Although terrestrial gastropods are remarkably diverse, our knowledge of them is still lacking, especially for species from the Global South. As such, new tools to help researchers collect data on these organisms are very welcome. With this in mind, we investigated Brazilian observations on iNaturalist to assess the feasibility of the data available on the platform as a basis for studies on the tropical terrestrial gastropod fauna. The observations on iNaturalist were filtered by country, Brazil, and higher taxa, namely Eupulmonata, Cyclophoroidea and Helicinoidea, yielding a sample of 4,983 observations. These observations were then reviewed in search of records of rare or little-known species, species found outside their previously known range, and interesting ecological interactions. Exotic species made up 35% to 39% of the sampled iNaturalist records. The most commonly observed species wereLissachatina fulica(Bowdich, 1822),Bradybaena similaris(Férussac, 1822),Drymaeus papyraceus(Mawe, 1823),Drymaeus interpunctus(E. von Martens, 1887),Limacus flavus(Linnaeus, 1758),Meghimatium pictum(Stoliczka, 1873),Cornu aspersum(O. F. Müller, 1774),Vaginulus taunaisii(Férussac, 1821),Ovachlamys fulgens(Gude, 1900), andBulimulus tenuissimus(Férussac, 1832). In total, 166 observations were deemed of interest to our purposes (e.g., rare species, range extensions, ecological interactions), totalling 46 identified species and 16 observations identified at genus level. Among the selected observations, we found pictures of live specimens of species that were previously known only from their shells, such asMegalobulimus pergranulatus(Pilsbry, 1901), bringing to light their appearances in life. Two potentially new species belonging to the generaPlekocheilusGuilding, 1827 andMegalobulimusK. Miller, 1878 were revealed. Additionally, we found records of living individuals of two species that were previously presumed to be possibly extinct,Leiostracus carnavalescusSimone & Salvador, 2016, andGonyostomus egregius(Pfeiffer, 1845). We take the opportunity to discuss individual records of interest, evaluate the quality of the data and possible improvements, as well the potential and implications of the use of the iNaturalist platform for research in Brazil and other tropical countries. While iNaturalist has its limitations, it holds great potential to help document biodiversity in the tropics.

We compiled taxonomic information about terrestrial gastropods in Brazil in an organized and user-friendly checklist that we hope will be useful for researchers and stakeholders alike. We also expect that it will serve as a springboard, garnering more interest and enabling a new wave of studies on this fauna, which has one the highest extinction rates of all animal groups while being essential ecosystem functioning and also includes species of importance to public health and agriculture. We list all species of terrestrial gastropods that occur in the country, with information regarding synonymized names and fossils. We also propose a few nomenclatural acts to address some pending issues of easy resolution. A total of 748 species of terrestrial gastropods are known in Brazil, including 33 exotic species that have been introduced to Brazil. A total of 48 families are present, the majority of which belong to Stylommatophora; only six families represent the Neritimorpha, Caenogastropoda and Systellommatophora. The most speciose families are Bulimulidae, Strophocheilidae, Cyclodontinidae, Streptaxidae, and Simpulopsidae. Changes in nomenclature proposed here are as follows: Drymaeus obliquus poecilogramma Ancey, 1901 is now reclassified as Sanniostracus poecilogramma (Ancey, 1901) comb. nov.; Helix uniplicata Férussac, 1827 as Clessinia uniplicata (Férussac, 1827) comb. nov.; Zonitoides parana Baker, 1914 as Miradiscops parana (Baker, 1914) comb. nov.; “Helix” circumplexa Deshayes, 1839 as Systrophiella circumplexa (Deshayes, 1839) comb. nov.; Bradybaena giovannalimae Lima & Cossignani, 2021 as Streptaxis giovannalimae (Lima & Cossignani, 2021) comb. nov.

The exotic Japanese jumping snail, Ovachlamys fulgens, was first recorded in Santa Catarina state, Brazil, in 2013. Based on data gathered from the literature, natural history collections, field samplings, and the iNaturalist platform, we assess its current distribution in the country. Our data show that the jumping snail has had a dramatic range expansion since its introduction, reaching six other states from the southern region of the country toward the Midwest. The affected locations are mostly urban but also include three biological reserves and protected areas, and possibly more. We discuss the consequences of this rapid invasion, its means of introduction, its local ecology, and prospects for monitoring and control.

The Asian mantleslug Meghimatium pictum is an exotic species introduced to Brazil in the late 1990s, but only formally reported in 2011. Since then, it has been deemed an agricultural pest and given the status of an invasive species; furthermore, it has been confirmed as an intermediate host for the nematode Angiostrongylus costaricensis in Brazil. Despite its potential for impacts, no additional studies on the status of its invasion have been conducted since the initial report. In this study, we used the citizen science platform iNaturalist to analyse the current distribution of M. pictum in Brazil, while also using genetic barcode data to understand the relationships between Brazilian and Asian populations and applying a species distribution model to investigate the suitable range for its distribution in Brazil. Our survey has recovered a total of 520 new records of this species in Brazil, confirming its spread to four additional states since its original report. Currently, M. pictum is recorded in the Distrito Federal and the states of Minas Gerais, Espírito Santo, Rio de Janeiro, São Paulo, Paraná, Santa Catarina, and Rio Grande do Sul. Our phylogenetic analysis suggests a close relationship between M. pictum populations in South America and those from Okinawa, Taiwan, and Guangzhou (mainland China), the latter being the most likely point of origin for the South American populations. Our species distribution model supports the idea that, in Brazil, the species is largely restricted to subtropical areas belonging to the Atlantic Forest ecoregion, while also showing suitable areas where the species has not been recorded yet and might become established in the near future. The implications of these findings are discussed, highlighting the recent surge in records and the usefulness of iNaturalist as a tool to monitor invasive species in the country.

Though only a small fraction of its original natural cover remains, the Atlantic Forest is considered a land snail diversity hotspot. While this biome has been widely explored by malacologists in the past, modern surveys of important conservation areas are lacking. Here we report the results of surveys conducted in two nature reserves and one national park in Espírito Santo state: Parque Nacional Caparaó (a fraction of which is located in Minas Gerais state), Reserva Biológica Córrego do Veado, and Reserva Biológica Sooretama. In total, 15 families of terrestrial gastropods were represented, with 35 species identified, plus another five additional morphospecies that could not be fully determined; 16 species-level taxa in Caparaó, 23 in Córrego do Veado, and 22 in Sooretama. The following are new records for Espírito Santo state (or Minas Gerais state in the case of Caparaó): Rectartemon piquetensis, Anthinus multicolor, Burringtonia labrosa, Rhinus velutinohispidus. Only two non-native species were found, Subulina octona in Sooretama and the marsh slug Deroceras laeve in Caparaó. Anecdotal natural history records are also provided, including depigmented individuals of Leiostracus perlucidus. The importance of local faunal surveys, particularly in preservation areas, cannot be overstated as we endeavour to understand our molluscan fauna.