Aim The distribution and genetic composition of marine populations is the result of climatic and oceanographic factors as well as life history strategies. Studying species with wide distributions and high dispersal potential in sites that were differentially affected during the Pleistocene glaciations provides an opportunity to evaluate the genetic and distributional effect of glaciations on marine populations, such as the limpet Siphonaria lesonii. The aim of the present study is to evaluate the differential effects of glaciations on areas covered and not covered by ice sheets during the Pleistocene glaciations. Location Intertidal zone of the south‐eastern Pacific covering approximately 5,000 km of coastline of Peru and Chile. Methods We performed molecular analyses of mitochondrial and nuclear data jointly, as well as environmental niche modelling (ENM) of populations of the limpet Siphonaria lessonii. Using ENM, we modelled the potential distributional range of the species in the present and its distribution during the Last Glacial Maximum (LGM). Results Two lineages were found that were separated by a break at 41° S, corresponding to the biogeographical discontinuity previously reported for this region. Both of these lineages experienced genetic and demographical fluctuations that match the Pleistocene glaciations; however, the variability was more intense in the southern lineage. Phylogeography and ENM yielded complementary results for the southern lineage, which experienced loss of genetic diversity and habitat during the LGM, whereas the northern lineage evidenced loss of genetic diversity without distributional changes. Main conclusions The phylogeographical and ENM approaches suggest a historical scenario involving demographic and distributional contractions of S. lessonii surviving in glacial refugia in the southern portion of the south‐eastern Pacific. This study is the first to include both phylogeographical and ENM analyses of marine species from the Southern Hemisphere.

Intertidal communities’ composition and diversity usually exhibit strong changes in relation to environmental gradients at different biogeographical scales. This study represents the first comprehensive diversity and composition description of polyplacophoran assemblages along the Peruvian Province (SE Pacific, 12°S–39°S), as a model system for ecological latitudinal gradients. A total of 4,775 chitons from 21 species were collected on twelve localities along the Peruvian Province. This sampling allowed us to quantitatively estimate the relative abundance of the species in this assemblage, and to test whether chitons conform to elementary predictions of major biogeographic patterns such as a latitudinal diversity gradient. We found that the species composition supported the division of the province into three ecoregional faunal groups (i.e. Humboldtian, Central Chile, and Araucanian). Though chiton diversity did not follow a clear latitudinal gradient, changes in species composition were dominated by smaller scale variability in salinity and temperature. Body size significantly differed by ecoregions and species, indicating latitudinal size-structure assamblages. In some localities body size ratios differed from a random assemblage, evidencing competition at local scale. Changes in composition between ecoregions influence body size structure, and their overlapping produce vertical size segregation, suggesting that competition coupled with environmental conditions structure these assemblages.

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Polyplacophorans, or chitons, are relatively common across the benthic habitats, where >1,000 species (MolluscaBase, 2019; Schwabe, 2005) are found from rocky intertidal shores to marine trenches (Schwabe, 2010). Although chitons are widely recognized as ecologically important herbivores on rocky shores worldwide (e.g., Hawkins & Hartnoll, 1983; Lubchenco & Gaines, 1981; Otway, 1994), much less is known of their life histories and reproductive cycles, particularly in the southern Pacific region. As in nearly all molluscs, most chitons are gonochoric (dioecious) and free spawning with external fertilization, although some genera include brooders. At least two species are hermaphrodites, possibly with self-fertilization (e.g., Eernisse, 1988), whereas others show low levels of hermaphroditism (e.g., Ramírez-Álvarez et al., 2014). The gonad of chitons, which is formed by the fusion of two gonadal primordia, is located in front of the pericardial cavity and develops as a single dorsal structure, which, when fully developed, usually extends between the second and seventh shell plates (Pearse, 1979;

Se propone una nueva especie de gasterópodo de la familia Fissurellidae para la isla Robinson Crusoe, archipiélago de Juan Fernández: Zeidora macleani sp. nov. La especie es descrita sobre la base del estudio de la morfología de la concha de especímenes provenientes de muestreos bentónicos. Con la adición de esta especie, el número de representantes del género Zeidora A. Adams, 1860 en Chile aumenta a dos, ambas para las costas de las islas oceánicas. Para el territorio continental aun no existen registros.

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Macroecological studies have mainly focused on exploring the relationships between body size and geographic distribution on large scales, whether regional, continental or even global, and most of them have been conducted on terrestrial species. Few studies have been conducted on aquatic species, and even fewer have considered the importance of phylogeny in the observed patterns. Cephalopod molluscs are a good model to tackle these problems given that they have large geographic and bathymetric ranges, a wide range of body sizes, as well as diverse fin sizes and shapes. Here, we evaluate the relationships between body and fin size with the geographic distribution of 30 squid species of the family Loliginidae distributed worldwide. To test a macroecological hypothesis, we evaluated the phylogenetic signal and correlated evolution of the three traits to assess the role of phylogenetic relationships in squid distribution using a molecular phylogeny based on two mitochondrial and one nuclear gene. The analyses showed the existence of a relationship between body size and geographic distribution. Similarly, relative fin size showed a positive relationship with distribution. Phylogenetic signals were high for morphological traits (body and fin size), while it was low for distribution. The geographic distribution of loliginid squids evolved in relation to body size, where larger squids with large fins (e.g. genus Sepioteuthis) have wide distributions, while small-finned species (e.g. genus Pickfordioteuthis) have narrow distributions. This study opens the gates to explore such relationships in other squid families or other marine swimming animals.