The expression ‘you need to know to conserve’ is a well-known cliche among biologists. Documenting the richness of a group of organisms is the first step towards understanding biodiversity and preparing efficient conservation plans. In this context, many efforts have been made to quantify the number of species on Earth and estimate the number of species still unknown to science. A few countries have complete and integrated databases estimating the approximate number of species recorded for their territory, particularly in the Global South. In Brazil, a country of continental dimensions, revealing the richness of the second most diverse clade of invertebrates (=Mollusca) has been a goal of taxonomists. Recently, in an unprecedented, collective, and integrated effort among Brazilian malacologists, it was possible to estimate how many valid species of molluscs are there in Brazil. In this effort, more than 30 mollusc experts joined together to update the Taxonomic Catalogue of the Brazilian Fauna (TCBF), a governmental website that allows a quick and real-time updating of all Metazoan. So far, more than 5,000 updates have been made in TCBF, indicating the presence of 3,552 valid species of molluscs in Brazil, distributed among the main clades as follows: Caudofoveata (10 spp.), Solenogastres (6 spp.), Polyplacophora (35 spp.), Scaphopoda (43 spp.), Cephalopoda (92 spp.), Bivalvia (629 spp.) and Gastropoda (2,737 spp.). The present study, in addition to demonstrating for the first time the richness of Brazilian molluscs, also presents the state of the art of this important phylum of invertebrates highlighting its most representative and neglected groups.

Climate change and invasive species are critical factors affecting native land snail diversity. In South America, the introduced Giant African Snail (Lissachatina fulica) has spread significantly in recent decades into the habitat of the threatened native giant snails of the genus Megalobulimus. We applied species distribution modeling (SDM), using the maximum entropy method (Maxent) and environmental niche analysis, to understand the ecological relationships between these species in a climate change scenario. We compiled a dataset of occurrences of L. fulica and 10 Megalobulimus species in South America and predicted the distribution of the species in current and future scenarios (2040–2060). We found that L. fulica has a broader environmental niche and potential distribution than the South American Megalobulimus species. The distribution of six Megalobulimus species will have their suitable areas decreased, whereas the distribution of the invasive species L. fulica will not change significantly in the near future. A correlation between the spread of L. fulica and the decline of native Megalobulimus species in South America was found due to habitat alteration from climate change, but this relationship does not seem to be related to a robust competitive interaction between the invasive and native species.

Native Megalobulimus paranaguensis was identified on Brazil’s Ilha Porchat promontory, an area that Achatina fulica commonly populates. The population structures of these species were investigated for interactions. Spatial distribution, niche overlap and mark–recapture analysis were conducted. The outer lip of M. paranaguensis and environmental variables were measured. One and two abundance peaks were observed for A. fulica and M. paranaguensis, respectively. Survivorship was higher in A. fulica. Distribution was aggregate for M. paranaguensis, whereas for A. fulica it varied from random to aggregate. Both species aggregate as abundance increases. The lifespan of M. paranaguensis in this location is shorter than its lifespan in a nearby location. Achatina fulica was affected by soil temperature and humidity; M. paranaguensis was influenced by humidity. Niche overlap was random. The results show that M. paranaguensis can keep its natural activity and abundance in the presence of A. fulica, but environmental degradation impacts M. paranaguensis and should be evaluated.

Keywords: Rat lungworm; Giant African snail; Eosinophilic meningitis; Nematode; Emerging parasitosis

Morphological and molecular evidence suggests that the ghost shrimp population in Brazil that had been assigned to Callichirus major (Say, 1818) represents a distinct species. A neotype of C. major is designated in the interest of nomenclature, because the holotype is no longer extant. Based on material from Brazil, a new species, Callichirus corruptus, is described. Differentiating characters between the new species and C. major are discussed and an identification key to species of Callichirus is provided. http://www.zoobank.org/urn:lsid:zoobank.org:pub:29450E54-130A-4838-B923-F9676609DB3A

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.