Three species of Mytilus and their hybrids identified in a Scottish Loch: natives, relicts and invaders?

Three species of the mussel, Mytilus, occur in the North Atlantic region, M. edulis, M. galloprovincialis and M. trossulus, and hybrid zones are present where their distributions overlap. M. edulis is a native species in the UK. M. galloprovincialis originated in the Mediterranean and its distribution extends northwards along the Atlantic seaboard to Scotland. Baltic Sea mussels have a M. trossulus ancestry but are highly introgressed by M. edulis. In recent decades, farming of mussels on long-line rope culture systems has been introduced into Scotland. On farms in Loch Etive, a form of mussel with a fragile shell and a different shape to either M. edulis or M. galloprovincialis has been increasing in frequency over recent years. Samples of fragile shelled, normal strong shelled and intermediate mussel types were sampled from two farms in 2006 and compared with samples of M. edulis, M. galloprovincialis and M. trossulus from other sources where their species identity is well established. Abundance relative to depth, shell strength, condition index and shell morphology were analysed together with 5 allozyme loci and one nuclear DNA genetic marker (Me 15/16). The fragile shelled mussels, and many of those classed as intermediate, were identified as a mixture of M. trossulus and M. trossulus x M. edulis hybrids. This identification was strongly supported by both morphological and genetic data and is the first record of the presence of M. trossulus in UK waters. M. trossulus in Loch Etive are most likely to be a post-glacial relict population restricted to the low salinity area of the Loch that has recently increased in abundance due to commercial mussel growing activity. In addition, individual mussels of all three species and their hybrids were detected amongst Loch Etive mussels. This is the first genetic demonstration of all three species and their hybrids occurring together in one location in the Atlantic region and provides a unique opportunity to study the processes of speciation, divergence, and introgression in the genus Mytilus.     

Leucothoid and Maerid Amphipods (Crustacea) from deep regions of the North Atlantic

From amphipod collections from the deep Norwegian Sea, three species are here redescribed: Maera loveni (Bruzelius 1859) (Maeridae), Leucothoe aff. spinicarpa (Abildgaard, 1789) and L. uschakovi Gurjanova, 1951 (Leucothoidae). A key to all Atlantic and Mediterranean Leucothoe species (males only) is provided.     

Bioinvasion threatens the genetic integrity of native diversity and a natural hybrid zone: smooth‐shelled blue mussels (Mytilus spp.) in the Strait of Magellan

Smooth‐shelled blue mussels of the Mytilus edulis species complex are widely distributed bivalve molluscs whose introductions threaten native marine biodiversity (non‐indigenous species – NIS). The aim of the present study was to identify the species and hybrids of Mytilus present in the Magellan Region (southern Chile). Results indicate that three mussel species of the Mytilus edulis complex are found in the region – M. edulis, M. chilensis (or the Southern Hemisphere lineage of Mytilus galloprovincialis), and M. galloprovincialis of Northern Hemisphere origin. For the first time, alleles of the introduced M. trossulus are reported from the Southern Hemisphere. In the Strait of Magellan the native Pacific blue mussel, Mytilus chilensis and the native Atlantic blue mussel, Mytilus edulis, meet and mix at a natural hybrid zone (about 125 km in length). This is the first record of a natural Mytilus hybrid zone in the Southern Hemisphere and is also the first record of the co‐occurrence of genes from all four Mytilus species in any one region. These results contribute to the knowledge of the biodiversity and delimitation of mussel species in southern South America, and highlight how introduced species may threaten the genetic integrity of native species through hybridization and introgression.     

Mytilus galloprovincialis Lmk. in Southern Africa

The Mediterranean mussel, Mytilus galloprovincialis Lmk. has been identified on the west coast of southern Africa using morphological and biochemical-genetic comparisons with samples of “pure” M. edulis L. from Denmark and M. galloprovincialis from the Mediterranean coast of Spain. Our results show that the southern African Mytilus more closely resembles M. galloprovincialis in anterior adductor, posterior adductor and hinge size. It also has a more ventrally located maximal shell width like the Mediterranean mussel. The electrophoretic examination of 23 proteins showed that many alleles diagnostic for M. galloprovincialis appeared in the southern African Mytilus. Nei's genetic distance between the southern African Mytilus and M. galloprovincialis was 0.010 ± 0.004 and the average genetic distance between these samples and M. edulis was 0.162 ± 0.077.The presence of M. galloprovincialis in southern Africa could be explained by biogeographic dispersal along the west coast of Africa during Pleistocene cooling, or by a recent inadvertant or intentional introduction by man. To test these two hypotheses, we examined ≈750 mussel shells collected from Koi-san middens and ≈350 shells from a raised-beach deposit all located on the west coast of Cape Province, South Africa. The ages of these deposits range from 1500 yr to 120000 yr and pre-date the arrival of Europeans to the Cape. This examination did not reveal any shells of Mytilus. We, therefore, conclude that the introduction of M. galloprovincialis to southern Africa was a recent event. We suggest that, since the first confirmed reference to Mytilus in southern Africa was made from a 1972 collection, the introduction occurred within the last two decades.     

Two ants (Insecta: Hymenoptera: Formicidae: Formicinae) from the Late Pliocene of Willershausen, Germany, with a nomenclatural note on the genus Camponotites

Two species of the genus Camponotites (Formicidae, Formicinae) are described from the Late Pliocene deposits of Willershausen, Lower Saxony, northern Germany: C. silvestris Steinbach, 1967, and C. steinbachi n. sp. The generic name Camponotites has been established for fossil (Tertiary) ants independently by Steinbach (Bericht der Naturhistorischen Gesellschaft zu Hannover 111:95–102, 1967) and by Dlussky (Trudy paleontologi?eskogo instituta, akademiâ nauk SSSR, 1981), each for materials of different stratigraphical and geographical origin. Though poorly described, Camponotites Steinbach, 1967, and the single included (type) species C. silvestris Steinbach, 1967 (a monotypic species from the Late Pliocene of Willershausen), were based upon indication in the sense of the ICZN. Therefore, both the generic and specific names are valid and available. Camponotites Dlussky, 1981 (and its type species C. macropterus Dlussky, 1981) were certainly introduced correctly and are therefore available, too; but due to its homonymy the generic name is not valid. The revision shows that in this rare case both generic names are not only homonyms but also synonyms.     

The (Paleo)Geography of Evolution: Making Sense of Changing Biology and Changing Continents

During the voyage of the H.M.S. Beagle, Charles Darwin quickly realized that geographic isolation led to significant changes in the adaptation of local flora and fauna (Darwin 1859). Genetic isolation is one of the well-known mechanisms by which adaptation (allopatric speciation) can occur (Palumbi, Annu Rev Ecol Syst 25:547?C72, 1994; Ricklefs, J Avian Biol 33:207?C11, 2002; Burns et al., Evolution 56:1240?C52, 2002; Hendry et al., Science 290:516?C8, 2009). Evolutionary changes can also occur when landmasses converge or are ??bridged.?? An important and relatively recent (Pliocene Epoch) example known as the ??Great American Biotic Interchange?? allowed for the migration of previously isolated species into new ecological niches between North and South America (Webb 1985, Ann Mo Bot Gard 93:245?C57, 2006; Kirby and MacFadden, Palaeogeogr Palaeoclimatol Palaeoecol 228:193?C202, 2005). Geographic isolation (vicariance) or geographic merging (geodispersal) can occur for a variety of reasons (sea level rise, splitting of continents, mountain building). In addition, the growth of a large supercontinent (or breakup) may change the climatic zonation on the globe and form a different type of barrier for species migration. This short review paper focuses on changing paleogeography throughout the Phanerozoic and the close ties between paleogeography and the evolutionary history of life on Earth.     

Glacial history of the European marine mussels Mytilus,inferred from distribution of mitochondrial DNA lineages

Mussels of the genus Mytilus have been used to assess the circumglacial phylogeography of the intertidal zone. These mussels are representative components of the intertidal zone and have rapidly evolving mitochondrial DNA, suitable for high resolution phylogeographic analyses. In Europe, the three Mytilus species currently share mitochondrial haplotypes, owing to the cases of extensive genetic introgression. Genetic diversity of Mytilus edulis, Mytilus trossulus and Mytilus galloprovincialis was studied using a 900-bp long part of the most variable fragment of the control region from one of their two mitochondrial genomes. To this end, 985 specimens were sampled along the European coasts, at sites ranging from the Black Sea to the White Sea. The relevant DNA fragments were amplified, sequenced and analyzed. Contrary to the earlier findings, our coalescence and nested cladistics results show that only a single M. edulis glacial refugium existed in the Atlantic. Despite that, the species survived the glaciation retaining much of its diversity. Unsurprisingly, M. galloprovincialis survived in the Mediterranean Sea. In a relatively short time period, around the climatic optimum at 10 ky ago, the species underwent rapid expansion coupled with population differentiation. Following the expansion, further contemporary gene flow between populations was limited.     

Redescriptions and reestablishments of some species belonging to the genus Prionospio (Polychaeta,Spionidae) and descriptions of three new species

Available type material of Prionospio heterobranchia Moore, 1907, P. (Prionospio) texana Hartman, 1951, P. spongicola Wesenberg-Lund, 1958 and P. (P.) newportensis Reish, 1959, as well as newly collected material from the Southern Gulf of Mexico and Chetumal Bay in the Caribbean Sea, was examined. Several important differences were found between P. heterobranchia, P. (Prionospio) texana, P. spongicola and P. (P.) newportensis, and as a result, these three species are removed from synonymy with P. heterobranchia Moore, 1907, and redescribed and reinstated as valid species. In addition, three new species were identified and described: P. caribensis sp. nov., P. rosariae sp. nov. and P. jamaicensis sp. nov. A key to all species of Prionospio with five pairs of branchiae is provided.     

Development of a real-time PCR assay for detection of Mytilus species specific alleles: Application to a sampling survey in Scotland

Shellfish aquaculture is a growing industry in Scotland, dominated by the production of the mussel Mytilus edulis, the native species. Recently the discovery of Mytilus galloprovincialis and Mytilus trossulus together with M. edulis and all 3 hybrids in cultivation in some Scottish sea lochs led to questions regarding the distribution of mussel species in Scotland. The establishment of an extensive sampling survey, involving the collection of mussels at 34 intertidal sites and 10 marinas around Scotland, motivated the development of a high-throughput method for identification of Mytilus alleles from samples. Three Taqman®-MGB probes and one set of primers were designed, based on the previously described Me 15/16 primers targeting the adhesive protein gene sequence, and samples were screened for the presence of M. edulis, M. galloprovincialis and M. trossulus alleles using real-time PCR. Mytilus edulis alleles were identified in samples from all 44 sites. Mytilus galloprovincialis alleles were found together with M. edulis alleles extensively in northern parts of the west and east coasts. Mytilus trossulus alleles were identified in samples from 6 sites in the west and south-west of Scotland. Because M. trossulus is generally undesirable in cultivation and therefore preventing the geographical spread of this species across Scotland is considered beneficial by the shellfish aquaculture industry, these 6 samples were further analysed for genotype frequencies using conventional PCR. Although distribution of the non-native species M. galloprovincialis and M. trossulus have proven to be more widespread than previously thought, there is no evidence from our study of either M. trossulus or M. galloprovincialis acting as an invasive species in Scotland. The real-time PCR method developed in this study has proven to be a rapid and effective tool for the identification of M. edulis, M. galloprovincialis and M. trossulus alleles from samples and should prove useful in future surveys, ecological or aquaculture management related studies in both unispecific and mixed species areas of these species.     

ASYMMETRIC INTROGRESSION OF MITOCHONDRIAL DNA AMONG EUROPEAN POPULATIONS OF BLUE MUSSELS (MYTILUS SPP.)

Abstract.—Mytilus edulis and M. galloprovincialis are two blue mussel species that coexist in western Europe. Previously, we reported that M. galloprovincialis populations contain female and male haplotypes that are fixed in M. edulis populations as well as unique haplotypes. This study assesses whether paraphyly for these species is due to introgression or incomplete lineage extinction. The lineage extinction hypothesis predicts that the shared mtDNA haplotypes in M. galloprovincialis will be significantly diverged from those in M. edulis and form distinct sequence clades. In contrast, the introgression hypothesis proposes that M. edulis haplotypes have only recently been introduced into M. galloprovincialis through hybridization with relatively little divergence accumulating between the shared RFLP haplotypes. We examined 80 mtl6S gene sequences for both the maternal and paternal mtDNA lineages from mussels sampled from various European populations and found strong support for the introgression hypothesis. In addition, we found that M. edulis mtDNA haplotypes appear to be introgressing into mussel populations in the Baltic Sea, which have predominantly M. trossulus nuclear genotypes, indicating that introgressive hybridization is prevalent among European mussel populations.     

Taxonomic review of Kyphosus (Pisces: Kyphosidae) in the Atlantic and Eastern Pacific Oceans

The taxonomy of the Atlantic and Eastern Pacific species of Kyphosus is reviewed with K. bosquii (Lacepède 1802), K. incisor (Cuvier 1831), K. analogus (Gill 1862) and K. elegans (Peters 1869) considered valid, and K. atlanticus sp. nov. newly described. Kyphosus bosquii and K. atlanticus are both characterized by 12 dorsal- and 11 anal-fin soft rays, but differ in the number of longitudinal scale rows along the midbody (61–66, mode 63 vs. 50–56, mode 54). Kyphosus incisor and K. analogus, characterized by 14 dorsal- and 13 anal-fin soft rays, similarly differ from each other in midbody longitudinal scale row counts (57–64, mode 60 vs. 68–74, mode 70 or 72). Kyphosus elegans is characterized by 13 dorsal- and 12 anal-fin soft rays, and 51–57 midbody longitudinal scale rows. Kyphosus bosquii, K. atlanticus and K. incisor are distributed in the Atlantic Ocean, K. analogus and K. elegans occurring in the Eastern Pacific. The holotype of Pimelepterus flavolineatus Poey 1866, here regarded as a junior synonym of K. incisor, was located within a collection of Cuban fishes donated to the Smithsonian Institution by Poey in 1873. A neotype is designated here for K. analogus. Pimelepterus gallveii Cunningham 1910, Kyphosus palpebrosus Miranda-Ribeiro 1919 and K. metzelaari Jordan and Evermann 1927 are recognized as junior synonyms of K. bosquii. Pimelepterus sandwicensis Sauvage 1880 is a junior synonym of K. elegans. Perca saltatrix Linnaeus 1758, together with the replacement name Perca sectatrix Linnaeus 1766, is regarded as nomina dubia.     

Thanetian gastropods from the Mesopotamian high folded zone in northern Iraq

An assemblage of gastropods from the Thanetian of the Kolosh Formation from the Zakho region in northern Iraq is documented for the first time. The ten species represent the families Campanilidae Douvillé 1904, Potamididae H. & A. Adams 1854, Batillariidae Thiele 1929, Thiaridae Gill 1871, Pachychilidae Fischer & Crosse 1892, Cerithiidae Fleming 1822 and Pseudolividae de Gregorio 1880, suggesting a littoral to shallow sublittoral depositional environment. Six of the species are new and five are formally described as new species. At least seven species are also known from the Thanetian and/or Early Ypresian of the Ankara region in Turkey. Only a single species occurs also in the Paleocene of the Paris Basin. No relation to Paleocene and Eocene faunas of Pakistan and India is detectable. This points to a considerably bioprovincialism along the northern coast of the Tethys. Consequently we suppose the existence of an Anatolian Province in the Thanetian/Ypresian Mediterranean Region of the Tethys Realm, represented by rather homogeneous mollusc faunas from western Turkey and northern Iraq. Campanile zakhoense nov. sp., Pyrazopsis hexagonpyramidalis nov. sp., Pachymelania islamogluae nov. sp., “Faunus” dominicii nov. sp. and Pseudoaluco mesopotamicus nov. sp. are introduced as new species. Varicipotamides Pacaud & Harzhauser nov. nom. is proposed as the replacement name for Exechestoma Cossmann (1889) non Brandt (1837).     

Heckerocrinus, a new substitute generic name for fossil crinoid Bockia Hecker 1940 (Echinodermata: Crinoidea) non Reisinger 1924 (Vermes: Turbellaria)

Heckerocrinus nom. nov., a new generic name of fossil Ordovician crinoid, is proposed for preoccupied fossil generic name Bockia Hecker 1940 non Reisinger 1924 [Vermes: Turbellaria??Typhloplanidae-Protoplanellinae]. Illegitimate family name Bockiidae Ubaghs 1972 is replaced with a new valid family name Heckerocrinidae nom. nov.     

Revision and new data on the Coniacian ammonite genus Hemitissotia in the Iberian Peninsula (Spain and Portugal)

The types of the species of the Coniacian ammonite genus Hemitissotia Peron, 1897, identified in the Iberian Peninsula (Spain and Portugal), which are currently held in the Wiedmann (Universität Tübingen, Germany) and Choffat (Instituto Geológico e Mineiro, Portugal) collections, have been revised and refigured. New specimens of the taxa Hemitissotia ceadouroensis Choffat, 1898, Hemitissotia celtiberica Wiedmann, 1975b, Hemitissotia turzoi Karrenberg, 1935, Hemitissotia dullai (Karrenberg 1935) and Hemitissotia lenticeratiformis Wiedmann in Wiedmann and Kauffman, 1978 have also been presented. As results, H. celtiberica has been considered as a junior synonym of H. ceadouroensis, and the lectotype of this species and the neotypes of H. turzoi and H. dullai have been designated and figured. Additionally, the geographical and stratigraphical distributions of all of these species have been determined with precision, and several phylogenetic relationships between them have been identified, revealing morphologies that become progressively smaller and more depressed and ornamented (hydrodynamically less efficient), interpreted as an adaptative response to sea-level changes.     

Icriocarcinidae: a family of portunoid crabs from the Upper Cretaceous of North America

Icriocarcininae ?tev?i?, 2005, an extinct North American subfamily of portunoid decapods, is elevated to family level to contain two Late Cretaceous genera—Icriocarcinus Bishop, 1988, from the Pacific Coast, and Branchiocarcinus Feldmann and Vega, 1995, from the Gulf of Mexico and Atlantic Coast Plain. The family is centered on Icriocarcinus xestos Bishop, 1988, described from the Late Campanian of Baja California. Closely allied with this species are: “Eryma” flecta Rathbun, 1926, originally described from the latest Campanian of Tennessee and now known to occur throughout the Maastrichtian of the adjoining Mississippi; Branchiocarcinus cornatus Feldmann and Vega, 1995, from the Maastrichtian of San Luis Potosí, Mexico; and undescribed material from the latest Maastrichtian of New Jersey. The Gulf and Atlantic populations compose a single new species—Branchiocarcinus flectus (Rathbun). Provisionally regarded as a lobster, on the basis of a single, eroded chela, B. flectus is now known from complete bodies found at several locations in the eastern US. The additional material also clarifies the identity of B. cornatus, which is based on a distorted external mold of a lone dorsal carapace. Members of the family lack the typical portunoid flattened fifth pereiopod but share other characters that enable placement within the Portunoidea.     

Stukalinia, a new substitute generic name for fossil crinoid Lobocrinus Stukalina non Wachsmuth and Springer 1897 (Echinodermata: Crinoidea)

A new generic name, Stukalinia nom. nov., is proposed for a fossil Ordoviacian crinoid that currently has the preoccupied fossil generic name Lobocrinus Stukalina 1982 non Wachsmuth and Springer (1897), along with a new family name, Stukaliniidae nom. nov., instead of the illegitimate family name Lobocrinidae Stukalina (1982).     

A morphometrical study of oribatid mites (Acari: Oribatida) of the genus Carabodes C.L. Koch, 1835 (Carabodidae) using a confocal laser scanning microscope: an alternative approach to quantitative analysis of various features

In the past, micro-arthropod taxonomists have mainly relied on qualitative characters to identify species, and relatively little attention has been paid to quantitative analysis. However, several taxonomic groups have high morphological variability, which creates problems in identification. Quantitative analysis of morphometrical data of specific characters could aid in understanding differences in the morphology of oribatid species. In this respect, confocal laser scanning microscopy and quantitative analysis were used to describe morphological traits of four oribatid mite species belonging to the genus Carabodes Koch, 1835—C. femoralis (Nicolet, 1855), C. labyrinthicus (Michael, 1879), C. ornatus Storkan, 1925 and C. subarcticus Trägårdh, 1902. All specimens were collected in Latvia. Thirteen morphological traits were measured for 838 adult individuals. The same traits were also measured with transmitted light microscopy, and results were compared. The impact of a number of environmental factors on traits was also assessed. High interspecific variability in size of most morphological features was observed. In many cases, sizes of the measured features correlated between different species. The ranges in length of notogastral setae p3 and h3 of C. femoralis did not overlap with those of C. labyrinthicus or C. ornatus. Significant correlations between body length and size of setal structures, as well as between setal structures, were detected. Size of morphological features was directly affected by the cover of lichens, a main food resource for Carabodes, and indirectly by the effect of soil moisture on lichen communities.     

A new species of Streptospinigera Kudenov, 1983 (Polychaeta, Syllidae, Anoplosyllinae) from the Arctic and north-western Atlantic with a key to all species of the genus

Since 2007, the ArcticNet and CHOne programmes have allowed researchers, through oceanographic surveys on the ‘NGCC Amundsen’, to collect yearly benthic samples in the Canadian High Arctic. From the Beaufort Sea to the Bay of Baffin, more than 262 samples have been collected and analysed to provide essential data to explain patterns of biodiversity in the Canadian Arctic archipelago. Whereas common species are well known, other more rare species belonging to a few minute species groups, with debatable taxonomy, were set aside for further analyses. Focusing on Syllidae (Annelida, Polychaeta), we found and describe here Streptospinigera niuqtuut sp. nov. from muddy habitats of bathyal Arctic and continental slope beds of northern Atlantic coasts of United States between depths of 169 and 707 m. S. niuqtuut differs from congeneric species by unique dorsal simple chaetae of 1–5 chaetigers dorsally curved and distally rounded, with some sub-distal serration. This species may have frequently been reported from the region as Syllides longocirrata Ørsted 1845 but in fact are species of the genus Streptospinigera Kudenov 1983. We also transfer Streptosyllis templadoi San Martín 1984 to this genus and provide herein a key for the identification of all species of the genus.