Tigriopus Norman, 1869

Chullasorn, Supawadee, Kangtia, Pawana, Song, Sung Joon & Khim, Jong Seong, 2021, Two new species of Tigriopus Norman, 1869 from Chonburi Province, Thailand (Crustacea: Copepoda: Harpacticidae), Zootaxa 5051 (1), pp. 41-67 : 64-66

Key to species of the genus Tigriopus Norman, 1869

1. Antennary exp-2 with two setae............................................................ T. brachydactylus .

- Antennary exp-2 with one seta...........................................................................2.

2. P4 exp-3 with two inner setae...........................................................................3.

- P4 exp-3 with three inner setae..........................................................................7.

3. Male P2 enp-2 inner seta discrete at base.......................................................... T. japonicus .

- Male P2 enp-2 inner seta fused to segment.................................................................4.

4. Anal operculum with fine hairs............................................................... T. californicus .

- Anal operculum naked.................................................................................5.

5. Innermost seta of female P6 not extending to posterior margin of genital double-somite; mandible with 3-segmented exopod; exopod of maxillule with three setae......................................................................6.

- Innermost seta of female P6 extending far beyond posterior margin of genital double-somite; mandible with 2-segmented exopod; exopod of maxillule with five setae............................................. T. wannapaensis sp. nov.

- Innermost seta of female P6 extending far beyond posterior margin of genital double-somite; mandible with 3-segmented exopod; exopod of maxillule with three setae................................................... T. sirindhornae .

6. Female P6 with outermost plumose seta and two bare setae; maxillulary coxa with four setae....... T. namsaiensis sp. nov. Female P6 with middle plumose seta, one bare, and one pinnate seta; maxillulary coxa with three setae..... T. thailandensis .

7. Female P5 endopod with four setae.......................................................................8. Female P5 endopod with five setae......................................................................10.

8. Mandibular basis with one seta; maxillipedal claw prehensile and well-developed............................. T. raki .

- Mandibular basis with two setae; maxillipedal claw reduced in length............................................9.

9. Male P5 endopod with one seta.................................................................. T. minutus .

- Male P5 endopod unarmed.......................................................................... T. igai .

10. Knob on male P2 enp-2 outer margin present..............................................................11.

- Knob on male P2 enp-2 outer margin absent...............................................................12.

11. Anal operculum with crenate margin; male P5 exopod with five setae.............................. T. kingsejongensis .

- Anal operculum with many fine hairs; P5 exopod with four setae...................................... T. angulatus .

12. Mandible with 1-segmented exopod; crescent shape between 1 st and 2 nd innermost seta on female P5 exopod present.....13.

- Mandible with 2-segmented exopod; crescent shape between 1 st and 2 nd innermost seta on female P5 exopod absent......14.

13. Female P5 exopod reaching to distal margin of baseoendopod (with setules on inner margin), male antennary allobasis with tiny abexopodal seta......................................................................... T. kerguelenensis .

- Female P5 exopod not reaching to distal margin of baseoendopod (without setules on inner margin), male antennary allobasis without abexopodal seta..................................................................... T. crozettensis .

14. Surfaces of antennary allobasis and P5 exopod in female with tuft of hairs.................................. T. fulvus .

- Surfaces of antennary allobasis and P5 exopod in female without tuft of hairs............................ T. brevicornis .