Figure 4.— Right fifth pereopod. A, Penaeupsis sp. USNM 170582, 24.5 mm cl. Bohol Strait, Phihppines, A/ftarross stn 

 5419. B.Penaeopsis rectacuta , USNM 170586, 5 24.5 mm cl, off Palompon, Leyte, Philippines, A /6a?ross stn 5403. 1 mm 

 indicated. 



large size, however, makes it unlikely that they 

 are in a transitional stage. Furthermore, herma- 

 phroditism has not been recorded in any species of 

 the genus Penoeopsis, consequently its occurrence 

 in these specimens would be exceptional. 



Effects of parasitism in a species of 

 Metapenaeopsis, a genus closely allied io Penaeop- 

 sis, were reported by Hiraiwa and Sato (1939). 

 These authors observed conspicuous changes in 

 the petasmata of males and the gonopores of males 

 and females in the shrimp Penaeopsis akayebi 

 Rathbun 1902 i = Mctapenaeopsis barbata de 

 Haan 1850) parasitized by the bopyrid isopod 

 Epipenaeon japonica Thielemann 1910. In males, 

 the petasmata were considerably smaller than 

 those in normal individuals of corresponding size 

 and their two parts were unjoined; the gonopores 

 were barely noticeable, and the papillae, at the 

 tips of which the gonopores are situated in normal 

 individuals, were lacking. In the females, the ovi- 

 pores were obscured, but the thelycum was not 

 apparently affected by the presence of the para- 

 site. In the extensive material examined, how- 

 ever, none of the specimens bore both a petasma 

 and a thelycum. Among the specimens of P. rec- 

 tacuta collected in the waters of the Phillippines, I 

 found a few that were parasitized by bopyrids (one 

 of them was taken at Bohol Strait, in a locality 

 near those at which two of my three individuals 



were obtained). The parasitized specimens had 

 normal external genitalia, thus lending no sup- 

 port to an assumption that the anomalies in the 

 genitalia of these three individuals were induced 

 by a bopyrid parasite. Nevertheless, parasitism 

 offers the only clue as to the possible origin of the 

 anomalies present in these shrimp. 



Acknow ledgments 



I am grateful to Horton H. Hobbs, Jr., for valu- 

 able suggestions during the study, and to Thomas 

 E. Bowman and Fenner A. Chace, Jr., for review- 

 ing the manuscript. My thanks are also due Maria 

 M. Dieguez for preparing the figures. 



Literature Cited 



CHACE, F. A., JR., AND G. M. MOORE. 



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Heegaard. p. 



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1971. Penaetis kerathurus Forskal, a protandric her- 

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1972. Sexual dimorphism in some Mediterranean 

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690 



