Vermicularia Lamarck, 1799 is a clade of Miocene–Recent gastropods with an unusual uncoiled shell morphology. Like other “worm-snails,” they are taxonomically troublesome, and although earlier work affirmed the turritellid affinity of one species, their systematic relationships have not otherwise been previously examined. Here, we present a molecular phylogeny of turritellids, including members of other previously named genera [Mesalia Gray, 1847; Zaria Gray, 1847; Torcula Gray, 1847; Protomella Thiele, 1929; Maoricolpus Finlay, 1926; and the recently named Turritellinella Harzhauser & Landau, 2019, represented by Turritellinella tricarinata (Brocchi, 1814) = “Turritella communis” Risso, 1826], to establish the monophyly of Vermicularia and determine higher level relationships. We provide a revised taxonomy with detailed diagnoses for all known living and fossil species of Vermicularia, including the synonymy of Vermicularia lumbricalis (Linnaeus, 1758) and the commonly used junior synonym Vermicularia knorrii (Deshayes, 1843). The new Miocene–Pliocene species Vermicularia katiae n. sp. is described from the Dominican Republic. The phylogenetic relationships within living and fossil Vermicularia are also established based on morphological characters and with close outgroup turritelliform species chosen based on the molecular phylogeny. Callostracum gracile (Maltzan, 1883) was found to be well nested among the other species and is reassigned to Vermicularia herein as Vermicularia gracilis (Maltzan, 1883). The reconstructed phylogeny indicates that new species arose via cladogenesis much more frequently than by anagenesis, with most lineages originating in the Pliocene, but prior to the complete closure of the Central American Seaway ∼ 3.5 million years ago.

Pacific island land snails are among the most imperiled animals on Earth, which elevates the practical conservation importance of their systematics and biogeography. The Micronesian endemic land-snail genus Semperdon Solem, 1983 is composed of five described species from Belau and the Mariana Islands. Although these species are readily identifiable based on morphology, the existence of cryptic lineages within described species on Belau was proposed in the only systematic treatment of Semperdon and its relatives. New specimens of Semperdon species from Belau allow a rare opportunity to test for putative cryptic lineages in this severely threatened genus and to examine phylogeographic patterns in a non-hotspot archipelago. During this study, species delimitation within the Belau Semperdon species was analyzed using one distance-based (ABGD) and two tree-based (single-threshold GMYC and bPTP) molecular species delimitation methods and DNA sequence data from cytochrome c oxidase subunit I (COI) and the nuclear Internal Transcribed Spacer 2 (ITS2) region. In addition, a TCS network was used to explore the relationships of COI and ITS2 haplotypes and newly identified cryptic lineages. Based on these results, the first morphologically cryptic lineages are reported from Pacific endemic Charopidae. The strong phylogeographic structuring and exceptionally high mtDNA divergence on the archipelago suggests highly insular populations over relatively short geographic distances, roughly corresponding to smaller island groups within the archipelago. Finally, protection for island groups closest to human habitation and further survey efforts are recommended to mitigate extinction in this genus.

Uncancylus Pilsbry, 1913, a neotropical genus of freshwater limpets, includes four species and the “variety” Ancylus concentricus bonariensis established by Strobel in 1874. Uncancylus concentricus (d'Orbigny, 1835) is the best-known of all species of the genus, both in terms of the morphology as well as its distribution. The goals of this study were to describe a new species of Uncancylus from São Paulo State, Brazil—Uncancylus paulistanus n. sp.—and raise the subspecies proposed by Strobel to the rank of species, providing a redescription of shell and morphology (muscle scars and radula). We also provide a molecular analysis that supports the anatomical results in comparison with other sequences of species of Ancylinae. The diagnostic characters of the new species include a shell with an apical angle of almost 90°; three small adhesive areas in the anterior region located between the muscular scars; and the rachidian tooth with five cusps and a long basal plate with height twice its base. Uncancylus bonariensis (Strobel, 1874) has a shell with apical angle of 45°; three small adhesive areas located in the posterior region of the body; the rachidian tooth with five cusps and a basal plate with height twice its longer base. Molecular analyses (both ML and BI) showed a dichotomy separating the genera of the Holarctic region from the Neotropical region. Also, both analyses were congruent showing similar topologies with high support values for the clade formed by Uncancylus concentricus, U. paulistanus n. sp., and U. bonariensis indicating that they are different species.

The minute bivalve Gregariella semigranata (Reeve, 1858) was first reported from the coralligenous algal reefs off of Marzamemi in southeastern Sicily. The species has a cryptic, nestling lifestyle within convolutions of calcareous algae and crevices, occurring also under the canopy of fleshy algae and inside the soft tissues of sponges. A peculiar cocoon of threads and agglutinated mud enveloping some Gregariella specimens was observed, partly filling the gaps between the shell and the walls of hosting crevices, with a possible function of protection and/or stabilization. The posterior half of the valves develops a hairy periostracum with a tuft of long branched barbules resembling the surrounding soft algae. The tuft is the only part protruding from the substratum, with a possible mimetic function against predators. The numerous specimens of G. semigranata from Marzamemi allowed us to better focus on the ecology and the life strategy of this bivalve and adds a further record from the Ionian coasts of Sicily to its known Mediterranean geographical distribution.

Haloa japonica (Pilsbry, 1895) is a cephalaspidean bubble snail of the family Haminoeidae Pilsbry, 1895, native to the northwestern Pacific. Haloa japonica has been introduced to the Mediterranean Sea and western North America, where it can be locally abundant in estuarine habitats. To predict the future spread and establishment of this non-native species, it is important to understand how the species responds to and is tolerant of fluctuating salinity levels, one of the most important limiting factors for this species. In this study, we tested the salinities at which specimens of Haloa japonica were able to survive and maintain normal life functions, either by direct or gradual transfer of specimens into different salinities. The results showed that specimens were able to survive at least three days after direct transfer from 35 ppt into 20 ppt higher or lower salinities. Gradual transfer of specimens into different salinities showed that all specimens survive and behave normally in water with salinity in the range of 20–45 ppt, although survival decreases at extreme salinities. In cases of extreme salinities, we also observed lower activity of Haloa japonica and a change in body shape. Furthermore, higher salinities were more lethal than lower salinities. Based on the feeding rate and faecal production of Haloa japonica, the optimum salinity ranges from 30–40 ppt. The results showed that Haloa japonica is well adapted to salinity fluctuations, thus enabling the species to survive in extreme environments, to disperse by human-mediated transport, and to colonise new areas.