Contribution to the knowledge of Brazilian troglobitic Pseudoscorpiones (Arachnida): description of Pseudochthonius lubueno sp. nov. (Chthoniidae) from Serra do Ramalho karst area, state of Bahia, Brazil

ABSTRACT Pseudochthonius lubueno sp. nov., a new obligatory cave-dwelling pseudoscorpion species is described from Gruna da Altina cave, the fifth species of the genus in the region of Serra do Ramalho karst area, southwestern Bahia, Brazil. This genus occurs in South and Central America, sub-Saharan central Africa, and in the Arabian Peninsula. The new species can be identified by the following combination of characters: eyes or eyespots absent, coxa I with two and coxa II with 4-5 coxal spines, without microdenticles on the fixed pedipalpal finger, rallum with five blades, ratio ist-est/ist-esb = 1.9. With this new description, the genus now includes 15 species from Brazil: P. biseriatus Mahnert, 2001, P. brasiliensis Beier, 1970, P. diamachi Prado & Ferreira, 2023, P. gracilimanus Mahnert, 2001, P. heterodentatus Hoff, 1946, P. homodentatus Chamberlin, 1929, P. koinopoliteia Prado & Ferreira, 2023, P. lubueno sp. nov., P. orthodactylus Muchmore, 1970, P. olegario Schimons ky, 2022, P. pali Prado & Ferreira, 2023, P. ramalho Assis, Schimonsky & Bichuette, 2021, P. ricardoi Mahnert, 2001, P. strinatii Beier, 1969 and P. tuxeni Mahnert, 1979. The new species shows troglomorphic characteristics such as the depigmentation of the carapace and the absence of eyes. In addition, illustrations, diagnoses, an identification key for cave-dwelling species of the genus, and distribution maps for all Brazilian species of Pseudochthonius are provided.

Pseudochthonius is characterized by the absence of an intercoxal tubercle, the presence of coxal spines on coxae I and II, and in most cases, having strongly sigmoid palpal chelal fingers (Muchmore 1986, Mahnert andAdis 2002).To date, Pseudochthonius includes 34 extant species distribu ted in America Central -six living species of which two are troglobites: P. troglobius Muchmore, 1986 from Mexico (Muchmore 1986) and P. arubensis WagenaarHummelinck, 1948, from the Netherlands Antilles (WagenaarHummelinck 1948) and one fossil species (Schawaller 1980) -and of South (with 14 species are from Brazil), subSaharan central Africa (five species distributed in the Republic of Congo and Ivory Coast), and the Middle East in the Arabian Peninsula, with one species (World Pseudoscorpiones Catalog 2022).
The known diversity of Pseudochthonius, as well as that of Chthoniidae, has been recently increased with the description of five troglobitic species from Brazilian caves (already added to the general numbers herein presented); P. ramalho, from a single cave in the Serra do Ramalho karst area, state of Bahia, Pseudochthonius diamachi Prado & Ferreira, 2023, Pseudochthonius koinopoliteia Prado & Ferreira, 2023, Pseudochthonius pali Prado & Ferreira, 2023, also from Serra do Ramalho karst area, and P. olegario from a single cave in municipality of Presidente Olegário, state of Minas Gerais (Assis et al. 2021, Schimonsky et al. 2022, Prado and Ferreira 2023).All areas belong to the Bambuí geomorphological group, the largest geomorphological unit in Brazil.Of the 14 Pseudochthonius from Brazil, nine occur inside caves, of which seven are considered troglobites: P. biseriatus, P. strinatii, P. ramalho, P. olegario, P. diamachi, P. koinopoliteia, and P. pali (Mahnert 2001, Harvey 2013, Assis et al. 2021, Schimonsky et al. 2022, Prado and Ferreira 2023).The present study provides the description of a new troglobitic Pseudochthonius species found in a single cave in municipality of Serra do Ramalho, in the Serra do Ramalho karst area, southwestern Bahia, Brazil.We also provide data regarding the conservation status of the new species and the area.A discussion about troglomorphisms in the genus is also provided.

Study area
The Serra do Ramalho karst area comprises the munic ipalities of Coribe, Feira da Mata, Carinhanha, and Serra do Ramalho.Plateaus are made of limestone rocks belonging to the Bambuí geomorphologic group (Rubbioli et al. 2019).This region is located in southwestern Bahia and comprises extensive limestone landscapes with several caves and karst systems (Figs 1,2).It belongs to the Sete Lagoas formation, Bambuí group, composed of dark, heterogeneous limestones, interspersed with layers of claystone, deposited approxi mately 750 to 600 million years ago (Rubbioli et al. 2019), and belongs to middle São Francisco River basin.The climate is tropical dry with a dry winter and the annual precipitation varies between 800 and 1000 mm (Gonçalves et al. 2018).The region is considered a spot of subterranean fauna (Trajano et al. 2016, Gallão andBichuette 2018) and the obligatory cavedwelling fauna is remarkable with representatives in a large variety of taxa (e.g., Bichuette and Trajano 2004, 2005, Bichuette and Rizzato 2012, Gallão and Bichuette 2018).

Material examined and treatment of specimens
Specimens were prepared by immersion in 85% lactic acid at room temperature for two weeks (Judson 1992).They were then examined by preparing temporary slide mounts with 10 mm coverslips supported by sections of nylon fish line (Harvey 2021).Specimens were examined with Nikon SMZ660 Stereomicroscope and Leica DMLS compound microscope and the male holotype was illustrated with the aid of a camera lucida.
Maps were produced with QuantumGis Desktop 3.10.12(QGis Open Source Geospatial Foundation).Coor dinates were obtained from field trips to the study location with a global positioning system (GPSGarmin 60CSx).

Comparative material
Brazil -Caatinga province
Description (male and female).Body: coloration of specimens in 70% ethanol generally pale yellow, tergites III-V with a dark median mark (Fig. 3); Male is slightly smaller than female.
Pedipalp (Fig. 5AB).1.4 (male), 1.2 (female) × longer than carapace and 2.2 (male), 2.6 (female) × longer than patella; movable finger 1.6 (male), 1.9 (female) × longer than hand; fixed finger 1.65 (male), 1.72 (female) × longer than hand.Fixed chelal finger long and strongly sigmoid in its distal half.Fixed finger with 34(male)/32(female) acute teeth, distinctly separated from each other, but paired and in each pair, one tooth is slightly directed retrolaterally and the other prolateral.Movable finger with 29(male)/32(fe male) flattened and separated teeth.Trichobothria.ib and isb situated close to each other sub-medially in the dorsal region of the chelal hand; eb closer to esb than to ist, forming a straight oblique row at the base of the fixed chelal finger; ist closer to esb than to the est (ratio istest/istesb = 1.9); et slightly near the tip of the fixed finger, near to the chelal teeth; dx, located near to the end of the fixed finger; t closer to st and situated at the same level as est.
Measurements and ratios: see   The Chthoniidae are characterized by the intercoxal tubercle (when present) with the existence of two setae (bisetosis) and transverse spiracles (Harvey 1992).The family is distributed in most regions of the world in both epigean and hypogean habitats (Harvey 2013, Schimonsky andBichuette 2019).In Brazil, the family is now represented by 35 valid species (World Pseudoscorpiones Catalog 2022), with a higher incidence in the center of the country, being considered the second with the most described species, 11% of the total for the country (second only to the family Cher netidae, with 39%) and occurring in high expressiveness in caves (Schimonsky and Bichuette 2019).
The species of Pseudochthonius occur in five Brazilian states (Fig. 1): in the state of São Paulo (southeastern Brazil) with representatives of P. strinatii and P. ricardoi (Alto Ribeira karst area), and P. brasiliensis (in the region of Barueri); in state of Minas Gerais (southeastern Brazil), with the troglo bitic species P. biseriatus endemic to the cave Olhos d'Água and P. olegario endemic to Lapa Zé de Sidinei cave; in the state of Bahia (northeastern Brazil), with the species herein described P. lubueno sp.nov., troglobitic and endemic to Gruna da Altina cave, P. ramalho endemic of the Gruna do Vandercir cave, P. diamachi found in Gruna das Três Cobras cave, P. koinopoliteia uncovered in Gruna da Água Clara and Pedro Cassiano caves, P. pali found Gruna do Google cave and also P. gracilimanus found in Gruta Azul cave; in the state of Pará (northern Brazil) with representatives P. orthodactylus and P. tuxeni; and in the state of Amazonas (northern Brazil) the species P. homodentatus has been found in the Ducke Reserve, and P. heterodentatus in the Urucu Oil Province.However, recently, this genus was recorded in other karst areas and biogeographical provinces, increasing  2019).Pseudochthonius lubueno sp.nov. is the 24 troglobitic pseudoscorpion from Brazil (Schimonsky et al. 2022).

Conservation remarks
Serra do Ramalho karst area emerges as one of the most important karst regions with obligatory cavedwelling fauna in Brazil (Trajano et al. 2016, Gallão andBichuette 2018).Up to now, there are troglobitic representatives in many groups such as collembolas, coleopterans, amblypy gids, opilionids, amphipods, isopods, diplopods, gastropods, planarians, fishes and pseudoscorpions, and many more are waiting for formal description.Indeed, the description of obligatory cavedwelling species is one of the most impor tant acts for the conservation of caves (Gallão andBichuette 2012, 2018).
Gruna da Altina cave is the type locality of Loxosceles cardosoi Bertani, von Schimonsky & Gallão, 2018, a tro glophile Sicariidae more related to the Amazonian brown recluse spider, as well as Loxosceles carinhanha Bertani, von Schimonsky & Gallão, 2018, from another cave in the same region (Bertani et al. 2018).Bertani et al. (2018) pointed out Serra do Ramalho karst area as an important center of Loxos celes distribution.The same is observed for pseudoscorpions.In addition to the remarkable troglobitic fauna, Serra do Ramalho karst area also presents a high diversity of troglo philic species.In this way, conservation acts are extremely urgent for the extraordinary Serra do Ramalho karst area.
Pseudochthonius lubueno sp.nov. is possibly endemic to Gruna da Altina cave since specimens were collected in only one of several collections in this cave.Also, we sampled more than 10 caves close to Gruna da Altina cave with no records of P. lubueno sp.nov.Up to now, there is no legal protection for Serra do Ramalho karst area, a spot of subterranean biodiversity that suffers with nonsustainable activities as deforestation (Gallão and Bichuette 2018).Official and legal protection in addition to longterm studies is needed to effectively protect this unique and fragile species from Serra do Ramalho karst area.
Figure 1.Map showing the distribution of Pseudochthonius lubueno sp.nov. in Gruna da Altina cave, located in Serra do Ramalho, Bahia, and the distribution of Brazilian epigean and hypogean Pseudochthonius species, with the troglobitic representatives

Table 1 .
Measurements in milimmeters and proportions (l/b, length/breadth; l/d, length/depth) of the holotype male and paratype female of Pseudochthonius lubueno sp.nov.
its distribution to 37 more caves(Schimonsky and Bichuette