Megachernes biyunensis, Xu & Gao & Zhang, 2022

Xu, Hongru, Gao, Zhizhong & Zhang, Feng, 2022, Two new species of the pseudoscorpion subfamily Lamprochernetinae Beier, 1932 from Guizhou, China (Pseudoscorpiones: Chernetidae), Zootaxa 5105 (4), pp. 581-592 : 587-591

Megachernes biyunensis sp. nov.

( Figs 5–7 )

http://zoobank.org/NomenclaturalActs/31be2f78-81ae-4bb7-aa18-076eb4722f89

Type material. Holotype ♀ (Ps.- MHBU-GZ19080501 ): China, Guizhou Province, Pan County, Biyun Park [25.775000°N, 104.638333°E], 5 August 2019, Zegang Feng & Zhaoyi Li leg. Paratypes: 1♀ (Ps.-SWUC-GZ19080502); 1♂ (Ps.- MHBU-GZ19080503 ), same data as holotype .

Etymology. The specific name refers to the type locality, Biyun Park, Pan County, Guizhou Province, China.

Diagnosis. This new species can be recognized by the following combined characters: subbasal transverse furrow on carapace located midway between posterior margin and central furrow, the trichobothria st situated closer to sb than to t, t situated midway between tip of finger and st.

Description. ( Fig. 5 ). Carapace, chelicera, tergites and sternites yellowish brown, pedipalps reddish brown, colour of chelal hand darker than that of trochanter, femur and patella; soft parts pale.

Carapace ( Fig. 6A ): evenly granulate; 1.07 (♂) 1.02 (♀) times longer than broad; eyes or eye-spots absent; with two distinct deep transverse furrows, subbasal transverse furrow situated midway between posterior margin and central furrow; posterior area with a small longitudinal furrow; with numerous setae including 16 (♂) 20 (♀) acuminate setae on anterior margin and 10 (♂) 14 (♀) on posterior margin.

Abdomen: all tergites and sternites narrowly divided. Tergal chaetotaxy (I–XI): ♂, 7–6: 10–8: 7–8: 7–8: 7–8: 9– 8: 9–9: 7–9: 8–6: 7–8: 6(2T)–7(2T); ♀, 7–7: 9–8: 8–8: 9–9: 9–8: 8–9: 8–9: 8–9: 9–7: 7–8: 7(2T)–7(2T); I–X tergites with paired dark spot. Sternal chaetotaxy (IV–XI): ♂, 4–5: 8–9: 13–11: 13–12: 10–11: 11–19: 11–9: 6(2T)–7(2T); ♀, 4–3: 10–12: 14–12: 14–14: 13–14: 12–14: 12–12: 6(2T)–6(2T); all sternal setae acuminate. Sternite II of ♀ with 33 setae arranged in a cluster ( Figs. 6E , 7F ).

Chelicerae ( Figs. 6D , 7D ): 7 setae on hand and 1 subdistal seta on movable finger; basal 5 setae finely dentate apically, ls, is and gs acuminate; fixed finger with 3 proximad-directed teeth; galea comprising 2 parts, first part with 5 branches and the second with 4 branches ( Fig. 7B ). Serrula exterior with 27 (♂, ♀) blades; rallum with 3 dentate blades, the apex of the first one slightly twisted and with anterior margin dentate, the other two blades apically dentate ( Fig. 7C ).

Pedipalp ( Figs 6B , 7A ): trochanter, femur, patella and chelal hand coarsely granulate, with acuminate setae; chelal fingers with short setae; trochanter 1.39 (♂) 1.67 (♀), femur 2.51 (♂) 2.31 (♀), patella 2.26 (♂) 2.23 (♀), chela (without pedicel) 3.02 (♂) 2.81 (♀), hand (without pedicel) 1.58 (♂) 1.51 (♀) times longer than board, movable finger 0.91 (♂) 0.96 (♀) times as long as hand (without pedicel). Fixed finger with 8 trichobothria, movable finger with 4 trichobothria ( Figs 6C , 7E ): eb situated basally; est situated closer to esb than to et; ib and esb situated sub-basally; it situated closer to tip of finger than to ib; st situated closer to sb than to t, sb situated closer to s t than to b, and t situated midway between tip of finger and st, fixed finger with 68 teeth, plus 13 prolateral accessory teeth, and 8 retrolateral accessory teeth; movable finger with 59 teeth, plus 12 prolateral accessory teeth, and 7 retrolateral accessory teeth. Venom apparatus only present in movable chelal finger, venom duct slender, nodus ramosus closer to t than to st.

Coxae: with numerous short setae over entire ventral surface and with long setae on posterior margin of coxae IV; posterior corner of coxae IV slightly protruding.

Genitalia ( Figs 6E , 7H ): ♂: typical of Chernetidae ; ♀: spermathecae T-shaped and with extremely elongated ends.

Leg I ( Figs 6F , 7G ): with long acuminate setae; proportions: trochanter 1.11 (♂, ♀), femur 1.50 (♂) 1.51 (♀), patella 2.60 (♂) 2.17 (♀), tibia3.71 (♂) 3.50 (♀), tarsus 4.41 (♂) 4.10 (♀) times longer than deep; claws simple, arolium shorter than claws.

Legs IV ( Figs 6H , 7I ): with long acuminate setae; proportions: trochanter 1.76 (♂) 1.44 (♀), femur + patella 3.96 (♂) 3.43 (♀), tibia 5.01 (♂) 4.71 (♀), tarsus 3.80 (♂) 3.83 (♀) times longer than deep; tactile seta in middle tarsus (TS=0.51 (♂) 0.54 (♀ )), length of tactile seta 2/3 of tarsus ( Fig. 7J ); claws simple, arolium shorter than claws.

Dimensions: (length/breadth or depth, in mm). ♀: Total length 4.22. Carapace 1.20/1.18. Pedipalps: trochanter 0.65/0.39, femur 0.99/0.43, patella 1.07/0.48, chela (with pedicel) 1.95, chela (without pedicel) 1.80, hand (without pedicel) length 0.97, movable finger length 0.94. Leg I: trochanter 0.21/0.18, femur 0.30/0.21, patella 0.39/0.18, tibia 0.49/0.14, tarsus 0.41/0.10. Leg IV: trochanter 0.36/0.25, femur + patella 0.79/0.23, tibia 0.80/0.17, tarsus 0.46/0.12, TS=0.54.

♂: Total length 4.10. Carapace 1.14/1.05. Pedipalps: trochanter 0.59/0.43, femur 1.05/0.41, patella 1.06/0.47, chela (with pedicel) 1.93/0.64, chela (without pedicel) length 1.87, hand (without pedicel) length 1.01, movable finger length 0.92. Leg I: trochanter 0.22/0.20, femur 0.36/0.24, patella 0.52/0.2, tibia 0.51/0.14, tarsus 0.48/0.11. Leg IV: trochanter 0.36/0.21, femur + patella 1.06/0.27, tibia 0.81/0.16, tarsus 0.57/0.15, TS=0.51.

Remarks. Based on the key of Megachernes species ( Mahrad & Reza 2017), this new species is similar to M. limatus Hoff & Parrack, 1958 from Oceania, but can be distinguished by the character of carapace (the subbasal transverse furrow situated closer to the posterior margin than to the median furrow in M. limatus , whereas the subbasal transverse furrow situated midway in M. biyunensis sp. nov.); and by the different trichobothrial pattern (st situated closer to sb than to t in M. biyunensis sp. nov., whereas st is closer to t than to sb in M. limatus ) ( Hoff & Parrack 1958).

It can be distinguished from M. himalayensis (Ellingsen, 1914) ( China (Fujian); India; Nepal) by the number of accessory teeth on the chelal fingers (movable finger with 12 accessory teeth and fixed finger with 13 accessory teeth in M. biyunensis sp. nov., whereas movable finger with 6 accessory teeth and fixed finger with 9 accessory teeth in M. himalayensis ); and by the stouter legs IV (tibia 5.01 (♂) 4.71 (♀) times longer than deep versus 6.20 (♀) in M. himalayensis ; tarsus 3.80 (♂) 3.83 (♀) times longer than deep vs 5.00 (♀) in M. himalayensis ) (Ellingsen 1914).

It can be distinguished from M. titanius Beier, 1951 ( China (Sichuan, Guangxi); Southeast Asia) by the trichobothrial pattern (st situated closer to sb than to t in M. biyunensis sp. nov., whereas st is closer to t than to sb in M. titanius ); and by the stouter legs IV (5.01 (♂) 4.71 (♀) times longer than wide versus 6.20 (♀) in M. titanius ; tarsus 3.80 (♂) 3.83 (♀) times longer than deep versus 5.20 (♀) in M. titanius ) ( Beier 1951).

It differs from M. tuberosus Mahnert, 2009 (Sichuan, China) by different the trichobothrial pattern (st situated closer to sb than to t in M. biyunensis sp. nov., whereas st is closer to t than to sb in M. tuberosus ); and by the morphology of the rallum (all three blades denticulate in M. biyunensis sp. nov., blades terminally scarcely dentate and apex of first blade slightly twisted in M. tuberosus ) ( Mahnert 2009).

It differs from M. vietnamensis Beier, 1967 ( China (Sichuan, Hubei, Yunnan); Vietnam) by the number of accessory teeth on the chelal fingers (movable finger with 12 accessory teeth and fixed finger with 13 accessory teeth in M. biyunensis sp. nov., whereas fixed finger with 21 accessory teeth in M. vietnamensis ); and by the cheliceral hand setae (basal 5 setae with terminally dentateand acuminate in M. biyunensis sp. nov., whereas all setae with acuminate in M. vietnamensis ) ( Beier 1967).

Distribution. Known only from the type locality, Guizhou, China.

Habitat. All specimens were collected in wet leaf litter under Populus (Salicaceae) .

Figures

FIGURE 5. Megachernes biyunensis sp. nov., A, Female habitus, dorsal view; B, Male habitus, dorsal view.

FIGURE 6. Megachernes biyunensis sp. nov., holotype female (A–F, H–I), paratype male (G): A, Carapace, dorsal view; B, Left pedipalp, dorsal view; C, Left chelal fingers, lateral view; D, Left chelicerae, dorsal view; E, Genital area of female, ventral view; F, Left leg I, lateral view; G, Genital area of male, ventral view; H, Left leg IV, lateral view; I, Tarsus of left leg IV, lateral view.

FIGURE 7. Megachernes biyunensis sp. nov., holotype female: A, Left pedipalp, ventral view; B, Galea; C, Rallum; D, Left chelicerae, dorsal view; E, Left chelal fingers, lateral view; F, Genital area of female; G, Left leg I, lateral view; H, Spermathecae; I, Left leg IV, lateral view; J, Tarsus of left leg IV, lateral view. Scale bars: 0.5 mm (G, I); 0.2 mm (A, D–F, J); 0.1 mm (B, C, H).