Terrestrial Gastropoda from the caves of Presidente Olegário, southeastern Brazil

Samples of terrestrial gastropods were collected year-round in seven caves in Presidente Olegário municipality, Minas Gerais state, southeastern Brazil, during several expeditions from 2012 to 2014. Twenty-four taxa (plus a single freshwater species), mainly stylommatophorans, were found in the material. The following species are reported for the first time for Minas Gerais state: Alcadia iheringi Wagner, 1910 and Helicina sordida King, 1831 (Helicinidae); Cecilioides consobrina (d’Orbigny, 1841) (Ferussaciidae); Entodina gionensis Morretes, 1940 and Scolodonta interrupta (Suter, 1900) (Scolodontidae); Megalobulimus sanctipauli (Ihering & Pilsbry, 1900) (Strophocheilidae); Drymaeus coarctatus (Pfeiffer, 1845) (Bulimulidae); Habroconus semenlini (Moricand, 1846) (Euconulidae); and Solaropsis aff. rosaria (Pfeiffer, 1849) (Solaropsidae). Furthermore, the species Drymaeus iracema (Simone, 2015) and Drymaeus terreus (Simone, 2015) are synonymized with Drymaeus coarctatus (L. Pfeiffer, 1845).


Introduction
Brazilian cave-dwelling invertebrates have historically received scarce attention from researchers (Simone & Moracchioli 1994;Bichuette & Trajano 1999, 2003Trajano & Bichuette 2010), a fact that is even more marked for mollusks (Salvador, 2019b). During the past decade, however, Dr. Maria E. Bichuette and her team from the Universidade Federal de São Carlos (UFSCar; São Carlos, Brazil) have been conducting collecting expeditions to cave systems throughout Brazil focusing on several animal taxa. The molluscan material they collected has been deposited in the malacological collection of the Museu de Zoologia da Universidade de São Paulo (MZSP; São Paulo, Brazil) and our team has been steadily studying it over the past years. Those efforts are leading to an increase in the amount of information on cave-dwelling mollusks (e.g.; Simone 2012Simone , 2013Salvador et al. , 2017Simone et al. 2020). This increase in studies is very welcome, both from the perspectives of mollusk taxonomy (Salvador 2019b) and of environmental protection, given that cave ecosystems are usually fragile but harbor a reasonable number of endemic species (Trajano 2000;Gallão & Bichuette 2012;Weigand 2013).
Some of those expeditions were undertaken by Dr. Bichuette to cave systems in the municipality of Presidente Olegário, Minas Gerais state, SE Brazil (September/2012 to June/2014). That karst region is famous for its multiple calcareous caves (Secutti & Buchuette 2013) and, amidst a wealth of specimens of varied taxa, Dr. Bichuette's team collected many terrestrial and a few freshwater snails. No surveys of the molluscan fauna have been published from that locality so far, so the material they collected brings new information. We study those specimens herein, reporting twenty-five species, some of which are new records for Minas Gerais state.

Material and Methods
All the material studied here was collected by Maria Elina Bichuette and her team (G.F. Damasceno, J.S. Gallo, L.P.A. Resende, I.A. Ribeiro, and T. Zepon) and is deposited in the MZSP. All the specimens were collected in calcareous caves in the municipality of Presidente Olegário, Minas Gerais state, SE Brazil ( Figure 1).  Presidente Olegário is located in the southern Alto São Francisco Basin, being inserted into the domains of the Cerrado Biome. The climate is tropical, semi-humid, with four to five months of drought (Nimer 1989). The karst of the region's landscape is rich with calcareous caves (Secutti & Buchuette 2013). Seven different caves were surveyed and collection took place in four instances, covering the whole seasonal range: September/2013, and January, April, and June/2014 (Table 1).
The material comprised both empty shells and a few animals collected live; the latter were preserved in ethanol 70%. For each collection effort, the time of active search used was always the same for each cave, according to the cave's size. Table 1 presents a list with all caves, alongside additional information on each.
Identification was conducted based on the original descriptions (and type material whenever possible), the catalog of Simone (2006), further taxonomic literature, and additional comparative material (preferably from Minas Gerais state when possible) housed in the collection of the MZSP. Selected specimens were analyzed under SEM in the Staatliches Museum für Naturkunde Stuttgart (SMNS, Stuttgart, Germany). Some specimens (either juvenile or fragmentary) could not be identified beyond genus or even family level (Table 1).
The following abbreviations are used herein. Shell dimensions: H, shell height (parallel to coiling axis); D, greatest shell width (perpendicular to H); h, aperture height (maximum length parallel to coiling axis); d, greatest width of aperture (maximum width perpendicular to coiling axis

Results
The complete list of species, the cave(s) (and the cave zone) where each occurs, and a relation of all the studied material are reported in Table 2. Species that require further discussion (i.e., those with new records for Minas Gerais state) are addressed below and figured ( Figure 2), arranged according to the classification of Bouchet et al. (2017). The other species (i.e., not new records for Minas Gerais) are, nevertheless, recorded here for the first time from these caves.
New records. Presidente Olegário: in cave "Lapa do Moacir". The present record extends the species range at least 400 km to the northwest.
Identification. Wide helicinid shell with prominent keel on body whorl; aperture D-shaped, laterally elongated, with strongly thickened peristome.
New records. Presidente Olegário: in cave "Lapa da Fazenda São Bernardo". Despite this species being widely distributed, this is, up to our knowledge, the first specific record from Minas Gerais state.
Identification. Minute smooth glossy bullet-like shell, with long and narrow aperture.
New records. Presidente Olegário: in cave "Lapa da Fazenda São Bernardo". The present record extends the species distribution ca. 700 to the north.
Identification. Discoid shell with flattened spire, sculptured by strongly sinuous ribs; aperture with strong parietal-columellar barrier and a marked palatal tooth. The present specimens have a slightly less developed parietal-columellar fold than typical E. gionensis.

Superfamily Rhytidoidea Family Strophocheilidae
Identification. Relatively tall and non-bulbous spire in comparison with congeners, with suture running almost perpendicular to shell axis.
Identification. Bulimoid shell; reticulate protoconch; aperture with reflected and strongly thickened peristome, unique among the congeners in Brazil. The peristome thickens with age, as younger specimens have a "typical" Drymaeus-like appearance ( Figure 2P).
Remarks. Drymaeus iracema (Simone, 2015) and D. terreus (Simone, 2015) were originally described as troglobiont species classified in the genus Kora Simone, 2012. The former is known from São Desidério municipality in Bahia state and the latter, from Presidente Olegário municipality, in Minas Gerais state.  argued that they belonged in Drymaeus Albers, 1850 based on the reticulate protoconch sculpture. Further conchological features such as the strongly expanded peristome, the straight profile of the spire, and the upright columellar region, allow us to propose here that both D. iracema (holotype MZSP 104964) and D. terreus (holotype MZSP 106215), conchologically indistinguishable from one another, are junior synonyms of Drymaeus coarctatus (lectotype NHMUK 1975560;Simone 2006: fig. 445;Breure & Ablett 2014: fig. 37F-H).
Drymaeus coarctatus is thus widely distributed in eastern Brazil: from western Bahia state (São Desidério municipality), through Minas Gerais state (Presidente Olegário municipality, and newly reported specimens MZSP 152050, 152078, and 152091 from the municipalities of Paracatu and Unaí) and Espírito Santo state (newly reported specimen, USNM IZ530536, from the collection of the Smithsonian National Museum of Natural History, Washington, D.C., USA), to northern São Paulo state (Simone 2006: Lussanvira, an old railway station in Pereira Barreto municipality).
The shell of this species can present tooth-like thickenings on the palatal and basal regions of the peristome, as well as a more marked fold on the apical end of the columellar region (e.g., lectotype and specimen USNM IZ530536). All these structures supposedly develop as the individual grows older and deposits more shell material on the peristome. The shell can have a flame-like coloration pattern of the periostracum (MZSP 106215) or a pattern composed of several brown narrow spiral stripes (USNM IZ530536). Such intraspecific variation in shell color is well documented in other species of Drymaeus (e.g., Salvador et al. 2018).
Identification. Typical euconulid shell; body whorl with marked angulation and relatively tall compared to congeners; broad D-shaped aperture.
Previously known distribution. From Amazonas to Mato Grosso do Sul, Brazil . Previous reports from Suriname and "New Granada" have been considered spurious (Pilsbry, 1933).
New records. Presidente Olegário: in caves "Lapa do Moacir" and "Toca do Charco". The present record, if confirmed, would mean an increase of ca. 300 km in the species' distribution towards the southeast.
Identification. The present specimens do not exactly match the species S. rosaria, typically known from the Amazon biome in South America. However, they are indistinguishable from the specimens from Tocantins state, in central Brazil, that  called S. rosarium [sic]. The present specimens thus belong to the same species as those of , but their identity remains elusive for now.
The specimens are also reminiscent of S. derbyi Ihering, 1900 from São Paulo state, southeastern Brazil. However, that species is poorly defined and its type specimen is badly preserved (Simone 2006 : fig. 937).
The taxonomy of Solaropsis in Brazil is riddled with poorly-defined species, a few potentially invalid names, several potential synonyms, unrecognized intraspecific variability of shell morphology, and almost no knowledge of anatomical features, DNA, and basic biology (Cuezzo 2002;Calcutt et al. 2020). As such, proper identification of the present specimens will have to wait until a better definition of species boundaries in the genus is in place.
Remarks. This species has been lately classified in the genus Psadara Miller, 1878 (e.g., Simone 2006); however, a recent molecular analysis has confirmed that Psadara is a synonym of Solaropsis (Calcutt et al. 2020).

Discussion
Orthalicoidea is usually the most diverse group of land snails in any sample of mollusks taken in Brazil (Salvador 2019b). However, as already pointed out by , this does not seem to hold for the troglofauna, in which Subulininae and Scolodontidae are represented by a more diverse assembly of species among the stylommatophorans. In the present material, only four orthalicoid species were found (and only in the epigean and the entrance zone of the caves; Table 2). Meanwhile, several subulinine and scolodontid taxa were recovered from the epigean to the dark aphotic zone of the caves (Table 2). From all species reported herein, only Habeastrum strangei is a known cave endemic (Simone et al., 2020); all the others have wider distributions in non-cave environments.
Moreover, a curiously high number (four) of helicinids species was found in the material, including living specimens in the aphotic zones of the caves (Table 2). Our previous studies on cavern snails have always been poor on helicinid specimens (e.g., Salvador et al. , 2017. Neotropical helicinids are typically considered arboreal species in the literature (e.g., Richling 2004), but here it can be seen that they might inhabit other habitats as well.
From the caves studied here, almost all of them have little left of the original Cerrado vegetation in their surroundings; the place was cleared to give way to pasture or agriculture and only a couple of meters of native vegetation remains in the entrance area of each cave (T. Zepon, personal communication 2016). Only a single cave ("Lapa Arco da Lapa") has a larger surrounding area of native vegetation (ca. 100 m) (T. Zepon, personal communication 2016). That does not seem to affect the species composition of that cave, as almost all the species found in Lapa Arco da Lapa were also recorded from other caves; the single exception is Leiostracus sp., an arboreal snail found in the epigean area there ( Table 2).
Several of the species reported here are first records for Minas Gerais state (Results section; Table 2). This report extends the geographical distribution of some species, while simply filling "distribution gaps" of others. Moreover, the present records are especially important, as they are among the few dealing with molluscan troglofauna in the region and Brazil as a whole. Land snails are considered the most threatened group of animals (Lydeard et al. 2004;Régnier et al. 2008) and many of them inhabit, and could likely be endemic to, caves (Simone & Moracchioli 1994;Simone 2013;Weigand 2013;Salvador 2019b).
The vast majority of caves in Brazil completely lack legal protection. Better known geographical distributions improve arguments for conservation, as the Brazilian legislation states that a cave must be protected if it harbors rare or endemic species (Campos-Filho et al. 2014). Hence the great importance of troglofaunal inventories, as delays in ensuring proper protection to those habitats might result in irreparable biodiversity loss. the specimens of Drymaeus coarctatus in the collections under their care; and to José H. Fontenelle (Orquidário Municipal de Santos, Brazil) for the information on Megalobulimus sanctipauli; to Cascon-Helena Matthews and two anonymous reviewers for their helpful comments and suggestions. This work was partly supported by a doctoral grant from Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq, Brazil, proc. #245575/2012-0) to RBS. RBS also acknowledges the support of SMNS for SEM analysis.

Author Contributions
Rodrigo B. Salvador: conceptualized the study; led the taxonomic study and writing of the manuscript. Fernanda S. Silva: led the taxonomic study and writing of the manuscript.
Daniel C. Cavallari: contributed to the study and manuscript writing. Luiz Ricardo L. Simone: contributed to the study and manuscript writing.