Figure 44. — Percentage of distribution of keel-sulcus 

 (K/S) values in Penaeus (.M.) aztecus aztecus Ivea. 



The range of P. a. aztecus is somewhat similar 

 to that of P. setiferus. P. a. aztecus, however, 

 wanders fartlier north and also farther south 

 along eastern United States, reaching the Florida 

 Keys. Both are absent along most of the Gnlf 

 Coast of peninsular Florida, and neither of the 

 two shrimps reaches Cuba. The female P. aztecus 

 from Cuba waters identified by Burkenroad as 

 P. aztecus "Fonn A" is most likely one of the 

 specimens of P. a. suitilis that show relatively long 

 and broad adrostral sulci. 



Brown shrimp are only moderately abundant 

 from North Carolina to northeast Florida and are 

 scarce in southern Florida. In spite of the exten- 

 sive sampling in the area, only a small population 

 has been found south of the Florida Keys, and 

 very few specimens have been reported from Flor- 

 ida Bay (Tabb and Manning, 1961). Recently the 

 brown shrimp was recorded for the first time 

 (Costello and Allen, 1964) from the northwest 

 Sanibel grounds, offshore from Fort Myers, in 



i 



z 



20- 



10 



20 



10 



20 



10 



z 

 i 



^ 30 



20 



10 



30 



20 



10 



20 



10 



:l. 9-15 



N=51 



C.I. 16-22 



N=50 



C.I. 23-29 



N=49 



C.I. 30-36 



N=57 



cl 37-43 



N=43 



C.I. 44-58 



N = 30 



0.75 1.25 1.75 2.25 2.75 3.25 



% 



Figure 45. — Frequency distribution of keel-sulcus (K/S) 

 values (both sexes included) in Penaeus (M.) aztecus 

 aztecus Ives of different size classes. 



WESTERN ATLANTIC SHRIMPS OF GENUS PENAEUS 



535 



