Lebbeus, White, 1847

Wang, Yan-Rong & Sha, Zhong-Li, 2024, Lebbeus dentatus n. sp. (Decapoda, Thoridae) described from a seamount of the Caroline Plate, NW Pacific, Zootaxa 5468 (1), pp. 191-200 : 196-199

Key to species of Lebbeus with epipods on pereopods 1 and 2 (modified from Hayashi 1992 and Komai et al. 2021)

1. Carapace high-crested, higher than long................................................................... 2

-. Carapace not high-crested, not higher than long............................................................. 6

2. Maxilliped 3 ultimate article armed with 10–13 cuspidate setae on mesial to distal margin............................ 3

-. Maxilliped 3 ultimate article armed with 19 or more cuspidate setae on mesial to distal margin........................ 4

3. Dactylus of pereopods 3–5 each with 7–9 accessory spiniform setae on flexor margin; carapace with stripes thicker than palepink parts in-between and dorsal teeth only whitish at tips.............................. L. compressus Holthuis, 1947

-. Dactylus of pereopods 3–5 each with 4–5 accessory spiniform setae on flexor margin; carapace with stripes thinner than palepink parts in-between and dorsal teeth mostly whitish........................... L. altus Komai, Chang & Chan, 2021

4. Carapace dorsal crest with profile almost triangular in lateral view; carapace dotted and with dots sometimes fused............................................................................. L. cristagalli McCallum & Poore, 2010

-. Carapace dorsal crest profile evenly convex................................................................ 5

5. Maxilliped 3 ultimate article with row of 23 cuspidate setae on mesial margin; carapace dotted........................................................................................... L. clarehannah McCallum & Poore, 2010

-. Maxilliped 3 ultimate article with row of 19–20 cuspidate setae on mesial margin; carapace striped..................................................................................... L. yaldwyni Kensley, Tranter & Griffin, 1987

6. Carapace with large supraorbital tooth, distinctly longer than antennal tooth....................................... 7

-. Carapace with small supraorbital tooth, not longer than antennal tooth........................................... 9

7. Rostrum not extending to distal margin of second article of antennular peduncle, without tooth on ventral margin......... 8

-. Rostrum beyond distal margin of second article of antennular peduncle, ventral margin bearing 2 teeth subdistally............................................................................................... L. dentatus n. sp.

8. Antennular stylocerite hardly reaching to distal margin of second article of antennular peduncle; fourth pleomere rounded, without posteroventral tooth........................................... L. brevirostris Chang, Komai & Chan, 2010

-. Antennular stylocerite extending to distal end of antennular peduncle; fourth pleomere with sharp posteroventral tooth................................................................................... L. laevirostris Crosnier, 1999

9. Fourth pleomere pleuron rounded, without posteroventral tooth................................................ 10

-. Fourth pleomere pleuron with sharp posteroventral tooth (uncertain in L. heterochaelus )............................ 16

10. Rostrum longer than carapace, extending beyond distal end of antennal scale..................................... 11

-. Rostrum shorter than carapace, not extending to distal end of antennal scale...................................... 12

11. Pereopods 3–5 dactyli simple................................................. L. longidactylus ( Kobjakova, 1936)

-. Pereopods 3–5 dactyli biunguiculate.................................... L. splendidus Wicksten & Méndez G., 1982

12. Rostrum slender, not broadened on lower margin near apex................................................... 13

-. Rostrum with lower margin broadened near apex........................................................... 14

13. Third pleomere produced mesiposteriorly, over fourth pleomere; dorsodistal margin of the first article of the antennular peduncle armed only with a lateral spine......................................................... L. balssi Hayashi, 1992

-. Third pleomere not produced mesiposteriorly; dorsodistal margin of the first article of the antennular peduncle armed with lateral multiple spines............................................................. L. brevicornis Komai, 2011

14. Pereopods 3–5 with dactylus simple...................................... L. scrippsi Wicksten & Méndez G., 1982

-. Pereopods 3–5 with dactylus biunguiculate................................................................ 15

15. Ultimate article of third maxilliped with a comb of numerous cuspidate setae on mesial margin................................................................................................ L. grandimanus ( Bražnikov, 1907)

-. Ultimate article of third maxilliped only with a few cuspidate setae near tip.................. L. acudactylus Jensen, 2006

16. Rostrum not extending to distal end of antennular peduncle; first article of antennular peduncle with 2 or 3 marginal teeth on dorsodistal margin................................................................................... 17

-. Rostrum extending to at least distal end of antennular peduncle; first article of antennular peduncle with single tooth at distolateral angle..................................................................................... 18

17. Antennal scale with distolateral tooth not reaching distal margin of lamella; telson with 6 pairs of dorsolateral spines........................................................................................ L. kuboi Hayashi, 1992

-. Antennal scale with distolateral tooth far overreaching distal margin of lamella; telson with 4 pairs of dorsolateral spines................................................................................. L. laurentae Wicksten, 2010

18. Rostrum falling far short of end of antennal scale...................................... L. brandti ( Bražnikov, 1907)

-. Rostrum almost to or beyond end of antennal scale.......................................................... 19

19. Rostrum longer than carapace and reaching beyond antennal scale............................................. 20

-. Rostrum as long as carapace and extending to end of antennal scale............................................ 22

20. Fingers of chela of second pereopod twice as long as palm............................ L. unalaskensis (Rathbun, 1902)

-. Fingers of chela of second pereopod distinctly shorter than palm............................................... 21

21. Rostrum with well-developed ventral blade; stylocerite extending to distal margin of first article of antennular peduncle........................................................................... L. tenuipes Komai & Matsuzaki, 2022

-. Rostrum without ventral blade; stylocerite not extending to distal margin of first article of antennular peduncle.................................................................................. L. subtilis Komai & Matsuzaki, 2022

22. Rostrum with teeth on almost entire dorsal margin................................... L. vinogradovi Zarenkov, 1960

-. Distal third or more of dorsal margin of rostrum unarmed.................................................... 23

23. Carpus of pereopods 3–5 with few outer spines; endopod of uropod with row of small spines on dorsal surface; fingers of chela of second pereopod twice as long as palm in large male; rostral teeth formula, male 0+0/2–5+1, female 2–3+2–3/2–5+1............................................................................ L. heterochaelus ( Kobjakova, 1936)

-. Carpus of pereopods 3–5 without few outer spines; endopod of uropod without spines; In large male chela of second pereopod similar in male and female; rostral teeth formula, male 0–3+0–5/3–7+1, female 2–3+1-6/3–9+1.... L. polaris (Sabine, 1824)