Torrenticolidae, Piersig, 1902

Gu, Xin-Yao, Jin, Dao-Chao & Guo, Jian-Jun, 2020, Three new species and one new record of Torrenticolidae (Acari, Hydrachnidia) from Wuyishan with an updated key for Chinese fauna, European Journal of Taxonomy 625, pp. 1-23 : 20-22

Key to the known species of the family Torrenticolidae in China.

(Updated Gu & Guo 2019 and Gu et al. 2019)

3. Infracapitulum dorsal apodeme short, P-2 and P-3 with obvious ventral protrusions or hyaline expansions (Genus Torrenticola ) ...................................................................................................... 4

– Infracapitulum dorsal apodeme long, P-2 and P-3 without projections on ventral side (Genus Monatractides ) ................................................................................................................................ 21

4. Dorsal plate arrangements: 4+1 ........................................................................................................ 5

– Dorsal plate arrangements: 2+1, 2+2p+1 ....................................................................................... 18

5. Infracapitular rostrum short (<½ of gnathosoma dL) ........................................................................... 6

– Infracapitular rostrum long (≥½ of gnathosoma dL) .......................................................................11

6. Palp relatively thin and long ............................................................................................................. 7

– Palp robust and compact, P-2 shorter than P-4, Cx-IV with a prominent suture line of starting at right angle from genital field, laterally curved anteriorly ............................... T. nanshihensis Pešić et al.

7. P-3 with a very long tapering ventral projection .............................................................................. 8

– P-3 with a triangular, relatively short ventral projection .................................................................. 9

8. P-2 and P-3 with the smooth and sharp ventral extension .......................... T. projectura Pešić et al.

– P-2 and P-3 with the serrated ventral extension .......................................... T. dentifera Wiles, 1991

9. Infracapitular bay deep, ventral apodeme L about two times of dorsal apodeme .......................... 10

– Infracapitular bay shallow, ventral apodeme L three times longer than dorsal apodeme ................... ................................................................................................................................. T. curta Jin, 1997

10. Idiosoma roundish, the lateral view of infracapitulum acute triangle-like ......................................... .............................................................................................................. T. siamis Pešić & Smit, 2009

– Idiosoma elliptical, infracapitulum regular triangle-like in the lateral view ...................................... ................................................................................................................. T. trigona Gu & Guo, 2019

11. Ventral extensions of P-2, P-3 serrate ............................................................................................. 12

– Ventral extensions of P-2, P-3 smooth ............................................................................................ 13

12. Dorsal apodeme of infracapitulum with a fine spine, AP close to the line of primary sclerotization, E 4 at the same level as the 3 rd pair of acetabula ....... T. yanjinensis Jin, 1997

– Dorsal apodeme of infracapitulum with a broad spine, AP on the line of primary sclerotization, E 4 at the same level as the 4 th pair of acetabula ...................................................... T. dentipalpis Jin, 1997

13. The concavity between the ventral prolongations of P-4 small, idiosoma elliptical ...................... 14

– The concavity between the ventral prolongations of P-4 big and obvious, idiosoma oblate ............. ........................................................................................................... T. fodingensis Gu & Guo, 2018

14. Ap anterior to V 2 .............................................................................................................................. 15

– Ap on the line with V 2 or posterior to V 2 ......................................................................................... 16

15. P-2 longer than ⅓ total palp L, gnathosoma elongated, vL 308–381, dL 263–30............................... ...................................................................................................... T. tenuichelicera Gu & Guo, 2018

– P-2 shorter than ⅓ total palp L, gnathosoma normal, vL 284–302, dL 229–231 ............................... ................................................................................................................. T. nipponica ( Enami, 1940)

16. Ap on the line with V 2, shoulder platelets normal ........................................................................... 17

– Ap posterior to V 2, shoulder platelets offset to the inside ............... T. hainanensis Gu & Guo, 2019

17. P-2 with a laterally compressed and apically serrated ventrodistal extension, spine-like .................. .................................................................................................... T. spinextension Gu & Guo sp. nov.

– P-2 with a small sharp ventrodistal extension ................................................. T. tetrapora Viets, 1935

18. Dorsal plate arrangements: 2+2p+1 ................................................................................................ 19

– Dorsal plate arrangements: 2+1, P-3 distal margin with denticles, P-4 stocky .......................................................................................................... T. taiwanicus Pešić et al.

19. Infracapitular rostrum short (<½ of gnathosoma dL) ......................................................................... 20

– Infracapitular rostrum long (≥½ of gnathosoma dL ................ T. suptilisrostrum Gu & Guo sp. nov.

20. About ¾ of shoulder platelet fused with the large dorsal plate, posterior suture line of Cx-I retrogressive ........................................................................................ T. postfusina Gu & Guo 2019

– About ½ of shoulder platelet fused with the large dorsal plate, posterior suture line of Cx-IV obvious and long ........................................................................................... T. wuyiensis Gu & Guo sp. nov.

Remark

Torrenticola semicolor Viets, 1977 and Torrenticola alargada Goldschmidt, 2007 , reported to be new records to Chinese fauna, were rechecked to be mis-determinated. So they are not included in the key.