Lagynochthonius galeatus, Sun, Guo & Zhang, 2024

Lagynochthonius galeatus sp. nov.

Chinese name. Ăẋȗ伪Dz

Figs 12–16 View FIGURE 12 View FIGURE 13 View FIGURE 14 View FIGURE15 View FIGURE 16

Type material. Holotype ♀ (Ps.- MHBU-GZ2024012801 ): China, Guizhou Province, Zunyi City, Yanshan County, Yanshan Cave [28.80022624°N, 107.90048060°E], 987 m a.s.l., 28 January 2024, Jiaqi Zhao, Yitin Xu & Jianzhou Sun leg. GoogleMaps

Etymology. The specific name is derived from the Latin word “ galeatus ”, meaning helmet-shaped, which refers to the shape of galea.

Diagnosis. (♀). Small sized hypogean species; galea helmet-shaped; carapace without eyes or eyespots, anterior margin smooth and epistome hump-shaped; tergites Ⅰ–IV each with four setae. Pedipalps slender, chela 6.11 times as long as broad; femur 7.00 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 female (holotype) ( Figs 12 View FIGURE 12 , 13 View FIGURE 13 , 14 View FIGURE 14 , 15 View FIGURE15 ).

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

Cephalothorax ( Figs 13E View FIGURE 13 , 14A View FIGURE 14 ): carapace nearly subquadrate, 0.95 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 hump-shaped, without eyes or eyespots; 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 terminally indented coxal spines on each side, set as an oblique and arc row, central spines slightly longer than the others ( Fig. 14D View FIGURE 14 ); intercoxal tubercle absent; chaetotaxy of coxae: P 3, I 3, II 4, III 5, IV 5.

Chelicera ( Figs13D View FIGURE 13 , 14B View FIGURE 14 ):almost as long as carapace, 1.76 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 11 teeth, distal one largest; movable finger with 8 contiguous small teeth; galea helmet-shaped ( Fig. 14B View FIGURE 14 ). Serrula exterior with 19 and serrula interior with 12 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. 14C View FIGURE 14 ).

Pedipalp ( Figs 13A–B, 13E View FIGURE 13 , 14E View FIGURE 14 , 15A–B View FIGURE15 ): trochanter 1.82, femur7.00 patella 2.33, chela 6.11, hand 2.44 times as long as broad; femur 2.75 times as long as patella; movable chelal finger 1.52 times as long as hand and 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. 13A View FIGURE 13 , 15A View FIGURE15 ). Microsetae (chemosensory setae) present on dorsum of chelal hand ( Figs. 13B View FIGURE 13 , 15B View FIGURE15 ). Both chelal fingers with a row of teeth, spaced regularly along the margin, teeth smaller distally and proximally: fixed finger with 23 well-spaced, pointed teeth, and a modified accessory tooth on prolateral-retrolateral face (td, slightly distal to dx); movable finger with 10 well-spaced, pointed teeth, plus 12 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: 4: 4: 4: 4: 4: 4: 4: 5: 5: 4: T2T: 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. ( Fig. 13C View FIGURE 13 ).

Legs ( Fig. 15C–D View FIGURE15 ): fine granulation present on anterodorsal faces of femur IV and patella IV. Leg Ⅰ: femur 2.00 times as long as patella; tarsus 2.05 times as long as tibia. Leg IV: femoropatella 3.53 times as long as deep; tibia 5.25 times as long as deep; with basal tactile setae on both tarsal segments: basitarsus 3.33times as long as deep (TS = 0.40), telotarsus 11.50 times as long as deep and 2.30 times as long as basitarsus (TS = 0.35). Setae of leg I (trochanter to tibia) 4: 9: 6: 8, setae of leg IV (trochanter to basitarsus) 1: 3: 6: 9: 9. Arolium not divided, slightly shorter than the simple claws.

Dimensions (length/breadth or, in the case of the legs, length/depth in mm; ratios in parentheses). Female: body length 1.49. Pedipalps: trochanter 0.20/0.11 (1.82), femur 0.77/0.11 (7.00), patella 0.28/0.12 (2.33), chela 1.10/0.18 (6.11), hand 0.44/0.18 (2.44), movable chelal finger length 0.67. Chelicera 0.37/0.21 (1.76), movable finger length 0.22. Carapace 0.40/0.42 (0.95). Leg I: trochanter 0.13/0.10 (1.30), femur 0.42/0.06 (7.00), patella 0.21/0.05 (4.20), tibia 0.21/0.05 (4.20), tarsus 0.43/0.05 (8.60). Leg IV: trochanter 0.20/0.12 (1.67), femoropatella 0.60/0.17 (3.53), tibia 0.42/0.08 (5.25), basitarsus 0.20/0.06 (3.33), telotarsus 0.46/0.04 (11.50).

Remarks. Lagynochthonius galeatus sp. nov. differs from all other hypogean Lagynochthonius species from China by the presence of helmet-shaped galea.

Ecology. The specimen was collected under a small stone block inside the cave.

Distribution. Known only from the type locality, Yanshan Cave ( China, Guizhou Province).