Thalassaphorura Bagnall 1949

Key to world species of the genus Thalassaphorura Bagnall, 1949

(Modified from Sun, Chen & Deharveng 2010)

1 Antennal base with 4 pso............................................................................... 2

- Antennal base with 3 pso.............................................................................. 4

2 AS absent, dorsal pso formula as 42/333/33332...................... T. hoguei (Palacios-Vargas & Díaz, 1995), Mexico

- AS present.......................................................................................... 3

3 Head with 3+3 posterior pso, Abd. I–III terga with 4+4 pso each.............................................................................................. T. halophila (Bagnall, 1937) sensu Fjellberg 1998; Northern Holarctic

- Head with 2+2 posterior pso, Abd. I–III terga with 3+3 pso each................... T. tamurai (Yue & Yin, 2000); China

4 AIIIO with 4 papillae................................................................................. 5

- AIIIO with 5 papillae................................................................................. 9

5 AS present.......................................................................................... 6

- AS absent........................................................................................... 8

6 Head with 3+3 posterior pso, dorsal pso formula as 33/033/333(4)43, pso absent ventrally, basal lamella on unguiculus absent, AS /unguis ratio as 0.8.................................................. T. biquaternata Sun & Li, 2015b; China

- Head with 2+2 posterior pso............................................................................ 7

7 Pso formula dorsally as 32/122/22332, ventrally as 1/000/001100, basal lamella on unguiculus present....................................................................................... T. butrosi (Christiansen, 1956); Lebanon

- Pso formula dorsally as 32/233/33343, ventrally as 11/000/01120, basal lamella on unguiculus absent........................................................................................... T. xihuensis Sun & Li, 2015a; China

8 Pso formula ventrally as 11/000/01000, VT with 0+0/6+6/1+1 chaetae..................................................................... T. cryptopyga (Denis, 1931) sensu Najt & Weiner, 1997; Neotropics, Pacific islands, Indonesia

- Pso formula ventrally as 11/000/01120, VT with 1+1/6+6/2+2 chaetae........................................................................................................... T. tovtrensis (Kaprus’ & Weiner, 1994); Ukraine

9 Th. I tergum without pso.............................................................................. 10

- Th. I tergum with pso................................................................................ 13

10 Head with 3+3 posterior pso, unguiculus with basal lamella, AS /unguis ratio as 1......................................................................................... T. alborufescens (Vogler, 1895) sensu Gisin (1957); Europe

- Head with 2+2 posterior pso, unguiculus without basal lamella................................................ 11

11 Abd. I –III terga with 2+2 pso, AS /unguis ratio as 0.9....................... T. bagnalli (Salmon, 1959); Great Britain.

- Abd. I–III terga with 3+3 pso, AS /unguis ratio as 0.6–0.7.................................................... 12

12 Pso formula dorsally as 32/022/33323.................................. T. kirgisica (Martynova, 1971); Kirghizstan

- Pso formula dorsally as 32/033/33333............................................... T. lolae Arbea, 2017; Spain

13 Th. I tergum with 1+1 pso............................................................................. 14

- Th. I tergum with 2+2 pso............................................................................. 25

14 Pso formula dorsally as 32/11(3)1(2)/22(3)2(3)2(3)3, AS /unguis ratio as 0.9........................................ T. moniezi (Bagnall, 1935) Great Britain. Note: Sun et al. (2010), following Bagnall (1937), consider the species as a member of his “group” “ T. debilis ”.

- Pso formula dorsally different.......................................................................... 15

15 Th. II–III terga with 2+2 pso each....................................................................... 16

- Th. II–III terga with 3+3 pso each....................................................................... 19

16 Subcoxa 1 of legs I, II, III with 1, 1, 1 pso................................................................ 17

- Subcoxa 1 of legs I, II, III with 2, 2, 2 pso................................................................ 18

17 Pso formula ventrally as 11/000/01000, VT with 1+1 anterior chaetae..... T. reducta Sun, Chen & Deharveng, 2010; China

- Pso formula ventrally as 11/000/01110, VT without anterior chaetae.................... T. guangxiensis sp. nov.; China

18 3+3 chaetae between posterior pso on head, VT with 1+1 basal chaetae, AS /unguis ratio as 0.4, unguiculus/unguis ratio as 0.4, 3+3 paired axial chaetae on Abd. I–III terga........................... T. bapen Sun, Chen & Deharveng, 2010; China

- 4+4 chaetae between posterior pso on head, VT with 2+2 basal chaetae, AS /unguis ratio as 0.6, unguiculus/unguis ratio as 0.7, 2+2 paired axial chaetae on Abd. I–III terga................................. guangdongensis Sun & Li, 2015a; China

19 Abdominal sterna without pso, AS /unguis ratio as 0.7–1.1............. T. thalassophila (Bagnall, 1937); Northern Europe

- Abdominal sterna with pso............................................................................ 20

20 Pso formula on Abd. I–V dorsally as 33334, ventrally as 0 1120, subcoxa 1 of legs I, II, III with 1, 1, 1 pso, AS /unguis ratio as 0.3, d0 on head absent........................................ T. jailolonis (Yoshii & Suhardjono, 1992); Indonesia

- Pso formula on Abd. I–V different...................................................................... 21

21 Subcoxa 1 of legs I, II, III with 1, 1, 1 pso, pso formula dorsally as 32/133/33343, ventrally as 11/000/00010, unguiculus reduced to small blunt process..................................... T. brevisetosa Sun, Gao & Potapov, 2014; China

- Subcoxa 1 of legs I, II, III with 2, 2, 2 pso................................................................ 22

22 Chaetae d0 on head absent, tibiotarsi with 6 chaetae in the distal whorl, labium type AB, VT with 0+0/8–11+8–11/1+1 (8– 10+ 8–10 in females, 11+ 11 in males, of which 9+9 modified) chaetae, pso formula on Abd. I –V dorsally as 33343, ventrally as 0 0 0 10, AS /unguis ratio as 1.1–1.2.............................. T. problematica Sun, Deharveng & Wu, 2013; China

- Chaetae d0 on head present, tibiotarsi with 9 chaetae in the distal whorl, labium type AC........................... 23

23 3+3 p-chaetae between two inner posterior pso on head, VT with 1+1/7+7(8)/2+2 chaetae, pso formula on Abd. I–V dorsally as 3,3-4,3,4-6,3-4, ventrally as 0111(2)0, AS /unguis ratio as 0.47–0.77.................................................................................................... T. debilis (Moniez, 1890); Western and northern Europe

- 4+4 p-chaetae between two inner posterior pso on head..................................................... 24

24 AS /unguis ratio as 0.75, Th. I sternum with 1+1 chaetae................ T. grandis Sun, Chen & Deharveng, 2010; China

- AS /unguis ratio as 0.2, Th. I sternum without chaetae................................ T. microspinata sp. nov.; China

25 Pso formula dorsally as 32/233/33343................................................................... 26

- Pso formula dorsally different.......................................................................... 45

26 AS absent.................................................................... T. franzi (Stach, 1946); Austria

- AS present.......................................................................................... 27

27 Tibiotarsi with 6–7 chaetae in the distal whorl............................................................. 28

- Tibiotarsi with 9 chaetae in the distal whorl............................................................... 31

28 Pso formula on Abd. I –V ventrally as 0 0 0 10............................................................................................ T. sensilata (Thibaud & Massoud, 1979); Dominica (France), Guadeloupe (France), Mexico

- Pso formula on Abd. I–V ventrally as 0 1120.............................................................. 29

29 1+1 dorsal S-chaetae on head, AS /unguis ratio as 1....... T. petaloides (Rusek, 1981); Irak, New Caledonia, Hawaii, China

- 2+2 dorsal S-chaetae on head.......................................................................... 30

30 Unguiculus/unguis ratio less than 0.2, head ventrally with 1+1 pso, AS /unguis ratio as 0.9................................................................................................. T. thaibinhensis Nguyen, 2001; Vietnam

- Unguiculus/unguis ratio as 0.5, head ventrally with 2+2 pso, AS /unguis ratio as 0.7............................................................................................ T. tibiotarsalis Sun, Chen & Deharveng, 2010; China

31 Pso formula on Abd. I–V ventrally 11/000/01110.......................................................... 32

- Pso formula on Abd. I–V ventrally as 11/000/01120 or 11/000/11120........................................... 33

32 Th. I tergum with 7+7 chaetae, body length 1.4 mm............................................................................................... T. duplopunctata (Strenzke, 1954) sensu Fjellberg 1998 and; Northern Holarctic

- Th. I tergum with 5+5 chaetae, body length 0.8–1.1 mm.............. T. pomorskii Sun, Chen & Deharveng, 2010; China

33 Pso formula ventrally as 11/000/11120, 1+1 dorsal S-chaetae on head, AS /unguis ratio as 1, Unguiculus /unguis ratio as 0.7, without basal lamella................................................... T. kwona (Thibaud & Lee, 1994); Korea

- Pso formula ventrally as 11/000/01120................................................................... 34

34 4+4 chaetae between inner posterior pso on head........................................................... 35

- 3+3 chaetae between inner posterior pso on head........................................................... 36

35 AS /unguis ratio as 0.5, VT with 1+1/6+6/2+2 chaetae, male ventral organ absent....................................

.................................................. T. lifouensis (Thibaud & Weiner, 1997); New Caledonia, China - AS /unguis ratio as 0.9–1.0, VT with 1+1/7+7/2+2 chaetae, male ventral organ presents on VT as 2+2 strongly modified distal chaetae.............................................................. T. qinlingensis Sun & Wu, 2013; China

36 Th. I sternum without chaetae, PAO with 16–17 vesicles, Th. I tergum with 5+5 chaetae, unguiculus with basal lamella, unguiculus/unguis as 0.7, AS /unguis ratio as 0.3, on indistinct papillae, VT with 1+1/6+6/2+2 chaetae, Abd. VI tergum with one unpaired chaeta a0............................................ T. hainanica Sun, Gao & Potapov, 2014; China

- Th. I sternum with 1+1 chaetae......................................................................... 37

37 PAO with about 10–13 vesicles, dorsal S-chaetae formula as 2/011/11101, unguiculus without basal lamella, unguiculus/unguis as 1, VT with 1+1/5+5/2+2 chaetae, Th. I tergum with 6+6 (7+7) chaetae, AS /unguis ratio as 0.4.................................................................................................. T. tenuis Babenko, 2007; Russia

- PAO with more than 20 vesicles........................................................................ 38

38 Th. I tergum with 5+5 chaetae.......................................................................... 39

- Th. I tergum with more than 5+5 chaetae................................................................. 41

39 Abd. VI tergum with one unpaired axial chaeta (m0)......... T. zschokkei (Handschin, 1919) sensu Pomorski 1998; Europe

- Abd. VI tergum with two unpaired axial chaetae (a0 and m0)................................................. 40

40 Unguiculus without basal lamella, PAO with 21–23 vesicles, unguiculus/unguis ratio as 0.6, AS /unguis ratio as 0.6..................................................................................... T. linzhiensis Sun & Li, 2015a

- Unguiculus with basal lamella, PAO with 24–26 vesicles, unguiculus/unguis ratio as 0.5, AS /unguis ratio as 1............................................................................. T. tiani Sun, Chen & Deharveng, 2010; China

41 Labial type A, VT with 1+1/6–7+6–7/1+1 (2+2) chaetae, 6 proximal chaetae on labium, AS/unguis ratio as 0.8............................................................. T. encarpata (Denis, 1931) sensu Fjellberg 1998; Cosmopolitan

- Labial type AC..................................................................................... 42

42 7 proximal chaetae on labium, VT with 0+0/6–7+6–7/0+0 chaetae, male ventral organ presents as 6–12 setae on Abd. II and 7– 10 on Abd. III arranged asymmetrically, AS /unguis ratio as 0.8.............. T. qixiaensis Yan, Shi, & Chen, 2006; China

- 6 proximal chaetae on labium.......................................................................... 43

43 Furca with only two small dental chaetae, chaetae on ventral tube as 1+1/7+7/2+2, male ventral organ presents on VT as 2+2 strongly modified distal chaetae, AS /unguis ratio as 0.9........................... T. bisetosa Sun & Wu, 2013; China

- Furca with four small dental chaetae..................................................................... 44

44 Chaetae on ventral tube as 1+1/7+7/2+2, male ventral organ presents on VT as 2+2 strongly modified distal chaetae, AS / unguis ratio as 0.7........................................................... T. petiti Sun & Wu, 2013; China

- Chaetae on ventral tube as 1+1/6+6/2+2, male ventral organ presents on VT as 5+5 strongly modified distal chaetae, AS / unguis ratio as 1.1..................................................... T. macrospinata Sun & Wu, 2012; China

45 Pso formula on Abd. I–V dorsally as 32/233/33333......................................................... 46

- Pso formula on Abd. I–V dorsally different............................................................... 49

46 PAO with about 45 vesicles, AS/unguis ratio as 0.4................................. T. ishikawai (Yosii, 1956); Japan

- PAO with less than 40 vesicles......................................................................... 47

47 Unguiculus with basal lamella, PAO with about 25 vesicles, AS /unguis ratio as 0.7......................................................................................................... T. guineaensis (Salmon, 1965); Guinea

- Unguiculus without basal lamella....................................................................... 48

48 Th. I sternum without chaetae, pso formula ventrally as 1/000/11120............... T. yolandae (Izarra, 1971); Venezuela

- Th. I sternum with 1+1 chaetae, pso formula ventrally as 11/000/11200......... T. yodai (Yosii, 1966); Nepal, China, Japan

49 Pso formula dorsally as as 32/1-233/3,3-4,3,4-6,3-4, ventrally as 11/000/0111(2)0, VT with 1+1/7+7(8)/2+2 chaetae, AS / unguis ratio as 0.47–0.77.............................................. T. debilis (Moniez, 1890); Northern Europe

- Pso formula different................................................................................. 50

50 Pso formula dorsally as 32/233/3333(4)2, ventrally as 11/000/00010, VT with “9–10+9–10” chaetae, AS /unguis ratio as 0.5............................................................................ T. orientalis (Stach, 1964); China

- Pso formula dorsally as 32/233/33342, ventrally as 1/111/00000, VT with 1+1/6+6/1+1 chaetae, AS /unguis ratio as about 0.7......................................................................... T. ghatensis (Prabhoo, 1971); India