Lagynochthonius serratus, Hou & Gao & Zhang, 2022

Hou, Yanmeng, Gao, Zhizhong & Zhang, Feng, 2022, Diversity of cave-dwelling pseudoscorpions from eastern Yunnan in China, with the description of eleven new species of the genus Lagynochthonius (Pseudoscorpiones, Chthoniidae), Zootaxa 5198 (1), pp. 1-65 : 33-38

publication ID	https://doi.org/ 10.11646/zootaxa.5198.1.1
publication LSID	lsid:zoobank.org:pub:019FE488-4263-4BC2-8606-446E599E226A
DOI	https://doi.org/10.5281/zenodo.7255283
persistent identifier	https://treatment.plazi.org/id/8A6487A5-FFEE-A90E-FF11-F9F8FA77FB22
treatment provided by	Plazi
scientific name	Lagynochthonius serratus
status	sp. nov.

Treatment

Lagynochthonius serratus sp. nov. (ǤffiIJ伪oi)

Figs 23–26 View FIGURE 23 View FIGURE 24 View FIGURE 25 View FIGURE 26

Type material. Holotype ♂ (Ps.- MHBU-HBUARA#2021-18401 ): China, Yunnan Province, Malipo County, Donggan Town,cave without name( Unnamed Cave 3), under the stones in deep zone[23°18′2.02″N, 105°11′45.84″E], 1643 m a.s.l., 23 July 2021, Zegang Feng, Hongru Xu, Liu Fu & Nana Zhan leg. GoogleMaps Paratypes: 4 ♂ (Ps.-MHBU-HBUARA#2021-18402-HBUARA#2021-18405), 2 ♀ (Ps.- MSWU-HBUARA#2021-18406 & HBUARA#2021- 18407), all with the same data as the holotype GoogleMaps .

Etymology. The specific name is derived from the Latin word “ serratus ” (= serrate) and refers to the shape of the chelal finger teeth.

Diagnosis (♂ ♀). Moderately sized troglomorphic species with elongated appendages; carapace without eyes or eyespots; anterior margin of carapace thin and finely denticulated, epistome pointed and small, triangular; posterior margin of the carapace with 2 setae; tergites I– IV each with 2 setae. Pedipalps slender, femur 8.64–8.93 (♂), 7.88–8.19 (♀) times longer than broad; chela 8.38–8.84 (♂), 7.46–7.54 (♀) times longer than broad; both chelal fingers with intercalary teeth and fixed chelal finger with a modified accessory tooth (td) on dorso-antiaxial face; chemosensory setae (sc) on dorsum of chelal hand absent; sensilla absent .

Description. Males (holotype and paratypes) ( Figs 23B View FIGURE 23 , 24A View FIGURE 24 , 25A–D View FIGURE 25 , 26 View FIGURE 26 ).

Colour ( Figs 23B View FIGURE 23 , 24A View FIGURE 24 , 25A–D View FIGURE 25 ): generally pale yellow, chelicerae, pedipalps and tergites slightly darker, soft parts pale.

Cephalothorax ( Figs 25B View FIGURE 25 , 26A View FIGURE 26 ): carapace 1.02 times longer than broad, markedly narrowed posteriorly; surface smooth, without furrows; no traces of eyes; anterior margin slightly serrate; epistome pointed and small, triangular, with 2 setae flanking base; with 18 setae arranged s4s: 4: 4: 2: 2, most setae heavy, long and gently curved, anterolateral setae much shorter than others; with two pairs of lyrifissures, first pair situated middle to the setae of ocular row, the second situated exterior to the sole pair of setae of posterior row. Chaetotaxy of coxae: P 3, I 3, II 4, III 5, IV 5; manducatory process with two acuminate distal setae, anterior seta less than 1/2 length of medial seta; apex of coxa I with small, rounded anteromedial process; coxae II with 7–8 terminally indented coxal spines on each side, set as an oblique and arc row, longer spines present in the middle of the row, becoming shorter distally and proximally and incised for about half their length ( Fig. 26C View FIGURE 26 ); intercoxal tubercle absent; without sub-oral seta.

Chelicera ( Figs 25C View FIGURE 25 , 26B View FIGURE 26 ): large, about as long as carapace, 2.45–2.52 times longer than broad; 5 setae and 2 lyrifissures (exterior condylar lyrifissure and exterior lyrifissure) present on hand, all setae acuminate, ventrobasal seta shorter than others; movable finger with one medial seta. Cheliceral palm with moderate hispid granulation on both ventral and dorsal sides. Both fingers well provided with teeth, fixed finger with 13–15 teeth, distal one largest; movable finger with 10–11 retrorse contiguous small teeth; galea represented by a very slight bump on movable finger ( Fig. 26B View FIGURE 26 ). Serrula exterior with 25–26 and serrula interior with 14–15 blades. Rallum with 8 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. 26D View FIGURE 26 ).

Pedipalp ( Figs 25A View FIGURE 25 , 26E–G View FIGURE 26 ): long and slender, trochanter 1.47–1.67, femur 8.64–8.93, patella 2.39–2.56, chela 8.38–8.84, hand 3.38–3.58 times longer than broad; femur 2.81–3.05 times longer than patella; movable chelal finger 1.46–1.48 times longer than hand and 0.59–0.60 times longer than chela. Setae generally long and acuminate; 1 distal lyrifissure present on patella ( Fig. 26E View FIGURE 26 ). Chelal palm gradually constricted towards fingers, apodeme complex of movable chelal finger strongly sclerotized, with weak granulation dorsally at base of fixed chelal finger and hand. Fixed chelal finger and hand with 8 trichobothria, movable chelal finger with 4 trichobothria, ib and isb situated close together, submedially on dorsum of chelal hand; eb, esb and ist forming a straight oblique row at base of fixed chelal finger; it slightly distal to est, situated subdistally; et slightly near to tip of fixed chelal finger, very close to chelal teeth; dx situated distal to et; sb closer to st than to b; b and t situated subdistally, b situated proximal to est, t situated distal to it ( Fig. 26F View FIGURE 26 ). A tiny antiaxial lyrifissure present at base of fixed chelal finger (situated distal to ist). Both chelal fingers with a row of teeth, heterodentate, spaced regularly along the margin, larger and well-spaced teeth present in the middle of the row, becoming smaller and closer distally and proximally: fixed chelal finger with 23–24 macrodenticles, slightly retrorse and pointed, plus 21– 22 intercalary microdenticles and a modified accessory tooth on dorso-antiaxial face (td, near tip), 45–47 in total; movable chelal finger with 24–25 macrodenticles (slightly smaller than teeth on fixed chelal finger), slightly retrorse and pointed, plus 10– 11 intercalary microdenticles, 34–36 in total ( Fig. 26F View FIGURE 26 ). Sensilla absent. Chelal fingers slightly curved in dorsal view; microsetae (chemosensory setae) on dorsum of chelal hand absent ( Fig. 26G View FIGURE 26 ).

Opisthosoma: generally typical, pleural membrane finely granulated. Tergites and sternites undivided; setae uniseriate and acuminate. Tergal chaetotaxy I–XII: 2: 2: 2: 2: 4: 4: 4: 4: 4: 2: T2T: 0. Sternal chaetotaxy III–XII: 10–12: 11–12: 8: 7–8: 8–9: 8–9: 7–8: 7: 0: 2. Anterior genital operculum with 10–11 setae, genital opening slit-like, with 11–13 marginal setae on each side, 34–35 in total ( Fig. 25D View FIGURE 25 ).

Legs ( Fig. 26H, I View FIGURE 26 ): generally typical, long and slender. Fine granulation present on anterodorsal faces of femur I, IV and patella IV. Femur of leg I 1.83–1.86 times longer than patella and with 1 lyrifissure at the base of femur; tarsus 2.50 times longer than tibia. Femoropatella of leg IV 3.88–4.13 times longer than deep; tibia 6.30–6.60 times longer than deep; with basal tactile setae on both tarsal segments: basitarsus 3.75–4.14 times longer than deep (TS= 0.34–0.37), telotarsus 13.00 times longer than deep and 2.60–2.69 times longer than basitarsus (TS= 0.22). Setae of leg I (trochanter to tibia) 3–4: 11–13: 8: 9, setae of leg IV (trochanter to basitarsus) 2: 3: 7–9: 10–12: 8–9. Arolium slightly shorter than the claws, not divided; claws simple.

Adult females (paratypes) ( Figs 24D View FIGURE 24 , 25E View FIGURE 25 ). Mostly same as males, but a little larger on average; chaetotaxy of coxae: P 3, I 3, II 3–4, III 5 , IV 5 ; with same tergal chaetotaxy as males; sternal chaetotaxy IV –XII: 13: 9–11: 7–8: 7–9: 7–9: 8: 7: 0: 2; anterior genital operculum with 10 setae, posterior margin with 10–12 marginal setae, 20–22 in total; leg IV with a long tactile seta on both tarsal segments: basitarsus 3.33–3.44 times longer than deep (TS= 0.32– 0.33), telotarsus 11.86–12.29 times longer than deep and 2.68–2.87 times longer than basitarsus (TS= 0.23–0.24) .

Dimensions (length/breadth or, in the case of the legs, length/depth in mm; ratios in parentheses). Males: body length 1.95–2.07. Pedipalps: trochanter 0.28–0.30/0.18–0.19 (1.47–1.67), femur 1.21–1.25/0.14 (8.64–8.93), patella 0.41–0.43/0.16–0.18 (2.39–2.56), chela 1.68–1.76/0.19–0.21 (8.38–8.84), hand 0.68–0.71/0.19–0.21 (3.38– 3.58), movable chelal finger length 0.99–1.05. Chelicera 0.68–0.71/0.27–0.29 (2.45–2.52), movable finger length 0.36–0.37. Carapace 0.56–0.60/0.55–0.59 (1.02). Leg I: trochanter 0.17–0.18/0.13–0.14 (1.29–1.31), femur 0.64– 0.67/0.08–0.09 (7.11–8.38), patella 0.35–0.36/0.07 (5.00–5.14), tibia 0.28/0.06 (4.67), tarsus 0.70/0.05–0.06 (11.67– 14.00). Leg IV: trochanter 0.23–0.24/0.16–0.17 (1.41–1.44), femoropatella 0.95–0.97/0.23–0.25 (3.88–4.13), tibia 0.63–0.66/0.10 (6.30–6.60), basitarsus 0.29–0.30/0.07–0.08 (3.75–4.14), telotarsus 0.78/0.06 (13.00).

Females: body length 1.93–2.23. Pedipalps: trochanter 0.33–0.34/0.18 (1.83–1.89), femur 1.31–1.34/0.16–0.17 (7.88–8.19), patella 0.46/0.19 (2.42), chela 1.79–1.81/0.24 (7.46–7.54), hand 0.72–0.73/0.24 (3.00–3.04), movable chelal finger length 1.05–1.08. Chelicera 0.76–0.77/0.33 (2.30–2.33), movable finger length 0.41–0.42. Carapace 0.61–0.68/0.63–0.65 (0.94–1.08). Leg I: trochanter 0.21–0.23/0.13–0.15 (1.53–1.62), femur 0.69/0.08–0.09 (7.67– 8.63), patella 0.36–0.37/0.08–0.09 (4.00–4.63), tibia 0.30–0.31/0.06 (5.00–5.17), tarsus 0.73–0.77/0.06 (12.17– 12.83). Leg IV: trochanter 0.24–0.25/0.16–0.17 (1.41–1.56), femoropatella 0.95–1.02/0.23–0.25 (4.08–4.13), tibia 0.63–0.67/0.10–0.11 (5.73–6.70), basitarsus 0.30–0.31/0.09 (3.33–3.44), telotarsus 0.83–0.86/0.07 (11.86–12.29).

Remarks. Lagynochthonius serratus sp. nov. is similar to L. xiaolinensis in having intercalary teeth on both chelal fingers and and equal number of setae on tergites I–III, but differs by having a thinner chela (e.g. chela 8.38– 8.84 times longer than broad vs. 7.00 times, hand 3.38–3.58 times longer than broad vs. 2.92 times; all in males), a smaller body (body length 1.95–2.07 vs. 2.18 mm in males), and the different positions of trichobothria t and it (t situated distal to it vs. basal to it).

Lagynochthonius serratus sp. nov. differs from L. bailongtanensis in the shape of the epistome (pointed and triangular vs. rounded and obtuse), the dentation of chelal fingers (with intercalary teeth on both chelal fingers vs. without intercalary teeth), and the number of setae on tergites I–IV (2 vs. 3–4).

Lagynochthonius serratus sp. nov. differs from L. laoxueyanensis by the presence of intercalary teeth on the chelal fingers, the number of setae on tergites III and IV (2 and 2, respectively vs. 4 and 4, respectively), and more slender chela (8.38–8.84 times longer than broad vs. 7.71 times in males) ( Li et al. 2019; Hou et al. 2022).

Distribution and habitat. This species is only known from the type locality, Unnamed Cave 3 ( Figs 1J View FIGURE 1 , 23A View FIGURE 23 ), which is located about 7 km southeast of Donggan Town (Malipo County). This limestone cave has one steep downward semicircular entrance (about 2 m high and 4 m wide), approximately 200 meters in length, and extends horizontally. The location is far from agricultural fields and residential areas, and the cave interior remains pristine. All of the specimens were collected under stones in the deep zone (temperature around 14°C, humidity over 85%).