Research Article |
Corresponding author: Diego Monteiro von Schimonsky ( dmvschimonsky@gmail.com ) Academic editor: Martina Pavlek
© 2021 Leonardo de Assis, Diego Monteiro von Schimonsky, Maria Elina Bichuette.
This is an open access article distributed under the terms of the Creative Commons Attribution License (CC BY 4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
Citation:
Assis L, von Schimonsky DM, Bichuette ME (2021) The first troglobitic Pseudochthonius Balzan, 1892 (Pseudoscorpiones, Chthoniidae) from the karst area of Serra do Ramalho, Brazil: a threatened species. Subterranean Biology 40: 109-128. https://doi.org/10.3897/subtbiol.40.77451
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Pseudochthonius ramalho sp. nov. is described to Gruna do Vandercir cave, in the Serra do Ramalho karst area, southwestern Bahia, Brazil. This area has an extensive limestone outcrop, with several caves, and the occurrence of potential minerals that are financially attractive for mining projects. The new species shows troglomorphic characteristics such as the depigmentation of the carapace and absence or reduction of eyes. It is a rare troglobitic species, and following the criteria of IUCN, we categorized the species as Critically Endangered – CR, IUCN criteria B1ab(iii)+2ab(iii). According to Brazilian legislation, locations, where critically endangered species live, can be protected by law, and we consider this cave/region to be of maximal relevance for protection.
Arachnida, Bahia State, Chthoniinae, conservation, endemic, troglobite
Pseudoscorpions are represented in the Brazilian fauna by 14 families and 176 species (
The genus 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 (
Here, we describe a new Pseudochthonius species found in a single cave in the Serra do Ramalho karst area, southwestern Bahia, Brazil. We also provide data regarding the conservation status of the species and the area.
The karst area of the Serra do Ramalho region (Fig.
Specimens were prepared by immersion in 85% lactic acid at room temperature for two weeks (
Images (Figs
The examined specimens are deposited in Laboratório de Estudos Subterrâneos, in Universidade Federal de São Carlos (LES, curator: Maria Elina Bichuette). For comparative purpose of some morphological characters like classical troglomorphisms in pseudoscorpions (eyes/ocular structures, proportionally longer body, and ratio pedipalpal chela/carapace), the new species was compared to two hypogean species, and one undetermined epigean species of Pseudochthonius sp.
Comparative material. Brazil – Parana Forest Province • Pseudochthonius strinatii;1♂, 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.; LES9391. – Parana Forest Province • Pseudochthonius biseriatus; 1♂Minas Gerais, Itacarambi, 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.; LES9434. – Caatinga Province • Pseudochthonius sp. undetermined species; 1♂; Bahia, Carinhanha, epigean habitat near Viração cave; 26.vii.2012; LES9629.
The terminology and measurements mostly follow
♂ male;
♀ female.
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.
gl galeal;
dt dorsal terminal;
dst dorsal sub–terminal;
db dorsal basal;
vt ventral terminal;
vb ventral basal;
di isolated subapical tooth.
The following body structures were measured and compared proportionally for the characterization of possible troglomorphisms: carapace; chelal hand; chelal fixed finger (
Family Chthoniidae Daday, 1889
Tribe Chthoniini Daday, 1889
Holotype : 1 ♂ (LES9601) Brazil Caatinga province, Serra do Ramalho karst area, Serra do Ramalho, Bahia, Gruna do Vandercir cave; 13°38'11.40"S, 43°50'5.10"W; 31 May 2012; Bichuette ME, Gallão JE, Hattori N leg. Paratype: 1 ♀ (LES9602), same data as holotype.
The species is named after the region of Serra do Ramalho due to its importance regarding the speleological heritage and the unique fauna and flora diversity. The name is to be treated as a noun in apposition.
Pseudochthonius ramalho sp. nov. can be identified by the following combination of characters: eyes absent (♂) or with eyes-spots (♀); the middle and distal fixed chelal finger teeth positioned two by two with 29–30 acuminate teeth and 3–4 slightly basally rounded ones, the presence of two rounded micro–denticles, along with pedipalpal fixed finger teeth in males; trichobothria ist closer to esb than to the est (ratio ist-est/ist-esb = 4.71); serrula exterior with 13 (♂) or 14 (♀) lamellae, rallum with seven blades, and coxae I and II with 3 to 5 coxal spines.
(adult ♂ and ♀) . Body: Coloration of specimens in 70% ethanol yellowish brown and translucent pedipalps, tergites III–V with a dark median mark, and a darker abdominal region. Live specimens present a light pinkish color on their carapace and appendages, and a light brown abdomen. Female is slightly smaller than male.
Chelicera
(Figs
Pedipalp
(Figs
A holotype left pedipalp showing the trichobothria distribution B details of chelal teeth C distal part of fixed chelal finger (lateral view) D detail with emphasis on the micro–denticles in two interdental spaces, on teeth 15 and 29, respectively E pedipalp femur F distal part of fixed chelal finger (ventral view).
Carapace
(Fig.
Abdomen : Chaetotaxy of tergites I–XI: ♂, 4: 4: 4: 4: 6: 6: 6: 6: 6: 5: 3; ♀, 4: 4: 4: 4: 5: 6: 6: 6: 6: 5: 3. Chaetotaxy of sternites III–XI: (♂/♀) 12: 13: 8: 8: 8: 8: 6: 5: 2, anal cone 0/2 setae.
Genital area : Anterior genital operculum with 8 (♂), 9 (♀) marginal and discal setae, arranged triangularly in male, with 7–8 unmodified marginal setae on each side; posterior operculum with 6 setae in female.
Coxae
(Fig.
Legs
(Fig.
Measurements and ratios
: see Table
Measurements (in mm) and proportions (l/b, length/breadth; l/d, length/depth) of the holotype male and paratype female of Pseudochthonius ramalho sp. nov.
Holotype (Paratype) | Holotype (Paratype) l/b; l/d | |
---|---|---|
Body | 1.55 (1.45) | |
Carapace | 0.46/0.42 (0.45/0.42) | 1.1 (1.0) |
narrower part posteriorly 0.27 | ||
(0.275) | ||
Pedipalpal trochanter | 0.18/0.12 (0.16/0.11) | 1.6 (1.5) l/b |
Pedipalpal femur | 0.65/0.16 (0.54/0.13) | 4.1 (4.1) l/b |
Pedipalpal patella | 0.29/0.15(0.25/0.12) | 4.1 (2.1) l/b |
Pedipalpal chela | 0.90/0.20 (0.81/0.14) | 4.5 (5.8) l/d |
Pedipalpal hand | 0.35/0.20 (0.29/0.14) | 1.9 (2.1) l/d |
Pedipalpal fixed finger | 0.58/0.05 (0.50/0.02) | |
Pedipalpal movable finger | 0.57/0.04 (0.55/0.02) | |
Chelicera | 0.39/0.19 (0.38/0.18) | 2.1 (2.1) l/b |
Chelicera movable finger | 0.18 (0.17) | |
Leg I femur | 0.35/0.06 (0.36/0.05) | 5.9 (7.2) l/d |
Leg I patella | 0.18/0.05 (0.16/0.05) | 3.6 (3.2) l/d |
Leg I tibia | 0.21/0.04 (0.15/0.04) | 5.2 (3.8) l/d |
Leg I tarsus | 0.33/0.03 (0.29/0.03) | 11 (9.6) l/d |
Leg IV trochanter | 0.18/0.16 (0.16/0.13) | 1.1 (1.2) l/b |
Leg IV femur + patella | 0.76/0.28 (0.70/0.12) | 2.7 (5.8) l/d |
Leg IV tibia | 0.38/0.08 (0.16/ 0.05) | 4.7 (3.2) l/d |
Leg IV basitarsus | 0.19/0.05 (0.18/0.05) | 3.8 (3.6) l/d |
Leg IV telotarsus | 0.35/0.03 (0.34/0.02) | 11.6 (17) l/d |
The new species Pseudochthonius ramalho sp. nov. is compared with other hypogean and epigean Pseudochthonius species. It most resembles other Brazilian species of Pseudochthonius that lack eyes, and occur in caves, like P. strinatii and P. biseriatus. Pseudochthonius ramalho sp. nov. has 5 coxal spines, almost ever–increasingly arranged; sternites V–VIII with 8 setae on sternal chaetotaxy; trichobothrium ist is 4× farther from est than from esb; the middle and distal fixed chelal finger teeth differ only in their direction, but not in their size or shape, with teeth arranged two by two; male is slightly larger; it has pedipalpal patella and pedipalpal femur proportionally larger and smaller (4.1 ♂ and ♀). Differently, Pseudochthonius strinatii has 2 longer and 2 shorter coxal spines; sternal chaetotaxy with 6 setae on each sternite; the position of trichobothria ist is 3× farther from est than from esb; its fixed chelal finger teeth show heterodontism; pedipalpal patella and pedipalpal femur proportionally smaller (2.0 ♂) and larger (5.3–6.1 ♂), respectively. Pseudochthonius biseriatus has 2 setae on tergites I and II, a rallum with nine setae, and 37–41 teeth arranged in an offset manner; chelal length 1.24–1.39. In contrast, P. ramalho sp. nov. has four setae on tergites I and II, a rallum with seven blades, and chela fixed finger with 30–33 teeth; chelal length 0.81–0.90. All three species share the unpigmented tegument with other troglobitc Pseudochthonius species, like P. troglobius and P. pulchellus (Ellingsen, 1902). However, P. ramalho sp. nov. differs from these and from P. biseriatus and P. strinatii due the presence of ocular spots in the female. Other nontroglobitic Pseudochthonius present in Brazilian caves, have eyespots (P. gracilimanus Mahnert, 2001 and P. ricardoi Mahnert, 2001). Pseudochthonius troglobius has a pedipalpal fixed finger with 65 teeth, and proportionally larger body features (e.g., movable finger 2.14× longer than hand). This is different from P. ramalho sp. nov. with 30–33 teeth in the fixed pedipalpal finger and a proportionally smaller body (e.g., movable finger 1.6× longer than hand). Considering the number of marginal teeth on the pedipalpal movable finger, P. ramalho sp. nov. resembles P. gracilimanus and P. strinatii with 30–33 teeth (
Species of Pseudochthonius occur in five Brazilian states (Fig.
Troglomorphic traits are characteristics that propose a relationship between hypogean species and the subterranean environment, associated with behavior, physiology, and mainly, morphology. Although these characteristics are useful to differentiate hypogean from epigean species, they do not explain the direct connection between the subterranean habitats and the species that inhabit it (
Most families of pseudoscorpions have at least one troglomorphic feature. Chthoniidae can be considered one of the most important families regarding occurrence in subterranean habitats (
Morphological differences on the carapace of hypogean and epigean species of Pseudochthonius: eyes (denoted with red circle), and the narrowing of the posterior region of the carapace (marked with dashed line on the sides of the carapace) A hypogean P. ramalho sp. nov. (male) B epigean P. thibaudi C epigean P. arabicus.
Pseudochthonius ramalho sp. nov. (Fig.
Comparison of morphology among some species of Pseudochthonius from Brazil A Holotype Pseudochthonius ramalho sp. nov. (troglobitic) (LES9601) and left chela (A1) B Pseudochthonius strinatii (troglobitic) (LES9391) and pedipalp detail (B1) C Pseudochthonius biseriatus (troglobitic) (LES9434) and pedipalp detail (C1) D Pseudochthonius sp. (epigean) (LES9629) and pedipalp detail (D1) (Images: A D. M. von Schimonsky; A1–C1 L.B.R Fernandes; D–D1 M. E. Bichuette).
In the pedipalpal chela of the three hypogean species, there is a slight decrease in the length and width of the hand and a significant increase in the length of the fixed finger. These pseudoscorpions have, respectively, the following length and width: hand (in mm) – 0.29/0.14 in P. ramalho sp. nov. (Fig.
The Serra do Ramalho region is formed by several masses of carbonate rocks, thus enabling the occurrence of many karst features, including caves. Cave extensions range from hundreds of meters to more than 5 km, some exceeding 15 km (
Pseudochthonius ramalho sp. nov. occurs exclusively in Gruna do Vandercir cave, being considered an endemic species to its type locality. By IUCN (International Union of Conservation of Nature) criteria, we classify this species as Critically Endangered (CR) according to criteria B1ab (iii) + B2ab (iii). This means that the species has a restricted geographical distribution, with an estimated occurrence of less than 100 km² (B1) and 10 km² (B2), and the severely fragmented population (a) lives in a few locations with the continued decline (b) in area, extension, and quality of habitat (iii). Therefore, effective protection measures must be taken so that there is no degradation of this environment, which is important in several aspects, and in this case, as the limited habitat of unique species that are very sensitive to disturbances.
This study was financed in part by the Coordenação de Aperfeiçoamento de Pessoal de Nível Superior – Brasil (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), FAPESP (process 2008/05678-7 and 2010/08459–4) and Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) for research fellow (303715/2011–1, 308557/2014–0 and 310378/2017–6) and regular project (457413/2014–0) to MEB. We also thank: A.M.P.M. Dias, coordinator of Instituto Nacional de Ciência e Tecnologia dos Hymenoptera Parasitoides da Região Sudeste Brasileira (INCT Hympar Sudeste – FAPESP 2008/57949–4 and CNPq 573802/2008–4) for making available the equipment and L.B.R. Fernandes for taking the SEM and stereomicroscope images and for image editing; to the members of Laboratório de Estudos Subterrâneos – LES, especially J. E. Gallão and N. Hattori for the collections of specimens and help in the field trips to Serra do Ramalho. To J. E. Gallão for critical reading and suggestions to the work. To A. Gambarini for his field assistance and the images of the new species and the cave habitat. To Grupo Bambuí de Pesquisas Espeleológicas (GBPE) for sharing information about Serra do Ramalho and to all support to MEB. To Institituo Chico Mendes de Conservação da Biodiversidade (ICMBIO) for collecting permit in caves (SISBIO 20165). We thank to Mark S. Harvey and János Novák for their valuable suggestions and comments. We are also grateful to the reviewers Giulio Gardini, André Lira, one anonymous reviewer and the subject editor Martina Pavlek.