Austinixa, Heard & RB Manning, 1997

Key to species of Austinixa View in CoL (modified from Palacios Theil and Felder, 2020b)

1. Carapace without branchial ridges .............................................................................................................................2

- Carapace with branchial ridges .....................................................................................................................................5

2. P4 propodus opposable margin bicarinate ...............................................................................................................3

- P4 propodus opposable margin with single carina (NE FL, GMx, Car) ............................................................... ............................................................................................................................ A. gorei ( Manning and Felder, 1989) View in CoL

3. Male carapace with patch of short setae on posterior third, just anterior to cardiac ridge. Male pleon telson subtriangular or semicircular, not wider than long.................................................................................................4

- Male carapace without patch of short setae on posterior third, just anterior to cardiac ridge. Male pleon telson semi-ellipsoid, clearly wider than long (E Pac) .......................................... A. felipensis ( Glassell, 1935) View in CoL

4. Male pleon telson subtriangular. Setal patch on male carapace posterior third connecting with setae on lateral regions. Female carapace with setae on lateral regions extending also onto anterolateral regions (E Pac) ....................................................................................................... A. cuestai Palacios Theil and Felder, 2020a View in CoL

- Male pleon telson semicircular. Setal patch on male carapace posterior third clearly separated from setae on lateral regions. Setae on female carapace confined to most lateral regions (SW Atl) ................................ ...................................................................................................................................................... A. aidae (Righi, 1967) View in CoL

5. Branchial ridges each extending to orbits (SW Atl) ................................... A. patagoniensis (Rathbun, 1918) View in CoL

- Branchial ridges falling short of orbits ........................................................................................................................6

6. P4 merus with distinct depression on posterior or dorsal surface ......................................................................7

- P4 merus without distinct depression on posterior or dorsal surface ................................................................. 9

7. P4 merus with proximal depression on posterior to postero-dorsal surface into which dactylus of P5 fits (SW Atl) .....................................................................................................................A. leptodactyla (Coelho, 1997)

- P4 merus with distal depression on dorsal surface, not positioned to fit P5 dactylus ......................................8

8. Male pleon subrectangular, lateral margins of pleonites subparallel, telson semi-ellipsoidal, about as long as sixth somite (Car). ........................................................................ A. roblesi Palacios Theil and Felder, 2020a View in CoL

- Male pleon subtriangular, tapering, margin of pleonites decreasing in width distally, telson triangular, clearly longer than the sixth pleonite (E Pac) ....................................................................... A. marianae View in CoL sp. nov.

9. Male carapace without patch of short setae on posterior third, just anterior to cardiac ridge ................... 10

- Male carapace with patch of short dark setae on posterior third, just anterior to cardiac ridge. (SW Atl) ... ........................................................................................................................................... A. bragantina Coelho, 2005 View in CoL

10. Branchial ridges angled laterally, with sharp bend toward posterior ............................................................ 11

- Branchial ridges extending laterally or gently curved towards posterior lacking sharp bend laterally...12

11. P4 propodus opposable margin with single carina. First gonopod with truncate apex (GMx) ................... ..................................................................................................................................................... A. chacei (Wass, 1955) View in CoL

- P4 propodus opposable margin bicarinate. First gonopod apex hooked, styliform (GMx).............................. ....................................................................................................................... A. behreae ( Manning and Felder, 1989) View in CoL

12. P5 dactylus clearly reaching beyond distal end of P4 merus. P4 merus anterior margin carinate, carina not clearly laminate. Carapace depressions lateral to front narrow and short, not reaching dorsally to near branchial ridges. Carapace 2.2–2.9 times wider than long. Male telson semicircular (NW Atl, GMx) ..... ............................................................................................................................................ A. cristata (Rathbun, 1900) View in CoL

- P5 dactylus not clearly reaching beyond distal end of P4 merus. P4 merus anterior margin flattened into strongly laminate crest; merus posterior half robust, clearly swollen. Carapace depressions lateral to front reaching nearly to branchial ridges. Carapace 1.7–2.3 times wider than long. Male telson prolate semi-ellipsoidal, less than twice as wide as long (Car)....................................................................................................... ............................................................................................................ A. artankeri Palacios Theil and Felder, 2020a View in CoL