Figure 18. — Carapace of Meta- 

 penaeus ensis protozoea II. Scale 

 = 0.1 mm. 



Protozoea III 



14(8) A single supraorbital spine, with 

 straight carapace border between sup- 

 raorbital spine and rostrum (Fig. 



3a) 15 



2 supraorbital spines, or 1 supraorbital 

 spine with 1 or 2 small denticles, or a 

 protrusion in carapace border between 

 supraorbital spine and rostrum (Fig. 

 lOai) 16 



15(14) Rostrum about same length as eye . . . 



Metapenaeus 



Rostrum about 1.5 times eye length . . 

 Atypopenaeus 



16(14) Two well-defined supraorbital spines . 



Parapenaeus 



One supraorbital spine with 1 or 2 

 small denticles, or a protrusion in 

 carapace border between supraorbital 



spine and rostrum (Fig. 10b) 



Metapenaeapsis 



Mysis 



1 Anteroventral margin of carapace ser- 

 rated (Fig. llbi) Metapenaeopsis 



Anteroventral margin of carapace 

 smooth 2 



2(1) 3rd abdominal segment with large dor- 

 728 



FISHERY BULLETIN: VOL. 87. NO. 3, 1989 



sal spine; abdomen permanently flexed 

 at 3rd abdominal segment (Fig. 19c) . . 



Parapenaeus 



3rd abdominal segment with no spine 

 or a small spine; no permanent flexion 

 of abdomen 3 



3(2) 5th abdominal segment with a large 

 dorsal spine, equal in length to diam- 

 eter of segment (Fig. 19a) 



Macropetasma 



5th abdominal segment with no spine 

 or with a spine of length less than half 

 diameter of segment 4 



4(3) Telson spine formula 8+8 5 



Telson spine formula 7 + 7 7 



5(4) Hepatic spine present Penaeus 



Hepatic spine absent 6 



6(5) Rostrum very short, less than half eye 



length Trachypenaeus 



Rostrum longer than half eye length . . 

 Parapenaeopsis 



7(4) Rostrum down-curved, longer than eye 



Atypopenaeus 



Rostrum straight, shorter than eye . . . 

 Metapenaeus 



Postlarva 



1 3rd abdominal segment with large 



dorsal spine; abdomen permanently 

 flexed at 3rd abdominal segment (Fig. 



19d) Parapenaeus 



3rd abdominal segment with no spine 

 or a small spine; no permanent flexion 

 of abdomen 2 



2(1) Rostrum with more than one dorsal 



tooth 3 



Rostrum with zero or one dorsal teeth 

 Macropetasma 



3(2) Telson with a median spine 4 



Telson without a median spine 5 



4(3) Telson with 8+1+8 spines 



Parapenaeopsis 



Telson with 7 + 1 + 7 spines; thoracic 

 sternal spine formula 2 + 2 + + + 

 (Fig. 15d) Metapenaeopsis 



