P6REZ FARFANTE: ROCK SHRIMP GENUS SICYONIA 



Postocular sulcus with anterior part deep, con- 

 tinuing posteriorly as shallow groove; hepatic sul- 

 cus well marked; hepatic carina weak; bran- 

 chiocardiac carina conspicuous, extending to or 

 almost to transverse ridge near posterior margin 

 of carapace. 



Antennular peduncle with stylocerite produced 

 in long, sharp spine, its length 0.85-0.90 distance 

 between lateral base of first antennular article and 

 mesial base of distolateral spine; latter extending 

 as far as distal end of proximal 0.80 of second 

 antennular article; antennular flagella short, me- 

 sial antennular flagellum shorter than lateral, 

 0.15-0.20 as long as carapace, lateral flagellum 

 0.19-0.23 as long. 



Scaphocerite reaching or slightly overreaching 

 distal margin of antennular peduncle; lateral rib 

 ending distally in long, acute spine distinctly 

 overreaching margin of lamella. Antennal flagel- 

 lum about twice as long as carapace. 



Third maxilliped stouter than pereopods. Basis 

 and ischium of first pereopod unarmed. 



Abdomen with high dorsomedian carina ex- 

 tending from first through sixth somites: on first 

 produced in strong anterior tooth, on fourth usu- 

 ally sloping posteriorly but sometimes abruptly 

 truncate, and on fifth and sixth terminating in 

 sharp tooth, latter longer. 



Anterolateral margin of pleuron of first abdom- 

 inal somite concave, anteroventral extremity of 

 first through fourth somites ending in spine, that 

 of first directed anterodorsally, those of second 

 through fourth curved posterolaterally; postero- 

 ventral extremity of fourth through sixth somites 

 bearing posteriorly directed, acute spine, that of 

 fifth largest. Pleural spination of first four somites 

 represented by tubercles in juveniles, becoming 

 longer with increasing length of carapace. 



First abdominal somite with long anteromedian 

 pleural sulcus ending dorsally at anterior margin 

 of tergum and converging with long posterome- 

 dian pleural sulcus ventrally; posterior tergal sul- 

 cus long or short, well marked or weak; posterior 

 pleural sulcus well defined. Second and third so- 

 mites with long anterior and posterior tergal sulci; 

 anteromedian pleural sulcus continuous with an- 

 teroventral depression setting off prominence dor- 

 sally and ridge posteriorly; posterior pleural sul- 

 cus as on first somite. Fourth and fifth somites 

 with anterior tergal joining curved, united pos- 

 terior tergal-posteromedian pleural sulci dorsally; 

 fourth also with shallow but clearly distinct 

 caudodorsal depression, placed close to posterior 

 margin. Sixth somite marked with faint anterior 



tergal and arched posteromedian pleural sulci, 

 also bearing longitudinal ridge along base of dor- 

 somedian carina and lateral depression (thickly 

 covered with setae) dorsal to interrupted cicatrix. 

 All sulci weak in juveniles, becoming deeper with 

 age. 



Telson with pair of short, often abraded, fixed 

 subterminal spines. Rami of uropod subequal in 

 length, reaching or slightly overreaching apex of 

 telson. 



Petasma (Fig. 23A, B) with rigid distal projec- 

 tion of dorsolateral lobule raised proximodorsally 

 in rounded prominence, strongly curved dorsome- 

 sially, its distal part compressed, rounded ven- 

 trally, produced dorsally in short, subacute salient; 

 mesial base of projection bearing short, dentiform 

 prominence. Distal projection of ventrolateral 

 lobule with firm terminal part curved laterally, 

 convex dorsally, plane ventrally, and tapering to 

 ventrally directed apex. 



Petasmal endopods coupled in males as small as 

 6.3 mm cl, about 22 mm tl, but in individuals with 

 as much as 13 mm cl, about 48 mm tl, they may not 

 be joined. 



Appendix masculina as illustrated in Figure 

 23C. 



Thelycum (Fig. 24) with plate of sternite XIV 

 produced in anterolateral lobules, almost flat or 

 raised in paired low bulges sloping toward an- 

 teriorly deep median depression. Median plate of 

 sternite XIII sagittiform, tapering gradually into 

 long, slender spine reaching as far as proximal 

 0.25 of basis of extended second pereopods; plate 

 strongly excavate and bearing shallow, lateral in- 

 cisions at level of fourth pereopods; posterior com- 

 ponent with deep, broad posteromedian emargina- 

 tion separating paired subtriangular processes 

 limited anteriorly by well-marked transverse su- 

 ture. Paired spines projecting anteroventral ly 

 from posterior margin of sternite XI, spines broad 

 basally, often spiculiform apically. Posterior 

 thoracic ridge narrow, with concave anteromedian 

 margin well marked. 



The smallest impregnated females encountered 

 have a carapace length of 10 mm, about 44 mm tl. 



Color. — The coloration of this shrimp was de- 

 scribed in detail from live specimens from the Gulf 

 of Mexico by Burkenroad (1939). Williams (1965) 

 presented notes on the color of materials of North 

 Carolina, and Cobb et al. (1973) recorded observa- 

 tions on individuals from the Yucatan shelf. In the 

 latter, the dorsal part of the body is more reddish 

 than in specimens from the northern Gulf of 



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