PEREZ FARFANTE: REVISION OF PENAEID SHRIMP GENUS PENAEOPSIS 



because in at least one locality (for which tempera- 

 ture data are lacking) it has been found at about 

 550 m (see "Material" herein), i.e., only 150 m 

 above the maximum depth at which it has been 

 taken in the northeast Gulf. Because the tempera- 

 ture-depth distribution of the population off the 

 southeast coast of the United States is based on 

 only 12 records, one may only point out the un- 

 usual conditions existing in this segment of the 

 range of P. serrata. According to my observations, 

 the specimens of that population exhibit no mor- 

 phological differences from those of other 

 localities throughout the broad range of the 

 species, but Harvey R. Bullis Jr." stated that the 

 specimens, observed by him immediately after 

 capture, had a different coloration from those 

 caught elsewhere. Furthermore, Bullis and 

 Rathjen ( 1959) found that off the southeast coast of 

 the United States P. serrata was most abundant at 

 slightly greater depths than Pleoticus robustus 

 (Smith 1885), whereas in all other areas megalops 

 was not abundant where it occurs with, or at shal- 

 lower depths than, P. robustus. 



Variation. — This species, like most members of 

 the genus, exhibits a large number of characters 

 that are highly variable. Among them, the ros- 

 trum, strongly arched in the young, may be 

 straight, arcuate only basally or sinuous in the 

 adult, and horizontal or upturned; the number of 

 rostral teeth ranges from 10 to 19. The scapho- 

 cerite may fall short of or surpass the distal end of 

 the antennular peduncle, and the mesial ramus of 

 the uropod may not reach the apex of telson or 

 may extend beyond it by as much as 0.15 of its 

 own length. The thelycal features, especially, 

 show a wide range of variation: the anterior bor- 

 der of the plate of sternite XIV, usually strongly 

 arched on each side of the posteromedian projec- 

 tion of sternite XIII, sometimes is moderately or 

 only slightly so; and the anterolateral lobules of 

 that plate although generally strongly developed 

 are sometimes quite short. The median plate of 

 sternite XIII varies in shape (from subsemicircu- 

 lar to roughly pentagonal), while the posterome- 

 dian projection, although always broad, may 

 range from slightly emarginate to deeply bifid. 

 The entire range of variations in some of the 

 characters cited have been observed in animals 

 from the same locality. 



■•Harvey R. Bullis, Jr., formerly Southeast Fisheries Center. 

 National Marine Fisheries Service, NOAA, 75 Virginia Beach 

 Drive, Miami, FL 33149, pers. commun. December 1978. 



At least in the western Atlantic populations, 

 there are also differences in the relative extension 

 of the third maxilliped and pereopods. I have 

 noticed that in the populations of the Caribbean 

 and Atlantic coast of South America they extend 

 distally slightly farther than they do in northern 

 populations. In the former populations the range 

 extension of these appendages falls within the 

 upper half of the limits cited herein and in the 

 northern ones within the lower half Because most 

 of the few specimens available to me from the 

 eastern Atlantic are poorly preserved, I have been 

 unable to arrive at definite conclusions as to the 

 relative length of the appendages in the popula- 

 tions occurring in that region. 



Affinities. — Penaeopsis serrata, the only Atlantic 

 member of the genus, differs from its congeners in 

 that the branchiocardiac carina and interrupted 

 cicatrix on the sixth abdominal somite are very 

 weak, and the knob at the distal end of the 

 semicircular part of the ventral antennular flagel- 

 lum in the male is rather inconspicuous. More 

 strikingly, it differs from its allies in a number of 

 features of the external genitalia, as pointed out 

 below. It appears to be closer to P. rectacuta than 

 to any of the other species. They share long rostra 

 which tend to possess a large number of teeth (up 

 to 18 in P. serrata and 17 in P. rectacuta), and the 

 second tooth is located at the level of the orbital 

 margin. In both, the hepatic spine is situated ven- 

 tral to the level of the antennal spine, and the 

 branchiocardiac carina does not approach closely 

 the hepatic sulcus. The petasmata are also rather 

 similar and the telson of P. serrata is sometimes, 

 although rarely, armed with three pairs of mov- 

 able spines as is typical of that of P. rectacuta. 



The thelyca exhibit the most obvious differences 

 between the two species. In P. serrata the plate of 

 sternite XIV is uniquely produced into laterally 

 directed lobules, beairs an entirely naked and 

 much stronger median ridge (usually subovoid in- 

 stead of flasklike as it is generally in P. rectacuta), 

 and the posterior thoracic ridge lacks setae across 

 its anterior border. Furthermore, in P. serrata the 

 median plate of sternite XIII, although variable in 

 shape, is generally semicircular or roughly pen- 

 tagonal, whereas in P. rectacuta it is cordiform. 

 The posteromedian projection of sternite XIII is 

 also broader and emarginate (often deeply) rather 

 than entire as it usually is in P. rectacuta. The 

 males of these species can also be distinguished by 

 the proximal plate of the dorsomedian lobule of the 



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