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 lubuenosp. 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.

KEY WORDS:
Caves; northeastern Brazil; subterranean; taxonomy; troglomorphic

INTRODUCTION

Brazilian pseudoscorpion fauna is remarkable with 183 species distributed in 15 families (Harvey 2013, Schimonsky and Bichuette 2019, Assis et al. 2021, Schimonsky et al. 2022, World Pseudoscorpiones Catalog 2022, Prado and Ferreira 2023). Chthoniidae is the most diverse family, with 881 species and 54 genera. It is distributed worldwide except in Antarctica, with its greatest diversity occurring in the USA (150 species), Spain (98), Italy (91), China (57), Croatia (43), Australia (36), France (35), and Greece (35) (World Pseudoscorpiones Catalog 2022, Hou et al. 2023). In Brazil, Chthoniidae is represented by 34 species in 11 genera: Hete rolophus Tömösváry, 1884 (2), Tridenchthonius Balzan, 1887 (2), Lechthyia Balzan, 1892 (1), Pseudochthonius Balzan, 1892 (14), Compsaditha Chamberlin, 1929 (1), Tyrannochthonius Chamberlin, 1929 (4), Austrochthonius Chamberlin, 1929 (4), Soroditha Chamberlin & Chamberlin, 1945 (1), Neoditha Feio, 1945 (1), Cryptoditha Chamberlin & Chamberlin, 1945 (2) and Lagynochthonius Beier, 1951 (2) (World Pseudoscorpiones Catalog 2022).

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 and Adis 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. arubensisWagenaar-Hummelinck, 1948, from the Netherlands Antilles (Wagenaar-Hummelinck 1948) and one fossil species (Schawaller 1980) - and of South (with 14 species are from Brazil), sub-Saharan 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 diamachiPrado and 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.

MATERIAL AND METHODS

Study area

The Serra do Ramalho karst area comprises the municipalities 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 approximately 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 and Bichuette 2018) and the obligatory cave-dwelling 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).

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

Figure 2
Gruna da Altina cave: (A) details of the microhabitat of P. lubueno sp. nov., Photo A. Gambarini; (B) Guano piles, a typical substrate of occurrence of the new species, Photo: M.E. Bichuette.

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). Coordinates were obtained from field trips to the study location with a global positioning system (GPS-Garmin 60CSx).

The examined specimens are deposited in Laboratório de Estudos Subterrâneos, at Universidade Federal de São Carlos (LES, curator: Maria Elina Bichuette), and Museu de Zoologia da Universidade de São Paulo (MZUSP, curator: Ricardo Pinto-da-Rocha).

Comparative material

Brazil - Caatinga province • Pseudochthonius ramalho; 1 male, Serra do Ramalho karst area, Serra do Ramalho, Bahia, Gruna do Vandercir cave; 13°38’11.40”S, 43°50’5.10”W; 31.V.2012; Bichuette ME, Gallão JE, Hattori N leg.; LES 009601. Parana Forest Province • Pseudochthonius biseriatus; 1 male, Itacarambi, Minas Gerais, Olhos d’Água cave, 15°7’0.10”S, 44°10’0.10”W, 24.VII.2012, Bichuette ME, Gallão JE and Rizzato PP leg.; LES 009433.

Parana Forest Province • Pseudochthonius strinatii; 1 male, São Paulo, Iporanga, Parque Estadual Turístico do Alto Ribeira, Sumidouro da Passoca cave; 24°33’57”S, 48°43’W; 03.XII.2013; Bichuette ME, Gallão JE, Fernandes CS, Rizzato PP, Fonseca R and Arnone I leg.; LES 009391. Atlantic province • Pseudochthonius olegario, 1 male, Minas Gerais, Presidente Olegário, Lapa Zé de Sidinei cave; 18.30156°S, 46.09462°W, Galena village, 16.iv.2014, Zepon T, Resende LA and Damasceno G leg.; MZSP76522.

Terminology and measurements

The terminology and measurements mostly follow Chamberlin (1931), except for legs, pedipalps, and trichobothria follow Harvey (1992); for chelal movable finger follow Mahnert et al. (2014); and for chelicera Judson (2007). The chaetotactic formulae of chelicera follow Gabbutt and Vachon (1963) and the duplex trichobothria follow Judson (2018). Abbreviations. Chelal trichobothria: (b) basal, sb sub-basal, (st) sub-terminal, (t) terminal, (ib) interior basal, (isb) interior sub-basal, (ist) interior sub-terminal, (it) interior terminal, (eb) exterior basal, (esb) exterior sub-basal, (est) exterior sub-terminal, (et) exterior terminal, (dx) duplicate trichobothria. Cheliceral setae: (gl) galeal, (dt) dorsal terminal, (dst) dorsal sub-terminal, (db) dorsal basal, (vt) ventral terminal, (vb) ventral basal, (di) isolated subapical tooth.

TAXONOMY

Chthoniidae Daday, 1889

Chthoniinae Daday, 1889

Chthoniini Daday, 1889

Pseudochthonius Balzan, 1892

Pseudochthonius lubueno sp. nov.

Fig. 3

https://zoobank.org/01864229-28C0-4FB4-B705-02A200D8AD89

Type material. Holotype male. BRAZIL: Bahia, Caatinga province, Serra do Ramalho karst area, Serra do Ramalho, Gruna da Altina cave; 13°33’39.2”S, 43°45’10.3”W; 27.XI.2015; Bichuette ME, Gallão JE leg.; LES 0014723. Paratype female, same data as holotype; LES 0014724.

Diagnosis. Pseudochthonius lubueno sp. nov. bears similarities to the troglobitic species of Pseudochthonius, P. strinatii, P. biseriatus, P. ramalho, P. olegario, P. diamachi, P. koinopoliteia and P. pali, due to it is a moderately sized troglomorphic species with elongate appendages and absence of body pigmentation. However, it differs in other characters and can be identified by the following combination: P. lubueno sp. nov. has the rallum with five blades (nine in P. biseriatus, 7 in P. olegario, seven in P. diamachi, seven in P. koinopoliteia, and seven in P. pali); one distal isolate teeth in movable finger of chelicera (isolated teeth in booth fingers in P. diamachi); has epistome with anterior margin slightly serrate on the sides and distinctly serrate with median denticles in the middle (in P. ramalho, the anterior margin distinctly serrate with median denticles larger than lateral ones); 1.10 male, 1.24 female body length (1.55 male, 1.45 female in P. ramalho, 1.20 male, 1.58-1.60 female in P. olegario, 2.02-2.33 female in P. diamachi, 1.69 male, 1.7-1.95 female in P. koinopoliteia and 1.33 male, 1.70 female in P. pali); eyes or eyespots absent (eyespots present in P. strinatii and P. ramalho); posteriorly constricted carapace (in P. koinopoliteia carapace rectangular practically without posterior constriction); without microdenticles on the fixed pedipalpal finger (2 present in P. ramalho), 30-31 teeth on the fixed chelal finger (41 in P. diamachi, 38 in P. koinopoliteia, and 34-39 in P. pali, and heterodentate chelal teeth on the fixed finger (homodentate in P. strinatii); trichobothrium et near to dx and it (et distal to it in P. diamachi and P. koinopoliteia). Concerning the position of trichobothrium ist, closer to esb than to est, P. lubueno sp. nov. has the ratio ist-est/ist-esb = 1.90 (3.0 in P. strinatii, 1.98 in P. ricardoi, 1.22 in P. gracilimanus, 4.71 in P. ramalho, 1.02 in P. diamachi, 0.68 in P. koinopoliteia, 2.46 in P. pali, 2.37 in P. tuxeni, 2.34 in P. brasiliensis and 2.06 in P. orthodactylus); 3 setae on tergites I-II (2 setae in P. biseriatus, 2-4 in P. diamachi); coxa I with 2 and coxa II with 4-5 coxal spines (in P. biseriatus, I 5+3-4 and II 5+5-6, in P. ramalho I 3-5 and coxa II 5-3, in P. diamachi I 3-5 and II 4, in P. koinopo liteia I 5-6 and II 4-5, P. pali I 3-5 and II 5-6, in P. olegario I 4 and II 5). The following characters are also different from other Brazilian cave species of Pseudochthonius: P. lubueno sp. nov. absent eyes, 30-31 teeth on the fixed chelal finger (in P. gracilimanus due to the presence of 2 small eyes and 23-26 teeth; in P. ricardoi due to 2 eyespots and 43 teeth). Pseudochthonius lubueno sp. nov. also differ from Pseudochthonius of the world: differs from P. arubensis, by the rallum with 6 blades (5 blades in P. lubueno sp. nov.) and the number of chelal fixed and movable finger with 28 teeth (in P. lubueno sp. nov. fixed finger with 34 male/32 female and movable finger with 29 male/30 female); differ from P. troglobius by the rallum with 8 blades, the homodentate chelal teeth on the fixed finger, with 65 teeth and the presence of one small coxal spine on coxa III (in P. lubueno sp. nov. rallum with 5 blades, 30 acute teeth and coxal spines on coxa III absent). In the case of ratio trichobothrium ist, ist-est/ist-esb, (P. lubueno sp. nov. = 1.90), 2.4 in P. arubensis and 1.72 in P. galapagensis Beier, 1977.

There are also differences in the proportions of some body parts: P. lubueno sp. nov. 1.3 (1.0 female) times longer than carapace and 2.6 (2.8 female) times longer than patella, differs from the P. strinatii 1.3 and 2.0 (2.5 female), and P. ramalho 1.4 (1.2 female) and 2.2 (2.6 female); P. lubueno sp. nov. pedipalp femur 3.0-4.5 times longer than broad, differs from the P. biseriatus (6.4-6.6), P. strinatii (5.3-6.8), P. homodentatus (4.6-4.9); P. lubueno sp. nov. pedipalp chela 5.3 (5.4 female), differs P. biseriatus (7.5-8.0), P. strinatii (6.7- 7.4), P. diamachi (7.7-7.8) and P. ricardoi (6.0); in P. biseriatus femur 1.89 (1.77 female) longer than patella, in P. ricardoi 1.72 longer than patella, differs of the P. lubueno sp. nov. 3.7 (2.25 female) longer than patella.

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.

Figure 3
Pseudochthonius lubueno sp. nov. Paratype female, habitus: (A) dorsal view; (B) ventral view. Scale bar: 0.5 mm. Photo: Luciana Bueno dos R. Fernandes.

Chelicera (Fig. 4C). Five setae on hand, with one seta (dt) on the basal position of the fixed finger and one seta (gl) close to the basal seta on the movable finger, with lateral microsetae (vb); All setae acuminate; Fixed finger with 7 (male)/8 (female) teeth proximally reduced in size; Movable finger with 8 (male)/9 (female) teeth proximally reduced in size with subapical isolated tooth (di); Serrula exterior with 12 (male), 13 (female) lamellae; Rallum with 5 blades pectinated (Fig. 4D); Dorsal face of cheliceral palm with 4 lyrifissures, 2 situated near setae it and vb, 1 lyrifissure positioned anteriorly on the fixed finger.

Carapace (Fig. 4A). Anterior margin slightly serrated on the sides and distinctly serrate with median denticles in the middle; Epistome prominent and dentate; without any traces of eyes; posteriorly constricted; Chaetotaxy 6:4:4:2:2 (18), of which one pair are preocular microseta; 2 lyrifissures anteriorly and 1 posteriorly.

Figure 4
Pseudochthonius lubueno sp. nov., male holotype (A-F) and female paratype (G): (A) carapace dorsal view; (B) detail of the anterior margin, with the epistome; (C) left chelicera; (D) rallum; (E) coxal spines of coxae I-II; (F) genital opening; (G) genital opening, paratype. Scale bars: A, C, E, F-G = 0.05 mm, B = 0.2 mm, D = 0.02 mm.

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(female) 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 ist-est/ist-esb = 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.

Abdomen. Chaetotaxy of tergites I-XI: male, 3: 3: 4: 3: 5: 4: 4: 3: 4: 4: 3; female, 4: 4: 4: 4:5: 6: 6: 6: 6: 5: 3. Chaetotaxy of sternites III-XI: (male/female) 12: 13: 8: 8: 8: 8: 6: 5: 2, anal cone 0/2 setae.

Genital area (Fig. 4F, G): Anterior genital operculum with 9(male)/8(female) marginal and discal setae, genital opening slit-like triangular in male, with 10 marginal setae on each side; posterior operculum with 8 setae in female.

Coxae (Fig. 4E): Manducatory process distally acute, with 2 setae; Pedipalpal coxa with 3 setae; Coxa I with 2 setae on anterior margin and coxa II with 4-5 highly dented coxal spines in decreasing size distally, Coxa III with 6 setae and coxa IV with 8 setae; Intercoxal tubercle absent.

Figure 5
Pseudochthonius lubueno sp. nov., male holotype: (A) left chela, lateral view; (B) left palpal trochanter, femur, and patella; (C) leg I, lateral view; (D) leg IV, lateral view. Scale bars: 0.2 mm.

Legs (Fig. 5C, D): Leg I (Fig. 5C): femur 5.9 (male)/7.2 (female) times longer than deep and 1.94 (male)/2.25 (female) longer than patella, patella 3.6 (male)/3.2 (female) times longer than deep, tibia 5.2 (male)/3.8 (female) times longer than deep, tarsus 11 (male)/9.6 (female) times longer than deep, tarsus 1.6 (male)/1 (female) times longer than tibia. Leg IV (Fig. 5D): Trochanter 1.1 (male)/1.2 (female) times longer than broad, femur + patella 2.7 (male)/5.8 (female); Tibia 4.8 (male)/3.2 (female) times longer than deep; basitarsus 4.3(male)/3.6 (female) times longer than deep; telotarsus 10.5 (male)/14 (female) times longer than deep.

Measurements and ratios: see Table 1.

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.

	Holotype (Paratype)	Holotype (Paratype) l/b; l/d
Body	1.10 (1.24)
Carapace	0.30/0.26 (0.47/0.39) narrower part posteriorly 0.19 (0.28)	1.1 (1.2)
Pedipalpal trochanter	0.11/0.07 (0.12/0.08)	1.6 (1.5) l/b
Pedipalpal femur	0.34/0.11 (0.50/0.11)	3.0 (4.5) l/b
Pedipalpal patella	0.13/0.08 (0.18/0.10)	1.6 (1.8) l/b
Pedipalpal chela	0.53/0.10 (0.76/0.14)	5.3 (5.4) l/d
Pedipalpal hand	0.16/0.10 (0.26/0.14)	1.6 (1.8) l/d
Pedipalpal fixed finger	0.38/0.02 (0.54/0.03)
Pedipalpal movable finger	0.34/0.01 (0.53/0.02)
Chelicera	0.22/0.10 (0.36/0.18)	2.2 (2.0) l/b
Chelicera movable finger	0.10 (0.17)
Leg I femur	0.30/0.04 (0.36/0.05)	7.5 (7.2) l/d
Leg I patella	0.10/0.05 (0.16/0.05)	2.0 (3.2) l/d
Leg I tibia	0.12/0.04 (0.15/0.04)	3.0 (3.8) l/d
Leg I tarsus	0.19/0.02 (0.29/0.03)	9.5 (9.7) l/d
Leg IV trochanter	0.18/0.16 (0.16/0.13)	1.1 (1.2) l/b
Leg IV femur + patella	0.43/0.18 (0.70/0.12)	2.4 (5.8) l/d
Leg IV tibia	0.24/0.05 (0.16/0.05)	4.8 (3.2) l/d
Leg IV basitarsus	0.13/0.03 (0.18/0.05)	4.3 (3.6) l/d
Leg IV telotarsus	0.21/0.02 (0.28/0.02)	10.5 (14) l/d

Etymology. The specific epithet is a combination in honor of Luciana Bueno dos Reis Fernandes, technician of Departamento de Ecologia e Biologia Evolutiva, Universidade Federal de São Carlos, an excellent photographer, illustrator, and enthusiast of cave fauna; it is a noun in apposition.

Key to cave-dwelling Pseudochthonius

1. Eyeless, eyespots present; trichobothrium ist at least 3×further away from est than from esb (ratio ist-est/ist-esb ≥ 3.0) .................... 2

1’. Eyeless, eyespots absent; trichobothrium ist less than 2.8× further away from est than from esb (ratio ist-est/ist-esb ≤ 2.8) .................... 3

2. Ratio ist-est/ist-esb = 4.71; chelal length = 0.82-0.90; pedipalpal patella larger (4.1), pedipalpal femur smaller (4.1); endemic to Gruna do Vandercir cave, Bahia, Brazil .................... P. ramalho Assis, Schimonsky & Bichuette, 2021

2’. Ratio ist-est/ist-esb = 3.0; chelal length = 0.82-1.06; pedipalpal patella smaller (2.0), pedipalpal femur larger (5.3-6.1); occurrence in São Paulo, Minas Gerais and Paraná, Brazil .................... P. strinatii Beier, 1969

3. Tergite I with 2 setae and tergite II with 4 setae .................... 4

3’. Setae configuration other than the step above .................... 5

4. Ratio ist-est/ist-esb = 1.02-1.11; coxa II with 4 coxal spines; chelal length = 1.43-1.59 pedipalpal femur larger (6.8) .................... P. diamachi Prado & Ferreira, 2023

4’. Ratio ist-est/ist-esb = 2.46-2.77; coxa II with 5-6 co xal spines; chelal length = 0.87-0.98, pedipalpal femur smaller (5.7) .................... P. pali Prado & Ferreira, 2023

5. Tergite I and II each with 2 setae .................... 6

5’. Tergite I and II each with 4 setae .................... 7

6. Ratio ist-est/ist-esb = 1.78-2.10; chelal length = 1.24-1.39; pedipalpal femur smaller (6.3-6.6); endemic to Olhos d’Água cave, Minas Gerais, Brazil .................... P. biseriatus Mahnert, 2001

6’. Ratio ist-est/ist-esb = 0.68-0.85; chelal length = 1.04-1.16, pedipalpal femur larger (6.8) .................... P. koinopoliteia Prado & Ferreira, 2023

7. Carapace with 20 setae, including four on posterior margin; coxal spines numerous and varied on coxae I and II and including one small spine on coxa III; ist-est/ist-esb = 1.0; chelal length= 1.73; occurrence at Cueva del Cenote Xtolok, Chichkn Itza, Yucatan, Mexico .................... P. troglobius Muchmore, 1986

7’. Carapace with 18 setae, including two on posterior margin; coxal spines present on coxae I and II, but absent from coxa III; trichobothrium ist closer to esb than to est (2.40 ≤ ist-est/ist- esb≤2.49) .................... 8

8. Rallum with five blades; ist-est/ist-esb = 1.9; chelal length = 0.53-0.76; coxa I with 2 spines, coxa II with 4-5 spines; pedipalpal fixed finger with 30-32 teeth, movable finger with 29-30 teeth; endemic to Gruna da Altina cave, Bahia, Brazil .................... P. lubueno sp. nov.

8’. Rallum with six or more blades; 2.40 ≤ ist-est/ist-esb ≤ 2.49 .................... 9

9. Coxa I with 2-3 spines, coxa II with 3-4 spines; ist-est/ist-esb = 2.40; chelal length = 0.7; rallum with six blades; occurrence at the cave of Quadirikiri, Aruba .................... P. arubensis Wagenaar-Hummelinck, 1948

9’. Coxa I with 4 spines, coxa II with 5 spines; ist-est/ist-esb = 2.49; chelal length = 0.89-0.99; rallum with seven blades; occurrence at Zé de Sidinei cave, Minas Gerais, Brazil .................... P. olegario Schimonsky, 2022

DISCUSSION

Distribution of Pseudochthonius in Brazil

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 and Bichuette 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 Chernetidae, 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 troglobitic 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 its distribution to 37 more caves (Schimonsky and Bichuette 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 cave-dwelling fauna in Brazil (Trajano et al. 2016, Gallão and Bichuette 2018). Up to now, there are troglobitic representatives in many groups such as collembolas, coleopterans, amblypygids, opilionids, amphipods, isopods, diplopods, gastropods, planarians, fishes and pseudoscorpions, and many more are waiting for formal description. Indeed, the description of obligatory cave-dwelling species is one of the most impor tant acts for the conservation of caves (Gallão and Bichuette 2012, 2018).

Gruna da Altina cave is the type locality of Loxosceles cardosoi Bertani, von Schimonsky & Gallão, 2018, a troglophile 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 Loxosceles 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 troglophilic 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 non-sustainable activities as deforestation (Gallão and Bichuette 2018). Official and legal protection in addition to long-term studies is needed to effectively protect this unique and fragile species from Serra do Ramalho karst area.

ACKNOWLEDGMENTS

This study was financed in part by the Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES, Finance Code 001) as a scholarship to LA; PROTAX II project (Fundação de Amparo à Pesquisa do Estado de São Paulo, FAPESP 2016/50381-9 and CAPES 88887.159166/2017-00, project number 440646/2015-4), by FAPESP (process 2010/08459-4) and Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) for productivity research fellow to MEB (308557/2014-0 and 310378/2017-6). We thank Luciana Bueno R. Fernandes for taking the stereomicroscope images and for image editing; A. Gambarini for the images of the cave habitat in Fig. 2A; Grupo Bambuí de Pesquisas Espeleológicas (GBPE) for sharing information about Serra do Ramalho and to all support to MEB. To Instituto Chico Mendes de Conservação da Biodiversidade (ICMBIO) for collecting permit in caves (SISBIO 20165 and 28992), and for financial support to the project “Estudos para definição de áreas prioritárias para a Conservação de Proteção Espeleológico na Serra do Ramalho - BA”, executed by the Grupo Bambuí de Pesquisas Espeleológicas (GBPE), coordinated by Ezio Rubbioli and integrated by MEB. The Instituto Brasileiro de Desenvolvimento e Sustentabilidade (IABS)/ICMBio/Vale S.A. provided the postdoctoral scholarship to JEG (TCCE ICMBio/Vale 02/2020: speleological compensation agreement signed between Vale S.A. and ICMBio, with operational management by the IABS). We thank to three anonymous reviewers for their valuable suggestions.

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ADDITIONAL NOTES

• ZooBank register

  https://zoobank.org/8DF089BD-F032-493C-B2DE-76FFCF415F7A

• How to cite this article

  Assis L de, von Schimonsky DM, Gallão JE, Bichuette ME (2023) 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. Zoologia 40: e22048. https://doi.org/10.1590/S1984-4689.v40.e22048

• Published by

  Sociedade Brasileira de Zoologia at Scientific Electronic Library Online (https://www.scielo.br/zool)

Edited by

Editorial responsibility

Ricardo Pinto da Rocha

Data availability

Data citations

Harvey MS (2013) Pseudoscorpions of the World. Version 3.0. Western Australian Museum, Perth. http://www.museum.wa.gov.au/catalogues-beta/pseudoscorpions [Accessed: 15/04/2022]

World Pseudoscorpiones Catalog (2022) World Pseudoscorpiones Catalog. Natural History Museum Bern, Avalaible online at Natural History Museum Bern, Avalaible online at http://wac.nmbe.ch [Accessed: 12/05/2022]

Publication Dates

• Publication in this collection
  18 Sept 2023
• Date of issue
  2023

History

• Received
  28 June 2022
• Accepted
  07 July 2023