Lagynochthonius baiguensis, Sun, Guo & Zhang, 2024

SUN, JIANZHOU, GUO, XIANGBO & ZHANG, FENG, 2024, A review of the genus Lagynochthonius Beier, 1951 (Pseudoscorpiones, Chthoniidae) from China, Megataxa 12 (2), pp. 177-250 : 188-192

Lagynochthonius baiguensis sp. nov.

Chinese name. ǝḃȗ伪Dz

Figs 7–11

Type material. Holotype ♂ (Ps.- MHBU-GX2023080101 ): China, Guangxi Zhuang Autonomous Region, Guilin City, Qixing County, Baigu Cave [25.22612311°N, 110.33612284°E], 216 m a.s.l., 1 August 2023, Kun Yu & Jianzhou Sun leg. Paratypes: 1 ♂ (Ps.- MHBU-GX2023080102 ) and 1 ♀ (Ps.- MHBU-GX2023080103 ), all with the same data as the holotype ; 2 ♂ (Ps.- MHBU-GX2023120204–05 ), 160 m a.s.l., 3 December 2023, Jiaqi Zhao, Tao Zheng, Songtao Shi & Jianzhou Sun legit, Except for the time, others with the same data as the holotype .

Etymology. Named after the type locality, Baigu Cave.

Diagnosis. (♂ ♀). Small sized hypogean species; carapace with four strongly reduced eyes, anterior margin smooth and epistome small and triangular; tergites Ⅰ with two setae. Pedipalps slender, chela 6.00–6.44 (♂), 6.00 (♀) times as long as broad; femur 6.53–8.11 (♂), 6.42 (♀) times as long as broad; both chelal fingers without intercalary teeth and a modified accessory tooth (td) on prolateral-retrolateral face; chemosensory setae (sc) present on dorsum of chelal hand.

Description. Adult males (holotype and paratypes) ( Figs 7A , 8A–G , 9 , 10 ).

Color generally pale yellow, chelicerae, carapace, pedipalps and tergites slightly darker black, soft parts pale.

Cephalothorax ( Figs 8D , 9A ): carapace nearly subquadrate, 0.93–1.00 times as long as broad, weakly constricted basally; posterior region with squamous sculpturing laterally, other area smooth, without furrows; anterior margin smooth, without serrations; epistome small and triangular, with four strongly reduced eyes; with 18 setae arranged s4s: 4: 4: 2: 2, most setae heavy, long and gently curved, anterolateral setae much shorter than others; with three pairs of lyrifissures, first and second pair situated middle and flank to the setae of ocular row, third pair situated lateral to the sole pair of setae of posterior row. Manducatory process with two acuminate distal setae, anterior seta more than 1/2 length of medial seta; apex of coxa I with a rounded anteromedial process; coxae II with 10–13 terminally indented coxal spines on each side, set as an oblique and arc row, central spines slightly longer than the others ( Fig. 9D ); intercoxal tubercle absent; chaetotaxy of coxae: P 3, I 3, II 4, III 5, IV 5.

Chelicera ( Figs 8C , 9B ): almost as long as carapace, 1.84–1.95 times as long as broad; five setae and two lyrifissures (exterior condylar lyrifissure and exterior lyrifissure) present on hand, all setae acuminate, ventrobasal setae shorter than others; movable finger with one medial seta. Cheliceral hand with moderate wrinkle on both ventral and dorsal sides. Both fingers well provided with teeth, fixed finger with 9–13 teeth, distal one largest; movable finger with 9–10 retrorse contiguous small teeth; galea completely vestigial ( Fig. 9B ). Serrula exterior with 18–20 and serrula interior with 10–13 blades. Rallum with eight blades, the distal one longest and recumbent basally, with fine barbules and slightly set apart from the other blades, latter tightly grouped and with long pinnae, some of which are subdivided ( Fig. 9C ).

Pedipalp ( Figs 8A–B, 8E , 9E , 10A–B ): trochanter 1.72–1.91, femur 6.54–8.11 patella 2.17–2.45, chela 6.00–6.44, hand 2.53–2.69 times as long as broad; femur 2.55–2.81 times as long as patella; movable chelal finger 1.42–1.45 times as long as hand and 0.59–0.61 times as long as chela. Setae generally long and acuminate. Chelal hand gradually constricted towards fingers, apodeme complex of movable chelal finger strongly sclerotized. Fixed chelal finger and hand with eight trichobothria, movable chelal finger with four trichobothria, ib and isb situated close together, submedially on dorsum of chelal hand; eb, esb and ist at base of fixed chelal finger; esb slightly distal eb and ist slightly distal to esb; it slightly distal to est, situated subdistally; et slightly near to tip of fixed chelal finger, slightly close to chelal teeth; dx situated distal to et; sb slightly closer to st than to b; b and t situated subdistally, t situated at the same level as it and distal to b; est situated distal to b and close to it ( Figs. 8A , 10A ). Microsetae (chemosensory setae)present on dorsum of chelal hand ( Figs. 8B , 10B ). Both chelal fingers with a row of teeth, spaced regularly along the margin, teeth smaller distally and proximally: fixed finger with 18–19 well-spaced, pointed teeth, and a modified accessory tooth on prolateral-retrolateral face (td, slightly distal to dx); movable finger with 8–10 well-spaced, pointed teeth, plus 7–9 vestigial, rounded and contiguous basal teeth.

Opisthosoma: generally typical, pleural membrane finely granulated. All tergites and sternites undivided; setae uniseriate and acuminate. Tergal chaetotaxy I– XII: 2: 2–3: 4: 4: 4: 4: 5: 5–7: 5–7: 4: T2T: 0. Sternal chaetotaxy IV–XII: 8–10: 10: 9–10: 8–10: 9: 9: 9: -: 2. Genital region: sternite II with 6–10 setae scattered on median area, genital opening slit-like, sternite III with 10–12 setae ( Fig. 8G ).

Legs ( Fig. 10C–D ): fine granulation present on anterodorsal faces of femur IV and patella IV. Leg Ⅰ: femur 1.73–1.89 times as long as patella; tarsus 2.14–2.44 times as long as tibia. Leg IV: femoropatella 2.70–2.85 times as long as deep; tibia 4.33–5.13 times as long as deep; with basal tactile setae on both tarsal segments: basitarsus 2.57–3.33 times as long as deep (TS = 0.25– 0.33), telotarsus 10.25–11.25 times as long as deep and 2.20–2.56 times as long as basitarsus (TS = 0.25–0.29). Setae of leg I (trochanter to tibia) 3: 6–9: 6–7: 5–9, setae of leg IV (trochanter to basitarsus) 1–3: 3: 6: 8–10: 6– 9. Arolium not divided, slightly shorter than the simple claws.

Adult female (paratype) ( Figs 7B , 8G ). Mostly same as males; tergal chaetotaxy Ⅰ–ⅩII: 2: 4: 4: 4: 4: 5: 5: 7: 6: 4: T2 T: 0; sternal chaetotaxy IV–ⅩII: 10: 10: 9: 9: 9: 11: 9: -: 2. Genital region : sternite II with 10 setae scattered on median area, sternite III with a row of 10 setae.

Dimensions (length/breadth or, in the case of the legs, length/depth in mm; ratios in parentheses). Males: body length 1.40–1.47. Pedipalps: trochanter 0.19–0.21/0.11 (1.72–1.91), femur 0.72–0.74/0.09–0.11 (6.54–8.11), patella 0.26–0.29/0.11–0.12 (2.17–2.45), chela 0.99– 1.03/0.16–0.17 (6.00–6.44), hand 0.42–0.43/0.16–0.17 (2.53–2.69), movable chelal finger length 0.60–0.61. Chelicera 0.35–0.37/0.19–0.20 (1.84–1.95), movable finger length 0.21. Carapace 0.37–0.41/0.39–0.41 (0.93– 1.00). Leg I: trochanter 0.13–0.14/0.09–0.11 (1.27– 1.63), femur 0.36–0.38/0.06–0.07 (5.14–6.33), patella 0.19–0.22/0.05–0.06 (3.33–3.80), tibia 0.18–0.21/0.04– 0.06 (3.00–4.75), tarsus 0.42–0.44/0.04 (10.50–11.25). Leg IV: trochanter 0.15–0.21/0.11–0.13 (1.23–1.91), femoropatella 0.54–0.59/0.20–0.21 (2.70–2.85), tibia 0.39–0.41/0.08–0.09 (4.33–5.13), basitarsus 0.16– 0.20/0.05–0.07 (2.57–3.33), telotarsus 0.41–0.45/0.04 (10.25–11.25).

Female: body length 1.43. Pedipalps: trochanter 0.20/0.12 (1.67), femur 0.77/0.12 (6.42), patella 0.30/0.13 (2.31), chela 1.08/0.18 (6.00), hand 0.46/0.18 (2.56), movable chelal finger length 0.64. Chelicera 0.40/0.21 (1.90), movable finger length 0.24. Carapace 0.45/0.44 (1.02). Leg I: trochanter 0.15/0.09 (1.67), femur 0.40/0.07 (5.71), patella 0.22/0.06 (3.67), tibia 0.22/0.05 (4.40), tarsus 0.45/0.04 (11.25). Leg IV: trochanter 0.23/0.13 (1.76), femoropatella 0.60/0.22 (2.73), tibia 0.40/0.09 (4.44), basitarsus 0.18/0.06 (3.00), telotarsus 0.40/0.05 (8.00).

Remarks. Lagynochthonius baiguensis sp. nov. differs from all other hypogean Lagynochthonius species from China by the presence of four strongly reduced eyes ( Fig. 8F ).

Ecology. All of the specimens were collected under mud and rocks inside the cave, which are relatively wet compared to the rest of the Baigu Cave ( Fig. 11D ).

Distribution. Known only from the Baigu Cave ( China, Guangxi Zhuang Autonomous Region).

Figures

FIGURE 7. Lagynochthonius baiguensis sp. nov., A. Holotype male (dorsal view); B. Paratype female (dorsal view).

FIGURE 8. Lagynochthonius baiguensis sp. nov., holotype male (A–F), paratype female (G): A. Right chela (lateral view); B. Right chela (dorsal view); C. Left chelicera (dorsal view); D. Carapace (dorsal view); E. Right pedipalp (minus chela, dorsal view); F. Carapace (dorsal-lateral view), indicate strongly reduced eyes (red arrow); G. Male genital area (ventral view); H. Female genital area (ventral view).

FIGURE 9. Lagynochthonius baiguensis sp. nov., holotype male:A. Carapace (dorsal view); B. Left chelicera (dorsal view), with details of teeth; C. Rallum; D. Coxal spines on coxae II (ventral view); E. Right pedipalp (minus chela, dorsal view).

FIGURE 10. Lagynochthonius baiguensis sp. nov., holotype male: A. Right chela (lateral view), with details of teeth and trichobothrial pattern; B. Right chela (dorsal view); C. Leg I (lateral view); D. Leg IV (lateral view).

FIGURE 11. Baigu Cave, type locality of Lagynochthonius baiguensis sp. nov., A. Entrance; B. The external environment; C: Inside the cave entrance; D. Areas where L. baiguensis sp. nov. specimens were collected.