Figure 66. — Pcnaciis (M.) paulensis Perez Farfante. 

 Thelycum, 2 -49.5 mm. c.l., Santos, Sao Paulo. Brazil. 



tends farther south than the previously generally 

 accepted southernmost limit of its range, Monte- 

 video. It is abundant along the northern jDortion 

 of its range and the coastal waters of Santa Cata- 

 rina. Farther south, the young are very numerous 

 in Lagoa dos Patos and the coastal lakes of Uru- 

 guay, but adults are rai'e along the southernmost 

 portion of the range. Mistakidis (1965) reported 

 having caught but one adult during exjiloratory 

 fishing between Rio Grande and Cabo Polonio. 

 Possibly the breeding poj^ulations extend only to 

 the neighborhood of Rio Grande. The young seem 

 to be able to invade waters that the larger adults 

 cannot tolerate. 



These shrimp live as deep as 65 fm. ; large con- 

 centrations are found between 20 and 30 fm. 



My studies indicate little variation in the diag- 

 nostic characters of P. pauJen-sis. The only rather 

 striking variation is that shown by the median 

 sulcus, which is usually interrupted but occasion- 

 ally continuous. Both types of sulcus were observed 

 in specimens from the same locality. 



Relationships 



P. paiulensis is closely related to P. a. aztecus and 

 P. a. mhtllis. It differs from both by having the ros- 

 trum usually almost straight and shorter; by hav- 

 ing a K/S ratio with a modal value of 6, which in- 

 dicates a very narrow dorsolateral sulcus; and by 

 having both lips of the sulcus sharp. The external 

 genitalia are also distinct. In males, the ventral 

 costa of the petasma is almost straight or only 

 slightly curved instead of markedly convex dis- 



tally and is armed with a group of medium-size, ir- 

 regularly set teeth almost at the apex. In females, 

 the anterior process is smaller and the posterior 

 process narrower than in P. a. aztecus and P. a. 

 suhtilis. P. pauleiisis also differs from P. a. aztecus 

 by the shorter, shallower, and often inteiTupted 

 median sulcus and the shorter third pereopod and 

 from P. a. suhtUls by the broader adrostral sulci. 



P. paulensis tends toward a smaller number of 

 rostral teeth than any other species oiPenaeus from 

 the western Atlantic; the mode of the rostral teeth 



7 8 



formula is -^ instead of -^ . Also, specimens with 



c 

 a formula greater than -^ must be uncommon be- 

 cause no specimen in the samples examined had 

 more than 8 dorsal and 2 ventral teeth. 



Reproduction 

 SUBADULT STAGE-SEXUAL MATURITY 



The series of small specimens available was too 

 small to pennit a determination of the size range 

 at which males and females become subadults. 



No studies have been made on the size at which 

 females attain sexual maturity. 

 OVARY DEVELOPMENT 



No studies have been made. 

 SPAWNING 



No studies are known on the spawning charac- 

 teristics of P. pauhn.sis. The information avail- 

 able on stages inshore, however, gives some indi- 

 cation of the spawning season through the range 

 of this shrunp. 



According to Tremel (1965), fishing for the 

 yomig in Conceigao and Imarui Lagoons, Santa 

 Catarina, Brazil, is carried out from August to 

 April (peak from December to February). This 

 timing appears to indicate that some spawning oc- 

 curs from mid-fall through early winter, but that 

 mass spawning probably takes place through late 

 winter and early spring. Mistakidis (1965) re- 

 ported that in Lagoa dos Patos, southeast Brazil, 

 small shrimp are found from September to No- 

 \'ember, that postlarvae have been taken in the 

 lakes of Uruguay in October and November, and 

 that fishing for young in lx)th areas is carried out 

 from March to May, with a peak in March. The 

 young, thus, arrive on these nursery gi-ounds later 

 than those that arrive in the lagoons of Santa 

 Catarina. Because large adults are apparently rare 

 off southern Brazil and Uruguay, the difference 

 in time of arrival may be due to the longer dis- 



560 



U.S. FISH AND WILDLIFE SERVICE 



