The Chilean Altiplano and the Atacama Desert in northern Chile harbor isolated hydrological systems or oases where it is possible to find minute aquatic snails of the genus Heleobia whose taxonomy is uncertain and where many populations remain unknown. Here, we obtained samples from 30 localities distributed in the region and used molecular (12S and 16S mitochondrial genes) and morphological (penis) characters to investigate diversity of this poorly known fauna.

Species recognition in freshwater snails of the genus Heleobia Stimpson, 1865 Stimpson, W. (1865). Researches upon the Hydrobiinae and allied forms; chiefly made upon materials in the Museum of the Smithsonian Institution. Smithsonian Miscellaneous Collections, 201, 1–59. [Google Scholar] in the Loa River basin is a difficult task to perform because these snails are similar in shell morphology. In this complex hydrological network, the genus comprises two endemic species, but the taxonomic status of other previously undescribed sympatric and allopatric populations is uncertain. Here we examined DNA sequences from cytochrome c oxidase subunit I (COI) gene and morphological data to investigate species boundaries along the system. Phylogenetic trees were inferred using maximum parsimony, neighbour joining, maximum likelihood and Bayesian inference methods based on samples ranging from the outlet of the Loa River on the Pacific coast to more than 4,200 m altitude in the Andes. Although not always well supported, four clades were consistently recovered in the phylogenies, one corresponding to Heleobia loaensis (Biese, 1947 Biese, W. A. (1947). Revisión de los moluscos terrestres y de agua dulce provistos de concha de Chile. Parte II, Familia Amnicolidae. Boletín del Museo de Historia Natural, Chile, 23, 63–77. [Google Scholar] ), another to Heleobia opachensis (Biese, 1947 Biese, W. A. (1947). Revisión de los moluscos terrestres y de agua dulce provistos de concha de Chile. Parte II, Familia Amnicolidae. Boletín del Museo de Historia Natural, Chile, 23, 63–77. [Google Scholar] ), and two more additional cryptic lineages. Additionally, a fifth cluster of sequences not recovered in these analyses was inferred in the BEAST analysis. Outline-based geometric morphometrics of the shell was useful to differentiate a single lineage sustaining that typological discrimination in Heleobia is challenging. Our results also indicate that all lineages diverged by independent non-adaptive allopatric processes during the Middle Pleistocene.

Aim: Antarctica's remote and extreme terrestrial environments are inhabited by only two species of native vascular plants. We assessed genetic connectivity amongst Antarctic and South American populations of one of these species,Colobanthus quitensis, to determine its origin and age in Antarctica.Location: Maritime Antarctic, sub‐Antarctic islands, South America.Taxon: Antarctic pearlwortColobanthus quitensis(Caryophyllaceae).Methods: Four chloroplast markers and one nuclear marker were sequenced from 270 samples from a latitudinal transect spanning 21–68° S. Phylogeographic, population genetic and molecular dating analyses were used to assess the demographic history ofC. quitensisand the age of the species in Antarctica.Results: Maritime Antarctic populations consisted of two different haplotype clusters, occupying the northern and southern Maritime Antarctic. Molecular dating analyses suggestedC. quitensisto be a young (<1 Ma) species, with contemporary population structure derived since the late‐Pleistocene.Main conclusions.: The Maritime Antarctic populations likely derived from two independent, late‐Pleistocene dispersal events. Both clusters shared haplotypes with sub‐Antarctic South Georgia, suggesting higher connectivity across the Southern Ocean than previously thought. The overall findings of multiple colonization events by a vascular plant species to Antarctica, and the recent timing of these events, are of significance with respect to future colonizations of the Antarctic Peninsula by vascular plants, particularly with predicted increases in ice‐free land in this area. This study fills a significant gap in our knowledge of the age of the contemporary Antarctic terrestrial biota. Adding to previous inferences on the other Antarctic vascular plant species (the grassDeschampsia antarctica), we suggest that both angiosperm species are likely to have arrived on a recent (late‐Pleistocene) time‐scale. While most major groups of Antarctic terrestrial biota include examples of much longer‐term Antarctic persistence, the vascular flora stands out as the first identified terrestrial group that appears to be of recent origin.

In the present study, we focus on the phylogeographic pattern, demographic history and morphological differentiation ofHeleobia ascotanensis, a freshwater gastropod restricted to the Ascotán saltpan in the Chilean Altiplano. The current distribution of the species is limited to twelve isolated or partially isolated springs that were affected by transitions between humid and arid periods during last glaciations. The genetic analysis of 322 specimens showed thatH. ascotanensisis subdivided into three genetically divergent populations, with low and moderate degrees of historical gene flow among them and incipient morphological differentiation as a consequence of genetic and geographical isolation. Molecular analyses revealed different demographic histories among populations which seem to respond independently to climatic events, probably due to an environmental imposition and idiosyncratic strategies developed to cope with water availability. The results of this study and co-distributed taxa support the hypothesis that contemporary and historical events have influenced microevolutionary differentiation of these snails, although there is a need to complement further information to predict genetic or morphological divergence at microgeographic scale.

Species delimitation in minute freshwater snails is often difficult to perform using solely shell morphology. The problem intensifies when invasive species spread within the distribution range of morphologically similar native species. In Chile, the Truncatelloidean snails are represented by the native genera Heleobia and Potamolithus plus the invasive mudsnail Potamopyrgus antipodarum, which can easily be confused. Using an integrative approach, we performed molecular phylogenetic analysis and studied reproductive and morphological features to identify superficially similar forms inhabiting the central area of the country. Truncatelloidean snails were identified in 40 of 51 localities sampled, 10 containing Potamopyrgus antipodarum, 23 Heleobia and 7 Potamolithus. Based on these results and previously published data, the known distribution of the mudsnail in Chile encompasses 6 hydrological basins, including 18 freshwater ecosystems. The finding of the mudsnails in several type localities of native species/subspecies of “Heleobia” that were not find in situ suggests species replacement or significant extinction of native fauna, a hypothesis supported by the restudy of type material that shows that endemic forms belong to the genus Potamolithus. This study shows the usefulness of integrative taxonomy not only resolving complex taxa with cryptic morphology but also measuring the extent of an ongoing invasion.

The chiton genus Tonicia is composed of 12 species, 11 of which are found in the eastern Pacific, but the taxonomic status and geographical distribution of these species have long been controversial. In this study, we compare eastern Pacific Tonicia species using molecular systematics. The molecular markers cytochrome oxidase c subunit I (COI), 16S and 18S ribosomal RNA were used to estimate the phylogenetic relationships and divergence times among species. Species delimitations were inferred using a Bayesian generalized mixed Yule coalescent (bGMYC) and a Bayesian Poisson tree processes (bPTP) approach. We assigned southeastern Pacific specimens to nine recognized species based on their morphology, but these were resolved into only six species in our molecular phylogeny, suggesting that three of the recognized morpho species need to be synonymized. The bGMYC and bPTP analyses indicate the existence of six total coalescent groups interpreted as seven species in our gene tree results. Likewise, pairwise genetic distances, phylogenetic estimates and coalescent approaches support only seven lineages when considering specimens that match the nine currently recognized southeastern Pacific Tonicia species. We suggest that the colouration and morphological characters used to identify Tonicia species must be re-examined in depth.