PEREZ FARFANTE: ROCK SHRIMP GENUS SICYONIA 



passing distal end of third antennular article; lat- 

 eral rib produced in long, slender spine slightly 

 overreaching lamella. Antennal flagellum as 

 much as 3 times as long as carapace. 



Third maxilliped much stouter than pereopods. 

 Basis and ischium of first pereopod armed with 

 short but well-developed sharp spine projecting 

 from distomesial margin. 



Abdomen with dorsomedian carina low an- 

 teriorly, increasing in height posteriorly; carina on 

 first somite produced in rather small, anteriorly 

 directed tooth, smaller than posterior tooth on 

 carapace; carina on second somite conspicuously 

 incised (just dorsal to juncture of tergal sulci) and 

 that on sixth terminating in short, sharp tooth. 



Antero ventral extremity of pleuron of first three 

 somites rounded; pleuron of fourth with postero- 

 ventral extremity angular or subangular, always 

 unarmed; postero ventral extremity of fifth and 

 sixth somites produced in very small, caudally 

 directed, sharp tooth. 



First somite with short anteromedian pleural 

 sulcus (usually well marked but sometimes 

 obscure dorsally, obsolete, or represented by shal- 

 low depression ventrally) and long, united pos- 

 terior tergal-posteromedian pleural sulci. Second 

 and third somites marked by 1) long anterior ter- 



gal (extending to base of pleuron) and short pos- 

 terior tergal sulci; 2) anteromedian pleural sulcus, 

 extending to near ventral margin on second somite 

 but restricted to dorsal part on third, in both so- 

 mites delimiting anterior shallow depression set- 

 ting off weak prominence dorsally; and 3) pos- 

 teromedian pleural sulcus, its dorsal extremity 

 curving anteriorly ventral to (not joining) pos- 

 terior tergal sulcus. Fourth and fifth somites with 

 anterior tergal sulcus (that of fourth obliterated 

 about midlength), merging with united posterior 

 tergal-posteromedian pleural sulci. Sixth somite 

 marked by weak, arched posteromedian pleural 

 sulcus and bearing shallow longitudinal depres- 

 sion between low dorsolateral ridge and elongate 

 cicatrix. 



Telson with pair of short but strong fixed spines 

 and two longitudinal rows of movable spinules on 

 each side of median sulcus. Rami of uropod reach- 

 ing or barely overreaching apex of telson. 



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

 tion of dorsolateral lobule bulbous proximally, al- 

 most straight but with terminal part strongly 

 curved dorsally; fleshy distal projection of ven- 

 trolateral lobule directed distolaterally, broad 

 basally, and with slender but blunt terminal part 

 curved proximally. Lateral margin of petasma 



Figure lO. —Sicyonia laevigata, 6 5.7 mm cl, Isla Taboga, Panama. A, Petasma, dorsal view; fi, ventral view; C, right appendix 



masculina, dorsolateral view. Scale = 0.5 mm. 



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