Chthonius kirghisicus, Prado 1 & Viana 1 & Milko 2 & Ferreira 1, 2021

Prado 1, Guilherme C., Viana 1, Ana Clara M., Milko 2, Dmitry A. & Ferreira 1, Rodrigo L., 2021, Chthonius kirghisicus (Pseudoscorpiones, Chthoniidae), a new cave-dwelling species from Kyrgyzstan, Subterranean Biology 40, pp. 27-41 : 27

Chthonius kirghisicus sp. nov.

Material examined.

Holotype female ( IBB 82002 , preserved in ethanol: Kyrgyzstan , Osh Province , vicinity of Aravan, Duvankhan Cave (40°32'30.15"N, 72°29'49.05"E), 09 August 2019, leg. R.L Ferreira. Paratype female ( ISLA 66250), on SEM stub: same data as holotype.

Etymology.

The epithet Chthonius kirghisicus is an adjective that refers to the country where the specimens were collected, Kyrgyzstan.

Diagnosis.

Chthonius kirghisicus sp. nov. differs from other members of the subgenus by the following combination of characters: one pair of eyes ( C. tadzhikistanicus with four feebly small eyes, C. aquasanctae with two eyespots, C. pagus and C. submontanus bearing two anterior well-developed eyes and two posterior eyespots, C. shelkovnikovi , C. carinthiacus , C. delmastroi and C. tenuis with four well developed eyes, C. azerbaidzhanus and C. satapliaensis lack eyes or eye spots) ( Redikorzev 1930; Schawaller and Dashdamirov 1988; Dashdamirov and Schawaller 1992; Gardini 2009; Christophoryová et al. 2011; Ćurčić et al. 2011, 2012a); epistome large and heavily dentated ( C. azerbaidzhanus , C Chthonius pagus and C. satapliaensis with small dentated epistome, C. carinthiacus and C. aquasanctae with a distinct but small epistome, C. ponticus , C. delmastroi , C. tenuis and C. submontanus without an epistome) (Beier 1964; Schawaller and Dashdamirov 1988; Gardini 2009; Christophoryová et al. 2011; Ćurčić et al. 2011, 2012a); anterior margin mostly serrated (ranging between seta ame and al) ( C. tadzhikistanicus with anterior margin entirely serrated, C. azerbaidzhanus , C. satapliaensis , C. pagus , C. aquasanctae , C. carinthiacus and C. ponticus with only epistome region serrated) (Beier 1964; Schawaller and Dashdamirov 1988; Christophoryová et al. 2011; Ćurčić et al. 2011, 2012a); carapace with 20 setae, chaetotaxy 4: 2: 4: 4: 2: 4 ( C. ponticus [4: 4: 2: 4: 2: 2], C. carinthiacus , C. delmastroi , C. tenuis and C. submontanus [4:6:4:2:2] with 18 setae); il located medially (in C. tadzhikistanicus , C. shelkovnikovi and C. azerbaidzhanus il is situated on the lateral margin), pl situated posteriorly to pm (in C. satapliaensis pl is located anteriorly to pm); palpal femur 5.2 times longer than wide (4.5 times in C. tadzhikistanicus , 3.0 times in C. shelkovnikovi , 5.4 times in C. azerbaidzhanus and 6.1 times in C. satapliaensis ); chela 5.8 times longer than wide (5.4 times in C. tadzhikistanicus , 5.1 times in C. satapliaensis , 4.0 times in C. shelkovnikovi and 5.1 times in C. ponticus , 4.9 times in C. aquasanctae , 4.4 times in C. delmastroi , 5.3 times in C. tenuis , 4.5 times in C. submontanus and 4.8 times in C. pagus ) ( Redikorzev 1930; Beier 1964; Dashdamirov and Schawaller 1992; Gardini 2009; Ćurčić et al. 2011, 2012a); fixed chelal finger with 75-77 contiguous, acute and reclined backwards teeth (25 acute and straight teeth in C. azerbaidzhanus , 28 in C. satapliaensis , 33-38 acute, reclined backwards and close-set teeth in C. carinthiacus , 23-25 in C. aquasanctae , 30-33 in C. pagus , 32-36 in C. submontanus , 38 in C. tenuis , and 27-29 in C. delmastroi ; 12-13 acute and sparse teeth in C. ponticus and 50 round and small teeth in C. shelkovnikovi ); movable finger with 59-60 contiguous acute and retrorse teeth (18 acute and small teeth in C. azerbaidzhanus , 18 acute and straight teeth in C. satapliaensis , 17-20 acute, reclined backwards and close-set teeth in C. carinthiacus , 19-21 in C. aquasanctae , 25-39 in C. pagus , 23-30 in C. submontanus , 34 in C. tenuis , 26-29 in C. delmastroi ; 24 flat and small teeth in C. ponticus and 50 round and small teeth in C. shelkovnikovi ); absence of a protuberance near ib and isb (found in C. tadzhikistanicus C. tenuis and C. delmastroi ); chelal hand long and slender ( C. ponticus presents a ventrally round portion of the hand, C. shelkovnikovi exhibits short and robust chela) ( Redikorzev 1930; Beier 1964; Schawaller and Dashdamirov 1988; Dashdamirov and Schawaller 1992; Gardini 2009; Christophoryová et al. 2011; Ćurčić et al. 2011, 2012a).

Description.

(Fig. 6E ). Body pale yellowish, mostly translucent; chelicerae slightly reddish orange, abdomen dark beige. Some parts of the body scaly. Vestitural setae sharp and anteriorly projected.

Carapace (Fig. 1A-C ). 1.0-1.1 times longer than broad, strongly constricted posteriorly showing a difference between ocular breadth and posterior breadth of 0.12 mm (0.06 from each side of the carapace); anterior margin mostly serrated (ranging between seta ame and al); one pair of eyes; epistome strongly dentate and saw-like; presence of three furrows, one from the posterior to anterior margin, splitting in two in the area between me and oc (Fig. 1A ); posterior margin of carapace scaly; chaetotaxy 4: 2: 4: 4: 2: 4 (20).

Chelicera (Figs 1D , 5A-D ). Hand with 6 setae; movable finger with 1 subdistal seta; galea present as a tubercle; fixed finger with 8-10 acute teeth including two large ones (the two distalmost); movable finger with 7-8 acute teeth including one large distal tooth; rallum with 10 blades, middle blades long, presenting ramifications at the apex; serrula exterior with 15-17 blades, serrula interior with 12 blades.

Tergites. Not divided; surface smooth; chaetotaxy uniseriate, I-XI 4: 4: 4: 4-6: 6: 6: 6: 6: 6: 4-6: 4. Anal operculum with two dorsal setae. Pleural membranes smooth.

Coxae (Fig. 3A, B ). Manducatory process with 2 apical enlarged setae, delicate lamellae outlined by 17-19 small spines; rest of palp coxae with 3 setae arranged in a triangle; presence of two conspicuous pores on anterior region of palpal coxae. Pedal (Fig. 3A ): coxal spines bipinnate, irregularly arranged in a rounded patch (Fig. 3A, B ), present in coxae II (8-14) and coxae III (3-5), chaetotaxy: I 6, II 4, III 5, IV 7; intercoxal tubercle present between coxae III and IV, bearing two setae.

Genital operculum of female: setae distributed in four horizontal rows: 2: 4: 4: 2, genital opening angularly bifurcated.

Sternites: chaetotaxy IV-XI: 10-12: 7-8: 6-8: 6: 4: 2-4: 2: 0. Anal operculum without ventral setae.

Palp (Figs 2A-D , 4A-D ). Trochanter 1.5-1.7 times longer than broad, patella 1.7-2.0 times longer than broad, femur 5.0-5.2 times longer than broad. Femoral chaetotaxy 3: 4: 2: 5: 1. Chelal hand fusiform, with 4 posterior setae (ph 3 present), apodeme reduced, almost absent, trichobothrial pattern: ib and isb located at the base of the hand, adjacent to each other, eb proximad to esb, ist distad to esb, eb - esb - ist located at the base of fixed finger, it proximad to est, et distad from est. Fixed finger almost straight, movable finger slightly bent (Fig. 2C, D ). Left chelal fixed finger with 75-77 acute, not widely spaced teeth. In holotype left fixed chelal finger, teeth divided in three groups by gaps (probably frayed teeth), counting from basal to distal: 31 teeth, a gap of ca. 10 teeth; followed by 5 teeth, a gap of ca. 6 teeth and 23 more teeth (Fig. 2B ). Movable finger with 59-60 acute teeth, growing from basal to distal; right chelal fixed finger with 75-77 teeth, not widely spaced, without gaps.

Leg IV (Figs 3C , 4E ). Arolia shorter than claws; a small protuberance near end of tarsus.

Measurements (length/breadth or depth inmm; ratios in parenthesis calculated by using three significant digits): Female holotype and female paratype range. Body length 1.46 [1.44]. Carapace 0.50-0.51/0.47-0.48 (1.0-1.1). Palps: trochanter 0.21-0.22/0.13 (1.5-1.7), femur 0.65-0.66/0.13 (5.0-5.2), patella 0.26-0.28/0.14-0.15 (1.7-2.0), chela 0.94-0.96/0.1 (5.7-5.8), movable finger length 0.60-0.61. Leg I: trochanter 0.10-0.12/0.08-0.09 (1.2-1.4), femur 0.34-0.36/0.05-0.07 (4.9-5.9), patella 0.14-0.17/0.06 (2.6-2.7), femur/patella 2.1-2.4, tibia 0.21-0.22/0.04 (4.8-5.8), tarsus 0.35-0.38/0.04 (10.0-10.1). Leg IV: Trochanter: 0.13-0.17/0.10-0.12 (1.1-1.8), femur + patella 0.54-0.61/0.21-0.22 (2.5-2.9), tibia 0.36-0.38/0.09 (4.1-4.2), basitarsus 0.18-0.20/0.06 (2.9-3.1), telotarsus 0.33-0.35/0.03-0.04 (9.7-9.9).

Habitat.

The two individuals of C. kirghisicus sp. nov. were found in the wet areas fed by percolating water. These drip areas were located approximately 30 m from the upper entrance and occurred within the cave’s twilight zone. Even considering the proximity of the upper entrance (approximately 30 m from the drip area), the individuals were observed in a depression in the cave floor located in a lateral portion of the cave conduit, so that the light coming from the upper entrance (which is small - about 1 m2) did not reach this area. Potential prey species include springtails, which were observed in this area.

Figures

Figure 1. Chthonius kirghisicus sp. nov. holotype A carapace, showing distribution of setae and furrows B left chelicera, antiaxial view C detail of anterior margin of carapace D detail of epistome, showing highly dentate margin. Scale bars: 0.5 mm (A); 0.2 mm (B).

Figure 2. Chthonius kirghisicus sp. nov. holotype A right pedipalp chela, showing teeth morphology and trichobothrial pattern, antiaxial view B left pedipalp chela, showing the arrangement of teeth with detailed gaps and lyrifissures arrangement, antiaxial view C left pedipalp chela, dorsal view D left pedipalp chela, ventral view. See Material and methods for abbreviations. Scale bar: 0.5 mm.

Figure 3. Chthonius kirghisicus sp. nov. holotype A pedal coxae B detail of coxae II and III showing coxal spines distribution and intercoxal tubercle bisetose C left leg IV, retrolateral view. Scale bar: 0.3 mm (A); 0.025 mm (B); 0.5 mm (C).

Figure 4. Chthonius kirghisicus sp. nov. SEM images of the paratype A right pedipalp chela, showing trichobothrial pattern and arrangement of antiaxial lyrifissures, antiaxial view B detail of fa lyrifissure at base of right chelal fixed finger, antiaxial view C detail of ma 1 lyrifissure at chelal movable finger, antiaxial view D detail of ma 2 lyrifissure at chelal movable finger, antiaxial view E claw and arolia of right Leg IV. Scale bars: 0.3 mm (A); 0.05 mm (B); 0.03 mm (C-E).

Figure 5. Chthonius kirghisicus sp. nov. SEM images of the paratype A left chelicera, showing the arrangement of setae, dorsal view B detail of left chelicera, showing dorsal lyrifissures, dorsal view C right chelicera, showing arrangement of lyrifissures, ventral view D detail of right chelicera, showing ventral lyrifissures. Scale bars: 0.2 mm (A-C); 0.1 mm (D).

Figure 6. Type locality and habitat of Chthonius kirghisicus sp. nov. A Kyrgyzstan karst landscape B general area where the cave is located with the lower entrance featured C detail of the lower cave entrance D cave interior E live holotype.