Tanaidomorpha, Sieg, 1980

Abarca-Ávila, Mónica Mariel, Herrera-Dorantes, María Teresa, Winfield, Ignacio & Ardisson, Pedro-Luis, 2019, Updated checklist and identification key of benthic tanaidaceans (Crustacea Peracarida) of the sublittoral zone of the northern Yucatan Peninsula, Mexico, Zootaxa 4711 (1), pp. 51-76 : 71

Suborder Tanaidomorpha

1. Pleon with last two pleonites fused or reduced; pereopods without ischium....................................... 2

- Pleon with five unfused pleonites; pereopods with ischium.................................................... 3

2. Pereopod-1 with anterior distinct lobe in the coxa; pereopod-6 dactylus with a row of six spines on lateral margin........................................................................................... .. Zeuxo cf. kurilensis

- Pereopod-1 with or without lobe in the coxa; pereopod-6 dactylus with a row of more than six spines on lateral margin.............................................................................................. Anatanais sp.

3. Uropodal endopod with two articles; with a plumose seta on lateral margins of first four pleonites.......... Paratanais sp.

- Uropodal endopod with three or more articles; without plumose setae on lateral margins of pleonites....................4

4. Antennule with three articles.....................................................................5 (females)

- Antennule with six or more articles................................................................12 (males)

5. Uropodal endopod with three or four articles............................................................... 6

- Uropodal endopod with five or six........................................................................9

6. Antennule with proximal article short and broad............................................................ 7

- Antennule with proximal article long and narrow............................................................ 8

7. Cephalothorax with demarcation of the second thoracomere by separation of two carapace plates; uropodal endopod with four articles.............................................................................. Parakonarus juliae

- Cephalothorax without demarcation of the second thoracomere; uropodal endopod with three articles. Pseudoleptochelia sp.

8. Distal margin of maxillipedal basis with three pairs of long simple setae; uropodal endopod with three articles in similar length..................................................................... Cacoheterotanais rogerbamberi

- Distal margin of maxillipedal basis with one or two pairs of long simple setae; uropodal endopod with four articles often of variable length....................................................................... Pseudonototanais sp.

9. Uropodal endopod with five articles.......................................................... Hargeria rapax

- Uropodal endopod with six articles...................................................................... 10

10. Uropodal exopod shorter than the first article of endopod.................................................... 11

- Uropodal exopod larger than the first article of endopod................................... Alloleptochelia longimana

11. Body with small dark dots............................................................... Leptochelia forresti

- Body without small dark dots..................................................... Leptochelia sp. aff. savignyi

12. Uropodal endopod with three or four articles.............................................................. 13

- Uropodal endopod with five or six articles................................................................ 16

13. Chela propo-chelate (normal form)...................................................................... 14

- Chela carpo-chelate (hook form).........................................................................15

14. Chela with fixed finger two-thirds length of dactylus, with a tooth on the subdistal inner margin; antennule with six articles; uropodal endopod with three articles............................................ Cacoheterotanais rogerbamberi

- Chela with fixed finger three-quarters length of dactylus, without a tooth on the subdistal inner margin; antennule with five articles; uropodal endopod with three articles ……………………………………………. Pseudonototanais sp.

15. Chela with a prominent carpal process, fixed finger reduced, about quarter length of dactylus; uropodal endopod with four articles … Parakonarus juliae

- Chela with an underdeveloped, or lacking, carpal process, fixed finger reduced, about quarter length of dactylus; uropodal endopod with four articles............................................................ .. Pseudoleptochelia sp.

16. Length of the antennule and extended chelipeds of almost two-thirds total length of the body........................ 17

- Length of the antennule and extended chelipeds equal to or greater than the total length of the body.................. 18

17. Post-anal spatulate process present; uropodal endopod with five articles.............................. Hargeria rapax

- Post-anal spatulate process absent; uropodal endopod with four to six articles............... Leptochelia sp. aff. savignyi

18. Body with small dark spots; chela without small teeth on proximal inner margin; fixed finger with a rounded process on subdistal part............................................................................ Leptochelia forresti

- Body without small dark spots; chela with small teeth on proximal inner margin; fixed finger without rounded process on subdistal part...................................................................... Alloleptochelia longimana