TAXONOMIC STUDY ON A COLLECTION OF TERRESTRIAL AND FRESHWATER GASTROPODS FROM CAVES IN BAHIA STATE, BRAZIL, WITH THE DESCRIPTION OF A NEW SPECIES

a BStRact : Gastropod samples were collected during expeditions to caves in Bahia state, northeastern Brazil, and are studied herein. Collection took place over the past five years, and gastropods were found in 14 caves distributed across six different municipalities: Campo Formoso, Carinhanha, Coribe, Feira da Mata, Central, and Ituaçu. A total of 19 species-level taxa of terrestrial and freshwater gastropods (representing 10 families) were collected, including representatives of the taxa Neritimorpha, Caenogastropoda, Hygrophila, and Stylommatophora. A new species is described herein: Helicina marfisae sp. nov. (Neritimorpha, Helicinidae). K ey


INTRODUCTION
Brazil is one of the most megadiverse countries in the world for many -if not most -animal taxa (lewinSohn et al. 2005).Nevertheless, multiple historical causes (e.g., colonialism, vast territory, inaccessible areas, lack of funding, and the current wrecking of science) have kept the knowledge of this biodiversity mostly in its infancy.That is especially true for invertebrates and, in particular, for terrestrial and freshwater gastropods (SalvadoR 2019, RoSa et al. 2022).
One particular region of interest in Brazil is Bahia, a large state in the east-northeastern part of the country.Despite being among the best-studied states in the country for land snails (SalvadoR 2019), it still hides a myriad of discoveries.For instance, that state contains the contact zones of three of Brazil's main biomes (Atlantic Forest, Cerrado, and Caatinga) and thus, has been identified as a potential biodiversity hotspot for land and freshwater snails (cavallaRi et al. 2016, Silva et al. 2021).Bahia also has numerous limestone and siliciclastic caves that have been tagged as hotspots for both terrestrial and freshwater invertebrates (tRajano & Bichuette 2009).The caves in Bahia are still largely unexplored regarding their molluscan fauna, but they should likewise harbor a wide range of potentially endemic snail species (SalvadoR et al. 2022b).Indeed, a few previous works have reported some gastropod species from caves in Bahia, including new species (e.g., SiMone 2015, SalvadoR & SiMone 2016, SalvadoR et al. 2022a), but the only more thorough molluscan survey of caves in Bahia state to date is that of SalvadoR et al. (2017).
Herein we examine material collected from caves in Bahia during several expeditions in the past five years.We describe a new species of Helicinidae and present new occurrences of previously known spe-cies that extend their known geographic distributions to Bahia state, including cave facultative species (i.e., troglophiles) and cave-restricted species (troglobites).

MATERIAL AND METHODS
Multiple expeditions have been conducted by the team from the LES (Laboratório de Estudos Subterrâneos, Universidade Federal de São Carlos; São Carlos, SP, Brazil) to caves in Bahia during the years 2017-2022.The collection efforts focused on a variety of animal taxa, of which the gastropods were a part.The collections were made by visual inspection of several microhabitats in the caves, using small brushes.
Specimens were collected in 14 of the sampled caves, which are located across the following municipalities: Campo Formoso, Carinhanha, Coribe, Feira da Mata, Central, and Ituaçu (Figs 1-4).A brief description of the municipalities' areas and the caves can be found below.
Central municipality: Gruta da Machadinha, Gruta do Leão, Toca Bonita, Toca da Mulher, Toca de Candeias, Toca do Cirilo, and Toca do Waldemar caves.This region is part of the Una geomorphological group, and the caves are formed by carbonates, most of them with a few to dozens of meters of development.The climate is hot semi-arid and the region belongs to the Caatinga domain, in the Middle São Francisco River basin.The main threats to these caves are related to the installation of wind parks, altering the limestone landscapes and, consequently, impacting the caves.

Streptaxidae
Streptartemon cf.cookeanus (F. Baker, 1914) Toca Bonita, Toca de Candeias, Toca do Cirilo, Lapa Pé de Morro LES 0028030 (1 sh), LES 0028031 (2 sh), LES 0028032 (1 sh), LES 0028033 (2 spm) Streptaxis luetzelburgi Weber, 1925 Gruna da Serra Verde LES 0028028 (1 sh) 96%.Their registration numbers are given in Table 1.Due to conservation concerns, the precise coordinates of each cave will not be presented here; geolocation data is available in the LES and MZSP collections' databases and can be shared upon request with the present authors or with the curatorial staff of those collections.Species identification was based on the catalogues of SiMone (2006) and BiRcKolz et al. ( 2016), more specialized taxonomic works (listed in each species' entry below, as appropriate), and comparisons with further voucher material (including types) housed in the following collections: MZSP; CMRP, Faculdade de Filosofia, Ciências e Letras de Ribeirão Preto (Ribeirão Preto, SP, Brazil); NMNZ, Museum of New Zealand Te Papa Tongarewa (Wellington, New Zealand).
Species of interest (new species and new records for Bahia state) are presented below, arranged in sys-tematic order (Bouchet et al. 2017).A complete list of species identified in the present material (but which were already known from Bahia) is compiled in Table 1.Some specimens were juveniles or fragmentary and thus, could not be identified at species level; for those specimens, identification is possible only at the genus level.Most of the species herein are widely distributed in Brazil and consequently are not restricted to caves.
Measurements of the shells were taken with a digital caliper (0.01 mm precision, rounded to the nearest 0.1 mm) or, for minute specimens, via the software ImageJ (v.1.8.0; SchneideR et al. 2012).

Subclass Neritimorpha Superfamily Helicinoidea Family Helicinidae Férussac, 1822 Genus Helicina Lamarck, 1799
Helicina marfisae sp.nov.Type locality.Brazil, Bahia state, Central municipality, Gruta do Leão cave, 11°03'09.0"S,42°07'32.4"W.Distribution.Known only from type locality.The specimens occur in the twilight and aphotic zone, in silty and rocky substrate.Etymology.After Marfisa, a fictional character in the epics Orlando Innamorato and Orlando Furioso.Marfisa was the Queen of India and one of the fiercest warriors on the land, often compared to a lioness.The name is an allusion to the name of the type locality, which translates to Cave of the Lion.Diagnosis.Shell minute, conical.Spire prominent in comparison to neotropical helicinids; step-like.Body whorl marked by two angulations: one on its mid-section and one on the middle of the apical area of the whorl.Aperture small, abapically positioned in relation to previous whorl.Description.Shell minute, conical, of c. 4¼ whorls.Colour yellowish-brown, translucent; spire top and peristome white.Protoconch bulbous, of c. ¾ whorl, seemingly marked by faint malleations; transition to teleoconch marled by a sudden constriction in whorl width.Teleoconch sculpture by numerous unevenly-spaced parallel radial cordlets; cordlets absent from abapical area of whorl.Spire prominent, steplike.Suture shallow.Whorl profile convex; body whorl marked by two angulations: one on mid-section and another on the middle of apical area of the whorl.Aperture small, trapezoid, abapically positioned in relation to previous whorl; transition of columellar region to basal region of aperture marked by strong angulation; a faint angulation is present on transition of basal to palatal region.Peristome very lightly thickened, reflexed on basal and columellar regions.Shell imperforate.Measurements.~4¼ whorls; H -4.4 mm; D -4.9 mm.Discussion.The present specimen, an empty shell, is a minute Helicinidae.Even though it is a singleton, the shell is so strikingly different from all other helicinids in the country (and in South America), that we are confident in assigning it to a new species.
All helicinids in Brazil present typical heliciniform (lenticular) shells (SiMone 2006), as it would be expected; that also includes the more minute animals of similar size to the present specimen.As such, the present specimen's minute and relatively-high spired and conical shell, with a step-like profile and abapically positioned aperture, is immediately distinct from all other known helicinids in South America.Some of its conchological traits can be observed in Central American helicinids, particularly in the Caribbean: the step-like spire is seen in Fadyenia Chitty, 1857, and the abapically-positioned aperture is seen in Lucidella Swainson, 1840.Nevertheless, the occurrence of all these traits together on a single shell is unique to the present specimen; this set of traits are thus a strong suite of morphological diagnostic characters.Thus, we consider that the present specimen belongs to a new species: Helicina marfisae sp.nov.Considering the uniqueness of its shell, it is possible that it could even represent a new genus; however, given that there is currently no phylogenetic background on Brazilian helicinids to sustain such a proposal, we provisionally classify it in Helicina.Helicina marfisae sp.nov.can be immediately distinguished from all other helicinids in Brazil (in particular those of similar size) by its prominent steplike spire and its abapically positioned aperture.A few of the larger snails (e.g., H. concentrica L. Pfeiffer, 1849 and H. juruana Ihering, 1905, both from the Amazon) can display shells with a step-like spire profile, though their profile is much less marked than that of H. marfisae sp.nov.Furthermore, the shells of those larger Helicina spp.are at least twice the size of the shell of H. marfisae sp.nov.
The two angulations on the body whorl of Helicina marfisae sp.nov.are likewise diagnostic in comparison to other Brazilian helicinids.Many of the larger-sized species of Helicina have a mid-whorl angulation, but the presence of the more apically positioned angulation is rare, being only present on a similar scale in H. leucozonalis Ancey, 1892 from western Brazil (which is a much larger snail).
Even though the single known specimen of Helicina marfisae sp.nov.was found inside Toca do Leão cave, we cannot ascertain whether this species is troglobiotic or not, as it could also be present in unsampled areas outside the cave.The lack of obvious shell troglomorphisms (the minute size notwithstanding, as it is within the size range of the genus in Brazil; SiMone 2006) could be an indication that this species is either troglophilic or even accidental, also considering it was collected in the cave's twilight zone.Its shell, however, is rather fragile and it can be expected that it would not resist long transport into a cave, so it must be at least parautochthonous.).Those authors also revised the status of all species in the genus and I. walkeri was considered a taxon inquirendum, given that its type specimens could not be located, no topotypes are known, and the simple line drawings of the species' shell (pilSBRy 1924) are not enough to allow its identification with certainty.

Subclass Caenogastropoda
Nevertheless, the wider shells of the present specimens (in comparison to other Idiopyrgus spp.) are a good match to the description of I. walkeri and its illustrations (pilSBRy 1924).As such, the specimens are here tentatively identified as Idiopyrgus cf.walkeri.Their occurrence in Carinhanha municipality is circa 450 km to the north of the river which is the type locality of the species.The specimens were in a humid substrate composed of silt and rock, in the twilight and aphotic zones of the cave.Discussion.Only two of the five species in the genus Plesiophysa occur in Brazil, P. guadeloupensis Mazé, 1883and P. dolichomastix Paraense, 2002(a) (paRaenSe 2002a, b, 2003, SiMone 2006).The latter is so far known only from its type locality in the Brazilian Midwest: a lake in Santa Rosa municipality, Goiás state (paRaenSe 2002a).The former, on the other hand, is widespread in Central and South America, being distributed from Guadeloupe and the Dominican Republic to southeastern Brazil (BiRcKolz et al. 2016).In Brazil, P. guadeloupensis has been reported from Rio Grande do Norte, Paraíba, Pernambuco, Sergipe, Bahia, Espírito Santo, Minas Gerais, and Rio de Janeiro states (BiRcKolz et al. 2016).Species of Plesiophysa are considered nearly indistinguishable from one another based on shell characters alone (paRaenSe 2002a(paRaenSe , b, 2003)).However, the present shells are easily diagnosable from them, displaying a much more raised spired while in its congeners the spire is depressed into the later whorls.Furthermore, the shape and position of the body whorl is different in the present specimens, being shorter/smaller and much more diagonally positioned in relation to the columellar axis (i.e., at a greater angle) than in congeners.Finally, the shell aperture of the present specimens is almost perfectly oval, being more vertically positioned in relation to the shell axis.

Remarks. Two new species of
Considering the conchological features described above, the present specimens could potentially represent a new species.However, the shells of freshwater snails are knowingly very plastic and variable in their morphology and a final verdict on the status of the present specimens will have to wait until more specimens become available, alongside anatomical and/or molecular data.For now, we identify the specimens simply as Plesiophysa sp.Discussion.Shells of this species can be identified by the sloping penultimate and body whorls, alongside a proportionately small aperture that lacks teeth.The present specimens generally fit within the conchological variation observed in S. cookeanus, but some factors make a definite identification uncertain: (1) small deviations in shell morphology, such as a lower body whorl  or more laterally elongated shells (Figs 19-21); (2) the vast geographic distance to previous records (the present records would extend the species distribution around 700 km SW); and (3) the fact that the present specimens come from cave environments, which are known to foster speciation.All these could be an indication that we are potentially dealing with a new species, particularly when taking into account that specimens from southeast Brazil previously identified as S. cookeanus have been recently described as a distinct species (SalvadoR & cunha 2020).As such, we consider it preferable to leave the present specimens in open classification for the time being, until anatomical and/or molecular data become available.

DISCUSSION
A total of 19 species-level taxa (representing 10 families) was found in the present material, 8 of which are freshwater caenogastropods and Hygrophila ("basommatophorans"), while the remainder are terrestrial helicinids and stylommatophorans (Table 1).As expected, there is reduced diversity in cave environments as compared to adjacent surface areas.
The previously reported trend of Achatinidae (Subulininae) and Scolodontidae being the most diverse terrestrial families in caves (e.g., SalvadoR et al. 2016SalvadoR et al. , 2017SalvadoR et al. , 2021) ) is further supported by our data (Table 1).Nevertheless, it is worth noting that most representatives of those families in caves belong to widespread species in the country (SalvadoR et al. 2022a).
By contrast, the family Helicinidae of operculated land snails is usually uncommon among cave snail checklists, with only a few species reported from subterranean environments (SalvadoR et al. 2016(SalvadoR et al. , 2017(SalvadoR et al. , 2021)).Nevertheless, the only new species of terrestrial snail described here, Helicina marfisae sp.nov., belongs to this family.Despite its unique shell shape (Figs 5-7), there are no obvious conchological characters that could be considered troglomor-phisms (the small size notwithstanding).As mentioned above, given that only a single empty shell was found, we cannot even ascertain whether this species is indeed troglobiotic, troglophilic, or just accidental.
Among the freshwater snails, there are more cave endemics and potentially troglobiotic species (e.g., Idiopyrgus minor), likely due to the populations becoming isolated.In those cases, it is also common to find morphoanatomical features that are probably troglomorphisms, such as translucent shells and lack of body pigmentation (Figs 10-13;SalvadoR et al. 2022a, b).Even though Plesiophysa sp.might represent a yet undescribed species, as mentioned above, no obvious troglomorphisms can be observed in the shell .
As recently suggested in the study of SalvadoR et al. (2022a), it is also notable that the caves in Bahia state could be a hotbed of speciation of Idiopyrgus, an otherwise low-diversity relict genus.Besides the three species reported herein (Table 1), I. souleyetanus Pilsbry, 1911 also occurs in Bahia, totaling four out of the seven currently-recognized species in the genus (SalvadoR et al. 2022a).

CONCLUSION
The present study improves the knowledge of the cave snail fauna in Bahia state and has brought a new species to light.Given that the region might be a hotspot for snails and other invertebrates (tRajano & Bichuette 2009, cavallaRi et al. 2016, Silva et al. 2021), the current lack of protection of the caves studied herein is worrying.The caves in the regions of Central municipality and Serra do Ramalho, for instance, are impacted by deforestation, agriculture, and mining, which increasingly shows the need for fauna studies in these places (gallão & Bichuette 2018, SalvadoR et al. 2021, 2022a).

Fig. 1 .
Fig. 1.Map of Bahia state showing the location of the studied caves

Figs
Figs 5-7 urn:lsid:zoobank.org:act:E4877EB4-7579-4506-930E-5F00FE7DDD13Typematerial.Holotype: MZSP 158915 (1 sh; Bahia, Central, Boqueirão do Maxixe, Gruta do Leão cave, twilight zone; M. E. Bichuette, j. e. gallão & t. zepon col.15/III/2017).Type locality.Brazil, Bahia state, Central municipality, Gruta do Leão cave, 11°03'09.0"S,42°07'32.4"W.Distribution.Known only from type locality.The specimens occur in the twilight and aphotic zone, in silty and rocky substrate.Etymology.After Marfisa, a fictional character in the epics Orlando Innamorato and Orlando Furioso.Marfisa was the Queen of India and one of the fiercest warriors on the land, often compared to a lioness.The name is an allusion to the name of the type locality, which translates to Cave of the Lion.Diagnosis.Shell minute, conical.Spire prominent in comparison to neotropical helicinids; step-like.Body whorl marked by two angulations: one on its mid-section and one on the middle of the apical area of the whorl.Aperture small, abapically positioned in relation to previous whorl.Description.Shell minute, conical, of c. 4¼ whorls.Colour yellowish-brown, translucent; spire top and peristome white.Protoconch bulbous, of c. ¾ whorl,

Table 1 .
List of taxa from the present study, with the names of the caves in which they were found, and the registration number of the voucher specimens in the LES or MZSP collections.

Superfamily Truncatelloidea Family Tomichiidae Wenz, 1938 Genus Idiopyrgus Pilsbry, 1911 Idiopyrgus cf. walkeri Pilsbry, 1924
Even though the genus Idiopyrgus has been typically classified in Pomatiopsidae, a recent molecular phylogenetic study demonstrated that it belongs instead to the Gondwanan family Tomichiidae (SalvadoR et al. 2022a

Scolodontoidea Family Scolodontidae Genus Entodina Ancey, 1887 Entodina derbyi (Ihering, 1912)
Entodina derbyi can be easily identified by the marked angulation on the middle section of the whorl (iheRing 1912).This species is reported from only two localities in Bahia state.The present record is thus an interesting occurrence, given that it is an intermediate point (longitudinally) between them, being closer to the São Francisco River.Furthermore, considering that E. derbyi is rarely recorded or illustrated in the literature, we hope the photographs provided here will be of help to future studies.
Tamayoa banghaasi is widespread in eastern Brazil.The present records fill a gap in the species known distribution, linking the records from the northeast (Paraíba, Pernambuco and Alagoas states) to those in the southeast (Minas Gerais, Espírito Santo and Rio de Janeiro states).