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One of the most relevant characteristics of the extant Southern Ocean fauna is its resiliency to survive glacial processes of the Quaternary. These climatic events produced catastrophic habitat reductions and forced some marine benthic species to move, adapt or go extinct. The marine benthic species inhabiting the Antarctic upper continental shelf faced the Quaternary glaciations with different strategies that drastically modified population sizes and thus affected the amount and distribution of intraspecific genetic variation. Here we present new genetic information for the most conspicuous regular sea urchin of the Antarctic continental shelf, Sterechinus neumayeri. We studied the patterns of genetic diversity and structure in this broadcast-spawner across three Antarctic regions: Antarctic Peninsula, the Weddell Sea and Adélie Land in East Antarctica. Genetic analyses based on mitochondrial and nuclear markers suggested that S. neumayeri is a single genetic unit around the Antarctic continent. The species is characterized by low levels of genetic diversity and exhibits a typical star-like haplotype genealogy that supports the hypothesis of a single in situ refugium. Based on two mutation rates standardized for this genus, the Bayesian Skyline plot analyses detected a rapid demographic expansion after the Last Glacial Maximum. We propose a scenario of rapid postglacial expansion and recolonization of Antarctic shallow areas from a less ice-impacted refugium where the species survived the LGM. Considering the patterns of genetic diversity and structure recorded in the species, this refugium was probably located in East Antarctica.

endemic to South Georgia), M. steineni (South Georgia and Crozet Island) and the morphologically variable M. violacea (=M. expansa , M. porcellana and M. pruinosa) , with populations in southern South America , the Falkland/Malvinas , Crozet and Kerguelen Islands. Margarella violacea and M. achilles are sister species, closely related to M. steineni, with M. antarctica sister to all these. This taxonomy reflects contrasting biogeographic patterns on either side of the APF in the Southern Ocean. Pop-ulations of Margarella north of the APF (M. violacea) showed significant genetic variation but with many shared haplotypes between geographically distant populations. By contrast, populations south of the APF (M. antarctica, M. steineni and M. achilles) exhibited fewer haplotypes and comprised three distinct species, each occurring across a separate geographical range. We hypothesize that the biogeographical differences may be the consequence of the presence north of the APF of buoyant kelpspotential longdistance dispersal vectors for these vetigastro-pods with benthic-protected developmentand their near-absence to the south. Finally, we suggest that the low levels of genetic diversity within higher-latitude Margarella reflect the impact of Quaternary glacial cycles that exterminated local populations during their maxima.

Copepods are present in numerous aquatic environments, playing key roles in food webs, and are thought to be useful indicators of environmental change. Boeckella is a calanoid copepod genus distributed mainly in the Southern Hemisphere, with 14 species reported at higher southern latitudes in South America and Antarctica. We present an updated database of these 14 species of Boeckella generated from a combination of three sources: 1) new field sampling data, 2) published records, and 3) Global Biodiversity Information Facility (GBIF), to provide a comprehensive description of the geographic distribution of the genus south of latitude 40°S in southern South America and the three main terrestrial biogeographic regions of Antarctica. The database includes 380 records, 62 from field sampling, 278 from the literature and 40 from GBIF. Southern South America, including the Falkland/Malvinas Islands, had the highest species richness and number of records (14 and 297, respectively), followed by the sub-Antarctic islands (5 and 34), South Orkney Islands (2 and 14), South Shetland Islands (1 and 23), Antarctic Peninsula (1 and 10) and finally continental Antarctica (1 and 2). Boeckellapoppei Mrázek, 1901 is the only representative of the genus, and more widely the only terrestrial/freshwater invertebrate, currently reported from all three main biogeographic regions in Antarctica (sub-Antarctic islands, maritime and continental Antarctic). Future development of molecular systematic studies in this group should contribute to assessing the correspondence between morphological taxonomy and molecular evolutionary radiation.

Aim The Antarctic Circumpolar Current imparts significant structure to the Southern Ocean biota. The Antarctic Polar Front is a major barrier to dispersal, with separate species (or sometimes intraspecific clades) normally occurring either side of this feature. We examined the biogeographic structure of an apparent exception to this rule in a widespread genus of the Southern Ocean, the periwinkle snail, Laevilitorina. Location Southern Ocean. Taxon Littorinidae, Laevilitorininae, Laevilitorina. Methods Using 750 specimens from 16 Southern Ocean Laevilitorina populations across >8000 km, we analysed mitochondrial COI and nuclear 28S sequences to uncover the evolutionary history of these marine near‐shore snails. We utilized multi‐locus phylogenetic reconstructions, species‐delimitation analyses, divergence‐time estimations and geometric morphometrics. Results Molecular data revealed that the widespread nominal species L. caliginosa comprises seven species‐level clades, all supported by morphological data, whereas the Antarctic nominal species L. antarctica, L. claviformis and L. umbilicata are conspecific. Six “caliginosa” clades are restricted to southern South America, but one lineage extends from Antarctica to distant sub‐Antarctic islands on both sides of the APF. Geometric morphometrics also identified significant differences among these clades, but uncoupled from genetic differentiation. Main conclusions The apparent trans‐APF distribution of the poorly dispersing Laevilitorina caliginosa is largely illusory: this taxon consists of at least seven discrete species, only one of which has a trans‐APF distribution. Similar to most Laevilitorina species, the remaining six “caliginosa” clades are narrow endemics. Biogeographical patterns in Laevilitorina reflect the role of vicariance associated with geological processes together with recent long‐distance dispersal events. Laevilitorina originated near the Eocene/Oligocene boundary and diversified during the Miocene and the Pliocene. Laevilitorina is not a cryptic‐species complex: speciation was accompanied by hitherto unrecognized morphological differentiation. This study represents the most detailed molecular work on Southern‐Ocean littorinids and reveals unforeseen diversity across this globally important region.

Resumen.-La identificación de especies se establece como una de las principales etapas para cualquier estudio sobre biodiversidad, en especial frente a cambios globales y sus repercusiones. Es por esto que se requiere un amplio conocimiento taxonómico en los diferentes grupos de organismos. La herramienta de ADN barcoding ha sido descrita como una importante alternativa a los estudios morfológicos tradicionales, permitiendo complementar las técnicas de identificación en un amplio número de taxa. En este estudio, se analiza la divergencia genética intraespecífica e interespecífica entre poliquetos marinos de los fiordos patagónicos del sur de Chile, utilizando el gen Citocromo c Oxidasa Subunidad I (COI). Los resultados muestran que las 31 secuencias obtenidas de 13 especies analizadas exhiben altos niveles de variación interespecífica. La comparación intraespecífica de distancias genéticas basadas en K2P varió entre 0,2 a 0,4%. En contraste, las comparaciones interespecíficas fueron mucho mayores y variaron entre 18 a 47%, con excepción de las especies congenéricas Asychis chilensis y Asychis amphiplypta, las cuales no presentaron monofilia recíproca. Este trabajo representa el primer estudio que muestra resultados mediante la herramienta de barcoding en poliquetos de la zona sur de Chile. Además establece la efectividad de esta herramienta alternativa para la identificación de especies de poliquetos marinos en los fiordos Patagónicos, y así disponerlo a la comunidad científica para sus futuras aplicaciones. Palabras clave: Taxonomía molecular, Polychaeta, Citocromo c Oxidasa Subunidad I, CIMAR-13 Fiordos, ChileAbstract.-Accurate species identification remains a basic first step in any study of biodiversity, particularly for global changes and their consequences. Thus, there is a pressing need for taxonomic expertise in a broad range of taxa. DNA barcoding has proved to be a powerful alternative method to traditional morphological approaches, allowing to complement identification techniques for living organisms. In this study, we assess intraspecific and interspecific genetic divergence among marine polychaetes from Patagonian fjords of southern Chile, using mitochondrial Cytochrome c Oxidase Subunit I (COI) gene. Our results showed that a total of 13 polychaetes species identified in this study exhibited high levels of interspecific variation among 31 analyzed sequences. Mean pairwise sequence distances comparisons based on K2P within species ranged from 0.2 to 0.4%. In contrast, interspecific comparisons were much higher and ranged between 18 to 47%, with the exception of the congeneric species Asychis chilensis and Asychis amphiglypta that showed high levels of genetic similarities and absence of reciprocal monophyly. This study presents the first information on DNA barcoding for polychaetes species in the southern Chile, and it establishes the effectiveness of DNA barcoding for identification of marine polychaetes species from Patagonian Fjords, thus making it available to a much broader range of scientists.

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Aim We investigated evolutionary relationships and biogeographical patterns within the genus Boeckella to evaluate (1) whether its current widespread distribution in the Southern Hemisphere is due to recent long‐distance dispersal or long‐term diversification; and (2) the age and origin of sub‐Antarctic and Antarctic Boeckella species, with particular focus on the most widely distributed species: Boeckella poppei. Location South America, sub‐Antarctic islands, maritime Antarctica, continental Antarctica and Australasia. Methods To reconstruct phylogenetic patterns of Boeckella, we used molecular sequence data collected from 12 regions and applied Bayesian and Maximum Likelihood analyses using multiple loci. We also estimated divergence times and reconstructed ancestral ranges using two different models of species evolution. Results Phylogenetic analyses and divergence time estimates suggested that Boeckella originated on the Gondwanan supercontinent and initially split into two main clades during the late Cretaceous (ca. 80 Ma). The first clade diversified in Australasia, and the second clade is currently distributed in South America, various sub‐Antarctic islands and Antarctica. Dispersal from South America to the Kerguelen and Crozet archipelagos occurred during the Eocene/Oligocene (B. vallentini) and in the late Pliocene (B. brevicaudata), while South Georgia and the maritime Antarctic were likely colonized during the late Pleistocene (B. poppei). Main conclusions Boeckella has a Gondwanan origin, with further diversifications after the physical separation of the continental landmasses. Extant populations of Boeckella from the Scotia Arc islands and Antarctic Peninsula originated from South America during the Pleistocene, suggesting that original Antarctic Gondwanan lineages did not survive repeated glacial cycles during the Quaternary ice ages. A continuous decline in the species accumulation rate is apparent within the genus as the early Eocene, suggesting that Boeckella diversification may have decreased due to progressive cooling throughout the Cenozoic era.