Pseudochthonius lundi, Schimonsky, 2024

Schimonsky, Diego Monteiro Von, 2024, Two new cavernicolous species of Pseudochthonius Balzan, 1892 (Pseudoscorpiones, Chthoniidae) from Lagoa Santa karst, Minas Gerais, Brazil, Zootaxa 5433 (1), pp. 107-120 : 114-117

Pseudochthonius lundi sp. nov.

Fig. 5–6

Type material. Holotype ♂. BRAZIL: Minas Gerais, Cerrado province, Limeira massif karst area, Prudente de Morais , 06L cave; S 19°26'19.1" W 44°06'27"; 17.viii.2019; Zampaulo, R. leg ( LES15563 ).

Paratypes. 1 ♀. ( LES15565 ), 58L cave; S19°26'26.1" W44°04'0.4"; 10.ix.2019; Zampaulo, R. A.; Reis, A. S. leg. 1 ♂ and 1 ♀ ( MZSP78849 ), 62L cave; S19º26'12.4'' W44º06'01.4 ''; 05.xii.2021; Zampaulo, R. A.; Reis, A. S. leg.

Etymology. The epithet lundi is in honor of the Danish naturalist Peter Lund who explored the karst of Lagoa Santa region, Minas Gerais State, Brazil, for many years.

Diagnosis. Pseudochthonius lundi sp. nov. can be identified by the presence of developed pair of eyes in both males and females; rectangular carapace without epistome and the anterior margin serrate in middle; ist–est / ist–esb trichobothria ratio of 2.0; chelal fixed finger with 23 acute teeth, chelal movable finger with 21 flattened retrorse teeth; cheliceral fixed finger with 8 teeth, cheliceral movable finger with 9 teeth with subapical isolated tooth; serrula exterior with 11 lamellae, serrula interior with 14 lamellae; coxa I with one coxal spine, coxa II with 5 coxal spines, rallum with 6 blades.

Description (male and female): Body: specimens in 70% ethanol generally yellowish-brown in color, tergites III–VI with dark median mark, darker in tergites III and VI ( Fig. 5 ); Male is smaller than female.

Carapace ( Fig.6A–C ): anterior margin laterally smooth, medially serrate and slightly concave in comparison to lateral margin; without prominent epistome; pair of eyes present in males and in females; rectangular in males and almost a square in females, slightly expanded posteriorly; chaetotaxy 6:4:4:2:2 (18), of which one pair are preocular microsetae; 2 lyrifissures anteriorly.

Chelicera ( Fig.6D–E ): 5 setae on hand, with seta dt on base of fixed finger, db closer to base of movable finger than to chelicera base, it smaller than and basely at the same level of db; with two lateral microsetae, vb proximally and vt distally; seta gl closer to base of movable finger than to tip of this finger; all setae acuminate; fixed finger with 8 teeth proximally reduced in size; movable finger with 9 teeth proximally reduced in size with subapical isolated tooth (di); serrula exterior with 11 lamellae; serrula interior with 14 lamellae; rallum with 6 pectinate blades; 2 lyrifissures, one close to base of movable finger, other on fixed finger, near junction with movable finger.

Pedipalp ( Figs.6F–H ): 1.4 (♂)/1.7 (♀) × longer than carapace and 3.6 (♂)/3.3 (♀) × longer than patella; movable finger 2.9 × longer than hand; fixed finger 1.9 × longer than hand. Fixed chelal finger slightly sigmoid in distal half. Fixed finger with 23 distinctly separated acute teeth. Movable finger with 21 flattened retrorse teeth. Trichobothria: ib and isb situated close to each other medially in dorsal region of chelal hand; eb closer to esb than to ist, forming a straight oblique row at base of fixed chelal finger; ist closer to esb than to est (ratio ist-est/ist-esb = 2.0); et near the tip of fixed finger; dx located at end of fixed finger; t closer to st and situated at same level as est.

Coxae ( Fig.6I ): manducatory process distally rounded, with 2 long setae; pedipalpal coxa with 2 setae on anterior margin and 1 smaller seta medially positioned; coxa I with 2 setae and 1 coxal spine; coxa II with 3 setae and 5 coxal spines; coxa III with 5 setae; coxa IV with 7 setae; intercoxal tubercle absent.

Abdomen: chaetotaxy of tergites I–XI: (♂ / ♀) 4: 4: 4: 4: 6: 6: 6: 6: 4: 4: 2; chaetotaxy of sternites III–XI: (♂) (Fig. 9J) 8: (6)12(6): 8: 4: 4: 4: 4: 3: 0/(♀) 6: 8: 8: 6: 6: 6: 4: 2: 1; sternites IV and VI–VIII with 2 lateral micro setae (one on each side); sternite V with 4 lateral microsetae (two on each side); lateral microsetae summed in sternite formula; anal cone with 0/2 setae.

Legs: leg I: femur 5.0 (♂)/5.1 (♀) times longer than deep and 1.6 (♂)/1.9 (♀) longer than patella; patella 3.0 (♂)/3.2 (♀) times longer than deep; tibia 3.2 (♂)/4.7 (♀) times longer than deep; tarsus 7.2 (♂)/9.3 (♀) times longer than deep; tarsus 2.2 (♂)/1.4 (♀) times longer than tibia. Leg IV: femur + patella 2.0 (♂)/2.5 (♀) times longer than deep; tibia 4.0 (♂)/4.2(♀) times longer than deep; basitarsus 3.2(♂)/ 3.6(♀) times longer than deep; telotarsus 7.2(♂ / ♀) times longer than deep.

Measurements and ratios: see Table 2 .

Remarks. The species resembles other Brazilian species of Pseudochthonius that have eyes or eyespots, P. gracilimanus , P. ramalho , P. strinatii and P. ricardoi but differs from them as follows: P. lundi sp. nov. has rallum with 6 blades (7 in P. ramalho , 8 in P. strinatii , 9 in P. gracilimanus ), has 8 teeth in fixed cheliceral finger (12 in P. ricardoi ), has 23 teeth in palpal fixed finger and 21 in palpal movable finger (43 on both palpal fingers in P. ricardoi ), absence of microdenticles on fixed pedipalpal finger (2 present in P. ramalho ), and ratio ist-est/ist-esb = 2.0 (4.71 in P. ramalho , 3.0 in P. strinatii , 1.22 in P. gracilimanus ). Pseudochthonius lundi sp. nov. differs from other cave-dwelling species of the genus by its ratio ist-est/ist-esb (0.68–0.85 in P. koinopoliteia , 1.0 in P. troglobius , 1.02 in P. diamachi , 1.22 in P. gracilimanus , 1.72 in P. galapagensis , 1.90 in P. lubueno , 2.4 in P. arubensis , 2.46–2.77 in P. pali , 2.49 in P. olegario and 3.0 in P. limettioides sp. nov).

Distribution and habitat. The type locality of Pseudochthonius lundi sp. nov. (Cave 06L). Speleometrically, this cave has 109.2 m of horizontal projection, 8 m of unevenness, 386.7 m ² of surface area and 2,310.5 m ³ of volume. Morphologically, it has two entrances; the main entrance and another one formed by a skylight located in the intermediate part of the main channel. It consists of a rectilinear channel about one hundred meters long. ( CANIE 2022, Robson de Almeida Zampaulo personal communication). The organic matter inside the cave is mainly contributed by the organic matter deposited near the entrances and by the presence of hematophagous bat guano. A large part of the cave is made up of aphotic zones (50% of its linear extension) and is prone to periods of flooding during the rainy season (December to March). This new species occurs in other caves in the surroundings (58L cave, 62L cave) with characteristics like those of the type locality.

Figures

FIGURE 5. A. Holotype ♂ of Pseudochthonius lundi sp. nov, habitus and B. ventral view; C. Paratype ♀ of Pseudochthonius lundi sp. nov habitus and D. ventral view.

FIGURE 6. Pseudochthonius lundi sp. nov., holotype (♂).A. anterior margin of carapace of a ♀; B. anterior margin of carapace; C. carapace; D. left chelicera; E. cheliceral movable finger of ♀; F. right chela, dorsal view; G. right chela, prolateral view with the trichobothria pattern; H. right palpal (except chela); I. coxal spines on coxa I and II; J. genital opening.