Key to species of the genus Sadayoshia

1. Abdominal somite 2 with spines on anterior ridge............................................................ 2

– Abdominal somite 2 unarmed............................................................................ 5

2. Abdominal somite 2 with 4 spines on anterior ridge........................................ S. balica (Boone, 1935)

– Abdominal somite 2 with 2 spines on anterior ridge.......................................................... 3

3. Rostrum with dorsal longitudinal carina........................................................ S. moorei n. sp .

– Rostrum without dorsal longitudinal carina, convex from side to side............................................. 4

4. Posterior branchial region with 10 or 11 transverse ridges (counting along lateral margin; exclusive of mid-transverse ridge directly behind cervical groove and posteriormost ridge anterior to posterior margin of carapace).......... S. aludra n. sp .

– Posterior branchial region with 3 or 4 transverse ridges (counting along lateral margin; exclusive of mid-transverse ridge directly behind cervical groove and posteriormost ridge anterior to posterior margin of carapace)... S. acroporae Baba, 1972

5. Antennular article 1 with accesory spine on lateral margin, proximal to distolateral spine............................ 6

– Antennular article 1 with lateral margin unarmed............................................................. 9

6. One (rarely 2) spine mesial to anterolateral spine of carapace. Rostrum with dorsal longitudinal carina................................................................................................... S. edwardsii (Miers, 1884)

– No spine mesial to anterolateral spine of carapace. Rostrum without dorsal longitudinal carina....................... 7

7. Postcervical spine absent............................................................... S. miyakei Baba, 1969

– Postcervical spine present............................................................................... 8

8. Flexor margin of Mxp 3 merus with 2 well-developed spines of subequal size, distally bearing small or obsolete spine. P2 merusmore than 3.5 times as long as broad.................................................... S. acamar n. sp .

– Flexor margin of Mxp 3 merus usually with 3 well-developed spines. P2 merus less than 3.5 times as long as broad................................................................................. S. lipkei Macpherson & Baba, 2010

9. Sternite 3 more than 3 times as broad as long; sternite 4 about twice as broad as sternite 3. Abdominal somites 2–4 without transverse ridges other than anterior ridge................................................................ 10

– Sternite 3 at most twice as broad as long; sternite 4 about 3 times as broad as sternite 3. Abdominal somites 2–4 with 1–3 trans- verse ridges in addition to anterior ridge................................................................... 11

10. Anterior branchial spine absent. Rostral spine 2 times longer than wide (measured at sinus between rostral and anterior lateral spines).................................................................................. S. actaea n. sp .

– Anterior branchial spine present. Rostral spine 3 times longer than wide (measured at sinus between rostral and anterior lateral spines).............................................................. S. latisternata Macpherson & Baba, 2010

11. Postcervical spine absent............................................................................... 12

– Postcervical spine present.............................................................................. 13

12. Rostral spine less than 2 times as long as wide (measured at sinus between rostral and anterior lateral spines). Mxp3 merus usu- ally with 2 flexor marginal spines.............................................................. S. adaro n. sp .

– Rostral spine 2.5–3 times as long as wide (measured at sinus between rostral and anterior lateral spines). Mxp3 usually with 3 or 4 flexor marginal spines................................................. S. inermis Macpherson & Baba, 2010

13. Rostral spine more than 3.5 times as long as wide (measured at sinus between rostral and first lateral spine).................................................................................. S. tenuirostris Macpherson & Baba, 2010

– Rostral spine less than 2.5 times as long as wide (measured at sinus between rostral and first lateral spine).... S. savali n. sp.