Research Article |
Corresponding author: Yun-Chun Li ( liyunchun2260@126.com ) Academic editor: Jana Christophoryová
© 2022 Yun-Chun Li, Ai-Min Shi.
This is an open access article distributed under the terms of the Creative Commons Attribution License (CC BY 4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
Citation:
Li Y-C, Shi A-M (2022) Cave-inhabiting Cheliferidae (Arachnida, Pseudoscorpiones) from Thailand, with description of four new species of Metachelifer Redikorzev. ZooKeys 1103: 171-188. https://doi.org/10.3897/zookeys.1103.78808
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Four new species of the genus Metachelifer Redikorzev, 1938 are described from caves in the provinces of Tak (M. takensis sp. nov. and M. thailandicus sp. nov.), Chiangmai (M. mahnerti sp. nov.), and Nakhon Ratchasima (M. cheni sp. nov.). An identification key is provided to all known world representatives of the genus Metachelifer.
Identification key, pseudoscorpion, Southeast Asia, taxonomy, troglobiont
The pseudoscorpion genus Metachelifer Redikorzev, 1938 belongs to the family Cheliferidae Risso, 1827 and the subfamily Cheliferinae. This subfamily contains 57 genera that are mostly distributed in Africa, southern Europe, central Asia, North America, and South America (
Males of the genus Metachelifer can be characterized by the carapace surface with tubercles; coxa IV with an anterolateral process and coxal sac; sternite III uplifted laterally and extending to short thorns; leg I tarsus lateral claw shorter than mesal one; subterminal seta simple (
The specimens were examined with a Leica M205FA stereomicroscope and an Olympus CX31 compound microscope. The specimens are preserved in 75% ethanol. They were cleared in lactic acid for 12–24 h at room temperature and, after the study, washed in distilled water and returned to alcohol. Photographs were taken using a Canon 6D Mark II camera fitted with a Laowa 25 mm f/2.8 2.5–5 × and 100 mm F2.8 2.0 × ultra macro lens. The final high depth of field images were stacked from 30 to 80 single photos using Helicon Focus 7.6.1., and CorelDRAW 2018 and SAI 2 software were used to draw the figures. The type specimens of the new species are deposited in the collection of the Museum of China West Normal University (MCWNU; Sichuan, China) and Muséum national d’Histoire naturelle (
Pseudoscorpion terminology and measurements mostly follow
Cheliferidae Risso, 1827
Metachelifer Redikorzev, 1938: 108.
Metachelifer duboscqui Redikorzev, 1938, by monotypy.
1 | Carapace slightly broader than long | 2 |
– | Carapace slightly longer than broad | 3 |
2 | Tergite XI with two tactile setae; pedipalpal femur 4.49 × longer than broad (1.08/0.24 mm) | M. macrotuberculatus (Krumpál, 1987) |
– | Tergite XI without tactile setae; pedipalpal femur 5.22 × longer than broad (1.41/0.27 mm) | M. nepalensis (Beier, 1974) |
3 | Fixed and movable chelal fingers with at least 57 teeth; trichobothrium st distinctly closer to sb than to t | 4 |
– | Fixed and movable chelal fingers with 35 teeth; trichobothrium st midway between sb and t | M. duboscqui Redikorzev, 1938 |
4 | Tergite XI with two tactile setae | 5 |
– | Tergite XI without tactile setae | M. mahnerti Li & Shi, sp. nov. |
5 | Venom ducts very short, not extending past et (Figs |
6 |
– | Venom ducts long, extending past et (Fig. |
M. takensis Li & Shi, sp. nov. |
6 | Carapace with 100–101 setae; coxal sac occupying 1/2 of coxal length; anterior genital operculum of female with tubular setae | M. cheni Li & Shi, sp. nov. |
– | Carapace with 86–88 setae; coxal sac occupying only 2/5 of coxal length; anterior genital operculum of female without tubular setae | M. thailandicus Li & Shi, sp. nov. |
Holotype
male: Thailand, Nakhon Ratchasima Province, Pak Chong district, Musee Village, Wat Dewaroop Song Cave 3, 14°33.714'N, 101°24.049'E, 402 m a.s.l., 24 Oct. 2014, Yun-Chun Li and Zhi-Gang Chen leg., in MCWNU (Ms20141014-01). Paratypes: 3 males, 7 females, 7 tritonymphs, collected with the holotype, in MCWNU (Ms20141014-01); 1 male, 2 females, 1 tritonymph, collected with the holotype, in
Troglobiont habitus. This new species is distinguished from other members of the genus Metachelifer by the following combination of characters: carapace with 100–101 setae; coxal sac occupying 1/2 of coxal length; male anterior genital operculum without tubular setae; female anterior genital operculum with 31 setae (24 of them tubular) and two lyrifissures; posterior operculum with 12 setae, without lyrifissures.
Latinized adjective, derived from the last name of the collector, Zhi-Gang Chen.
Adult male (Fig.
Carapace
(Fig.
Metachelifer cheni sp. nov., holotype male (A–J) and paratype female (K) A carapace B left chelicera C right leg I, lateral view D right leg IV, lateral view E coxa IV, ventral view F palp (minus chela) G chela, retrolateral view H chela, dorsal view I male genital area J male genitalia, dorsal view K female genital area. Scale bars: 0.50 mm.
Adult female (Fig.
Carapace
: slightly longer than broad (1.12–1.13 ×), anterior margin with 6 setae, posterior margin with 12–13 setae. Well-developed paramedian impressions behind eyes as in male. Coxae: pedipalpal coxa with 14 setae, coxa I 12–15, II 19–21, III 22–25, IV 33–38. Chelicera: 1.98–2.01 × longer than broad, movable finger with 3 teeth. Pedipalp: trochanter 2.07–2.09 × longer than broad, femur 6.46–6.48 × longer than broad, patella 5.11–5.15 × longer than broad, femur 1.12–1.13 × longer than patella. Chela with pedicel 5.53–5.56 × longer than broad, hand with pedicel 2.82–2.84 × longer than broad; movable finger 1.02–1.03 × longer than hand with pedicel length. Opisthosoma: tergal chaetotaxy (I–XI): 11: 14: 13: 14: 16: 18: 18: 18: 18: 16: 9; sternal chaetotaxy (IV–XI): 2 × 1 + 9: 15: 12: 13: 11: 14: 14: 7; anal cone with 2 dorsal and 2 ventral setae. Anterior genital operculum with 31 setae (24 of them tubular) and 2 lyrifissures; posterior operculum with 12 setae, without lyrifissures (Fig.
(length/width or, in the case of the legs, length/depth in mm). Males (females in parentheses): body length 2.52–2.74 (3.70–3.92). Carapace 0.96–0.98/0.84–0.86 (1.05–1.09/0.94–0.96). Pedipalp: trochanter 0.50–0.52/0.26–0.27 (0.58–0.60/0.28–0.29), femur 1.44–1.46/0.22–0.23 (1.55–1.58/0.24–0.25), patella 1.27–1.29/0.24–0.25 (1.38–1.41/0.27–0.28), hand with pedicel 0.95–0.97/0.31–0.32 (1.07–1.10/0.38–0.39), length of movable chelal finger 0.98–0.99 (1.09–1.11), chela 1.89–1.93/0.31–0.32 (2.10–2.13/0.38–0.39). Chelicera: 0.24–0.26/0.13–0.14 (0.26–0.28/0.14–0.15). Leg I: trochanter 0.21–0.22/0.17–0.18 (0.25–0.26/0.18–0.19), femur 0.30–0.32/0.17–0.18 (0.35–0.37/0.17–0.18), patella 0.59–0.61/0.14–0.15 (0.61–0.65/0.15–0.16), tibia 0.59–0.60/0.10–0.11 (0.65–0.66/0.10–0.11), tarsus 0.46–0.49/0.09–0.10 (0.65–0.67/0.10–0.11). Leg IV: trochanter 0.33–0.34/0.17–0.18 (0.35–0.37/0.23–0.24), femoropatella 1.08–1.10/0.22–0.23 (1.06–1.09/0.25–0.26), tibia 0.92–0.95/0.10–0.11 (0.98–0.99/0.12–0.13), tarsus 0.64–0.65/0.08–0.09 (0.65–0.68/0.09–0.10).
Thailand (Nakhon Ratchasima).
Holotype
male: Thailand, Chiangmai Province, Chom Thong district, Ban Luang Village, Tham Borichinda Cave, 18°29'53.01"N, 98°40'49.97"E, 379 m a.s.l., 15 Oct. 2014, Yun-Chun Li and Zhi-Gang Chen leg., in MCWNU (Ms20141015-01). Paratypes: 1 male, 7 females, 1 tritonymph, collected with the holotype in MCWNU (Ms20141015-01); 1 male, 1 female, collected with the holotype, in
Troglobiont habitus. This new species is distinguished from other members of the genus Metachelifer by the following combination of characters: anterior margin of carapace with 4 denticuloclavate setae and 91–93 setae; tergite XI without tactile setae; male anterior genital operculum with 68–70 setae (11–16 of them tubular); female anterior genital operculum without tubular setae, posterior operculum with 8 lyrifissures; and female body very large, 4.76–4.85 mm.
The new species is named in honour of the late Volker Mahnert (Muséum d’histoire naturelle, Genève, Switzerland).
Adult male (Fig.
Carapace
(Fig.
Metachelifer mahnerti sp. nov., holotype male (A–I) and paratype female (J) A carapace B left chelicera C rallum of left chelicera D detail on tarsus I, lateral view E coxa IV, ventral view F palp (minus chela) G chela, retrolateral view H chela, dorsal view I male genital area J female genital area. Scale bars: 0.50 mm.
Adult female (Fig.
Carapace
: slightly longer than broad (1.00–1.01 ×), anterior margin with 4 setae, posterior margin with 12–13 setae. Well-developed paramedian impressions behind eyes like in male. Coxae: pedipalpal coxa with 9 (non-denticulate) + 4–6 (denticulate) setae, coxa I 20–21, II 18, III 17–19, IV 52–55. Chelicera: 1.94–1.97 × longer than broad, movable finger with 2–3 teeth. Pedipalp: trochanter 2.03–2.05 × longer than broad, femur 6.18–6.21 × longer than broad, patella 4.81–4.86 × longer than broad, femur 1.16–1.17 × longer than patella. Chela with pedicel 5.10–5.11 × longer than broad, hand with pedicel 2.51–2.53 × longer than broad; movable finger 1.01–1.02 × longer than hand with pedicel length. Opisthosoma: tergal chaetotaxy (I–XI): 15: 18: 20: 24: 23: 25: 25: 26: 23: 16: 15; sternal chaetotaxy (IV–XI): 2 × 1 + 11: 15: 15: 15: 13: 14: 13: 10; anal cone with 2 dorsal and 2 ventral setae. Anterior genital operculum with 28 setae (without tubular setae) and 2 lyrifissures; posterior operculum with 13 setae, 8 lyrifissures (Fig.
(length/width or, in the case of the legs, length/depth in mm). Males (females in parentheses): body length 3.23–3.35 (4.76–4.85). Carapace 1.05–1.06/1.00–1.01 (1.21–1.23/1.21–1.22). Pedipalp: trochanter 0.59–0.61/0.30–0.31 (0.67–0.69/0.33–0.35), femur 1.51–1.53/0.22–0.24 (1.73–1.75/0.28–0.29), patella 1.32–1.34/0.27–0.29 (1.49–1.51/0.31–0.33), hand with pedicel 1.04–1.05/0.35–0.37 (1.23–1.25/0.49–0.51), length of movable chelal finger 1.10–1.11 (1.24–1.26), length of chela 2.14–2.15/0.35–0.37 (2.50–2.53/0.49–0.51). Chelicera: 0.26–0.27/0.14–0.15 (0.28–0.30/0.14–0.15). Leg I: trochanter 0.23–0.25/0.17–0.18 (0.31–0.33/0.22–0.23), femur 0.35–0.37/0.19–0.20 (0.30–0.32/0.21–0.23), patella 0.60–0.61/0.15–0.16 (0.76–0.79/0.16–0.17), tibia 0.60–0.62/0.12–0.13 (0.73–0.75/0.11–0.12), tarsus 0.55–0.56/0.09–0.10 (0.70–0.71/0.10–0.11). Leg IV: trochanter 0.31–0.33/0.19–0.21 (0.39–0.41/0.25–0.26), femoropatella 1.06–1.08/0.27–0.28 (1.18–1.20/0.32–0.33), tibia 0.96–0.97/0.13–0.14 (1.15–1.16/0.14–0.15), tarsus 0.65–0.67/0.09–0.10 (0.78–0.80/0.10–0.11).
Thailand (Chiangmai).
Holotype male: Thailand, Tak Province, Umphang district, Umphang subdistrict, Huai Lao Poo Cave, 15°57.680'N, 098°52.510'E, 534 m a.s.l., 16 Nov 2016, Yun-Chun Li and Zhi-Gang Chen leg, in MCWNU (Ms20161116-01). Paratypes: 1 male, 1 female, 4 tritonymphs, collected with the holotype, in MCWNU (Ms20161116-01).
Troglobiont habitus. This new species is distinguished from other members of the genus Metachelifer by the following combination of characters: coxa IV with 45–50 setae; movable finger with 2 pseudotactile setae; male anterior genital operculum with 75–80 setae (without tubular setae); female anterior genital operculum with 22 setae (without tubular setae), posterior operculum with 8 lyrifissures.
Latinized adjective, derived from the province of Tak, where the type locality is located.
Adult male (Fig.
Carapace
(Fig.
Metachelifer takensis sp. nov., holotype male (A–I) and paratype female (J) A carapace B left chelicera C rallum of left chelicera D detail on tarsus I, lateral view E coxa IV, ventral view F palp (minus chela) G chela, retrolateral view H chela, dorsal view I male genital area J female genital area. Scale bars: 0.50 mm.
Adult female (Fig.
Carapace
: slightly longer than broad (1.10 ×), anterior margin with 4 setae, posterior margin with 10 setae. Well-developed paramedian impressions behind eyes like in male. Coxae: pedipalpal coxa with 14 (non-denticulate) + 4 (denticulate) setae, coxa I 11, II 15, III 23, IV 46. Chelicera: 1.79 × longer than broad, movable finger with 2 teeth. Pedipalp: trochanter 1.88 × longer than broad, femur 6.04 × longer than broad, patella 4.37 × longer than broad, femur 1.15 × longer than patella. Chela with pedicel 5.31 × longer than broad, hand with pedicel 2.71 × longer than broad; movable finger 1.01 × longer than hand with pedicel length. Opisthosoma: tergal chaetotaxy (I–XI): 14: 16: 14: 17: 20: 18: 19: 20: 18: 14: 13; sternal chaetotaxy (IV–XI): 2 × 1 + 11: 13: 14:14: 13: 12: 10: 10; anal cone with 2 dorsal and 2 ventral setae. Anterior genital operculum with 22 setae (without tubular setae) and 2 lyrifissures; posterior operculum with 12 setae, 8 lyrifissures (Fig.
(length/width or, in the case of the legs, length/depth in mm). Males (female in parentheses): body length 3.63–3.75 (3.52). Carapace 1.05–1.06/0.99–1.00 (1.11/1.01). Pedipalp: trochanter 0.60–0.62/0.30–0.31 (0.60/0.32), femur 1.51–1.53/0.25–0.26 (1.51/0.25), patella 1.30–1.32/0.28–0.29 (1.31/0.30), hand with pedicel 1.07–1.09/0.36–0.38 (1.14/0.42), length of movable chelal finger 1.09–1.10 (1.15), length of chela 2.14–2.17/0.36–0.38 (2.23/0.42). Chelicera: 0.32–0.34/0.19–0.20 (0.25/0.14). Leg I: trochanter 0.25–0.26/0.18–0.19 (0.25/0.19), femur 0.26–0.28/0.17–0.18 (0.35/0.18), patella 0.60–0.62/0.14–0.15 (0.62/0.15), tibia 0.57–0.59/0.12–0.13 (0.62/0.15), tarsus 0.51–0.52/0.09–0.10 (0.53/0.08). Leg IV: trochanter 0.39–0.41/0.22–0.23 (0.42/0.21), femoropatella 0.95–0.97/0.28–0.29 (1.05/0.29), tibia 0.90–0.92/0.13–0.14 (0.92/0.13), tarsus 0.59–0.60/0.09–0.10 (0.61/0.09).
Thailand (Tak).
Holotype male: Thailand, Tak Province, Phop Phra district, Mae Ku subdistrict, Tham Sua Yai Cave, 16°40.336'N, 98°40.138'E, 466 m a.s.l., 14 Nov 2016, Yun-Chun Li and Zhi-Gang Chen leg., in MCWNU (Ms20161116-01). Paratypes: 1 male, 4 females, collected with the holotype in MCWNU (Ms20161116-01).
Troglobiont habitus. This new species is distinguished from other members of the genus Metachelifer by the following combination of characters: anterior margin of carapace with 6 denticuloclavate setae and a total of 86–88 setae; chelicera galea with 2 short branches; male movable chelal finger 0.96–0.98 × and female 0.93–0.95 × longer than hand with pedicel length; male anterior genital operculum without tubular setae; female genital posterior operculum with 6 setae, without lyrifissures.
Latinized adjective, derived from the country of Thailand, where the type locality is located.
Adult male (Fig.
Carapace
(Fig.
Metachelifer thailandicus sp. nov., holotype male (A–H) and paratype female (I) A carapace B right chelicera C detail on tarsus I, lateral view D coxa IV, ventral view E palp (minus chela) F chela, retrolateral view G chela, dorsal view H male genital area I female genital area. Scale bars: 0.50 mm.
Adult female (Fig.
(length/width or, in the case of the legs, length/depth in mm). Males (females in parentheses): body length 3.38–3.42 (2.86–3.32). Carapace 0.99–1.01/0.93–0.94 (0.81–0.82/0.80–0.81). Pedipalp: trochanter 0.60–0.62/0.30–0.31 (0.49–0.51/0.24–0.26), femur 1.47–1.49/0.24–0.25 (1.07–1.09/0.18–0.20), patella 1.28–1.30/0.27–0.28 (0.90–0.92/0.21–0.22), hand with pedicel 1.08–1.10/0.38–0.39 (0.86–0.89/0.30–0.32), length of movable chelal finger 1.04–1.06 (0.80–0.83), length of chela 2.09–2.11/0.38–0.39 (1.64–1.67/0.30–0.32). Chelicera: 0.27–0.28/0.14–0.15 (0.23–0.25/0.13–0.14). Leg I: trochanter 0.24–0.25/0.18–0.19 (0.18–0.20/0.14–0.16), femur 0.35–0.37/0.17–0.19 (0.21–0.23/0.14–0.15), patella 0.56–0.58/0.14–0.15 (0.46–0.49/0.13–0.14), tibia 0.56–0.58/0.12–0.13 (0.40–0.43/0.10–0.11), tarsus 0.50–0.51/0.10–0.11 (0.41–0.42/0.09–0.10). Leg IV: trochanter 0.33–0.34/0.17–0.19 (0.31–0.33/0.17–0.19), femoropatella 0.94–0.97/0.28–0.29 (0.72–0.75/0.22–0.23), tibia 0.90–0.93/0.12–0.13 (0.65–0.68/0.11–0.12), tarsus 0.60–0.61/0.09–0.10 (0.45–0.49/0.08–0.09).
Thailand (Tak).
Except for Metachelifer macrotuberculatus and M. nepalensis in Nepal, all other species of Metachelifer are distributed in Southeast Asia (Fig.
We are very grateful to Dr Prasit Wongprom (Thai Nature Education Centre) for his collaboration during the fieldwork. We thank Dr Mark Judson (Muséum national d’Histoire naturelle, Paris, France) for help with the identification of specimens from Wat Dewaroop Song Cave 3 and Tham Borichinda Cave. Dr Meng-Lin Wang (College of Life Science, China West Normal University, Nanchong, China) kindly helped to review the original English manuscript. We thank Prof. Mark Harvey (Western Australian Museum, Perth, Australia) and Dr Catalina Romero-Ortiz (Universidad Nacional de Colombia, Bogotá, Colombia) who provided useful comments and suggestions for improvements to the manuscript. This study was supported by the Doctoral Scientific Research Foundation of China West Normal University (18Q043).