FISHERY BULLETIN: VOL. 75, NO. 2 



about 0.35 length of telson, flanked by low 

 carinae, latter becoming sharp posteriorly, reach- 

 ing base of lateral spines; length of spine 1.1 

 to 1.5 times width of terminal portion at base; 

 terminal portion length 3 to 4 times basal width. 

 Mesial ramus of uropod overreaching apex of 

 telson by about 0.2 of its length; lateral ramus, 

 in turn, overreaching mesial by as much as 0.25 

 of its own length, and bearing minute, terminal, 

 distolateral spine. 



Petasma (Figure 32A, B) cincinnulate along 

 entire median line, with distal margin spinulous; 

 midrib of dorsolateral lobule broadest proximally, 

 and ending distally in narrow, sometimes sinuous 

 tip; ventrolateral lobule almost entirely sclero- 

 tized, but produced distally into rather flexible, 

 elongate flap, strongly inclined toward median 

 lobe; ventral costa with free terminal part curved 

 dorsally and armed with minute spines on distal 

 margin. 



Appendix masculina (Figure 32C, D) elongate, 

 deeply excavate ventromesially for reception of 

 appendix interna, broad proximal part raised in 

 longitudinal, lateral rib extending to base of 

 narrower distal part; strong dorsal thickness 

 along distal part curving around terminal margin, 

 there bearing tuft of rigid setae. Appendix interna 

 considerably shorter than appendix masculina 

 and consisting of short bulbous basal portion 



and elongate, narrow but thick distal portion. 

 Ventrolateral spur abruptly narrowing slightly 

 distal to midlength, becoming fingerlike. 



Thelycum (Figure 33A) microscopically setose- 

 punctate (Figure 335), with paired subtriangular 

 projections on anteriormost part of sternite XIV, 

 usually inclined anteriorly, overlapping posterior 

 margin of sternite XIII; posterior part of sternite 

 XIV strongly bulging, often bearing midlongitu- 

 dinal groove. Median plate of sternite XIII de- 

 limited anteriorly by paired deep depressions, and 

 armed with strong anteromedian rib; sternite XII 

 with central elevation, and paired, transverse 

 marginal ridges overlapping sternite XIII. 



Color-Both coloration, as previously indicated 

 by various authors, and color pattern are very 

 variable. Burkenroad (1936) described fresh, 

 though dead, juveniles, caught in the waters off 

 Alabama, as follows: "Eyes deep reddish-brown 

 with greenish reflections; gastric gland grayish- 

 brown with light yellow-green flecks, stomach 

 red; body pale orange-red, with a band of deeper 

 salmon on the posterior part of each pleonic 

 tergum; an iridescent blue-green area on the 

 dorsum of each pleonic segment and of the telson." 

 Springer (1951b) indicated that shrimp taken in 

 the northern Gulf of Mexico were "brick red as 

 they come from the water." Anderson and Bullis 



FIGURE 32.— Pleoticus robustus, 6 32 mm cl, east of Peninsula Valiente, Panama. A, Petasma, dorsolateral view of left half. 

 B, Ventrolateral view (extended). C, Right appendices masculina and interna, lateral view. D, Mesial view. 



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