Xenylla, Tullberg, 1869

Jia, Junli & Skarżyński, Dariusz, 2019, A new species of Xenylla Tullberg, 1869 (Collembola: Hypogastruridae) from China, with a key to Asian species of the genus, Zootaxa 4608 (3), pp. 579-585 : 581-582

Key to Asian Xenylla species

The key is based on Babenko et al. (1994), Thibaud et al. (2004), Park (2016) and Skarżyński et al. (2018). The species Xenylla aristides Fernando, 1959 , X. hadialii Baijal, 1955 , X. longicauda Folsom, 1898 , X. reducta Prabhoo, 1971 , X. similata Denis, 1948 and X. sincta Baijal, 1956 are not included in the key because of insufficient descriptions. In contrast, Xenylla acauda and X. boerneri are included in the key, although their occurrence in Asia, after Zhao et al. (1997) and Furuno et al. (2000), requires confirmation. Encoding of chaetotactic characters after Gama (1969, 1988) and Thibaud et al. (2004).

1. Furca and tenaculum absent............................................................................. 2

- Furca and tenaculum present............................................................................ 4

2. Head with dorsal setae c 1 present and c 2 absent (c), six cylindrical sensilla on Ant. IV......................................................... acauda Gisin, 1947 ( Switzerland, Austria, Spain, Great Britain, Poland, Japan, USA, Mexico)

- Head with dorsal setae c 1 absent (b) and c 2 present, four cylindrical sensilla on Ant. IV.............................. 3

3. Abd. III without ventral medial setae, Abd. IV without ventral m 1 setae (a4)............... nepalensis Gama, 1988 ( Nepal)

- Abd. III with ventral medial setae, Abd. IV with ventral m 1 setae.......... mongolica Martynova, 1975 ( Mongolia, Russia)

4. Dens with one seta.................................................................................... 5

- Dens with two setae.................................................................................. 13

5. Head with dorsal setae c 1 and c 2. Labrum with 2, 5, 4 setae...... myrmecophila Stebaeva & Potapov, 1994 ( Russia, Siberia)

- Head without dorsal setae c 1 or c 2 (b/c). Labrum with 5, 5, 4 setae............................................... 6

6. Head with dorsal setae c 1 present and c 2 absent (c)........................................................... 7

- Head with dorsal setae c 1 absent (b) and c 2 present........................................................... 8

7. Mucro absent, dens strongly reduced, papilla-like (ratio dens/claw III = 0.3–0.4); head with dorso-lateral setae l 3 longer than l 1 (g), two dorsoexternal sensillae on Ant. IV strongly thickened......................... boerneri Axelson, 1905 (Europe)

- Mucro present, mucrodens longer (ratio mucrodens/claw III = 0.6–0.8); head with dorso-lateral setae l 3 subequal to l 1, all dorsoexternal sensillae on Ant. IV elongate......................... babenkoi Stebaeva & Potapov, 1994 ( Russia, Siberia)

8. Mucro absent, dens strongly reduced, papilla-like............................................................ 9

- Mucro present, mucrodens longer....................................................................... 10

9. Tibiotarsi I, II, III with 1, 2, 2 dorsal clavate tenent hairs, unguis with inner tooth, Abd. IV without dorsal a 3 setae.............................................................................. badakhsanica Yosii, 1966 ( Afghanistan)

- Tibiotarsi I, II, III with 2, 2, 2 dorsal clavate tenent hairs, unguis without inner tooth, Abd. IV with dorsal a 3 setae.................................................................... stepposa Stebaeva, 1980 ( Kirghizia, Russia, Siberia)

10. Th. II and III without dorsal setae m 3 (k), la 1 (i) and ventral medial setae present............................................................................................ betulae Fjellberg, 1985 ( USA, Russia, Siberia, Poland)

- Th. II and III with dorsal setae m 3, la 1 and ventral medial setae absent (t)........................................ 11

11. Maxillary outer lobe with three sublobal hairs....................... trisubloba Stebaeva & Potapov, 1994 ( Kazakhstan)

- Maxillary outer lobe with one sublobal hair................................................................ 12

12. Mucrodens more than 1.5 times longer than claw III, tibiotarsi I, II, III with 1, 2, 2 dorsal clavate tenent hairs.......................................................... continentalis Stebaeva & Potapov, 1994 ( Russia, Siberia, Mongolia)

- Mucrodens shorter than claw III, tibiotarsi I, II, III with 2, 2, 2 dorsal clavate tenent hairs................................................................................................... kirgisica Martynova, 1976 ( Kirghizia)

13. Mucro fused with dens................................................................................ 14

- Mucro separated from dens............................................................................ 16

14. Setae la 1 absent on Th. II and III (i), maxillary outer lobe with one sublobal hair...... grisea Axelson, 1900 (Cosmopolitan)

- Setae la 1 present on Th. II and III, maxillary outer lobe with three sublobal hairs.................................. 15

15. Setae in front of retinaculum on Abd. III and dorsal setae m5 on Abd. IV absent.... maritima Tullberg, 1869 (Cosmopolitan)

- Setae in front of retinaculum on Abd. III and dorsal setae m5 on Abd. IV present...... asiatica Martynova, 1975 ( Mongolia)

16. Head with dorsal setae c1 and c2........................................................................ 17

- Head without dorsal setae c1 or c2 (b/c).................................................................. 23

17. 4 + 4 ocelli............................................................... yucatana Mills, 1938 (Pantropical)

- 5 + 5 ocelli......................................................................................... 18

18. Head with ventral setae p1............................................................................. 19

- Head without ventral setae p1 (r)........................................................................ 21

19. Head without ventral setae m3 (s)................. malayana Salmon, 1951 ( Malaysia, Singapore, Canary Islands, Cuba)

- Head with ventral setae m3............................................................................ 20

20. Pleurite of Th. III with conical projection, mucro very long with a narrow inner lamella, tapering to a fine point; head with setae l1 longer than l3; tergites with numerous additional setae................... littoralis Womersley, 1933 ( Australia, Japan)

- Pleurite of Th. III without conical projection, mucro with rounded upturned apex and broad inner lamella; head with setae l1 subequal to l3; tergites without additional setae................................. welchi Folsom, 1916 (Cosmopolitan)

21. Head with ventral setae m3............................... humicola (Fabricius, 1780) (Circumpolar, Cosmopolitan?)

- Head without ventral setae m3 (s)....................................................................... 22

22. Th. II and III with dorsal setae m3............................................. brevispina Kinoshita, 1916 ( Japan)

- Th. II and III without dorsal setae m3 (k)............................... convexopyga Lee, Park & Park, 2005 ( Korea)

23. Head with dorsal setae c1 absent (b) and c2 present......................................................... 24

- Head with dorsal setae c1 present and c2 absent (c)......................................................... 34

24. Th. II and III with a pair of ventral medial setae............................. changchunensis Wu & Yin, 2007 ( China)

- Th. II and III without ventral medial setae (t).............................................................. 25

25. Th. II and III without dorsal setae m3 (k), setae a1 and a2, p1 and p2 disposed at the same level, head without ventral setae p1 (r).............................................................................................................................................................. vanharteni Weiner, Najt & Paśnik ,, 2012 ( Yemen)

- Th. II and III with dorsal setae m3, setae a2 displaced posteriorly compared with setae a1 (h1); setae p2 displaced anteriorly compared with setae p1 (h2), head with ventral setae p1...................................................... 26

26. Th. II and III with setae la1............................................................................ 27

- Th. II and III without setae la1 (i)....................................................................... 30

27. Head without ventral setae m3 (s), Abd. IV without dorsal setae m3 (o)................... yosiiana Gama, 1971 ( Nepal)

- Head with ventral setae m3, Abd. IV with dorsal setae m3.................................................... 28

28. Ant. IV with six cylindrical sensilla................................................... weinerae sp. nov. ( China)

- Ant. IV with four or five cylindrical sensilla............................................................... 29

29. Tibiotarsi I, II, III with 2, 2, 2 dorsal clavate tenent hairs, unguis with inner tooth............................................ obscura Imms, 1912 sensu Thibaud et al. (2004) ( India, Nepal, Vietnam, Thailand, Russia, Siberia, Australia, New Caledonia)

- Tibiotarsi I, II, III with 1, 2, 2 dorsal clavate tenent hairs, unguis without inner tooth..................................................................................................... tadzhika Martynova, 1968 ( Tadjikistan)

30. Head with dorsal setae a0, Abd. IV without dorsal setae p3 (n) and m3 (o)........... thailandensis Gama, 1986 ( Thailand)

- Head without dorsal setae a0, Abd. IV with dorsal setae p3 and m3............................................. 31

31. Head with ventral setae m3............................................................................ 32

- Head without ventral setae m3 (s)....................................................................... 33

32. Abd. IV with ventral setae m1.................................... malasica Gama, 1969 ( Malaysia, Thailand, Nepal)

- Abd. IV without ventral setae m1 (a4)........................................................................ stachi Gama, 1966 ( Angola, Zimbabwe, Aldabra Island, Picard Island, Thailand, Bismarck Archipelago, Salomon Islands, New Hebrides, Australia)

33. Head with dorsal setae c3................................................................................................................... manusiensis Gama, 1967 ( Bismarck Archipelago, Australia, continental SE Asia)

- Head without dorsal setae c3 (d)............................................... murphyi Gama, 1969 ( Singapore)

34. Th. II with setae la2.................................................................................. 35

- Th. II without setae la2 (j)............................................................................. 37

35. Head without ventral setae p1 (r) and m3 (s)................................. changlingensis Wu & Yin, 2007 ( China)

- Head with ventral setae p1 and m3....................................................................... 36

36. Mucro with lamella on its basal part....................... martynovae Dunger, 1983 ( Mongolia, Central Asia, Siberia)

- Mucro with lamella on its distal part......................................... mucronata Axelson, 1903 (Palearctic)

37. Abd. III with a pair of ventral medial setae................................................................ 38

- Abd. III with one ventral median seta.................................................................... 39

38. Head with ventral setae p1, four prelabral setae, mucro without tooth......... longistriata Lee, Park & Park., 2005 ( Korea)

- Head without ventral setae p1 (r), two prelabral setae, mucro with subapical tooth............................................................................................. piceeta Stebaeva & Potapov, 1994 ( Russia, Far East)

39. Abd. II without a pair of ventral medial setae................................ marina Lee, Park & Park ,, 2005 ( Korea)

- Abd. II with a pair of ventral medial setae................................................................. 40

40. Four prelabral setae..................................................... dotata Lee, Park & Park, 2005 ( Korea)

- Two prelabral setae................................................................ namia Park, 2016 ( Korea)