pfiREZ FARFANTE: ROCK SHRIMP GENUS SICYONIA 



FIGURE 19. 



-Sicyonia mixta , 6 12 mm cl, off Cabo San Lucas, Baja California Sur, Mexico. A , Petasma, dorsal view; B , ventral 

 view of same; C, right appendix masculina, dorsolateral view. Scale = 1 mm. 



tergal, and sixth bearing weak anterior tergal and 

 arched posteromedian pleural sulci. 



Telson with paired fixed spines extremely mi- 

 nute (in the only specimen examined by me in 

 which they are present). Rami of uropod, subequal 

 in length, falling slightly short of apex of telson. 



Petasma (Fig. 19A, B ) with rigid distal projec- 

 tion of dorsolateral lobule bearing rounded prox- 

 imodorsal prominence, extending almost straight 

 distally but with tip curved dorsally Distal projec- 

 tion of ventrolateral lobule bifid (arms curved), 

 inclined laterally, and falling considerably short of 

 adjacent projection. 



Appendix masculina as illustrated in Figure 

 19C. 



Thelycum (Fig. 20) with plate of sternite XIV, 

 delimited by rounded lateral margins, raised in 

 paired bulges sloping towards deep median de- 

 pression. Median plate of sternite XIII roughly 

 flaskshaped in outline, tapering into long, slender 

 spine reaching proximal extremity of basis of an- 

 teriorly extended second pereopods; posterior 

 component of plate with arched posterior borders 

 flanking shallow to deep, broad median emargina- 

 tion, and traversed by strongly incised suture. 

 Sternite XI armed posteriorly with paired, mod- 

 erately long, acute spines. Posterior thoracic ridge 

 with sharp, concave, anteromedian margin over- 



FIGURE 20. —Sicyonia mixta, 9 13 mm cl, off Isla T^boga, Golfo 

 de Panama, Panama. Thelycum. Scale = 1 mm. 



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