Eusiroides, Guedes-Silva & Souza-Filho & Tavares, 2024

Guedes-Silva, Elkênita, Souza-Filho, Jesser F. & Tavares, Marcos, 2024, Three new species of Amphipoda (Crustacea: Peracarida) from the remote oceanic island of Trindade, off the coast of south-eastern Brazil, Journal of Natural History 58 (45 - 48), pp. 2075-2098 : 2094-2095

Key to world species of Eusiroides *

1a. Epimeron 3 with posterior margin strongly serrate ........................................... 2

1b. Epimeron 3 with posterior margin smooth or with short spines ................. 8

2a. Pleonites 1 and 2 with a posterodorsal spine .. .. E. caesaris Stebbing, 1888

2b. Pleonites 1 and 2 without a posterodorsal spine ............................................... 3

3a. Telson cleft for 1/3 of its total length ................................... ................................... 4

3b. Telson cleft for 1/2 or more of its total length .................................................... 5

4a. Antenna 1 peduncular article 1 and 3 with very long plumose setae on posterior margin; gnathopod 2 propodus palm corner defined by a subcute spine and a robust seta ...................................................... E. sarsi Chevreux, 1900

4b. Antenna 1 peduncular article 1 and 3 with short setae on posterior margin; gnathopod 2 propodus palm corner defined by a robust seta .......................... .......................................................................................... E. pilopalpus Jung et al., 2016

5a. Antenna 2 longer than antenna 1 ................................ E. lippus ( Haswell, 1879)

5b. Antenna 2 shorter than antenna 1 ........................................................................... 6

6a. Eyes large, nearly meeting dorsally ...... ...... E. monoculoides ( Haswell, 1879)

6b. Eyes large, not nearly meeting dorsally .................................................................. 7

7a. Gnathopod 2 carpus and propodus lined with very long setae on posterior margin ....................................... ....................................... E. japonica Hirayama, 1985

7b. Gnathopod 2 carpus and propodus lined with short setae on posterior margin .................................................................................................. E. yucatanensis McKinney, 1980

8a. Epimeron 3 smooth and posteroventral angle without a spine ................... 9

8b. Epimeron 3 smooth or with spines, and posteroventral angle with a spine ................................................................................................................... 11

9a. Pereopod 7 basis with posteroventral margin produced into a strongly developed and subacute process ................ E. stenopleura Barnard KH, 1932

9b. Pereopod 7 basis with posteroventral margin short and rounded ........... 10

10a. Eyes very enlarged, coalesced dorsally, epimeron 3 posterior margin rounded ............................................ ............................................ E. picta ( Giles, 1890)

10b. Eyes of medium size, not coalesced dorsally, epimeron 3 posterior margin quadrate .................................................................................. E. crassi Stebbing, 1888

11a. Epimeron 3 smooth ....................................................................................................... 12

11b. 8b. Epimeron 3 with 2–4 spines ............................................................................... 14

12a. Telson lined with short setae on lateral margins ...................................................... ................................... E. lucai Siqueira and Iwasa –Arai, in Iwasa–Arai et al. 2021

12b. Telson with one seta on lateral margin ................................................................ 13

13a. Telson with one very long seta on lateral margin, apex lacking seta ............... ......................................................................................... E. georgiana Barnard KH, 1932

13b. Telson with one very short seta on lateral margin, apex bearing a short seta ............................................................................................... E. dentimera Ledoyer, 1982

14a. Urosomite 1 produced into a posterodorsal carina .................................................. .......................................................................................... E. orchomenipes Walker, 1904

14b. Urosomite 1 smooth and not produced into a posterodorsal carina ....... 15

15a. Telson with truncated apex ............................................ E. diplonyx Walker, 1909

15b. Telson with rounded apex ........................................................ E. dimorphus sp. n.

* Eusiroides dellavallei Chevreux, 1899 was not included in the key.