes (16S rRNA, COI and COIII) are presented. The morphological data confirm that specimens newly acquired from off the coast of Chile comprise two species: Muusoctopus longibrachus and the poorly described species, Muusoctopus eicomar. The latter is here redescribed and is clearly distinguished from M. longibrachus and other closely related species in the region. A gene tree was built using Bayesian analysis to infer the phylogenetic position of these species within the species group, revealing that a large genetic distance separates the two sympatric Chilean species. M. longibrachus is confirmed as the sister species of Muusooctopus eureka from the Falkland Islands; while M. eicomar is a sister species of Muusoctopus yaquinae from the North Pacific, most closely related to the amphi‐Atlantic species Muusoctopus januarii. Molecular divergence times and ancestral distribution analyses suggest that genus Muusoctopus may have originated in the North Atlantic: one lineage dispersed directly southward to the Magellan region and another dispersed southward along the Eastern Pacific to the Southern Ocean and Antarctica. The Muusoctopus species in the Southern Hemisphere have different phylogenetic origins and represent independent invasions of this region.     

A molecular evaluation of the Liagoraceae sensu lato (Nemaliales,Rhodophyta) in Bermuda including Liagora nesophila sp. nov. and Yamadaella grassyi sp. nov.

We have undertaken a comprehensive, molecular‐assisted alpha‐taxonomic examination of the rhodophyte family Liagoraceae sensu lato, a group that has not previously been targeted for molecular studies in the western Atlantic. Sequence data from three molecular markers indicate that in Bermuda alone there are 10 species in nine different genera. These include the addition of three genera to the flora — Hommersandiophycus, Trichogloeopsis, and Yamadaella. Liagora pectinata, a species with a type locality in Bermuda, is phylogenetically allied with Indo‐Pacific species of Hommersandiophycus, and the species historically reported as L. ceranoides for the islands is morphologically and genetically distinct from that taxon, and is herein described as L. nesophila sp. nov. Molecular sequence data have also uncovered the Indo‐Pacific L. mannarensis in Bermuda, a long‐distance new western Atlantic record. DNA sequences of Trichogloeopsis pedicellata from the type locality (Bahamas) match with local specimens demonstrating its presence in Bermuda. We described Yamadaella grassyi sp. nov. from Bermuda, a species phylogenetically and morphologically distinct from the generitype, Y. caenomyce of the Indo‐Pacific. Our data also indicated a single species each of Ganonema, Gloiocallis, Helminthocladia, Titanophycus, and Trichogloea in the flora.     

Species-level phylogeography and evolutionary history of the hyperdiverse marine gastropod genus Conus

Phylogenetic and paleontological analyses are combined to reveal patterns of species origination and divergence and to define the significance of potential and actual barriers to dispersal in Conus, a species-rich genus of predatory gastropods distributed throughout the world's tropical oceans. Species-level phylogenetic hypotheses are based on nucleotide sequences from the nuclear calmodulin and mitochondrial 16S rRNA genes of 138 Conus species from the Indo-Pacific, eastern Pacific, and Atlantic Ocean regions. Results indicate that extant species descend from two major lineages that diverged at least 33 mya. Their geographic distributions suggest that one clade originated in the Indo-Pacific and the other in the eastern Pacific + western Atlantic. Impediments to dispersal between the western Atlantic and Indian Oceans and the central and eastern Pacific Ocean may have promoted this early separation of Indo-Pacific and eastern Pacific + western Atlantic lineages of Conus. However, because both clades contain both Indo-Pacific and eastern Pacific + western Atlantic species, migrations must have occurred between these regions; at least four migration events took place between regions at different times. In at least three cases, incursions between regions appear to have crossed the East Pacific Barrier. The paleontological record illustrates that distinct sets of Conus species inhabited the Indo-Pacific, eastern Pacific + western Atlantic, and eastern Atlantic + former Tethys Realm in the Tertiary, as is the case today. The ranges of <1% of fossil species (N=841) spanned more than one of these regions throughout the evolutionary history of this group.     

Untangling the Spurilla neapolitana (Delle Chiaje, 1841) species complex: a review of the genus Spurilla Bergh, 1864 (Mollusca: Nudibranchia: Aeolidiidae)

Spurilla neapolitana (Delle Chiaje, 1823) was considered to be a species with a broad geographic range and substantial colour variability; however, analyses of mitochondrial and nuclear gene data revealed that it is a complex of five distinct species. Further anatomical and morphological examinations determined that coloration is one of the main diagnostic traits for all five species, although some display substantial colour pattern variation. As a result of this study, S. neapolitana is determined to be restricted to the Mediterranean and eastern Atlantic. Spurilla sargassicola Bergh, 1871 from the Caribbean is redescribed and confirmed as a valid species. The name Spurilla braziliana MacFarland, 1909 is retained for western Atlantic and Pacific populations. Two new species are described herein. S purilla onubensis sp. nov. occurs in Europe, with a range overlapping that of S. neapolitana. Finally, S purilla dupontae sp. nov. is found in the Bahamas. © 2014 The Linnean Society of London     

Welcome back Janolidae and Antiopella: Improving the understanding of Janolidae and Madrellidae (Cladobranchia,Heterobranchia) with description of four new species

Proctonotidae and Madrellidae are families that belong to the suborder Cladobranchia. Historically, both have been the subjects of taxonomic confusion. Thus, Proctonotidae Gray, 1853, was subsequently named as Zephyrinidae Iredale and O'Donoghue, 1923 and Janolidae Pruvot‐Fol, 1933, but currently both are considered as synonyms of Proctonotidae. On the other hand, Alder and Hancock (1864) erected the genus Madrella in Proctonotidae. Here, we completed a detailed morphological and molecular study of four apparently undescribed species of Madrellidae and Proctonotidae from the Indo‐Pacific. We performed a maximum likelihood and Bayesian inference phylogenetic analyses using two mitochondrial and one nuclear genes to improve the understanding of the families. Prompted by our results, Janolidae is removed from synonymy with Proctonotidae. Within Janolidae, there are two well‐supported clades. One includes species with smooth cerata that are found in the Atlantic and eastern Pacific Oceans. The taxa in this clade include the type species of Antiopella and several other species. We resurrect Antiopella as the valid name for this clade. The sister clade to Antiopella includes a variety of taxa with species that have been traditionally included in Janolus Bergh, 1884 and Bonisa Gosliner, 1981. Further systematic revision requires more comprehensive taxon sampling. The new species discovered have clear morphological differences and strong molecular support. They include Madrella amphora Pola and Gosliner sp. nov. , Janolus tricellariodes Pola and Gosliner sp. nov. , Janolus flavoanulatus Pola and Gosliner sp. nov., and Janolus incrustans Pola and Gosliner sp. nov.     

PHYLOGEOGRAPHY OF THE PANTROPICAL SEA URCHIN EUCIDARIS IN RELATION TO LAND BARRIERS AND OCEAN CURRENTS

The pantropical sea urchin genus Eucidaris contains four currently recognized species, all of them allopatric: E. metularia in the Indo-West Pacific, E. thouarsi in the eastern Pacific, E. tribuloides in both the western and eastern Atlantic, and E. clavata at the central Atlantic islands of Ascension and St. Helena. We sequenced a 640-bp region of the cytochrome oxidase I (COI) gene of mitochondrial DNA to determine whether this division of the genus into species was confirmed by molecular markers, to ascertain their phylogenetic relations, and to reconstruct the history of possible dispersal and vicariance events that led to present-day patterns of species distribution. We found that E. metularia split first from the rest of the extant species of the genus. If COI divergence is calibrated by the emergence of the Isthmus of Panama, the estimated date of the separation of the Indo-West Pacific species is 4.7–6.4 million years ago. This date suggests that the last available route of genetic contact between the Indo-Pacific and the rest of the tropics was from west to east through the Eastern Pacific Barrier, rather than through the Tethyan Sea or around the southern tip of Africa. The second cladogenic event was the separation of eastern Pacific and Atlantic populations by the Isthmus of Panama. Eucidaris at the outer eastern Pacific islands (Galapagos, Isla del Coco, Clipperton Atoll) belong to a separate clade, so distinct from mainland E. thouarsi as to suggest that this is a different species, for which the name E. galapagensis is revived from the older taxonomic literature. Complete lack of shared alleles in three allozyme loci between island and mainland populations support their separate specific status. Eucidaris galapagensis and E. thouarsi are estimated from their COI divergence to have split at about the same time that E. thouarsi and E. tribuloides were being separated by the Isthmus of Panama. Even though currents could easily convey larvae between the eastern Pacific islands and the American mainland, the two species do not appear to have invaded each other's ranges. Conversely, the central Atlantic E. clavata at St. Helena and Ascension is genetically similar to E. tribuloides from the American and African coasts. Populations on these islands are either genetically connected to the coasts of the Atlantic or have been colonized by extant mitochondrial DNA lineages of Eucidaris within the last 200,000 years. Although it is hard to explain how larvae can cross the entire width of the Atlantic within their competent lifetimes, COI sequences of Eucidaris from the west coast of Africa are very similar to those of E. tribuloides from the Caribbean. F_ST statistics indicate that gene flow between E. metularia from the Indian Ocean and from the western and central Pacific is restricted. Low gene flow is also evident between populations of E. clavata from Ascension and St. Helena. Rates of intraspecific exchange of genes in E. thouarsi, E. galapagensis, and E. tribuloides, on the other hand, are high. The phylogeny of Eucidaris confirms Ernst Mayr's conclusions that major barriers to the dispersal of tropical echinoids have been the wide stretch of deep water between central and eastern Pacific, the cold water off the southwest coast of Africa, and the Isthmus of Panama. It also suggests that a colonization event in the eastern Pacific has led to speciation between mainland and island populations.     

Molecular data illuminate cryptic nudibranch species: the evolution of the Scyllaeidae (Nudibranchia: Dendronotina) with a revision of Notobryon

Scyllaeidae represents a small clade of dendronotoid nudibranchs. Notobryon wardi Odhner, 1936, has been reported to occur in tropical oceans from the Indo‐Pacific and eastern Pacific to temperate South Africa. The systematics of Notobryon has not been reviewed using modern systematic tools. Here, specimens of Notobryon were examined from the eastern Pacific, the Indo‐Pacific, and from temperate South Africa. Additionally, representatives of Scyllaea and Crosslandia were studied. Scyllaeidae was found to be monophyletic. Notobryon was also found to be monophyletic and is the sister group to Crosslandia plus Scyllaea. The molecular data also clearly indicate that within Notobryon, at least three distinct species are present, two of which are here described. Genetic distance data indicate that eastern Pacific and South African exemplars are 10–23% divergent from Indo‐Pacific exemplars of Notobryon wardi. Scyllaea pelagica has been regarded as a single, circumtropical species. Our molecular studies clearly indicate that the Atlantic and Indo‐Pacific populations are distinct and we resurrect Scyllaea fulva Quoy & Gaimard, 1824 for the Indo‐Pacific species. Our morphological studies clearly corroborate our molecular findings and differences in morphology distinguish closely related species. Different species clearly have distinct penial morphology. These studies clearly reinforce the view that eastern Pacific, Indo‐Pacific, and temperate biotas consist largely of distinct faunas, with only a minor degree of faunal overlap. © 2012 The Linnean Society of London, Zoological Journal of the Linnean Society, 2012, 165 , 311–336.     

RECENT RADIATION OF THE PALMARIACEAE (RHODOPHYTA)1

Molecular phylogenetic studies on the evolution of the red algae indicate that this ancient division has many lineages that have recently undergone radiations. One such example is the cold–temperate family Palmariaceae. In this study, sequences from the ribosomal DNA internal transcribed spacer regions were compared among ten species in the Palmariaceae from both Atlantic and Pacific sites, Phylogenetic analyses of sequence data, in which Rhodophysema georgii Batters was used as outgroup and root, indicate a radiation into four clades, three of which contain species of “Palmaria” and the fourth species of Halosaccion. Palmaria palmata (L.) Kuntze, the type and only North Atlantic species in the genus, stands apart from all remaining species in the family and terminates the most basal branch in the rooted tree. The three more derived clades have radiated mainly in the North Pacific. Southern Ocean Palmaria and North Atlantic Devaleraea are hypothesized to have invaded from separate but closely related North Pacific ancestors. The ease with which sequences could be aligned combined with an unsaturated transition: transversion ratio and modest divergence involving predominantly point mutations suggests that the initial radiation is relatively recent (late Miocene–Pliocene) and that the Devaleraea–Palmaria clade is even more recent (late Pliocene–Pleistocene).