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Claudio A Gonzalezwevar - One of the best experts on this subject based on the ideXlab platform.
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systematic revision of nacella Patellogastropoda nacellidae based on a complete phylogeny of the genus with the description of a new species from the southern tip of south america
Zoological Journal of the Linnean Society, 2019Co-Authors: Tomoyuki Nakano, Claudio A Gonzalezwevar, Mathias Hüne, Hamish G. Spencer, Thomas Saucède, Sebastian Rosenfeld, Elie PoulinAbstract:True limpets of the genus Nacella (Patellogastropoda: Nacellidae) include at least 11 nominal species distributed in different provinces of the Southern Ocean. Here, we present new molecular analyses and a comprehensive morphological revision of Nacella confirming the validity of all the currently recognized species, but with important amendments to the published distributions of several. We also show that specimens collected along two fjords in the Beagle Channel, southern South America, constitute a new taxon: Nacella yaghana sp. nov. The phylogenetic position of this new taxon in our molecular tree reveals that it represents an ancestral South American lineage of Nacella, markedly separated from the previously recognized and evolutionary recent Magellanic radiation. In addition, this new Nacella species was clearly distinguished from the rest of the species by morphological comparisons, including shell characteristics, radular-tooth shape and configuration, as well as by the coloration pattern of the mantle tentacles. This study provides new evidence about the evolutionary history of this important Southern Ocean, marine, near-shore benthic group and the role of the Antarctic Circumpolar Current in the biogeography of the genus.
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antarctic and sub antarctic nacella limpets reveal novel evolutionary characteristics of mitochondrial genomes in Patellogastropoda
Molecular Phylogenetics and Evolution, 2019Co-Authors: Elie Poulin, Claudio A Gonzalezwevar, Juan Diego Gaitanespitia, Leyla CardenasAbstract:Abstract Mitochondrial genomes (mitogenomes) provide valuable phylogenetic information and genome-level characters that are useful in resolving evolutionary relationships within major lineages of gastropods. However, for more than one decade, these relationships and the phylogenetic position of Patellogastropoda have been inferred based on the genomic architecture as well as the nucleotide and protein sequences of a single representative, the limpet Lottia digitalis. This mitogenome exhibits extensive rearrangements and several repetitive units that may not represent universal features for Patellogastropoda. Here, we sequenced the complete mitogenomes of three Nacella limpets, providing new insights into the dynamics of gene order and phylogenetic relationships of Patellogastropoda. Comparative analyses revealed novel gene rearrangements in Gastropoda, characterised by two main translocations that affect the KARNI and the MYCWQ clusters in Nacella limpets. Our phylogenetic reconstructions using combined sequence datasets of 13 mitochondrial protein-coding genes and two rRNAs, recovered Patellogastropoda, and Gastropoda in general, as non-monophyletic. These findings could be related to the long-branch attraction tendency of these groups, and/or taxon sampling bias. In our novel mitogenome-based phylogenetic hypothesis, L. digitalis is placed in a sister position to Bivalvia and Heterobranchia, whereas Nacella limpets are placed sister to a clade containing Caenogastropoda + Neritimorpha and Vetigastropoda + Neomphalina.
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following the antarctic circumpolar current patterns and processes in the biogeography of the limpet nacella mollusca Patellogastropoda across the southern ocean
Journal of Biogeography, 2017Co-Authors: Tomoyuki Nakano, Claudio A Gonzalezwevar, Mathias Hüne, Nicolás I. Segovia, Hamish G. Spencer, Steven L. Chown, Thomas Saucède, Glenn Johnstone, Andrés MansillaAbstract:Aim We use an integrative biogeographical approach to further understand the evolution of an important Southern Ocean marine benthic element, the limpet genus Nacella (Mollusca: Patellogastropoda). Location Southern Ocean. Methods We used multi-locus time-calibrated phylogeny of Nacella at the scale of the whole Southern Ocean to elucidate the underlying processes involved in the origin and diversification of the genus. Results Divergence-time estimates suggest that soon after its origin during the mid-Miocene (c. 12.5 Ma), Nacella separated into two main lineages currently distributed in (1) South America and (2) Antarctica and the sub-Antarctic islands. We identified two pulses of diversification, during the late Miocene (8 to 5.5 Ma) and the Pleistocene (< 1 Ma). Main conclusions Major periods of climatic and oceanographical change strongly affected the biogeography of Nacella and demonstrate both the long- and short-term influence of the Antarctic Circumpolar Current across the Southern Ocean. Our analyses support the validity of all currently recognized Nacella species and reveal a new South-American lineage. This work constitutes the most detailed molecular-based study of an ecologically important, near-shore invertebrate Southern Ocean group and in so doing contributes to the improved understanding of the underlying patterns and processes in the origin and diversification of marine benthic fauna across this globally important region.
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biogeography in cellana Patellogastropoda nacellidae with special emphasis on the relationships of southern hemisphere oceanic island species
PLOS ONE, 2017Co-Authors: Claudio A Gonzalezwevar, Tomoyuki Nakano, Alvaro T Palma, Elie PoulinAbstract:Oceanic islands lacking connections to other land are extremely isolated from sources of potential colonists and have acquired their biota mainly through dispersal from geographically distant areas. Hence, isolated island biota constitutes interesting models to infer biogeographical mechanisms of dispersal, colonization, differentiation, and speciation. Limpets of the genus Cellana (Nacellidae: Patellogastropoda) show limited dispersal capacity but are broadly distributed across the Indo-Pacific including many endemic species in isolated oceanic islands. Here, we examined main distributional patterns and geographic boundaries among Cellana lineages with special emphasis in the relationships of Southern Hemisphere oceanic islands species. Phylogenetic reconstructions based on mtDNA (COI) recognized three main clades in Cellana including taxa from different provinces of the Indo-Pacific. Clear genetic discontinuities characterize the biogeography of Cellana and several lineages are associated to particular areas of the Indo-Pacific supporting the low dispersal capacity of the genus across recognized biogeographical barriers in the region. However, evolutionary relationships within Cellana suggest that long-distance dispersal processes have been common in the history of the genus and probably associated to the origin of the species in Hawaii and Juan Fernandez Archipelago. Therefore, the presence of Cellana species in geographically distant Southern Hemisphere oceanic islands, such as the Juan Fernandez Archipelago, suggests that long-distance dispersal mediated by rafting may have played an important role in the biogeography of the genus.
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patterns of genetic diversity and structure in antarctic and sub antarctic nacella Patellogastropoda nacellidae species
Biodiversity, 2016Co-Authors: Claudio A Gonzalezwevar, Mathias Hüne, Thomas Saucède, Andrés Mansilla, Sebastian Rosenfeld, Jeanpierre Feral, Elie PoulinAbstract:The biogeography of the Southern Ocean reflects complex interactions between major macro-evolutionary forces and biotic elements. Major gateway openings, the establishment of the Antarctic Circumpolar Current and climate cooling are deeply connected to the composition, abundance and distribution of the Southern Ocean marine benthic fauna. Glacial episodes of the Quaternary heavily impacted the distribution of the genetic variation of the Southern Ocean biota. The genus Nacella includes 12 nominal species in different provinces of the Southern Ocean. In this study, we compared patterns of mitochondrial DNA diversity in three Nacella species from Antarctic Peninsula, Kerguelen Island and Patagonia. Low levels of genetic diversity and absence of genetic structure characterise each one of them showing the strong impact of ice advances and retreats over their respective demographics. Haplotype diversity, short genealogies and demographic inference recorded suggest the occurrence of a more dramatic demographic process in Antarctic Peninsula than in the sub-Antarctic.
Elie Poulin - One of the best experts on this subject based on the ideXlab platform.
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systematic revision of nacella Patellogastropoda nacellidae based on a complete phylogeny of the genus with the description of a new species from the southern tip of south america
Zoological Journal of the Linnean Society, 2019Co-Authors: Tomoyuki Nakano, Claudio A Gonzalezwevar, Mathias Hüne, Hamish G. Spencer, Thomas Saucède, Sebastian Rosenfeld, Elie PoulinAbstract:True limpets of the genus Nacella (Patellogastropoda: Nacellidae) include at least 11 nominal species distributed in different provinces of the Southern Ocean. Here, we present new molecular analyses and a comprehensive morphological revision of Nacella confirming the validity of all the currently recognized species, but with important amendments to the published distributions of several. We also show that specimens collected along two fjords in the Beagle Channel, southern South America, constitute a new taxon: Nacella yaghana sp. nov. The phylogenetic position of this new taxon in our molecular tree reveals that it represents an ancestral South American lineage of Nacella, markedly separated from the previously recognized and evolutionary recent Magellanic radiation. In addition, this new Nacella species was clearly distinguished from the rest of the species by morphological comparisons, including shell characteristics, radular-tooth shape and configuration, as well as by the coloration pattern of the mantle tentacles. This study provides new evidence about the evolutionary history of this important Southern Ocean, marine, near-shore benthic group and the role of the Antarctic Circumpolar Current in the biogeography of the genus.
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antarctic and sub antarctic nacella limpets reveal novel evolutionary characteristics of mitochondrial genomes in Patellogastropoda
Molecular Phylogenetics and Evolution, 2019Co-Authors: Elie Poulin, Claudio A Gonzalezwevar, Juan Diego Gaitanespitia, Leyla CardenasAbstract:Abstract Mitochondrial genomes (mitogenomes) provide valuable phylogenetic information and genome-level characters that are useful in resolving evolutionary relationships within major lineages of gastropods. However, for more than one decade, these relationships and the phylogenetic position of Patellogastropoda have been inferred based on the genomic architecture as well as the nucleotide and protein sequences of a single representative, the limpet Lottia digitalis. This mitogenome exhibits extensive rearrangements and several repetitive units that may not represent universal features for Patellogastropoda. Here, we sequenced the complete mitogenomes of three Nacella limpets, providing new insights into the dynamics of gene order and phylogenetic relationships of Patellogastropoda. Comparative analyses revealed novel gene rearrangements in Gastropoda, characterised by two main translocations that affect the KARNI and the MYCWQ clusters in Nacella limpets. Our phylogenetic reconstructions using combined sequence datasets of 13 mitochondrial protein-coding genes and two rRNAs, recovered Patellogastropoda, and Gastropoda in general, as non-monophyletic. These findings could be related to the long-branch attraction tendency of these groups, and/or taxon sampling bias. In our novel mitogenome-based phylogenetic hypothesis, L. digitalis is placed in a sister position to Bivalvia and Heterobranchia, whereas Nacella limpets are placed sister to a clade containing Caenogastropoda + Neritimorpha and Vetigastropoda + Neomphalina.
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biogeography in cellana Patellogastropoda nacellidae with special emphasis on the relationships of southern hemisphere oceanic island species
PLOS ONE, 2017Co-Authors: Claudio A Gonzalezwevar, Tomoyuki Nakano, Alvaro T Palma, Elie PoulinAbstract:Oceanic islands lacking connections to other land are extremely isolated from sources of potential colonists and have acquired their biota mainly through dispersal from geographically distant areas. Hence, isolated island biota constitutes interesting models to infer biogeographical mechanisms of dispersal, colonization, differentiation, and speciation. Limpets of the genus Cellana (Nacellidae: Patellogastropoda) show limited dispersal capacity but are broadly distributed across the Indo-Pacific including many endemic species in isolated oceanic islands. Here, we examined main distributional patterns and geographic boundaries among Cellana lineages with special emphasis in the relationships of Southern Hemisphere oceanic islands species. Phylogenetic reconstructions based on mtDNA (COI) recognized three main clades in Cellana including taxa from different provinces of the Indo-Pacific. Clear genetic discontinuities characterize the biogeography of Cellana and several lineages are associated to particular areas of the Indo-Pacific supporting the low dispersal capacity of the genus across recognized biogeographical barriers in the region. However, evolutionary relationships within Cellana suggest that long-distance dispersal processes have been common in the history of the genus and probably associated to the origin of the species in Hawaii and Juan Fernandez Archipelago. Therefore, the presence of Cellana species in geographically distant Southern Hemisphere oceanic islands, such as the Juan Fernandez Archipelago, suggests that long-distance dispersal mediated by rafting may have played an important role in the biogeography of the genus.
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Following the Antarctic Circumpolar Current: patterns and processes in the biogeography of the limpet Nacella (Mollusca: Patellogastropoda) across the Southern Ocean
Journal of Biogeography, 2016Co-Authors: Claudio A. González-wevar, Tomoyuki Nakano, Mathias Hüne, Nicolás I. Segovia, Hamish G. Spencer, Steven L. Chown, Thomas Saucède, Glenn Johnstone, Andrés Mansilla, Elie PoulinAbstract:Aim We use an integrative biogeographical approach to further understand the evolution of an important Southern Ocean marine benthic element, the limpet genus Nacella (Mollusca: Patellogastropoda). Location Southern Ocean. Methods We used multi-locus time-calibrated phylogeny of Nacella at the scale of the whole Southern Ocean to elucidate the underlying processes involved in the origin and diversification of the genus. Results Divergence-time estimates suggest that soon after its origin during the mid-Miocene (c. 12.5 Ma), Nacella separated into two main lineages currently distributed in (1) South America and (2) Antarctica and the sub-Antarctic islands. We identified two pulses of diversification, during the late Miocene (8 to 5.5 Ma) and the Pleistocene (
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patterns of genetic diversity and structure in antarctic and sub antarctic nacella Patellogastropoda nacellidae species
Biodiversity, 2016Co-Authors: Claudio A Gonzalezwevar, Mathias Hüne, Thomas Saucède, Andrés Mansilla, Sebastian Rosenfeld, Jeanpierre Feral, Elie PoulinAbstract:The biogeography of the Southern Ocean reflects complex interactions between major macro-evolutionary forces and biotic elements. Major gateway openings, the establishment of the Antarctic Circumpolar Current and climate cooling are deeply connected to the composition, abundance and distribution of the Southern Ocean marine benthic fauna. Glacial episodes of the Quaternary heavily impacted the distribution of the genetic variation of the Southern Ocean biota. The genus Nacella includes 12 nominal species in different provinces of the Southern Ocean. In this study, we compared patterns of mitochondrial DNA diversity in three Nacella species from Antarctic Peninsula, Kerguelen Island and Patagonia. Low levels of genetic diversity and absence of genetic structure characterise each one of them showing the strong impact of ice advances and retreats over their respective demographics. Haplotype diversity, short genealogies and demographic inference recorded suggest the occurrence of a more dramatic demographic process in Antarctic Peninsula than in the sub-Antarctic.
A. N. Hodgson - One of the best experts on this subject based on the ideXlab platform.
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structure and formation of the unusual sperm of patelloida latistrigata mollusca Patellogastropoda implications for fertilization biology
The Biological Bulletin, 2012Co-Authors: A. N. Hodgson, Valerie Hodgson, Kevin J EckelbargerAbstract:The structure of the spermatozoa and spermatogenesis of the lottiid limpet Patelloida latistrigata is described by transmission electron microscopy. Although the lengths of the spermatozoa (about 60 μm) and their head region (about 12 μm) are similar to those of other patellogastropods, the structure of the sperm head and midpiece are very different. The head consists of an unusually large acrosome (about 11-μm long) with a broad posterior invagination that houses the relatively small nucleus. The midpiece mitochondria, which are rather elongate with large folded tubular cristae, are housed in a cytoplasmic sheath posterior to the nucleus. The proximal centriole is unusually elongate (about 2-μm long). The axoneme that emerges from the distal centriole is surrounded anteriorly by the cytoplasmic sheath in which the cytoplasmic side of the plasma membrane has electron-dense material. The flagellum is enlarged at its terminal end. Spermatogenesis is similar to that described for other patellogastropods. Pat...
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ultrastructure of the ovary and oogenesis in six species of patellid limpets gastropoda Patellogastropoda from south africa
Invertebrate Biology, 2005Co-Authors: A. N. Hodgson, Kevin J EckelbargerAbstract:. The ultrastructural features of the ovary and oogenesis have been described in 6 species of patellid limpets from South Africa. The ovary is a complex organ that is divided radially into numerous compartments or lacunae by plate-like, blind-ended, hollow trabeculae that extend from the outer wall of the ovary to its central lumen. Trabeculae are composed of outer epithelial cells, intermittent smooth muscle bands, and extensive connective tissue. Oocytes arise within the walls of the trabeculae and progressively bulge outward into the ovarian lumen during growth while partially surrounded by squamous follicle cells. During early vitellogenesis, the follicle cells lift from the surface of the underlying oocytes and microvilli appear in the perivitelline space. Follicle cells restrict their contact with the oocytes to digitate foot processes that form desmosomes with the oolamina. When vitellogenesis is initiated, the trabecular epithelial cells hypertrophy and become proteosynthetically active. Yolk synthesis involves the direct incorporation of extraoocytic precursors from the lumen of the trabeculae (hemocoel) into yolk granules via receptor-mediated endocytosis. Lipid droplets arise de novo and Golgi complexes synthesize cortical granules that form a thin band beneath the oolamina. A fibrous jelly coat forms between the vitelline envelope and the overlying follicle cells in all species.
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growth and reproduction in the high shore south african limpet helcion pectunculus mollusca Patellogastropoda
African Zoology, 2003Co-Authors: D R Gray, A. N. HodgsonAbstract:Growth and aspects of the reproductive biology of the high-shore limpet Helcion pectunculusl/Ig were determined for a southeast and southwest coast population. Limpets grew allometrically, increasing in height faster than length (a =1.3 to 1.6). Growth rates (about 5-6 mm / year shell length), were similar in both the southeast and southwest coast population, as were the theoretical Llsubgmaxl/subg values of 30.86 mm and 30.71 mm, respectively. Maximum age of limpets was calculated to be 5-6 years. H. pectunculusl/Ig is a protandrous hermaphrodite, males becoming sexually mature at about 10-12 mm shell length (about one year old), and changing sex at about 16 mm shell length (about two years old). This resulted in sex ratios of about two males to one female. Limpets from both geographic locations spawned mainly in summer (November / December) with a second smaller spawning in autumn (April). There was no significant difference in the gonad index (GI) between southeast coast males and females. However the GI of southwest coast males was about 5% greater than that of the females. The gonad indices of southeast coast and southwest coast limpets was not significantly different.
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Growth and reproduction in the high-shore South African limpet Helcion pectunculus (Mollusca : Patellogastropoda)
African Zoology, 2003Co-Authors: D R Gray, A. N. HodgsonAbstract:Growth and aspects of the reproductive biology of the high-shore limpet Helcion pectunculusl/Ig were determined for a southeast and southwest coast population. Limpets grew allometrically, increasing in height faster than length (a =1.3 to 1.6). Growth rates (about 5-6 mm / year shell length), were similar in both the southeast and southwest coast population, as were the theoretical Llsubgmaxl/subg values of 30.86 mm and 30.71 mm, respectively. Maximum age of limpets was calculated to be 5-6 years. H. pectunculusl/Ig is a protandrous hermaphrodite, males becoming sexually mature at about 10-12 mm shell length (about one year old), and changing sex at about 16 mm shell length (about two years old). This resulted in sex ratios of about two males to one female. Limpets from both geographic locations spawned mainly in summer (November / December) with a second smaller spawning in autumn (April). There was no significant difference in the gonad index (GI) between southeast coast males and females. However the GI of southwest coast males was about 5% greater than that of the females. The gonad indices of southeast coast and southwest coast limpets was not significantly different.
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the reproductive cycle of helcion pruinosus Patellogastropoda on two south african boulder shores
Journal of Molluscan Studies, 2001Co-Authors: Tony O Henninger, A. N. HodgsonAbstract:The reproductive cycle of the South African limpet Helcion pruinosus was determined over 19 months for a south-east and south-west coast population. Despite inhabiting shores subjected to different oceanographic conditions, limpets from both populations spawned mainly in summer with early gametogenesis occurring in spring. The gonads of limpets were never completely spent suggesting that they are partial spawners. The gonad index (G.I.) of males was significantly greater than that of females in both populations and the G.I. of south-west coast limpets greater than that of limpets from the southeast coast. The sex ratio of the population on the south-west coast was 1:1 whereas the south-east coast population contained significantly more males.
Tomoyuki Nakano - One of the best experts on this subject based on the ideXlab platform.
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artificial fertilisation and early development of a limpet lottia tenuisculpta Patellogastropoda lottiidae
Molluscan Research, 2020Co-Authors: Tomoyuki Nakano, Ryo Nakayama, Yoko TakahashiAbstract:ABSTRACTPatellogastropoda is an ecologically widely diversified group living on various substrata. Juveniles of Lottia tenuisculpta live on rocks and also on the shell of trochid snails, from which...
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systematic revision of nacella Patellogastropoda nacellidae based on a complete phylogeny of the genus with the description of a new species from the southern tip of south america
Zoological Journal of the Linnean Society, 2019Co-Authors: Tomoyuki Nakano, Claudio A Gonzalezwevar, Mathias Hüne, Hamish G. Spencer, Thomas Saucède, Sebastian Rosenfeld, Elie PoulinAbstract:True limpets of the genus Nacella (Patellogastropoda: Nacellidae) include at least 11 nominal species distributed in different provinces of the Southern Ocean. Here, we present new molecular analyses and a comprehensive morphological revision of Nacella confirming the validity of all the currently recognized species, but with important amendments to the published distributions of several. We also show that specimens collected along two fjords in the Beagle Channel, southern South America, constitute a new taxon: Nacella yaghana sp. nov. The phylogenetic position of this new taxon in our molecular tree reveals that it represents an ancestral South American lineage of Nacella, markedly separated from the previously recognized and evolutionary recent Magellanic radiation. In addition, this new Nacella species was clearly distinguished from the rest of the species by morphological comparisons, including shell characteristics, radular-tooth shape and configuration, as well as by the coloration pattern of the mantle tentacles. This study provides new evidence about the evolutionary history of this important Southern Ocean, marine, near-shore benthic group and the role of the Antarctic Circumpolar Current in the biogeography of the genus.
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molecular analysis reveals a new cryptic species in a limpet lottia kogamogai Patellogastropoda lottiidae from japan
Zootaxa, 2017Co-Authors: Ryo Nakayama, Takenori Sasaki, Tomoyuki NakanoAbstract:A group of small lottiid species in Japan, the Lottia kogamogai complex, was phylogenetically analyzed based on the mitochondrial COI gene. As a result, L. kogamogai is subdivided into two geographic clades. Lottia kogamogai s.s. is limited to southern temperate Japan. The northern population formerly considered an intraspecific variation of the species is shown to be a distinct new species, here described as Lottia goshimai n. sp. The new species is distinguishable from L. kogamogai not only genetically, but in radular morphology and shell sculpture.
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following the antarctic circumpolar current patterns and processes in the biogeography of the limpet nacella mollusca Patellogastropoda across the southern ocean
Journal of Biogeography, 2017Co-Authors: Tomoyuki Nakano, Claudio A Gonzalezwevar, Mathias Hüne, Nicolás I. Segovia, Hamish G. Spencer, Steven L. Chown, Thomas Saucède, Glenn Johnstone, Andrés MansillaAbstract:Aim We use an integrative biogeographical approach to further understand the evolution of an important Southern Ocean marine benthic element, the limpet genus Nacella (Mollusca: Patellogastropoda). Location Southern Ocean. Methods We used multi-locus time-calibrated phylogeny of Nacella at the scale of the whole Southern Ocean to elucidate the underlying processes involved in the origin and diversification of the genus. Results Divergence-time estimates suggest that soon after its origin during the mid-Miocene (c. 12.5 Ma), Nacella separated into two main lineages currently distributed in (1) South America and (2) Antarctica and the sub-Antarctic islands. We identified two pulses of diversification, during the late Miocene (8 to 5.5 Ma) and the Pleistocene (< 1 Ma). Main conclusions Major periods of climatic and oceanographical change strongly affected the biogeography of Nacella and demonstrate both the long- and short-term influence of the Antarctic Circumpolar Current across the Southern Ocean. Our analyses support the validity of all currently recognized Nacella species and reveal a new South-American lineage. This work constitutes the most detailed molecular-based study of an ecologically important, near-shore invertebrate Southern Ocean group and in so doing contributes to the improved understanding of the underlying patterns and processes in the origin and diversification of marine benthic fauna across this globally important region.
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biogeography in cellana Patellogastropoda nacellidae with special emphasis on the relationships of southern hemisphere oceanic island species
PLOS ONE, 2017Co-Authors: Claudio A Gonzalezwevar, Tomoyuki Nakano, Alvaro T Palma, Elie PoulinAbstract:Oceanic islands lacking connections to other land are extremely isolated from sources of potential colonists and have acquired their biota mainly through dispersal from geographically distant areas. Hence, isolated island biota constitutes interesting models to infer biogeographical mechanisms of dispersal, colonization, differentiation, and speciation. Limpets of the genus Cellana (Nacellidae: Patellogastropoda) show limited dispersal capacity but are broadly distributed across the Indo-Pacific including many endemic species in isolated oceanic islands. Here, we examined main distributional patterns and geographic boundaries among Cellana lineages with special emphasis in the relationships of Southern Hemisphere oceanic islands species. Phylogenetic reconstructions based on mtDNA (COI) recognized three main clades in Cellana including taxa from different provinces of the Indo-Pacific. Clear genetic discontinuities characterize the biogeography of Cellana and several lineages are associated to particular areas of the Indo-Pacific supporting the low dispersal capacity of the genus across recognized biogeographical barriers in the region. However, evolutionary relationships within Cellana suggest that long-distance dispersal processes have been common in the history of the genus and probably associated to the origin of the species in Hawaii and Juan Fernandez Archipelago. Therefore, the presence of Cellana species in geographically distant Southern Hemisphere oceanic islands, such as the Juan Fernandez Archipelago, suggests that long-distance dispersal mediated by rafting may have played an important role in the biogeography of the genus.
Takenori Sasaki - One of the best experts on this subject based on the ideXlab platform.
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molecular analysis reveals a new cryptic species in a limpet lottia kogamogai Patellogastropoda lottiidae from japan
Zootaxa, 2017Co-Authors: Ryo Nakayama, Takenori Sasaki, Tomoyuki NakanoAbstract:A group of small lottiid species in Japan, the Lottia kogamogai complex, was phylogenetically analyzed based on the mitochondrial COI gene. As a result, L. kogamogai is subdivided into two geographic clades. Lottia kogamogai s.s. is limited to southern temperate Japan. The northern population formerly considered an intraspecific variation of the species is shown to be a distinct new species, here described as Lottia goshimai n. sp. The new species is distinguishable from L. kogamogai not only genetically, but in radular morphology and shell sculpture.
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Recent advances in molecular phylogeny, systematics and evolution of patellogastropod limpets
Journal of Molluscan Studies, 2011Co-Authors: Tomoyuki Nakano, Takenori SasakiAbstract:With the advent of molecular phylogenetics, the systematics and taxonomy of Patellogastropoda have been greatly improved. Eight families and 36 genera are currently recognized in the order. We review recent published papers that have used molecular data, discuss the resulting advances in systematics and evolution of Patellogastropoda and suggest directions of future research.
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color polymorphism and historical biogeography in the japanese patellogastropod limpet cellana nigrolineata reeve Patellogastropoda nacellidae
Zoological Science, 2010Co-Authors: Tomoyuki Nakano, Takenori Sasaki, Tomoki KaseAbstract:Cellana nigrolineata is amongst the most common and largest patellogastropod limpets in Japan, and has two color morphs. Analyses of anatomical and morphological characters, shell structure, and mitochondrial COI data (658bp) of these color morphs suggested that they represent intraspecific genetic variation. Molecular analysis demonstrated that the species can be subdivided into three genetically distinct groups: (Clade 1) Honshu, Shikoku to Eastern Kyushu, (Clade 2) Western Kyushu and (Clade 3) Southern Kyushu. Clade 1 and Clade 2 + 3 are distributed on the coastlines adjacent to two warm-water currents, the Kuroshio and Tsushima Currents, respectively. The southern population (Clade 3) is currently isolated by inhospitable sandy shores. The subdivision of these groups likely dates from the glacial period of Plio-Pleistocene time.
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characterization of the multilayered shell of a limpet lottia kogamogai mollusca Patellogastropoda using sem ebsd and fib tem techniques
Journal of Structural Biology, 2010Co-Authors: Michio Suzuki, Takenori Sasaki, Jun Kameda, Kazuko Saruwatari, Hiromichi Nagasawa, Toshihiro KogureAbstract:The microstructure and its crystallographic aspect of the shell of a limpet, Lottia kogamogai, have been investigated, as the first step to clarify the mechanism of shell formation in limpet. The shell consists of five distinct layers stacked along the shell thickness direction. Transmission electron microscopy (TEM) with the focused ion beam (FIB) sample preparation technique was primarily adopted, as well as scanning electron microscopy (SEM) with electron back-scattered diffraction (EBSD). The five layers were termed as M + 3, M + 2, M + 1, M, M � 1 from the outside to the inside in previous works, where M means myostracum. The outmost M + 3 layer consists of calcite with a ‘‘mosaic” structure; granular submicron sub-grains with small-angle grain boundaries often accompanying dislocation arrays. M + 2 layer consists of flat prismatic aragonite crystals with a leaf-like cross section, stacked obliquely to the shell surface. It looks that the prismatic crystals are surrounded by organic sheets, forming a compartment structure. M + 1 and M � 1 layers adopt a crossed lamellar structure consisting of aragonite flat prisms with rectangular cross section. M layer has a prismatic structure of aragonite perpendicular to the shell surface and with irregular shaped cross sections. Distinct organic sheets were not observed between the crystals in M + 1, M and M � 1 layers. The {1 1 0} twins are common in all aragonite M + 2, M + 1, M and M � 1 layers, with the twin boundaries parallel to the prisms. These results for the microstructure of each layer should be considered in the discussion of the formation mechanism of the limpet shell structure.
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the southernmost record of nipponacmea fuscoviridis Patellogastropoda lottiidae from iriomote island okinawa
Venus : journal of the Malacological Society of Japan, 2007Co-Authors: Takenori Sasaki, Tomoyuki NakanoAbstract:Nipponacmea fuscoviridis (Teramachi, 1949) is enormously abundant in the intertidal zone throughout the temperate area of the Japanese islands (southern Hokkaido and southward: Sasaki & Okutani, 1993). It also occurs in part of the Ryukyu Islands, but known subtropical localities are extremely few in number. In the literature, reliable records exist only from four of the Nansei Islands, viz. Amami-Oshima Island, Kakeroma Island, Tokashiki Island and Kunigami, Okinawa Island (Sasaki & Okutani, 1993; Kubo & Kurozumi, 1995). In 2004 one of us (T. S.) surveyed the molluscan fauna of Iriomote Island, Okinawa (Sasaki et al., 2006) and unexpectedly collected specimens of the genus Nipponacmea, which is mainly distributed in temperate areas. As a result of morphological examinations they were identified as N. fuscoviridis based on shell characters, animal pigmentation and radular sac configuration. In addition, molecular phylogenetic analysis confirmed that the material is genetically conspecific with temperate population of N. fuscoviridis. We report this interesting range extension in this paper.