PEREZ FARFANTE: ROCK SHRIMP GENUS SICYONIA 



mesial base of distolateral spine; latter, slender 

 and sharp, extending to about midlength of second 

 antennular article; antennular fiagella short, me- 

 sial one slightly shorter, 0.20-0.30 cl, than lateral, 

 0.25-0.35 cl. 



Scaphocerite extending to midlength of third 

 antennular article or slightly overreaching it. An- 

 tennal flagellum about twice as much as twice 

 length of carapace. 



Third maxilliped slightly stouter than 

 pereopods. Basis and ischium of first pereopod un- 

 armed. 



Abdomen with dorsomedian carina extending 

 from first through sixth somites, carina on first 

 produced in strong, anterodorsally directed tooth 

 tapering to sharp apex and considerably larger 

 than posterior tooth on carapace; carina on fifth 

 produced in conspicuous sharp tooth and that on 

 sixth terminating in strong, acute one. 



Anteroventral margin of pleuron of first abdom- 

 inal somite concave; posteroventral margin of first 

 through fourth somites rounded; anteroventral 

 extremity of pleuron of first through fourth so- 

 mites ending in spine, that of first directed ven- 

 trolaterally, those of second through fourth curved 

 posterolate rally. Pleuron of fifth and sixth somites 

 bearing posteroventral, caudally directed, rela- 

 tively small spine, that of fifth slightly larger than 

 that on sixth. 



First abdominal somite traversed by anterome- 

 dian pleural sulcus, deep dorsally and disappear- 

 ing at about 0.30 height of somite before reappear- 

 ing ventrally as broad shallow depression merging 

 with united posterior tergal-posteromedian 



pleural sulci. Second and third somites with an- 

 terior tergal and posterior tergal sulci joining an- 

 terodorsally; anteromedian pleural sulcus short 

 (not reaching dorsally posteromedian pleural) but 

 deep and merging with shallow anteroventral 

 depression, latter setting off subelliptical promi- 

 nence dorsally and low ridge posteriorly; pos- 

 teromedian pleural sulcus long, extending 

 anterodorsally ventral to (not joining) posterior 

 tergal. Fourth and fifth somites with anterior ter- 

 gal sulcus and curved, united posterior tergal- 

 posteromedian pleural sulci merging. Sixth so- 

 mite with arched posteromedian pleural sulcus 

 and longitudinal rib situated along base of mid- 

 dorsal carina and delimited ventrally by deep de- 

 pression lying just dorsal to weak cicatrix. 



Telson with median sulcus deep anteriorly, in- 

 creasingly shallow posteriorly, its terminal por- 

 tion elongate and sharp, and bearing pair of small 

 fixed subterminal spines. Rami of uropod sub- 

 equal in length, falling slightly short of or barely 

 overreaching apex of telson. 



Petasma (Fig. 50A, B) with rigid distal projec- 

 tion of dorsolateral lobule only slightly curved me- 

 sially, raised proximodorsally in rounded promi- 

 nence and compressed distally, its tip with ventral 

 extremity rounded and dorsal extremity produced 

 in strong, sharp spine directed dorsally. Fleshy 

 distal projection of ventrolateral lobule curving 

 laterally, roughly sickle shaped in outline, with 

 apex directed proximoventrally. 



Petasmal endopods coupled in males as small as 

 6.7 mm cl, about 27 mm tl, but may not be joined in 

 individuals as much as 9 mm cl, about 34 mm tl. 



Figure 49.— Skyonia picta. A, c? 16 mm cl, NW of Isla 

 Monserrate, Baja California Sur, Mexico. Lateral view of 

 carapace. Scale = 5 mm. B, syntjrpe 6 15.5 mm cl. Golfo 

 de Panama. Lateral view of dorsal part of cara- 

 pace. Scale = 2 mm. 



59 



