Pseudochthonius maquinensis, Guimarães & Prado & Ferreira, 2025

Pseudochthonius maquinensis sp. nov.

urn:lsid:zoobank.org:act:2A7FE0A6-CAF0-4BE7-902D-41A45DB1399E

Material Examined. Holotype male ( ISLA 125638 ), preserved in ethanol: Brazil, Cosdisburgo, Minas Gerais, Maquiné Cave (19° 7’ 30.85” S 44° 21’ 6.80” W), November 12, 2020, collected by R.L. Ferreira GoogleMaps . Paratype female ( ISLA 125639 ), same data as the holotype GoogleMaps .

Etymology. The epithet ‘maquinensis’ refers to the name of the cave, “Gruta do Maquiné” where the species was collected. This should be treated as an adjective.

Diagnosis. Pseudochthonius maquinensis sp. nov. most closely resembles P. limettioides in the following combination: absence of eyes or eyespots in male individuals; anterior carapace margin serrated up to seta ame; fixed and movable chelal fingers with 34 and 35 teeth, respectively; rallum with 7 blades. Pseudochthonius maquinensis sp. nov. differs from P. limettioides by the ist–est/ist–esb trichobothria ratio of 2.6 ( P. limettioides with 3.0); fixed and movable cheliceral fingers with 10–12 and 9–11 teeth, respectively ( P. limettioides with 7 and 6, respectively).

Description. Body beige, translucent; appendices in a slightly darker shade of beige ( Fig. 1A View FIGURE 1 ) Some parts of the body scaly. Vestitural setae thin, sharp and anteriorly projected on prosoma and posteriorly projected on opisthosoma.

Carapace ( Figs 2A–B View FIGURE 2 ). 0.95 (0.97) times longer than wide, posteriorly constricted, showing a difference between ocular width and posterior width of 0,106 mm (0,104 mm); smooth anterior margin, except in the central portion; epistome strongly toothed and serrated ( Fig. 2A View FIGURE 2 ); absence of ocular apparatus; posterior margin of the carapace smooth; chaetotaxy 4+2: 4: 4: 2: 2 (18).

Chelicerae ( Figs 3D–E View FIGURE 3 ). Hand with 5 setae; movable finger with 1 subdistal seta; galea present as a tubercle; fixed finger with 10 (12) acute teeth, the proximal four smaller; movable finger with 9 (11) acute teeth, in distal portion, the first tooth is separated and the second is bicuspid ( Fig. 3E View FIGURE 3 ); rallum with 7 blades; exterior and interior serrulae with 17 and 13 blades, respectively.

Tergites. Undivided; smooth surface; chaetotaxy uniseriate: I–XI 8: 8: 8: 8: 8: 6: 6: 6: 6: 6: 2 + 2 sensory setae. Pleural membranes striated.

Coxae ( Fig. 2C View FIGURE 2 ). Manducatory process with two apical setae; the rest of the palpal coxae with 3 setae arranged in a triangle; delicate lamellae bordered by 7(8) small spines. Pedal coxae: plumose coxal spines arranged in a single transverse row on coxae I (4–5) and II (3–5) ( Fig. 2E View FIGURE 2 ), chaetotaxy: I 5–4(5), II 5, III 7, IV 8–9(8); intercoxal tubercle absent.

Male genital operculum ( Fig. 2D View FIGURE 2 ). Anterior genital operculum with 8 discal setae, 6 valvular genital setae, and 10 setae along the third sternite, with 2 lateral microsetae on each side.

Female genital operculum. 8 setae distributed in three transversal rows: 2: 2: 4, genital opening not bifurcated.

Sternites. Chaetotaxy IV‒XI: 10: 8: 8: 8: 7: 7: 6: 2+2 sensory. Anal operculum with 2 ventral setae.

Palp ( Figs 3A–B–C View FIGURE 3 ). Trochanter 1.39 times wider than long, patella 1.37 times longer than wide, femur 5.13 times longer than wide. Femoral chaetotaxy 4: 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 = 2.6); chelal fixed finger with alternating heterodonty after the 7 th teeth, with 34 acute teeth, except in the most proximal portion, which is rounded; movable finger with 35(32) acute and projected backwards teeth ( Figs 3A, C View FIGURE 3 ).

Leg IV ( Fig. 4B View FIGURE 4 ). Arolia slightly smaller than claws.

Measurements (length/width or depth in mm and ratios in parentheses calculated with three significant digits). Male holotype. Body length 1.35. Carapace 0.58/0.56 (1.04), Palps: trochanter 0.15/0.11 (1.36), femur 0.53/0.10 (5.30), patella 0.14/0.10 (1.40), chela 0.81/0.12 (6.75), movable finger length 0.51. Leg I: trochanter 0.11/0.07 (1.57), femur 0.25/0.05 (6.25), patella 0.18/0.04 (4.50), tibia 0.11/0.04 (3.66), tarsus 0.27/0.03 (8.66). Leg IV: trochanter 0.13/0.10, femur 0.26/0.18, patella 0.29/0.14, femur/patella ratio 0.90, tibia 0.32/0.07, basitarsus 0.16/0.05, telotarsus 0.32/0.03.

Ecological remarks

Maquiné Cave is Brazil’s oldest tourist cave, open since 1908. In 1967, its infrastructure was modernized with stairs, topographical modifications, and electric lighting. Although incorporated into a conservation unit in 2005 ( Fig. 5A View FIGURE 5 ), its entrance remains altered to facilitate tourist access ( Fig. 5B View FIGURE 5 ). Extending approximately 600 meters, the cave’s deeper sections ( Fig. 5C View FIGURE 5 ) maintain a relative humidity of 91% and an average temperature of 24ºC.

For years, a fine mesh gate prevented bats from entering the cave to reduce guano accumulation on speleothems and minimize disturbances to visitors. This significantly reduced organic input, forcing invertebrates to rely on debris from tourist infrastructure, such as wood scraps and food remnants. Consequently, cave fauna became concentrated along the tourist path, increasing their risk of trampling.

Fortunately, the removal of the gate about a decade ago allowed bats to recolonize the cave, restoring guano deposits, particularly in non-touristic areas. This led to a resurgence of invertebrate populations in more protected zones. The first P. maquinensis sp. nov. specimens were recorded in 1999 within the tourist area ( Fig. 5E View FIGURE 5 ), and early surveys (1999–2001) typically detected only a single specimen per sampling event. However, more recent surveys (after the gate removal) recorded around five specimens, suggesting a potential population recovery.

Other troglobitic species in Maquiné Cave include Spaeleoleptes spaeleus Soares, 1966 , Tricongius ybyguara Rheims & Brescovit, 2004 , and Eukoenenia maquinensis Souza & Ferreira, 2010 . Despite conservation efforts, remnants of tourist infrastructure persist, posing potential risks to the cave fauna ( Fig. 5D View FIGURE 5 ).