20 



10 



30 



20 



z 



uj 

 i 



10 



u. 



10 



20 



10 



10 



C.I. 9-15 



N = 35 



C.I. 16-22 



N=61 



C.I. 23-29 



N=16 



30-36 



N = 30 



C.I. 37-43 



N = 9 



2.0 



3.0 4.0 



5.0 



Figure 54. — Frequeucy distribution of keel-sulcus (K/S) 

 values (both sexes ineliuleil) in Pcnactis (J/.) nztecux 

 nuhtilis Perez Farfante of different size classes from 

 the Caribbean region and eastern Brazil. 



spines along distoniedian margin. Anterior surface 

 subplane, posterior surface strongly concave, witli 

 sharp longitudinal ridge projecting from median 

 margin. 



THELYCUM (fig. 58) 



Anterior process projecting ventrally in sharp, 

 relatively low, marginal arc-shaped ridge, often 

 expanding on both sides, and surrounding shallow 

 depression with knob usually present at center. 



30- 



20 



N = 173 



-^ 



10- 



01 L 





_l I L_ 



2.0 3.0 



4.0 5.0 6.0 



7.0 8.0 



Figure 55. — Percentage of distribution of keel-sulcus 

 (K/S) values in Pcnacus (J/.) aztecus siibtilis Perez 

 Farfante from the Gulf of Paria to Camocim, Brazil. 



Posterior process broad, with anteriorly bifurcate 

 median carina, resulting ribs turning medially and 

 converging at base of anterior process, giving rise 

 to diamondlike structure; enclosed area deeply 

 concave or almost flat, plain, or, more often, bearing 

 median rib anteriorly, posteriorly, or along entire 

 length. 



COLOR 



P. a. subtilis, although variable in color, is most 

 often bi-own — thus, the name camaron marron 

 (brown shrimp) in Venezuela, and camarao lixo 

 (dirty shrimp) in Brazil. Grayish brown or yel- 

 lowish specimens are rather common, and in some 

 localities individuals are translucent pale yellow 

 and are called camarao branco (white shrimp) in 

 Brazil. 



According to Holthuis (1959) and Davant 

 (1963), no large dark spots have been observed 

 on the sides, at the junction of the third and fourth 

 abdominal somites, in this shrimiJ, at least in those 

 along the northern and northeastern coasts of 

 South America. 



5.50 



U.S. FISH AND WILDLIFE SERVICE 



