Lagynochthonius zhakouensis SUN, GUO & ZHANG, 2024, sp. nov.
Creators: name: SUN, JIANZHOU
name: GUO, XIANGBO
name: ZHANG, FENG
Publisher: name: Zenodo
Year: 2024
Subjects: Biodiversity
Taxonomy
Animalia
Arthropoda
Arachnida
Pseudoscorpiones
Chthoniidae
Lagynochthonius
Lagynochthonius zhakouensis

description: Lagynochthonius zhakouensis sp. nov.
Chinese name. Ǻ口ȗ伪Dz
Figs 50–53
Type material. Holotype ♂ (Ps.- MHBU-SC2022073001): China, Sichuan Province, Luzhou City, Xuyong County, Zhengdon Town, Zhakou Cave [28.06668357°N, 105.54505348°E], 805 m a.s.l., 30 July 2022, Zegang Feng, Liu Fu, Long Hao & Jiaqi Zhao leg. Paratypes: 1 ♀ (Ps.- MHBU-SC2022073002), all with the same data as the holotype.
Etymology. Named after the type locality, Zhakou Cave.
Diagnosis. (♂ ♀). Small sized hypogean species; carapace with two eyespots, anterior margin smooth and epistome absent; tergites Ⅰ– ⅠⅠ each with two setae, tergites ⅠⅠⅠ –Ⅰ V each with four setae. Rallum with eight blades. Pedipalps slender, chela 5.69 (♂), 4.32 (♀) times as long as broad; femur 7.40 (♂), 7.80 (♀) 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 male (holotype) (Figs 50A, 51A– G, 52, 53).
Color generally pale yellow, chelicerae, carapace, pedipalps and tergites slightly darker black, soft parts pale.
Cephalothorax (Figs 51D, 52A): carapace nearly subquadrate, 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 absent, with two eyespots; with 18 setae arranged s4s: 4: 4: 2: 2; 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 7–8 terminally indented coxal spines on each side, set as an oblique and arc row, central spines slightly longer than the others (Fig. 52D); intercoxal tubercle absent; chaetotaxy of coxae: P 3, I 3, II 4, III 5, IV 5.
Chelicera (Figs 51C, 52B): almost as long as carapace, 1.65 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 7 teeth, distal one largest; movable finger with 12 retrorse contiguous small teeth; galea completely vestigial (Fig. 52B). Serrula exterior with 24 and serrula interior with 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. 52C).
Pedipalp (Figs 51A–B, 51E, 52E, 53A–B): trochanter 2.00,femur7.40,patella2.36,chela5.69,hand 2.44times as long as broad; femur 2.85 times as long as patella; movable chelal finger 1.51 times as long as hand and 0.65 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 slightly distal to it and distal to b; est situated distal to b and close to it (Figs. 51A, 53A). Microsetae (chemosensory setae) present on dorsum of chelal hand (Figs. 51B, 53B). Both chelal fingers with a row of teeth, spaced regularly along the margin, teeth smaller distally and proximally: fixed finger with 25 well-spaced, pointed teeth, and a modified accessory tooth on prolateral-retrolateral face (td, slightly distal to dx); movable finger with 9 well-spaced, pointed teeth, plus 13 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: 4: 4: 4: 4: 4: 5: 5: 4: T2T: 0. Sternal chaetotaxy IV– XII: 8: 10: 10: 9: 9: 11: 9: -: 2. Genital region: sternite II with 8 setae scattered on median area, genital opening slit-like, sternite III with 24 setae (Fig. 51G).
Legs (Fig. 53C–D): fine granulation present on anterodorsal faces of femur IV and patella IV. Leg Ⅰ: femur 2.00 times as long as patella; tarsus 2.44 times as long as tibia. Leg IV: femoropatella 3.59 times as long as deep; tibia 6.14 times as long as deep; with basal tactile setae on both tarsal segments: basitarsus 3.00 times as long as deep (TS = 0.38), telotarsus 9.60 times as long as deep and 2.67 times as long as basitarsus (TS = 0.38). Setae of leg I (trochanter to tibia) 3: 10: 5: 10, setae of leg IV (trochanter to basitarsus) 1: 1: 5: 6: 9. Arolium not divided, slightly shorter than the simple claws.
Adult female (paratype) (Figs 50B, 51H). Mostly same as male; tergal chaetotaxy Ⅰ–Ⅹ II: 2: 2: 4: 4: 4: 4: 4: 5: 6: 4: T2 T: 0; sternal chaetotaxy IV–Ⅹ II: 8: 8: 10: 9: 8: 9: 9: -: 2. Genital region: sternite II with nine 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). Male: body length 1.21. Pedipalps: trochanter 0.20/0.10 (2.00), femur 0.74/0.10 (7.40), patella 0.26/0.11 (2.36), chela 0.91/0.16 (5.69), hand 0.39/0.16 (2.44), movable chelal finger length 0.59. Chelicera 0.33/0.20 (1.65), movable finger length 0.20. Carapace 0.41/0.41 (1.00). Leg I: trochanter 0.13/0.09 (1.44), femur 0.40/0.06 (6.67), patella 0.20/0.05 (4.00), tibia 0.18/0.05 (3.60), tarsus 0.44/0.04 (11.00). Leg IV: trochanter 0.20/0.11 (1.82), femoropatella 0.61/0.17 (3.57), tibia 0.43/0.07 (6.14), basitarsus 0.18/0.06 (3.00), telotarsus 0.48/0.05 (9.60).
Female: body length 1.31. Pedipalps: trochanter 0.22/0.11 (2.00), femur 0.78/0.10 (7.80), patella 0.30/0.10 (3.00), chela 1.08/0.25 (4.32), hand 0.46/0.25 (1.84), movable chelal finger length 0.61. Chelicera 0.36/0.22 (1.64), movable finger length 0.23. Carapace 0.43/0.44 (0.98). Leg I: trochanter 0.20/0.11 (1.82), femur 0.45/0.06 (7.50), patella 0.21/0.06 (3.50), tibia 0.20/0.05 (4.00), tarsus 0.47/0.04 (11.75). Leg IV: trochanter 0.18/0.11 (1.64), femoropatella 0.60/0.19 (3.16), tibia 0.45/0.08 (5.63), basitarsus 0.21/0.06 (3.50), telotarsus 0.46/0.05 (9.20).
Remarks. Lagynochthonius zhakouensis sp. nov. most closely resembles L. longquanensis sp. nov. in the absence of intercalary teeth, the presence of two setae on tergites I–II each, the presence of four setae on tergites III–IV, the absence of epistome, and the presence of two eyespots on the carapace but differs in the following characters: longer chela femur (0.78 mm (♀) vs 0.61 mm (♀) in L. longquanensis sp. nov.) and thinner chela femur (7.80 (♀) times longer than broad vs 5.54 (♀) times longer than broad in L. longquanensis sp. nov.) and longer chela (1.08 mm (♀) vs 0.88 mm (♀) in L. longquanensis sp. nov.)
Distribution. Known only from the type locality, Zhakou Cave (China, Sichuan Province).
description: Published as part of SUN, JIANZHOU, GUO, XIANGBO & ZHANG, FENG, 2024, A review of the genus Lagynochthonius Beier, 1951 (Pseudoscorpiones, Chthoniidae) from China, pp. 177-250 in Megataxa 12 (2) on pages 239-243, DOI: 10.11646/megataxa.12.2.1, http://zenodo.org/record/15002032