Lagynochthonius xinjiaoensis Hou & Gao & Zhang 2022, sp. nov.
Creators: name: Hou, Yanmeng
name: Gao, Zhizhong
name: Zhang, Feng
Publisher: name: Zenodo
Year: 2022
Subjects: Biodiversity
Taxonomy
Animalia
Arthropoda
Arachnida
Pseudoscorpiones
Chthoniidae
Lagynochthonius
Lagynochthonius xinjiaoensis

description: Lagynochthonius xinjiaoensis sp. nov. (ṀfflIJ伪oi)
Figs 38–41
Type material. Holotype ♂ (Ps.- MHBU-HBUARA#2021-43001): China, Yunnan Province, Fuyuan County, Laochang Town, Xinjiao Village, Yueliang Cave, under a stone in deep zone [25°12′47.73″N, 104°29′3.26″E], 2017 m a.s.l., 8 October 2021, Zegang Feng, Yanmeng Hou, Lu Zhang & Liu Fu leg.
Etymology. Named after the village of Xinjiao, near the type locality.
Diagnosis (♂). Moderately sized troglomorphic species with elongated appendages; carapace without eyes or eyespots; anterior margin of carapace thin, finely denticulated, with 4 setae (including preocular setae) only, epistome pointed, small and triangular, without flanking basal setae; posterior margin of carapace with 2 setae; tergites I–IV each with 2 setae. Pedipalps slender, femur 8.59 times longer than broad; chela robust, 7.03 times longer than broad; both chelal fingers without intercalary teeth; fixed chelal finger with a row of teeth that are distinctly larger than the teeth on the movable chelal finger, pointed and slightly retrorse and without a modified accessory tooth (td) on dorso-antiaxial face; chemosensory setae (sc) present on dorsum of chelal hand; sensilla absent.
Description. Male (holotype), female unknown (Figs 38E, 39–41).
Colour (Figs 38E, 39, 40): generally pale yellow, chelicerae, pedipalps and tergites slightly darker, soft parts pale.
Cephalothorax (Figs 40B, 41A): carapace 0.98 times longer than broad, squarish, gently narrowed posteriorly; surface smooth, without furrows; no traces of eyes; anterior margin slightly serrate; epistome pointed and small, triangular; with 16 setae arranged s2s: 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 setae of ocular row, second pair situated lateral to the sole pair of setae of posterior row. Chaetotaxy of coxae: P 3, I 2, 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 10–11 terminally indented coxal spines on each side, set as an oblique row, longer spines present in the middle of the row, becoming shorter distally and proximally and incised for about half their length (Fig. 41C); intercoxal tubercle absent; without sub-oral seta.
Chelicera (Figs 40C, 41B): large, about as long as carapace, 2.45 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 22 teeth, distal one largest; movable finger with 16 retrorse contiguous small teeth; galea represented by a very slight bump on movable finger (Fig. 41B). Serrula exterior with 27 and serrula interior with 14 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. 41D).
Pedipalp (Figs 40A, 41E–G): long and slender, trochanter 1.90, femur 8.59, patella 2.22, chela 7.03, hand 2.62 times longer than broad; femur 2.86 times longer than patella; movable chelal finger 1.71 times longer than hand and 0.64 times longer than chela. Setae generally long and acuminate; 1 distal lyrifissure present on patella (Fig. 41E). Chelal palm gradually constricted towards fingers, apodeme complex of movable chelal finger 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 slightly closer to b than to st; b and t situated subdistally, b situated at same level as est; t distal to it (Fig. 41F). 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 35 macrodenticles, pointed and gently retrorse, without a modified accessory tooth (td) on dorso-antiaxial face; movable chelal finger with 28 macrodenticles (markedly smaller than the teeth on fixed chelal finger), pointed and gently retrorse, plus 4 vestigial, rounded and contiguous basal teeth, 33 in total (Fig. 5F). Sensilla absent. Chelal fingers slightly curved in dorsal view; microsetae (chemosensory setae) present on dorsum of chelal hand (Fig. 41G).
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: 5: 2: T2T: 0, tergites IX with an unpaired median seta. Sternal chaetotaxy III–XII: 7: 10: 10: 9: 9: 9: 9: 7: 0: 2. Anterior genital operculum with 12 setae, genital opening slit-like, with 11–12 marginal setae on each side, 35 in total (Fig. 40D).
Legs (Fig. 41H, I): generally typical, long and slender. Fine granulation present on anterodorsal faces of femur I, IV and patella IV. Femur of leg I 1.89 times longer than patella and with 1 lyrifissure at the base of femur; tarsus 2.69 times longer than tibia. Femoropatella of leg IV 4.85 times longer than deep; tibia 7.17 times longer than deep; with basal tactile setae on both tarsal segments: basitarsus 4.10 times longer than deep (TS= 0.24), telotarsus 15.14 times longer than deep and 2.59 times longer than basitarsus (TS= 0.33). Setae of leg I (trochanter to tibia) 4: 12: 11: 11, setae of leg IV (trochanter to basitarsus) 2: 3: 6: 11: 13. Arolium slightly shorter than the claws, not divided; claws simple.
Dimensions (length/breadth or, in the case of the legs, length/depth in mm; ratios in parentheses). Male: body length 2.15. Pedipalps: trochanter 0.40/0.21 (1.90), femur 1.46/0.17 (8.59), patella 0.51/0.23 (2.22), chela 2.04/0.29 (7.03), hand 0.76/0.29 (2.62), movable chelal finger length 1.30. Chelicera 0.76/0.31 (2.45), movable finger length 0.41. Carapace 0.65/0.66 (0.98). Leg I: trochanter 0.24/0.16 (1.50), femur 0.85/0.10 (8.50), patella 0.45/0.09 (5.00), tibia 0.35/0.06 (5.83), tarsus 0.94/0.07 (13.43). Leg IV: trochanter 0.33/0.18 (1.83), femoropatella 1.26/0.26 (4.85), tibia 0.86/0.12 (7.17), basitarsus 0.41/0.10 (4.10), telotarsus 1.06/0.07 (15.14).
Remarks. Female unknown. Lagynochthonius xinjiaoensis sp. nov. is most similar to L. magnidentatus sp. nov. in having only 2 anterolateral setae on the carapace (except preocular setae), an equal number of setae on tergites I–IV, and a similarly-shaped chelal hand, but differs by the presence of a larger chela (e.g. chela 7.03 times as long as broad vs. 6.44–6.46 times, chela length 2.04 vs. 1.55–1.61 mm, movable chelal finger length 1.30 vs. 0.96–0.99 mm; all in males), a different epistome shape (pointed and triangular vs. rounded and obtuse), and the position of trichobothrium sb (sb 1.07 times as far from b as from st vs. 1.28–1.30 times as far from b as from st).
The discovery of two new species (L. magnidentatus sp. nov. and L. xinjiaoensis sp. nov.) that lack the anteriormedian setae on the carapace is significant. Indeed, there is no other chthoniid that lacks these two setae.Unfortunately, apart from this character, we failed to find any other evidence not belonging to the genus Lagynochthonius, therefore, it is inappropriate to name a new genus.
Distribution and habitat. This species is known only from the type locality, Yueliang Cave (Figs 1F, 38A–D), which is located near the top of a mountain and is about 0.5 km north of Xinjiao Village (Fuyuan County). This limestone cave has one small and oval entrance (about 1 m high and 2 m wide) and another large circular entrance directly above the cave. The total length of the cave is unknown. There is a certain vertical drop in the cave, which requires a 7-8 m descent to a deep pit and a 10 m ascent along a tunnel to reach the depth of the cave. The specimen was collected under a stone adjacent to a stalactite in the deep zone (temperature around 14°C, humidity is approximate 90%).
description: Published as part of 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), pp. 1-65 in Zootaxa 5198 (1) on pages 51-56, DOI: 10.11646/zootaxa.5198.1.1, http://zenodo.org/record/7251602