Tyrannochthonius zhai, Gao & Zhang & Chen, 2020

Gao, Zhizhong, Zhang, Feng & Chen, Huiming, 2020, Two new cave-dwelling species of Tyrannochthonius Chamberlin 1929 (Pseudoscorpiones: Chthoniidae) from the Guizhou karst, China, Zootaxa 4853 (4), pp. 572-580 : 576-579

Tyrannochthonius zhai sp. nov.

Figs. 4–6

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Type material. Holotype female (Ps.- MHBU-GZ11060701 ): China, Guizhou Province, Xingyi City, Dushan Town, Jiangjia Cave , dark zone, [25°18'096”N, 105°36'007”E], 7 June 2011, Zuwei Zha leg.

Etymology. The specific epithet is a patronym in honor of Mr. Zuwei Zha, who collected the specimen.

Diagnosis. Small sized troglomorphic species (Body length 1.40); carapace without eyes or eyespots, both anterior and posterior margin with 4 setae respectively, without epistome; tergites I–III with 4 setae; chelal fixed finger with intercalary teeth, movable finger with numerous pointed retrorse and contiguous teeth; no chemosensory setae on dorsum of chelal hand.

Description. Adult female ( Fig. 4 ).

Colour: Generally pale yellow, carapace, chelicera, pedipalps and tergites slightly darker, soft parts pale.

Chelicera ( Figs 5C , 6B ): Five setae on hand, all setae acuminate; movable finger with one medial seta; fixed finger and movable finger with about 10 teeth; galea represented by a very slight bump on movable finger; rallum ( Fig. 6C ) with 6 blades, distal one longer than others, all blades bipinnate.

Pedipalp ( Figs 5A , 6 E–H): All setae acuminate; femur 6.00, patella 2.20, chela 6.37, hand 1.89 times longer than deep; movable finger 2.14 times longer than hand, without large basal apodeme, only slightly sclerotized section is present. Femur without tactile setae. 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 finger, very close to chelal teeth; xs situated distal to et, microsetae (chemosensory setae) absent on both palpal fingers; sb situated slightly closer to b than to st; b and t situated subdistally, t situated at same level as est; b situated basal to est; microsetae (chemosensory setae) absent on both palpal fingers. Sensilla absent. Chelal teeth ( Fig. 6H ) heterodentate: fixed finger with 22 large, slightly retrorse, well-spaced teeth, plus 15 small intercalary teeth; movable finger with 26 middle size retrorse, pointed and continuous teeth, without intercalary teeth.

Cephalothorax ( Figs 5B , 6A ): Carapace as broad as long; anterior margin smooth; lateral margins constricted posteriorly; without any traces of eyes; without epistome; with 16 setae arranged 4: 4: 4: 2: 2; without furrows. Chaetotaxy of coxae: 4: 3: 4: 4; manducatory process with two acuminate distal setae, anterior seta less than 1/2 length of medial seta; coxae II with 5–6 terminally indented coxal spines on each side, set in oblique row; intercoxal tubercle absent; without sub-oral seta.

Abdomen: Pleural membrane papillostriate. Tergites and sternites undivided; setae uniseriate and acuminate. Each tergite with four setae except last one which has two only. Sternal chaetotaxy V–XI: 8: 8: 10: 9: 10: 10: 8. Anterior genital operculum with 10 setae plus 8 setae on posterior margin.

Legs ( Figs 6 I–J): Typical. Femur + patella of leg IV 2.90 times longer than deep; arolium slightly shorter than the claws, not divided; claws simple.

Measurements: (length/breadth or depth in mm, ratios in parentheses). Female holotype: Body length 1.40. Pedipalps: trochanter 0.24/0.14 (1.71), femur 0.84/0.14 (6.00), patella 0.33/0.15 (2.20), chela 1.21/0.19 (6.37), hand length 0.36/0.16 (1.89), movable finger length 0.77. Carapace 0.48/0.48 (1.00). Leg I: trochanter 0.15/0.11 (1.36), femur 0.44/0.07 (6.29), patella 0.24/0.06 (4.00), tibia 0.22/0.06 (3.67), tarsus 0.46/0.05 (9.20). Leg IV: trochanter 0.20/0.11 (1.82), femur + patella 0.61/0.21 (2.90), tibia 0.45/0.08 (5.63), basitarsus 0.19/0.06 (3.17), telotarsus 0.46/0.05 (9.20).

Remarks. Of the Chinese species, T. zhai has the same tergal chaetotaxy on tergites I–II as T. akaelus , T. harveyi and T. ganshuanensis (only 2 setae), but can be distinguished from T. akaelus and T. ganshuanensis by the number of setae on the anterior margin of carapace ( T. zhai with 4, T. akaelus and T. ganshuanensis with 6; Mahnert (2009)) and by the stouter pedipalps (e.g. femur 6.00 times vs. 6.60 times; Mahnert (2009)). T. zhai differs from T. akaelus by the number of chelal teeth fixed finger with 22 large, slightly retrorse, well-spaced teeth, plus 15 small intercalary teeth in T. zhai but 43 pointed teeth of equal length in T. akaelus ; movable finger with 26 middle-sized retrorse, pointed and continuous teeth in T. zhai but with 37 marginal teeth and 8 intercalary teeth in T. akaelus ). It differs from T. harveyi by having only 2 setae on the posterior margin of the carapace (4 in T. harveyi ), and the fixed chelal finger with 15 small intercalary teeth in T. zhai , whereas intercalary teeth are absent in T. harveyi .

Figures

FIGURE 4. Tyrannochthonius zhai sp. nov., holotype female, habitus, dorsal view.

FIGURE 5. Tyrannochthonius zhai sp. nov., holotype female: A. Chelal fingers (lateral view); B. Carapace (dorsal view); C. Left chelicerae (dorsal view); D. Genital (ventral view). Scale bars: 0.1 mm.

FIGURE 6. Tyrannochthonius zhai sp. nov., holotype female: A. Carapace (dorsal view); B. Left chelicerae (dorsal view); C. Rallum; D. Coxal spines on coxae II (ventral view); E. Finger tips of chela (lateral view); F. Left pedipalp (minus chela, dorsal view); G. Left chela (lateral view); H. Chelal fingers (lateral view, showing the teeth); I. Leg I (lateral view); J. Leg IV (lateral view). Scale bars: 0.10 mm (C–E); 0.25 mm (A–B, F–J).