First record of Thysanophoridae from Brazil (Gastropoda, Stylommatophora)

The terrestrial gastropod family Thysanophoridae is reported herein for the first time from Brazil. The new record stems from a 2015 survey in the Reserva Biológica de Pedra Talhada, a protected Atlantic Forest fragment in Alagoas state, in the northeastern part of the country. Only two empty juvenile shells were found, and the specimens can be tentatively identified as Thysanophora cf. plagioptycha (Shuttleworth, 1854). Given the location is a reserve, this is potentially a natural occurrence and not a case of introduction.

Oxygen isotopes in terrestrial gastropod shells track Quaternary climate change in the American Southwest

Recent studies have shown the oxygen isotopic composition (δ18O) of modern terrestrial gastropod shells is determined largely by the δ18O of precipitation. This implies that fossil shells could be used to reconstruct the δ18O of paleo-precipitation as long as the isotopic system, including the hydrologic pathways of the local watershed and the gastropod systematics, is well understood. In this study, we measured the δ18O values of 456 individual gastropod shells collected from paleowetland deposits in the San Pedro Valley, Arizona that range in age from ca. 29.1 to 9.8 ka. Isotopic differences of up to 2‰ were identified among the four taxa analyzed (Succineidae, Pupilla hebes, Gastrocopta tappaniana, and Vallonia gracilicosta), with Succineidae shells yielding the highest values and V. gracilicosta shells exhibiting the lowest values. We used these data to construct a composite isotopic record that incorporates these taxonomic offsets, and found shell δ18O values increased by ~4‰ between the last glacial maximum and early Holocene, which is similar to the magnitude, direction, and rate of isotopic change recorded by speleothems in the region. These results suggest the terrestrial gastropods analyzed here may be used as a proxy for past climate in a manner that is complementary to speleothems, but potentially with much greater spatial coverage.

Vitreous body of the camera-like eyes of terrestrial gastropod mollusks (Heterobranchia, Stylommatophora)

Using the methods of light and electron microscopy, the morphological properties were studied, and the evolutionary changes in the vitreous body of the camera-like eyes of some species of terrestrial gastropod pulmonate molluscs were traced. It was demonstrated that all the considered properties of the vitreous body of molluscs are typical for terrestrial pulmonates. In the course of evolution, as a result of the land development by mollusks, the properties of their vitreous body have hardly changed.

Light-insulating apparatus of the camera-like eye of the terrestrial gastropod mollusk Arion rufus (Heterobranchia, Stylommatophora)

The cellular composition, the morphology of the components, and the screening function and evolutionary changes of the light-insulating apparatus of the camera-like eye of the terrestrial gastropod pulmonate mollusk Arion rufus were studied and evaluated using light and electron microscopy. According to all the considered characteristics, the light-insulating apparatus of A. rufus is typical for terrestrial pulmonate mollusks. Evolutionary transformations of the light-insulating apparatus, caused by the change in the mollusks' environment, are insignificant and affect the cellular composition, the morphology of pigmented cells and the isolation of the light-sensitive parts of photoreceptor cells from each other.

Cellular composition, morphological characteristic and evolutionary changes of photoreceptor apparatus of the camera eyes of terrestrial gastropod molluscs (Heterobranchia, Stylommatophora)

Cellular composition and morphology of components of photoreceptor apparatus of the retinae of camera eyes of some species of terrestrial gastropod pulmonate molluscs were studied and its evolutionary transformations were traced. It was demonstrated that all examined characteristics of photoreceptor apparatus of the most investigated species were normal for terrestrial pulmonates, while those of one species were special. Evolutionary transformations of photoreceptor apparatus of terrestrial pulmonate molluscs due to habitat shift were quite significant and concerned of its cellular composition and morphology of photoreceptor cells.

First report of Helicina chionea Pilsbry, 1949 from Brazil (Gastropoda, Helicinidae) and new records of Helicina spp. from Acre

The present study stems from initial efforts in surveying the terrestrial gastropod fauna of Acre state, an undersampled Amazonian region in northwestern Brazil. Herein, we report the first record of the operculate snail Helicina chionea Pilsbry, 1949 in Brazil, alongside the first records of two other helicinids from Acre: H. juruana Ihering, 1905 and H. laterculus F.C. Baker, 1914. With the present new record, there is a total of 38 helicinid species reported from Brazil.