FISHERY BULLETIN: VOL. 75. NO. 2 



Lr" 



10 



1 I 



FIGURE 56. — Mesopenaeus tropicalis, 2 23.5 mm cl, east of Cayosde Albuquerque, western Caribbean. Lateral view. 



Rostrum rather short, its length not exceeding 

 0.4 that of carapace, reaching, at most, base of 

 second antennular article, straight or slightly 

 tilted upward, moderately high, its ventral mar- 

 gin strongly convex, often with subapical concav- 

 ity giving rise to saber shaped tip. Rostral plus 

 epigastric teeth 7-10, mode 8 (percentage distribu- 

 tion in North America: 7-2, 8-60, 9-36, 10-2, 

 N = 100; percentage distribution in South 

 America: 7-4, 8-80, 9-15, 10-1, N = 100); teeth 

 long and sharp; usually third rostral tooth, some- 

 times second, at level of orbital margin. Adrostral 

 carina sharp, extending from orbital margin to 

 ultimate tooth; postrostral carina low, short, ex- 

 tending only to level of cervical sulcus. Orbital 

 spine with broad base, short but sharp; postorbital 

 spine longest of lateral spines on carapace; anten- 

 nal spine moderately long, and hepatic spine 

 about same length. Cervical sulcus deep, gently 

 sinuous, extending almost to, but not crossing, 

 postrostral carina, ending at about 0.55 cl; hepatic 

 sulcus almost horizontal posteriorly, turning 

 anteroventrally in broad arc below hepatic spine, 



334 



and nearly reaching anterior margin of carapace. 



Eye (Figure 57) with basal article produced 

 distomesially into densely pubescent, elongate, 

 narrow scale; ocular peduncle short; cornea rather 

 broad, greatest diameter about 1.8 times that of 

 base of ocular peduncle, its proximal margin 

 strongly slanting posterolateral^. 



Mandibular palp (Figure 58A ) broad, distal 

 article almost as long as proximal, and armed 

 with unique distomesial series of hooks. First 

 maxilliped as illustrated (Figure 585); rudimen- 

 tary arthrobranchia on articular membrane (Fig- 

 ure 58BC-C 1 ). Antennular peduncle length about 

 0.6 cl; prosartema long, reaching as far as mid- 

 length of second antennular article; stylocerite 

 long, spiculiform distally, its length about 0.7 of 

 distance between its base and that of distolateral 

 spine; latter rather long, very slender, and sharp. 

 Ventral antennular flagellum typically de- 

 pressed, slightly shorter than subcylindrical 

 dorsal flagellum. Flagella longer in North Amer- 

 ican than in West Indian, Central American, and 

 South American populations (Figure 59). Ratio of 



