Lagynochthonius crassus, 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 : 6-11

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.7255273
persistent identifier	https://treatment.plazi.org/id/C14025A7-C5FE-498D-94CD-8526C33D7E94
taxon LSID	lsid:zoobank.org:act:C14025A7-C5FE-498D-94CD-8526C33D7E94
treatment provided by	Plazi
scientific name	Lagynochthonius crassus
status	sp. nov.

Treatment

Lagynochthonius crassus sp. nov. (DḆIJ伪oi)

Figs 2–5 View FIGURE 2 View FIGURE 3 View FIGURE 4 View FIGURE 5

Type material. Holotype ♂ (Ps.- MHBU-HBUARA#2021-28801 ): China, Yunnan Province, Maguan County, Miechang Township, Laomenzhai Village , cave without name ( Unnamed Cave 1), under stones and detritus in deep zone [22°53'31.35"N, 104°05'49.52"E], 1508 m a.s.l., 21 April 2021, Zegang Feng leg. GoogleMaps Paratypes: 1 ♂ (Ps.-MHBU-HBUARA#2021-28802), 2 ♀ (Ps.- MSWU-HBUARA#2021-28803 & HBUARA#2021-28804), all with the same data as the holotype GoogleMaps .

Etymology. The specific name is derived from the Latin word “ crassus ”, meaning thick, which refers to the character of a thickened chelal hand.

Diagnosis (♂ ♀). Moderately sized troglomorphic species with elongated appendages; carapace with a pair of anterior eyespots only; anterior margin of carapace thin, finely denticulated, epistome obtuse and small, round; posterior margin of carapace with 2 setae; tergites I–Ⅴ each with 4 setae. Pedipalps slender, femur 8.21–8.50 (♂), 7.50–7.87 (♀) times longer than broad; chela 7.00–7.14 (♂), 6.40–6.46 (♀) times longer than broad; chelal hand strong and thick; both chelal fingers without intercalary teeth but fixed chelal finger with a modified accessory tooth (td) on dorso-antiaxial face; chemosensory setae (sc) present on dorsum of chelal hand; sensilla present.

Description. Males (holotype and paratype) ( Figs 2D View FIGURE 2 , 3A View FIGURE 3 , 4A–D View FIGURE 4 , 5 View FIGURE 5 ).

Colour ( Figs 2D View FIGURE 2 , 3A View FIGURE 3 , 4A–D View FIGURE 4 ): generally pale yellow, chelicerae, pedipalps and tergites slightly darker, soft parts pale.

Cephalothorax ( Figs 4B View FIGURE 4 , 5A View FIGURE 5 ): carapace 0.90–0.93 times longer than broad, gently narrowed posteriorly; surface smooth, without furrows; anterior eyes reduced into eyespots, posterior eyes reduced completely; anterior margin slightly serrate; epistome obtuse and small, round, with 2 setae flanking base; with 18 setae arranged s4s: 4: 4: 2: 2, preocular setae absent in one male, 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 4–5, IV 5; manducatory process with two acuminate distal setae, anterior seta more than 1/2 length of medial seta; apex of coxa I with small, rounded anteromedial process; coxae II with 8–9 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. 5C View FIGURE 5 ); intercoxal tubercle absent; without sub-oral seta.

Chelicera ( Figs 4C View FIGURE 4 , 5B View FIGURE 5 ): large, about as long as carapace, 2.33–2.35 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 dorsal side. Both fingers well provided with teeth, fixed finger with 13–15 teeth, distal one largest; movable finger with 11 retrorse contiguous small teeth; galea represented by a very slight bump on movable finger ( Fig. 5B View FIGURE 5 ). Serrula exterior with 21–22 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. 5D View FIGURE 5 ).

Pedipalp ( Figs 4A View FIGURE 4 , 5E–G View FIGURE 5 ): long and slender, trochanter 1.94–2.20, femur 8.21–8.50, patella 2.69–2.71, chela 7.00–7.14, hand 2.73–2.82 times longer than broad; femur 2.59–2.67 times longer than patella; movable chelal finger 1.53–1.57 times longer than hand and 0.61 times longer than chela. Setae generally long and acuminate; 1 distal lyrifissure present on patella ( Fig. 5E View FIGURE 5 ). Chelal palm gradually constricted towards fingers, apodeme complex of movable chelal finger strongly sclerotized, with weak granulation dorsally at base of fixed chelal finger. 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 nearly 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 at same level as est; t situated distal to it ( Fig. 5F View FIGURE 5 ). A tiny antiaxial lyrifissure present at base of fixed chelal finger (situated distal to ist). Both chelal fingers with a row of teeth, homodentate, 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 30–31 macrodenticles, slightly retrorse and pointed, plus a modified accessory tooth on dorso-antiaxial face (td, slightly distal to dx); movable chelal finger with 15 macrodenticles (slightly smaller than teeth on fixed chelal finger), slightly retrorse and pointed, plus 13–15 small, rounded and contiguous basal teeth, 28–30 in total ( Fig. 5F View FIGURE 5 ). Fixed chelal finger with sensilla af 1–2 close together, near tip; movable chelal finger with 4 sensilla: am 1–2 near tip, p 1 slightly distad of sb and very close to chelal teeth, p 2 slightly distad of p 1 ( Fig. 5F View FIGURE 5 ). Chelal fingers slightly curved in dorsal view; microsetae (chemosensory setae) present on dorsum of chelal hand ( Fig. 5G View FIGURE 5 ).

Opisthosoma: generally typical, pleural membrane finely granulated. Tergites and sternites undivided; setae uniseriate and acuminate. Tergal chaetotaxy I–XII: 4: 4: 4: 4: 4: 4: 5: 5: 5–6: 4: T2T: 0; tergites VII–IX each with an unpaired median seta. Sternal chaetotaxy III–XII: 9–11: 10–12: 8–9: 8–10: 8–9: 9–10: 9–11: 7–8: 0: 2. Anterior genital operculum with 10–11 setae, genital opening slit-like, with 14–16 marginal setae on each side, 40–41 in total ( Fig. 4D View FIGURE 4 ).

Legs ( Fig. 5H, I View FIGURE 5 ): generally typical, long and slender. Fine granulation present on anterodorsal faces of femur I, IV and patella I, IV. Femur of leg I 1.83–1.84 times longer than patella and with 1 lyrifissure at the base of femur; tarsus 2.28–2.29 times longer than tibia. Femoropatella of leg IV 4.26–5.30 times longer than deep; tibia 6.60–7.44 times longer than deep; with basal tactile setae on both tarsal segments: basitarsus 4.00–4.25 times longer than deep (TS= 0.34–0.35), telotarsus 14.67–17.40 times longer than deep and 2.56–2.75 times longer than basitarsus (TS= 0.34–0.36). Setae of leg I (trochanter to tibia) 3: 11: 8–10: 10–11, setae of leg IV (trochanter to basitarsus) 2–3: 4: 4: 11: 10–11. Arolium slightly shorter than the claws, not divided; claws simple.

Adult females (paratypes) ( Figs 2E View FIGURE 2 , 3B View FIGURE 3 , 4E View FIGURE 4 ). Mostly same as males, but a little larger; preocular setae absent in one female; chaetotaxy of coxae: P 3, I 3, II 4, III 5 , IV 5 ; tergal chaetotaxy I–XII: 4: 4: 4: 4: 4: 4–5: 5: 6: 5: 4: T2 T: 0; sternal chaetotaxy IV –XII: 8–11: 9–11: 9–10: 9–11: 10: 11: 7–8: 0: 2; anterior genital operculum with 10 setae, posterior margin with 8–10 marginal setae, 18–20 in total; leg IV with a long tactile seta on both tarsal segments: basitarsus 4.25 times longer than deep (TS= 0.29–0.35), telotarsus 15.00–16.60 times longer than deep and 2.44–2.65 times longer than basitarsus (TS= 0.31–0.36) .

Dimensions (length/breadth or, in the case of the legs, length/depth in mm; ratios in parentheses). Males: body length 1.84–1.94. Pedipalps: trochanter 0.31–0.33/0.15–0.16 (1.94–2.20), femur 1.15–1.19/0.14 (8.21–8.50), patella 0.43–0.46/0.16–0.17 (2.69–2.71), chela 1.54–1.57/0.22 (7.00–7.14), hand 0.60–0.62/0.22 (2.73–2.82), movable chelal finger length 0.94–0.95. Chelicera 0.61–0.63/0.26–0.27 (2.33–2.35), movable finger length 0.34–0.35. Carapace 0.54/0.58–0.60 (0.90–0.93). Leg I: trochanter 0.18–0.21/0.11–0.13 (1.62–1.64), femur 0.66–0.68/0.07– 0.08 (8.50–9.43), patella 0.36–0.37/0.06–0.07 (5.29–6.00), tibia 0.31–0.32/0.07 (4.43–4.57), tarsus 0.71–0.73/0.06 (11.83–12.17). Leg IV: trochanter 0.22–0.26/0.16 (1.38–1.63), femoropatella 0.98–1.06/0.20–0.23 (4.26–5.30), tibia 0.66–0.67/0.09–0.10 (6.60–7.44), basitarsus 0.32–0.34/0.08 (4.00–4.25), telotarsus 0.87–0.88/0.05–0.06 (14.67–17.40).

Females: body length 1.95–2.01. Pedipalps: trochanter 0.31–0.32/0.16–0.17 (1.82–2.20), femur 1.18– 1.20/0.15–0.16 (7.50–7.87), patella 0.42–0.47/0.17–0.19 (2.47), chela 1.55–1.60/0.24–0.25 (6.40–6.46), hand 0.61– 0.64/0.24–0.25 (2.44–2.67), movable chelal finger length 0.96–0.98. Chelicera 0.62–0.64/0.27–0.30 (2.13–2.30), movable finger length 0.34–0.35.Carapace 0.56–0.57/0.58–0.60 (0.95–0.97).Leg I: trochanter0.20–0.21/0.12 (1.67– 1.75), femur 0.69–0.71/0.07–0.08 (8.63–10.14), patella 0.35–0.37/0.07 (5.00–5.29), tibia 0.34/0.06–0.07 (4.86– 5.67), tarsus 0.72/0.05–0.06 (12.00–14.40). Leg IV: trochanter 0.24–0.25/0.14–0.16 (1.50–1.79), femoropatella 0.99–1.07/0.22–0.24 (4.46–4.50), tibia 0.65–0.69/0.10 (6.50–6.90), basitarsus 0.34/0.08 (4.25), telotarsus 0.83– 0.90/0.05–0.06 (15.00–16.60).

Remarks. Lagynochthonius crassus sp. nov. can be distinguished from L. bailongtanensis and L. laoxueyanensis , as well as the 10 new troglomorphic Lagynochthonius species described below, by the presence of a pair of eyespots (not corneate eyes) and a pair of thickened chelal hands (e.g. chela 7.00–7.14 times longer than broad, hand 2.73– 2.82 times longer than broad, all in males).

The new species is similar to another troglomorphic species from continental Asia: L. fragilis Judson, 2007 ( Vietnam) , by having a pair of eyespots, the same chaetotaxy of carapace (s4s-4-4-2-2) and the presence of same number of setae on tergites I–V, but differs in having more slender pedipalps (e.g. femur 7.50–7.87 times longer than broad vs. 6.3–6.6 times in females, chela length 1.55–1.60 vs. 1.19–1.32 mm in females), the presence of more chelal teeth, and a larger body size (body length 1.95–2.01 vs. 1.60 mm in females) ( Judson 2007; Li et al. 2019; Hou et al. 2022).

Distribution and habitat. This species is only known from the type locality, Unnamed Cave 1 ( Figs 1L View FIGURE 1 , 2A–C View FIGURE 2 ), which is located about 1 km northwest of Laomenzhai Village (Maguan County). This limestone cave has one triangular entrance (about 1.5 meters high and 1 meter wide), approximately 200 meters in length. The interior space is large and extends horizontally. All of the specimens were collected under stones and detritus in the deep zone (temperature around 14°C, humidity over 85%).