SPERMATOPHORES AND THELYCA OF THE AMERICAN WHITE 

 SHRIMPS, GENUS PENAEUS, SUBGENUS LITOPENAEUS 



Isabel P^rez Farfante' 



ABSTRACT 



The spermaiophores of the five species of the American subgenus Litopenaeus of the genus Penaeus 

 three in the Pacific-P. (L.) occidentalis, P. (L.) stylirostris, and P (L.) vannamei-^^nd two in the 

 Atlantic-P. (L.) schmith and P. (L.) setiferus-are described in detail and illustrated. The sperma- 

 tophore of P. vannamei uniquely lacks a wing and a lateral blade. That of P. stylirostris possesses a sac 

 with overlapping walls, the free lateral margin not being attached to the underlying wall throughout 

 most of its length; this spermatophore also exhibits the broadest wing, consisting of a rigid anterior 

 region and a posterior membranous one. The spermatophore of P. occidentalis is the only one armed 

 with an anterior lobe, a transverse anterior lamina, and a sclerotized flap. The spermatophores of the 

 Atlantic species are very similar, both possessing moderately broad wings, large caudolateral flanges, 

 and a lateral blade; however, in P. schmitti the blade is broad anteriorly, whereas in P. setiferus it is 

 very narrow. During copulation, as the males deposit paired spermatophores on the females, the sperm 

 masses are released through anterodorsal ruptures of the sperm sacs and become lodged on the thelycum, 

 protected ventrally by the anterior part of the sacs. The open-type thelycum (sperm receptacle lacking),' 

 characteristic of the members of Litopenaeus, is unique within the genus Penaeus. The thelyca are 

 described in order to facilitate understanding how the compound spermatophores are held in place. The 

 thelycum of each species exhibits at least one obvious typical feature by which it may be easily 

 recognized: that of P. vannamei is provided with an inverted troughlike median protuberance on 

 sternite XIII; in P. occidentalis it possesses densely set setae over most of sternite XIV; in P. styliros- 

 tris it is armed with a strong, subpyramidal median protuberance on sternite XIV; in P. schmitti, on the 

 other hand, it exhibits paired subparallel anterolateral ridges; and in P. setiferus paired crescentic 

 anterolateral ridges are present which, although convergent, do not meet on the midline. In all but one 

 species, thelycal concavities of sternite XIII serve to lodge the sperm masses which protrude from 

 attached spermatophores; however, in P. occidentalis spoonlike coxal plates of the third pereopods 

 receive the sperm masses. 



The five species of Penaeus, subgenus Li- 

 topenaeus, commonly known as white shrimps, 

 support some of the most intensive and valuable 

 fisheries in American waters. Three species are 

 limited to the eastern Pacific, Penaeus occiden- 

 talis, P. stylirostris, and P. vannamei, and two 

 occur in the western Atlantic, P. schmitti and P. 

 setiferus. Mass rearing experiments to discover 

 methods for artificial cultivation on a commercial 

 scale are being conducted on all five species, and 

 spermatophore-bearing or "impregnated" females 

 are needed for this undertaking. Despite these ef- 

 forts, and the considerable interest of biologists in 

 the reproduction of these species (including mat- 

 ing, spawning, and fertilization), descriptions of 

 the spermatophores of only two of them and brief 

 notes on a third are available. General features of 

 the spermatophore of P. setiferus were presented 

 by both Burkenroad (1934) and King (1948), and an 



'Systematics Laboratory, National Marine Fisheries Service, 

 NOAA, National Museum of Natural History, Washington, DC 

 20560. 



Manuscript accepted December 1974. 

 FISHERY BULLETIN: VOL. 73, NO. 3, 1975. 



account of that of P. stylirostris was given by 

 Cardenas Figueroa (1952). Subsequently, Ewald 

 (1965) and Perez Farfante (1969) recorded a few 

 observations on the spermatophore of P. schmitti. 

 The spermatophores of the remaining two species, 

 P. occidentalis and P. vannamei, have not been 

 mentioned previously. 



Lack of information on spermatophores of the 

 subgenus Lit&penaeus is due, at least in part, to 

 the fact that impregnated females are not readily 

 found (Weymouth et al. 1933; Burkenroad 1939; 

 Heegaard 1953). In this exclusively American 

 group, the females possess an open-type thelycum 

 (Burkenroad 1934; Perez Farfante 1969), lacking a 

 seminal receptacle and consisting, instead, of pro- 

 tuberances, ridges, concavities, or grooves and, oc- 

 casionally, lamellae on sternites XII to XIV to 

 whichthe spermatophore is attached. The latter is 

 thus exposed to the surrounding water and might 

 be dislpdged during capture, as suggested by 

 Burkenroad (1939), or retained for only a short 

 period after copulation. In the females of all other 



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