Gu, Xin-yao ¹ ; Li, Hai-tao ² ; Jin, Dao-chao ³ and Guo, Jian-jun ⁴

¹College of Animal Sciences, Guizhou University, Guiyang 550025, P. R. China.
²Institute of Entomology, Guizhou University, Guizhou Provincial Key Laboratory for Plant Pest Management of the Mountainous Region, the Scientific Observing and Experimental Station of Crop Pest in Guiyang, Ministry of Agriculture, P. R. China, Guiyang 550025, P. R. China.
³Institute of Entomology, Guizhou University, Guizhou Provincial Key Laboratory for Plant Pest Management of the Mountainous Region, the Scientific Observing and Experimental Station of Crop Pest in Guiyang, Ministry of Agriculture, P. R. China, Guiyang 550025, P. R. China.
⁴✉ Institute of Entomology, Guizhou University, Guizhou Provincial Key Laboratory for Plant Pest Management of the Mountainous Region, the Scientific Observing and Experimental Station of Crop Pest in Guiyang, Ministry of Agriculture, P. R. China, Guiyang 550025, P. R. China.

2024 - Volume: 64 Issue: 1 pages: 18-31

ZooBank LSID: FEB3DBE2-4578-4EBC-909A-0CF49F106D52

Original research

Keywords

Abstract

Introduction

According to the latest classification system, Torrenticolidae is divided into two subfamilies, seven genera and 12 subgenera (Simt 2020). According to statistics from the European Watermite Research (http://www.watermite.org/ ) and the latest published paper, 618 species belong to this family (Gu et al. 2023). However, there are only 22 known species (including the new species reported in this contribution) in the Testudacarinae Walter, 1928, mainly distributed in North America, with a few species occurring in Asia (O'Neill et al. 2016). From China, only one species, Testudacarus binodipalpis Guo & Jin, 2005, was reported in 2005 (Guo & Jin 2005).

In this paper, one new species of Testudacarinae from China, Testudacarus sinensis Gu & Guo sp. nov., is described. Furthermore, one new record for the Chinese fauna is given, i.e. Torrenticola rangareddyi Pešić & Smit, 2019, which was previously reported from Thailand (Pešić & Smit 2019). In addition, an updated key of Chinese torrenticolid mites is provided.

Material and methods

All the material was collected, preserved, cleaned, and mounted following Jin & Gu (Jin 1997; Gu et al. 2023). Measurements are according to Goldschmidt (2007) and are given in µm. Morphological terminology follows Jin (1997) and Fisher et al. (2015). All the specimens examined are deposited at the Institute of Entomology, Guizhou University, Guizhou, P. R. China.

The following abbreviations are used (Jin 1997; Gu et al. 2022): aL = apical length; Ap = anal pore; bs = basal segment of chelicera; Cx-I–Cx-IV = coxae I–IV; dL = dorsal length; Gf = Genital field; I-L-1–6, etc. = first leg's segment 1–6, etc.; L = length; mL = medial length; P-1–5 = palp segment 1–5; vL = ventral length; W = width. The chaetotaxy and nomenclature of glandularia used follows Jin (1997); A₂ = postantennal glandularia; D₁ –D₄ = dorsoglandularia 1–4; C₂ , C₄ = coxoglandularia 2, 4; L₁ –L₄ = lateroglandularia 1–4; O₂ = postocularia; V₁ –V₄ = ventroglandularia 1–4.

Abbreviations of dorsal plate arrangements according to Wiles (1997) are updated: 3+14+1 = three anterior platelets (one frontal and two shoulder platelets), one dorsal plate and 14 platelets (surrounded the dorsal plate); 4+1= four anterior platelets (two frontal and two shoulder platelets) and one single large dorsal plate; 2+2p+1 = two frontal platelets, and the shoulder platelets partially fused to the dorsal plate; 2+1 = two frontal platelets and a single large dorsal plate, the shoulder platelets are fused to the large dorsal plate; 1+2 = the frontal and shoulder platelets of each side are fused to each other but are separated from the large dorsal plate. 0+1 = two frontal and two shoulder platelets are fused to the large dorsal plate. (Figure 1).

Taxonomy

Torrenticolidae Piersig, 1902

Testudacarinae Cook, 1974

Testudacarus Walter, 1928

Testudacarus sinensis Gu & Guo sp. nov.

ZOOBANK: E39E392A-71B8-444B-B67B-E7D4835402C3

(Figures 2–5)

Material examined

Holotype male, No. GZ-TO-20160722, Fodingshan, Guizhou Province, China (27°20′14″N, 108°03′08″E, 930 m a.s.l.), collected by Xinyao Gu, 11 Jul. 2016. Paratypes, 5 males and 8 females, same collection data as for holotype, No. GZ-TO-20160723 – GZ-TO-20160735; 3 males and 2 females, Doupengshan, Guizhou province (26°07′55″N, 107°18′54″E, 1000 m a.s.l.), No. GZ-TO-20160901 – GZ-TO-20160905, collected by Xinyao Gu and Zhuhui Ding, 30 Sept. 2016; 4 females and 5 males, Anzhihe, Sichuan province (30°47′43″N, 103°12′36″E, 1690 m a.s.l.), No. SC-TO-20160705 – SC-TO-20160713, 29 Jul. 2016, collected by Zhuhui Ding; 1 male and 4 females, Xiaoxi National Nature Reserve, Hunan Province (28°45′21″N, 110°18′36″E, 690 m a.s.l.), 19 Aug. 2016, collected by Xinyao Gu and Zhuhui Ding, No. HN-TO-20160801 – HN-TO-20160805.

Diagnosis

Dorsal plate arrangement 3+14+1, median anterior platelet trapezoid, shoulder platelets oblong; dorsal apodeme long and blunt, ventral apodeme pointed and curved to dorsum in gnathosoma; P-4 without ventral seta.

Description

Male — (n = 15) – Idiosoma L 726 (611–726), W 463 (400–463), L/W ratio 1.6 (1.5–1.6). Dorsal plate arrangement 3+14+1; dorsal plate surrounded by seven pairs of small platelets, L 532 (461–535), W 372 (306–372), L/W ratio 1.4 (1.4–1.5); median anterior platelet trapezoid L 132 (129–153), W 74 (74–82), L/W ratio 1.8 (1.7–1.9); shoulder platelets oblong, L 185 (155–185), W 70 (70–90), L/W ratio 2.6 (2.0–2.6) (Figure 2A). Gnathosomal bay U-shaped, depth 147 (126–147); Cx-I L 256 (228–256), mL 110 (102–113); Cx-II + III L 111 (106–111), C₄ posterior to the trailing edge of Cx-IV. V₁ on the same line with Ap, V₂ posterior to Ap, V₄ at the line of primary sclerotization (Figure 2B). Gf oblong, L 170 (122–170), W 125 (104–151), L/W ratio 1.4 (1.1–1.4). Distance between Gf and Ap 68 (58–72). Gnathosoma: dL 95 (95–99), vL 156 (143–156), dorsal apodeme long and blunt, ventral apodeme pointed and curved to dorsum; chelicera bs L 141 (134–142), and curved to the abdomen, claw L 19 (17–19) (Figure 2E). Palp (Figure 2D): P-1 short and with one dorsal seta; P-2 with three dorsal setae, one ventral seta; P-3 with two dorsal setae and one ventral seta; P-4 with one long and one shot dorsal setae; dL of palp: P-1, 22 (16–22); P-2, 50 (45–57); P-3, 39 (36–40); P-4, 50 (34–52); P-5, 14 (14–17). dL of leg segments: I-L-1–6: 43 (43–72), 75 (42–75), 60 (60–64), 86 (68–88), 86 (76–88), 81 (72–81); II-L-1–6: 64 (43–64), 67 (60–92), 60 (60–65), 93 (77–93), 95 (80–108), 111 (90–111); III-L-1–6: 53 (50–58), 88 (76–88), 64 (52–71), 110 (104–112), 121 (104–121), 141 (121–141); IV-L-1–6: 85 (83–97), 92 (85–92), 115 (101–115), 150 (120–150), 159 (148–159), 161 (125–161).

Female — (n=18) – Idiosoma features same as in male except: Ap away from the line of primary sclerotization, at the same level with V₁ and V₂ ; Gf pentagonal (Figure 4B). Idiosoma L 756 (637–756), W 501 (452–507), L/W ratio 1.5 (1.4–1.5); dorsal shield L 626 (563–626), W 471 (380–471), L/W ratio 1.3 (1.3–1.5); dorsal plate L 500 (468–500), median anterior platelets L 133 (122–139), W 89 (89–90), L/W ratio 1.5 (1.4–1.5); shoulder platelets L 193 (182–193), W 77 (77–88), L/W ratio 2.5 (2.2–2.5); gnathosomal bay 190 (137–190); Cx-I L 296 (233–296), mL 101 (92–108), Cx-II+III mL 43 (43–54); Gf L 160 (132–160), W 133 (123–171), L/W ratio 1.2 (0.9–1.2); distance between Gf and Ap 193 (193–199). Gnathosoma: vL 149 (149–161), dL 147 (96–147); chelicera bs L 145 (145–147), claw L 31 (19–31). dL of palp: P-1, 27 (25–27); P-2, 54 (45–54); P-3, 42 (38–42); P-4, 48 (41–48); P-5, 20 (12–20). dL of leg segments: I-L-1–6: 38 (38–60), 85 (52–85), 68 (59–68), 93 (83–93), 97 (87–97), 96 (86–96); II-L-1–6: 40 (40–64), 70 (70–92), 66 (44–66), 114 (87–114), 121 (88–121), 137 (88–137); III-L-1–6: 46 (46–66), 97 (62–97), 75 (66–75), 114 (96–114), 127 (113–127), 125 (125–128); IV-L-1–6: 98 (89–104), 127 (90–127), 122 (102–122), 156 (137–156), 168 (152–168), 156 (143–156).

Habitat

Streams, with large stones, turbulent.

Remarks

Due to the length of idiosoma (600–900 μm), median anterior platelets wide and prismatic, this species differs from most species of Testudacarus in O'Neill et al. (2016). However, it is similar to Testudacarus tripeltatus Walter, 1928 and Testudacarus okadai Imamura, 1976 due to the short median suture of Cx-II+III (Pešić & Smit 2007). Compared to T. tripeltatus, differences are found in: (1) P-2 ventrodistal setae pinnate in T. tripeltatus, but smooth in Chinese specimens; (2) Tips of Cx-I with one distinct protrusion in T. tripeltatus, but absent in Chinese specimens; (3) Ap located after V₁ before V₂ in T. tripeltatus, but on the same line with V₁ in Chinese specimens. Meanwhile, T. okadai has one pair of small and narrow shoulder platelets, but shoulder platelets are broad and large in the new species.

We also compared the new species with Testudacarus binodipalpis Guo & Jin, 2005 (Guo & Jin 2005), which was the first species of Testudacarus reported from China. Distinct differences between this new species and T. binodipalpis are: (1) P-4 with two ventral extensions in T. binodipalpis, but without ventral extensions in the new species; (2) P-3 and P-4 eachwith one pinnate ventral seta in T. binodipalpis, but ventral seta smooth in the new species; (3) the tips of Cx-I with one triangular protrusion in T. binodipalpis, but without protrusion in the new species.

Etymology

The new species is named after China. The specific name ''sinensis'' is from Latin roots ''sino-'', which means China.

Distribution

China (Guizhou, Hunan, Sichuan).

Torrenticolinae Piersig, 1902

Torrenticola Piersig, 1896

Torrenticola rangareddyi Pešić & Smit, 2019

(Figures 6–7)

Torrenticola turkestanica Pešić & Smit, 2009: 50.

Torrenticola rangareddyi Pešić & Smit, 2019: 1872.

Material examined

Two males, No. FJ-TO-20180814, FJ-TO-20180815, Wuyishan National Nature Reserve, Fujian Province (27°45′24″N, 117°41′20″E, 710 m a.s.l.), collected by Xinyao Gu, 6 Aug. 2018; 2 males, No. GX-TO-20190901, GX-TO-20190902, Dayaoshan National Nature Reserve, Guangxi Province (24°08′41″N, 110°14′21″E, 1000 m a.s.l.), collected by Min Ao and Haitao Li, 4 Sept. 2019.

Description

Male — (n = 4) – Idiosoma elliptical, L 612 (612–641), W 394 (390–410), L/W ratio 1.55 (1.55–1.57). Dorsal plate arrangement 4+1 (Figure 6A), dorsal shield L 497 (497–537), W 349 (349–374), L/W ratio 1.42 (1.42–1.43); dorsal plate L 471 (471–502); frontal platelets L 115 (113–118), W 40 (39–44), L/W ratio 2.9 (2.7–2.9); shoulder platelets L 146 (142–155), W 43 (43–46), L/W ratio 3.4 (3.3–3.5). Gnathosomal bay U-shaped, deep 109 (104–119); Cx-Ⅰ L 210 (210–241), mL 101 (101–122), Cx-II+III mL 104 (76–104); Gf L 143 (134–143), W 105 (103–108), L/W ratio 1.4 (1.3–1.4); C₄ at the same level as the 5^th pair of acetabula (Figure 6B); distance between Gf and Ap 96 (96–112). Gnathosoma: dorsal apodeme short and blunt, ventral apodeme long and blunt, rostrum rude; gnathosoma dL 196 (192–198), vL 268 (263–274); chelicera bs L 270 (266–275), claw L 48 (48–55) (Figure 6D); P-1 short, with one dorsal seta; P-2 wide, with three dorsal setae, and one ventral seta on a serrated rectangular extension; P-3 with two dorsal setae and one long ventral seta on serrated ventral extension; P-4 with two dorsal setae, one long and three short ventral setae on the two ventral extensions (Figure 6C). L of palp: P-1, 30 (30–42); P-2, 80 (80–85); P-3, 55 (48–56); P-4, 80 (72–81); P-5, 13 (13–17). L of leg segments: I-L-1–6: 31 (31–38), 56 (56–82), 65 (59–65), 70 (70–78), 80 (80–88), 82 (80–84); Ⅱ-L-1–6: 35 (35–45), 57 (57–73), 62 (62–70), 76 (76–97), 87 (87–118), 102 (102–131); III-L-1–6: 35 (35–42), 77 (67–77), 66 (56–66), 91 (78–93), 109 (93–109), 121 (113–125); IV-L-1–6: 88 (88–106), 90 (90–100), 95 (93–99), 118 (118–146), 130 (130–152), 136 (136–148). Ejaculatory complex L 185 (185–194), AL 131 (131–143).

Female Unknown.

Habitat

Stream, with many big stones at the bottom; the water is clear and rapid.

Remarks

Due to the characteristics of palp: P-2 and P-3 with one subrectangular ventrodistal projection respectively, the ventral margin of P-2 convex, the P-2 with one ventral seta exceeding the distal end of the ventrodistal projection, the Chinese specimens match the description of Torrenticola rangareddyi Pešić & Smit, 2019 (Pešić & Smit 2009, 2019). The only difference between the Chinese specimens and T. rangareddyi is P-4 with a stubby dorsodistal seta, which is absent in the Chinese specimens. Therefore, we considered that the difference is they belong to different geographical populations.

In addition, we noted that T. rangareddyi and Torrenticola wonchoeli Pešić & Smit, 2019 had been provisionally assigned to Torrenticola turkestanica (Sokolow, 1926) by Pešić & Smit (2009, 2013, 2019). Therefore, we also compared the Chinese specimens with T. turkestanica and T. wonchoeli. Differences between them are given in Table 1 (Pešić & Smit 2007, 2009, 2013, 2019; Pešić et al. 2022). Although those species can be distinguished from morphological characteristics, we also agree with the view of Pešić, Smit and Gurung that should be tested with the application of molecular techniques″(Pešić & Smit 2019; Pešić et al. 2022).

Distribution

Thailand (Pešić & Smit 2009; Pešić et al. 2013); New for the fauna of China.

Key to the known species of the family Torrenticolidae in China

Updated from Gu et al. 2019, Gu & Guo 2019

1. Three pairs of acetabula
...... (Subfamily Testudacarinae) – 2

— Six pairs of acetabula
...... (Subfamily Torrenticolinae) – 3

2. The tips of Cx-I with one triangular protrusion, P-4 with two ventral extensions, P-3 and P-4 each with one pinnate ventral seta
...... Testudacarus binodipalpis Guo & Jin, 2005

— Tips of Cx-I without any protrusions, P-4 without ventral extensions, P-3 and P-4 each with one smooth ventral seta
...... Testudacarus sinensis Gu & Guo sp. nov.

3. P-4 short, not more than twice as long as W, P-5 with broad, blunt terminal setae
...... (Genus Neoatractides) – 4

— P-4 long, more than twice as long as W
...... 5

4. Length of frontal platelet about 2/3 of shoulder platelet, the tip of Cx-I with seven slender setae
...... Neoatractides proclusteroseta Gu & Guo, 2018

— Length of frontal platelet about 3/2 of shoulder platelet, the tip of Cx-I with only one slender seta
...... Neoatractides malayensis (Wiles, 1991)

5. Gnathosomal dorsal apodeme short, P-2 and P-3 with distinct ventral prolongations or hyaline extensions
...... (Genus Torrenticola) – 6

— Gnathosomal dorsal apodeme long, P-2 and P-3 without projections on ventral margin
...... (Genus Monatractides) – 44

6. Rostrum curved; most of P-2 and P-3 without distinct ventral prolongations, P-2 and P-4 thin and long, P-2 longer than or equal to P-4
...... (Subgenus Megapalpis) – 7

— Rostrum straight, P-2 and P-3 with distinct ventral prolongations or hyaline extensions, P-2 and P-4 short, P-2 shorter than P-4
...... (Subgenus Torrenticola) – 9

7. P-4 with distinct ventral extensions
...... 8

— P-4 without any ventral extensions
...... Torrenticola yii Gu & Guo, 2022

8. Gnathosomal bay V-shaped
...... Torrenticola aduncrostrum Gu, Jin & Guo, 2020

— Gnathosomal bay U-shaped
...... Torrenticola distans K.O. Viets, 1981

9. Dorsal plate arrangements: 4+1
...... 10

— Dorsal plate arrangements: 2+1 or 2+2p+1
...... 36

10. Rostrum short (>1/2 of gnathosoma dL)
...... 11

— Rostrum long (≥1/2 of gnathosoma dL)
...... 20

11. Palp relatively slender and long
...... 12

— Palp robust and compact
...... 19

12. Ventral extensions of P-3 with some teeth
...... 13

— Ventral extensions of P-3 smooth
...... 14

13. P-2 with a distinct and irregular serrated terminal margin
...... Torrenticola multiserrater Gu & Guo, 2023

— P-2 with a distinct rectangular serrated margin
...... Torrenticola dentifera Wiles, 1991

14. P-3 with a triangular or cylindrical, relatively short ventral projection
...... 15

— P-3 with a very long tapering ventral projection which is curved distally, larger than projection on P-2
...... Torrenticola projectura Pešić, Chatterjee, Yam, Chan, 2012

15. Gnathosomal bay deep, ventral apodeme L about two times of dorsal apodeme
...... 16

— Gnathosomal bay shallow, ventral apodeme L three times longer than dorsal apodeme
...... Torrenticola curta Jin, 1997

16. Idiosoma roundish
...... 17

— Idiosoma elliptical
...... 18

17. Lateral view of gnathosoma regular triangle-like
...... Torrenticola trigona Gu & Guo, 2019

— Lateral view of gnathosoma irregular
...... Torrenticola brevisuturae Gu & Guo, 2022

18. Ap away from the line of primary sclerotization
...... Torrenticola siamis Pešić & Smit, 2009

— Ap on the same level with the line of primary sclerotization
...... Torrenticola pseudosiamis Gu & Guo, 2020

19. Ventral extensions of P-2 and P-3 smooth
...... Torrenticola nanshihensis Pešić, Semenchenko, Chatterjee, Yam, Chan, 2011

— Ventral extensions of P-2 and P-3 with some teeth
...... Torrenticola rangareddyi Pešić & Smit, 2019}

20. Ventral extension of P-2 or P-3 with some teeth
...... 21

— Ventral extensions of P-2 & P-3 smooth
...... 27

21. Dorsal apodeme of gnathosoma with a fine seta, Ap close to or away from the line of primary sclerotization, C₄ at the same level as the 3^rd pair of acetabula
...... 22

— Dorsal apodeme of gnathosoma with a broad seta, Ap on the line of primary sclerotization, C₄ at the same level as the 4^th pair of acetabula
...... Torrenticola dentipalpis Jin, 1997

22. Ventral extension of P-2 with some teeth
...... 23

— Ventral extension of P-2 smooth
...... 25

23. Ventral extension of P-3 with some teeth
...... 24

— Ventral extension of P-3 smooth, P-2 with a laterally compressed, apically serrated and spine-like ventrodistal extension
...... Torrenticola spinextension Gu & Guo, 2020

24. Gnathosomal bay U-shaped, C₄ at the same level as the 4^th pair of acetabula
...... Torrenticola pseudoalargada Gu & Guo, 2023

— Gnathosomal bay V-shaped, C₄ at the same level as the 2^nd (male) or 5^th (female) pair of acetabula
...... Torrenticola alargada Goldschmidt, 2007

25. Dorsal shield with a reddish-purple colour pattern
...... Torrenticola nipponicella Gu & Guo, 2022

— Dorsal shield without colour pattern
...... 26

26. Frontal platelets rectangle
...... Torrenticola yanjinensis Jin, 1997

— Frontal platelets trapezoid
...... Torrenticola anziensis Gu & Guo, 2020

27. The concavity between the ventral prolongations of P-4 small
...... 28

— The concavity between the ventral prolongations of P-4 large and distinct, with four setae on the ventral prolongations, idiosoma oblate
...... Torrenticola fodingensis Gu & Guo, 2018

28. Ap anterior to V₂
...... 29

— Ap on the line with V₂ or posterior to V₂
...... 30

29. P-2 shorter than 1/3 palp L, idiosomal frontal margin with a convex outline
...... Torrenticola nipponica (Enami, 1940)

— P-2 longer than 1/3 palp L, ventral margin convex, ventrodistal protrusion bluntly pointed and slightly curved towards distal, gnathosoma elongated, chelicera long and straight
...... Torrenticola tenuichelicera Gu & Guo, 2018

30. Ap on the line with V₂ , shoulder platelets close to the sides of idiosoma
...... 31

— Ap posterior to V₂, shoulder platelets offset to the inside, away from the sides of idiosoma
...... Torrenticola hainanensis Gu & Guo, 2019

31. Gnathosomal bay V-shaped
...... Torrenticola planusirostrum Gu, Jin & Guo, 2020

— Gnathosomal bay U-shaped
...... 32

32. Dorsal apodeme of gnathosoma almost absent, rostrum extremely slender, and curved slightly to the venter
...... Torrenticola yunnanensis Gu, Jin & Guo, 2020

— Dorsal apodeme of gnthaosoma distinct, rostrum straight
...... 33

33. Gnathosoma dorsal apodeme absent
...... Torrenticola rectrostrum Gu, Jin & Guo, 2020

— Gnathosoma dorsal apodeme distinct
...... 34

34. Cx-I more elongated, tips rounded
...... Torrenticola semicolor K.O. Viets, 1977

— Cx-I wider nearly triangular, tips pointed
...... 35

35. Body without color pattern
...... Torrenticola tetrapora (Viets, 1935)

— The posterior half of the dorsal plate reddish, dorsal plate with a reddish-purple coloration, hour-glassshaped with pale ''shoulder-patches''
...... Torrenticola lushanensis Gu, Jin & Guo, 2020

36. Dorsal plate arrangements: 2+2p+1
...... 37

— Dorsal plate arrangements: 2+1, P-3 distal margin with denticles, P-4 stocky
...... Torrenticola taiwanicus Pešić, Semenchenko, Chatterjee, Yam, Chan, 2011

37. Posterior suture line of Cx-IV indistinct
...... 41

— Posterior suture line of Cx-IV distinct
...... 38

38. P-4 with three ventral extensions
...... Torrenticola triextensio Gu, Jia, Jin & Guo, 2020

— P-4 with two ventral extensions
...... 39

39. Cx-I-III exceeding the anterior margin of idiosoma
...... Torrenticola wuyiensis Gu & Guo, 2020

— Only Cx-I and Cx-II exceeding the anterior margin of idiosoma
...... 40

40. Gnathosoma rostrum thick
...... Torrenticola neoungeri Pešić, Asadi & Smit, 2019

— Gnathosoma rostrum thin
...... Torrenticola suptilisrostrum Gu & Guo, 2020

41. Rostrum short (>1/2 of gnathosoma dL), gnathosoma dorsal apodeme blunt
...... Torrenticola postfusina Gu & Guo, 2019

— Rostrum long (≥1/2 of gnathosoma dL), gnathosoma dorsal apodeme sharp
...... 42

42. Gnathosoma ventral apodeme straight
...... Torrenticola acrisarostrum Gu, Jia, Jin & Guo, 2020

— Gnathosoma ventral apodeme curved to the dorsum
...... 43

43. Ap away from the line of primary sclerotization
...... Torrenticola songhuaensis Gu, Jia, Jin & Guo, 2020

— Ap close to the line of primary sclerotization
...... Torrenticola changbaiensis Gu, Jia, Jin & Guo, 2020

44. Idiosoma elongated, L/W ratio more than 1.5
...... 45

— Idiosoma roundish or slightly oval, L/W ratio less than 1.5
...... 49

45. C₄ posterior to Gf
...... 46

— C₄ on the same line with 4^th, 5^th or 6^th some pair of acetabula or C₄ at the same level as the posterior edge of Gf
...... 47

46. The tip of Cx-I with a cuticular extension, Cx-I-III exceeding the anterior margin of idiosoma
...... Monatractides tuzovskyi Pešić, N. Kumar, K. Kumar & S. Kumar, 2006

— The tip of Cx-I without cuticalar extension, and only Cx-I and Cx-II exceeding the anterior margin of idiosoma
...... Monatractides dingi Gu, Jin & Guo, 2020

47. C₄ on the same line with 4^th, 5^th or 6^th acetabula
...... 48

— C₄ at the same level as the posterior edge of Gf, idiosoma L/W ratio 1.5–1.6, gnathosomal dorsal apodeme with a blunt tip
...... Monatractides xiaoxiensis Gu & Guo, 2019

48. The tip of Cx-I long and sharp and with a small cuticular extension
...... Monatractides cuspiscoxer Gu & Guo, 2019

— The tip of Cx-I short and without an extension
...... Monatractides vietusacoxer Gu & Guo, 2019

49. Dorsal platelets fused with the dorsal plate or fused with each other
...... 50

— Dorsal platelets without any fusion (Dorsal plate arrangements: 4+1)
...... 51

50. Dorsal plate arrangements: 0+1
...... Monatractides jini Gu & Guo, 2019

— Dorsal plate arrangements: 1+2
...... Monatractides trilaminatus Gu, Jin & Guo, 2020

51. Gnathosoma and palp normal, chelicera more or less curved
...... 52

— Gnathosoma relatively long and slender, palp comparatively short and stocky, chelicera straight
...... Monatractides pinapalpis (Cook, 1967)

52. P-2 and P-3 ventrodistal setae smooth
...... 53

— P-2 and P-3 ventrodistal setae pinnate
...... 56

53. C₄ posterior to Gf, Idiosoma oval
...... 54

— C₄ on the same line with the 4^th (male) or 5^th (female) pair of acetabula, Idiosoma roundish
...... 55

54. P-2 and P-3 ventral setae pinnate
...... Monatractides setivalvata (Cook, 1967)

— P-2 and P-3 ventral setae smooth
...... Monatractides sichuanensis Gu & Guo, 2020

55. The tip of Cx-I with a long elongated cuticular extension
...... Monatractides hamatapodemus Gu & Guo, 2019

— The tip of Cx-I with a short and small cuticular extension
...... Monatractides macrocorpis Gu & Guo, 2019

56. Gnathosomal bay V-shaped
...... 57

— Gnathosomal bay U-shaped, frontal margin of idiosoma distinctly concave, P-2 almost as long as P-4
...... Monatractides stadleri (Walter, 1924)

57. Gnathosomal ventral apodeme shorter than dorsal apodeme, and with a blunt end, P-4 longer than P-2
...... Monatractides oxystomus (K. Viets, 1935)

— Gnathosomal ventral apodeme equal in length to the dorsal apodeme, P-4 shorter than P-2
...... Monatractides serratifera Jin, 1997

Notes

Two North American species, Torrenticola semicolor Viets, 1977 and Torrenticola alargada Goldschmidt, 2007, were reported as a new recorded species from China by Zhang et al. (2011). Will North American species be distributed in China, which is far apart? To further clarify this point, we have conducted careful identification again, and the Chinese specimens are still very similar in morphological characteristics to the two North American species, and even the length-to-width ratio of each part is consistent. Maybe, it belongs to different faunal regions. We agreed with other scholars, that those species should be tested by other methods (such as DNA barcoding), but it is currently difficult to confirm due to the lack of fresh specimens. Neither having sufficient evidence to draw up a species or establish a species is not a good decision. We still believe that they are the same species until there is new evidence to prove that they are not the same species.

Acknowledgments

We are grateful to Zhuhui Ding (Guizhou University, P. R. China), Min Ao (Guizhou University, P. R. China) for collections of specimens.

Funding

This research was supported by the National Natural Science Foundation of China No.32260125; Guizhou Provincial Science and Technology Projects (Qiankehe Pingtai Rencai-GCC [2022]029-1); the Talent Introduction Research Project of Guizhou University (Gui Da Ren Ji He Zi [2022]32).

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