PEREZ FARFANTE: AMERICAN SOLENOCERID SHRIMPS 



abundantly in littoral waters at depths between 

 2 and 20-30 m (Figure 9), and rarely as deep as 

 80-100 m (Angelescu and Boschi 1960; Boschi and 

 Scelzo 1969a), and from near the shoreline to 

 0.5 km offshore, occasionally as far as 56 km 

 (Angelescu and Boschi 1960). This species was 

 reported by Iwai (1973) to range north to 21°36'S, 

 the first record north of Ilha Santana, 22°25'S, 

 Rio de Janeiro, where da Silva ( 1965) had reported 

 a fishery for this shrimp. The specimens taken at 

 Praia de Santana, Espfrito Santo, about 178 km 

 north of the locality where Iwai recorded the 

 species, have confirmed the presence of H. 

 muelleri beyond the state of Rio de Janeiro. The 

 southernmost limit of the species given above is 

 based on Boschi and Scelzo ( 1969a), who identified 

 a number of large specimens caught in the Golfo 

 de San Jorge at a depth of 80 m. 



Affinities -Pleoticus muelleri has its closest affini- 

 ties with its Atlantic congener P. robustus, but 

 it may be readily separated from it by its almost 

 entirely glabrous body, long prosartema, which 

 may overreach the midlength of the second anten- 

 nular article, the absence of branchiostegal spines 

 and the presence of orbital spines. Also it may 

 be distinguished by the disposition of the sub- 

 marginal carina, the posterior part of which is 

 horizontal and situated far from the free ventral 

 border of the carapace, instead of extending sub- 

 parallel to that border as it does in all other species 

 of this generic complex. The external genitalia of 

 the two are also markedly different, as pointed out 

 under P. robustus. In the petasma of P. muelleri 

 the ventromedian lobule is cornified distally, 

 terminates in a rounded to ovate platelike pro- 

 jection which bears at its base a spurlike projec- 

 tion, and the ventral costa is produced into a 

 dorsally directed hook. The thelycum, in turn, 

 exhibits paired short plates on the anterior part 

 of sternite XIV, each bearing a pair of minute 

 knobs, and also an exceedingly strong projection 

 on the median plate of sternite XIII. 



Spermatophore. -Compound spermatophore (Fig- 

 ure 41) consisting of broad geminate body with 

 angular hump at about midlength, and bearing 

 small pair of wings anterolaterally; also provided 

 with large, highly sculptured midlateral flaps, 

 and pair of broad, posterolateral flanges. Thick, 

 opaque ventral wall of each spermatophore (Fig- 

 ure 42A) truncate, lacking anterior lobe, broad- 

 ened and swollen at about midlength forming 



hump; area posterior to hump dorsally depressed, 

 and strengthened by longitudinal ridge. Lateral 

 wall mostly thick, concave, and insensibly con- 

 tinuous with wing anteriorly, merging with 

 broad, subrectangular flap, and posteriorly bear- 

 ing prominent longitudinal ridge parallel to that 

 of ventral wall. Dorsomesial wall largely trans- 

 lucent, but heavily sclerotized and opaque mesi- 

 ally forming axial part of complex armature (Fig- 

 ure 42C). Latter bearing three transverse ribs: 

 1) anterior, forming arc, with one arm (ventral) 

 strengthening ventral hump and another running 

 across dorsomesial wall, then ending in foliaceous 

 process; 2) intermediate, close to former, very 

 strong, tonguelike, and deeply excavated; 3) pos- 

 terior, forming shelf projecting inside lumen of 

 sperm sac from dorsomesial wall. Wing short, 

 broad, and flexible except for posterior thickening 

 running along its entire length. Anterior part of 

 flap broad, subrectangular, elevated in marginal 



FIGURE 41. — Pleoticus muelleri. Compound spermatophore 

 attached to female, $ 37 mm cl, Rawson, Chubut, Argentina 

 (setae omitted). 



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