Pseudochthonius urubuquaqua Guimarães, Prado & Ferreira, 2025, sp. nov.
Creators: name: Guimarães, Lucas
name: Prado, Guilherme C.
name: Ferreira, Rodrigo L.
Publisher: name: Zenodo
Year: 2025
Subjects: Biodiversity
Taxonomy
Animalia
Arthropoda
Arachnida
Pseudoscorpiones
Chthoniidae
Pseudochthonius
Pseudochthonius urubuquaqua

description: Pseudochthonius urubuquaqua sp. nov.
urn:lsid:zoobank.org:act: AF047933-5787-49FA-B5D6-F98F3C19C600
Material Examined. Holotype male (ISLA 125640), preserved in ethanol: Brazil, Cosdisburgo, Minas Gerais, Gruta da Morena Cave (19°10’09.0”S 44°20’21.0”W), December 16, 2009, collected by. R. Bessi et al. Paratype female (ISLA 125641), same locality as the holotype, collected by R.L. Ferreira on December 20, 2022.
Etymology. The specific name urubuquaqua refers to “ No Urubuquaquá, no Pinhém ”, a book of stories by the famous Brazilian writer João Guimarães Rosa, born in Cordisburgo. Within the pages of this romance, the author finds an answer to his need to explore living things. It is to be treated as a noun in apposition.
Diagnosis. Pseudochthonius urubuquaqua sp. nov. most closely resembles P. biseriatus in the following combination: absence of eyes or eyespots; fixed and movable chelal fingers with 38 and 33–39 teeth, respectively; fixed and movable cheliceral fingers with 10–13 and 10–11 teeth, respectively. Pseudochthonius urubuquaqua sp. nov. differs from P. biseriatus by the anterior carapace margin entirely serrated (P. biseriatus serrated up to seta ame); ist–est/ist–esb trichobothria ratio of 2.5 (P. biseriatus with 1.78–2.10); rallum with 7 blades (P. biseriatus with 9).
P. urubuquaqua sp. nov. differs from P. maquinensis sp. nov. in the following combinations: P. urubuquaqua sp. nov. larger. 1.43–1.77 mm (P. maquinensis sp. nov. 1.35–1.51 mm); carapace narrower, 0.46/ 0.43 mm (P. maquinensis sp. nov. 0.58/ 0.56 mm), with a pronounced posterior constriction, 0.131 mm in females (P. maquinensis sp. nov. 0.104 mm in females); anterior margin serrated between setae ml (P. maquinensis sp. nov. with fully serrated). Palps more elongated, femur slimmer; ratio 7.1 (P. maquinensis sp. nov. ratio 5.13). Chela longer, 1.15/ 0.18 mm (P. maquinensis sp. nov. 0.81/ 0.12 mm); chelal fixed finger with alternating heterodonty starting after the 8th tooth, with 38 teeth (P. maquinensis sp. nov. with alternating heterodonty after the 7 th teeth, 34 teeth). Chelal movable finger with 33 teeth and 39 in female (P. maquinensis sp. nov. 35 and 32 in female). Leg I thinner, femur longer, ratio 7.0 (P. maquinensis sp. nov.; ratio 5.25). Tarsus more elongated, ratio 12.3 (P. maquinensis sp. nov., ratio 8.96). Male genital operculum more pronounced, with a larger opening and two straight-line marks on the third tergite. Females of P. urubuquaqua sp. nov. with a distinctly evident tubercle-shaped galea on the cheliceral movable finger, absent in males (P. maquinensis present in both males and females).
Description. Male body beige, translucent (females slightly darker beige); appendices beige similar to the body (Fig. 1B). Some parts of the body scaly. Vestitural setae thin, sharp and anteriorly projected on prosoma and posteriorly projected on opisthosoma.
Carapace (Figs 6A–B). 1.07 (0.93) times longer than wide, posteriorly constricted, showing a difference between ocular width and posterior width of 0.108 mm (0.131); anterior margin serrated between the setae al and aml, the most prominent at the central region (between the ame setae and the epistome); epistome strongly toothed and serrated (Fig. 6A); absence of ocular apparatus; posterior margin of the carapace smooth; chaetotaxy 4+2: 4: 4: 2: 2 (18).
Chelicerae (Figs 6F, 7A). Hand with 5 setae; movable finger with 1 subdistal seta; galea present only in females as a tubercle and absent in males; fixed finger with 10 (13) acute teeth, movable finger with 11 (10) acute teeth, the first distal tooth is separated; rallum with 7 blades; exterior and interior serrulae with 18 and 13 (14) blades, respectively.
Tergites. Undivided; smooth surface; chaetotaxy uniseriate: I–XI: 4: 2 (4): 2: 4: 4: 6: 4: 4: 4(2): 2: 1(2) + 2 sensory setae. Pleural membranes striated.
Coxae (Fig. 6C). Manducatory process with two apical setae; the rest of the palpal coxae with 3 setae arranged in a triangle; delicate lamellae bordered by 10 small spines. Pedal coxae: plumose coxal spines arranged in a single transverse row on coxae I (3–4) and II (6–5) (Figs 6C–E), chaetotaxy: I 3–4 (5), II 4 (5), III 7, IV 9 (8); intercoxal tubercle absent.
Male genital operculum (Fig. 6D). Anterior genital operculum with 8 discal setae, 6 valvular genital setae, and 6 setae along the sternite, with 2 lateral microsetae on each side. Well-pronounced, with a larger opening that extends almost to the end of the third sternite, and bearing two straight-line marks on the third tergite.
Female genital operculum. 8 setae distributed in three transverse rows: 2: 2: 4, genital opening not bifurcated.
Sternites. Chaetotaxy IV‒XI: 10 (6): 8 (10): 8 (6): 6: 6 (4): 6: 4: 2 Anal operculum with 2 ventral setae.
Palp (Fig. 7C). Trochanter 1.4 times wider than long, patella 1.8 times longer than wide, femur 7.1 times longer than wide. Femoral chaetotaxy 5: 6 (5): 3: 6: 1. Trichobothrial pattern: ib and isb located halfway on the hand portion, adjacent to each other and slightly displaced towards the paraxial face of the chela, eb proximal to esb, ist is slightly distal to esb, it distal to est, et proximal to dx, ist is halfway between esb and est, closer to esb than est (ist -est / ist -esb distance ratio = 2.2). Chelal fixed finger with 38 acute teeth; mobile finger with 36(38) acute and projected backwards teeth.
Leg IV (Fig. 8B). Arolia almost the same size as claw.
Measurements (length/width or depth in mm and ratios in parentheses calculated with three significant digits). Male holotype. Body length 1.43 (paratype female 1.77 mm). Carapace 0.46/0.43 (1.07). Palps: trochanter 0.24/0.14 (1.71), femur 0.79/0.11 (7.18), patella 0.31/0.15 (2.06), chela 1.15/0.18 (6.39), movable finger length 0.70. Leg I: trochanter 0.15/0.11 (1.36), femur 0.42/0.06 (7.00), patella 0.22/0.05 (4.40), tibia 0.22/0.04 (5.50), tarsus 0.37/0.03 (12.3). Leg IV: trochanter 0.13/0.09 (1.44), femur 0.25/0.18 (1.39), patella 0.22/0.13 (1.69), femur/patella ratio 1.17, tibia 0.30/0.07 (4.28), basitarsus 0.16/0.05 (3.2), telotarsus 0.29/0.03 (9.67).
Ecological Remarks
Morena Cave is one of the largest in Minas Gerais, extending over 5 km and intersected by three watercourses that converge within it. The system includes a second cave, Gruta do Meio, located upstream and crossed by the main watercourse flowing through Morena Cave. Although the cave has multiple entrances, the largest one is the primary access point for visitors (Figs 9A–B).
Specimens of P. urubuquaqua sp. nov. have been found throughout the cave, from watercourse galleries to higher levels, where they are rarely encountered. In the watercourse galleries, they are typically associated with sediment banks, sheltering beneath rocks (Fig. 9C). Despite their connection to watercourse conduits, they avoid direct contact with water, preferring higher sections of sediment banks. Their potential prey includes various springtail species and small arthropods like symphylans.
Although Morena Cave hosts several troglobitic species, most remain undescribed. Exceptions include the harvestman Spinopilar moria Kury & Pérez-González, 2008 and the highly troglomorphic palpigrade Eukoenenia sagarana Souza & Ferreira, 2012. While not a tourist cave, Morena Cave attracts speleologists and casual visitors, leading to noticeable substrate compaction from excessive trampling. It is surrounded by secondary forest, though nearby pastures are used for cattle farming.
Given the threats faced by P. urubuquaqua sp. nov. and other troglobitic species, immediate conservation action is needed. This cave represents one of the richest subterranean biodiversity sites in Minas Gerais, yet, like many ecologically significant caves in Brazil, it remains at risk (Ferreira et al. 2022).
Morena cave is one of the largest caves in Minas Gerais state. The cave presents several entrances, although the main entrance (the bigger) is the most used by visitors to access the cave (Figs 9A–B). The cave extends over 5 km of galleries and is intersected by three different watercourses that converge within it. The system also includes a second cave, Gruta do Meio cave, located upstream and crossed by the main watercourse that runs through the Morena cave. Specimens of P. urubuquaqua sp. nov. have been found in various sections of the cave, from watercourse galleries to higher levels, where they are rarely encountered. In the watercourse galleries, they are often associated with sediment banks, typically sheltering beneath rocks (Fig. 9C). Although they are linked to watercourse conduits, they are never observed close to the water, instead preferring to take refuge in the higher parts of the sediment banks. Their potential prey includes a variety of springtail species and other small arthropods, such as symphylans. Although several cave-restricted species have been discovered in this cave, most remain undescribed, with a few exceptions, such as the troglobitic harvestman Spinopilar moria Kury & Pérez-González, 2008 and the highly troglomorphic palpigrade Eukoenenia sagarana Souza & Ferreira, 2012.
Although Morena cave is not a tourist cave, it receives a significant number of visitors, particularly speleologists, as well as many casual visitors. Consequently, some of the cave’s substrates have become notably compacted due to excessive trampling. The cave is situated in an area covered by secondary forest, though nearby pastures are used for cattle farming.
It is crucial to recognize that this species, along with most troglobitic species in the cave, faces serious threats. Immediate action by a competent environmental agency is essential to protect this vital site of subterranean biodiversity, one of the richest caves in Minas Gerais for cave-restricted species. This need for action is underscored by the current situation in Brazil, where even ecologically significant caves are at risk of destruction (Ferreira et al. 2022).
description: Published as part of Guimarães, Lucas, Prado, Guilherme C. & Ferreira, Rodrigo L., 2025, Two new troglobitic species of Pseudochthonius Balzan, 1892 (Pseudoscorpiones, Chthoniidae) from Southeastern Brazil, pp. 52-68 in Zootaxa 5621 (1) on pages 59-65, DOI: 10.11646/zootaxa.5621.1.2, http://zenodo.org/record/15219921