PEREZ FARFANTE: AMERICAN SOLENOCERII) SHRIMPS 



FIGURE 38.— Pleoticus muelleri, 9 33 mm cl, north of Cabo 

 Santa Maria, Uruguay. Eye. 



dorsal and ventral flagella to that of carapace 2.90 

 and 2.25 respectively and in shrimp 30 mm cl, 

 2.5 and 2.0. Scaphocerite exceeding antennular 

 peduncle by 0.2 to 0.3 its own length; lateral rib 

 ending in long spine falling short of distal margin 

 of lamella; antennal fiagellum almost 3 times 

 total length of shrimp. Third maxilliped reaching 

 almost to distal margin of third antennular article 

 or surpassing it by as much as 0.5 length of dactyl. 

 First pereopod reaching between proximal 0.3 

 and distal margin of carpocerite. Second pereopod 

 overreaching antennular peduncle by almost 

 length of dactyl or by entire propodus. Third pere- 

 opod surpassing antennular peduncle by at least 

 length of dactyl and, at most, by propodus and 

 0.15 length of carpus. Fourth pereopod exceeding 

 carpocerite by as much as entire length of dactyl. 

 Fifth pereopod, longest of all appendages, exceed- 

 ing antennular peduncle by length of dactyl and 

 0. 15 or 0.20 length of propodus. Order of pereopods 

 in terms of their maximal anterior extensions: 

 first, fourth, second, third, and fifth. First pereo- 

 pod with spine at midlength of mesial border of 

 basis very long and sharp, and spine on ischium 

 sharp, but smaller than that on basis; second 

 pereopod with setose, squamiform tubercle on 

 distoventral border of coxa, and with long sharp 

 spine on basis. In females, coxa of fifth pereopod 

 produced as rounded, posteromesially directed 

 plate, terminating in tooth anteriorly, plate hing- 

 ing on horn of posterior plate of sternite XIV; coxa 

 of fourth pereopod narrow, thick, with two 



rounded mesial projections, base of posterior one 

 hinging on anterior horn of median plate of 

 sternite XIII; coxa of third pereopod produced 

 mesially in subtrapezoidal plate provided with 

 long mesial setae overlapping those of opposite 

 plate, coxa bearing gonopore on dorsomesial sur- 

 face. In males, coxa of fifth pereopod with large 

 tooth on anterior margin. 



Abdomen with middorsal carina along entire 

 length, carina low and rounded from first to third 

 somites (imperceptible in young), and keellike 

 posteriorly; posterodorsal margins of third 

 through fifth somites with median incision; sixth 

 bearing small, sharp spine at posterior end of 

 carina, and small posteroventral spines. Telson 

 with median sulcus moderately deep anteriorly, 

 posteriorly bearing median elevation merging 

 into convex terminal portion; lateral spines mod- 

 erately long; length of terminal portion about 4 

 times width at base. Mesial ramus of uropod sur- 

 passing apex of telson by 0.15-0.25 of its own 

 length; lateral ramus slightly overreaching 

 mesial ramus and bearing small, terminal disto- 

 lateral spine. 



Petasma (Figure 39A, B) cincinnulate along 

 proximal 0.4 of median line; distal part of ventro- 

 median lobule cornified, forming plate bearing 

 terminal subqval projection and lateral spurlike 

 projection; much of lateral lobe heavily sclero- 

 tized, overlapping ventral costa, and with shallow 

 lateral emargination marking base of distal por- 

 tion; latter flexible, subelliptical, directed toward, 

 and partly covered (dorsally) by, ventromedian 

 lobule; ventral costa bearing membranous flap, 

 broadening distally and terminating in paired 

 unequal convexities; free terminal part of costa 

 forming dorsally directed, strongly curved, sharp 

 projection. 



Appendix masculina (Figure 39C, D) elongate, 

 with heavily sclerotized dorsolateral portion and 

 flexible, subelliptical mesial portion. Appendix 

 interna spatulate, embracing ventromesial mar- 

 gin of appendix masculina proximally, and bear- 

 ing distolateral tuft of rigid, long setae. Basal 

 sclerite with deep distolateral groove along base 

 of sharp dorsal ridge; ventrolateral spur relatively 

 short. 



Thelycum (Figure 40) microscopically setose- 

 punctate, with posterior plate on sternite XIV 

 often divided by median longitudinal groove, 

 and bearing lateral elevations terminating anter- 

 iorly in small knob; short anterior part of sternite 

 XIV heavily sclerotized, forming slightly convex, 



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