FISHERY BULLETIN: VOL. 73, NO. 3 



subgenera of Penaeus, the thelycum exhibits a 

 seminal receptacle where the spermatophores, 

 deposited by the male, remain well protected until 

 the time of spawning or until the succeeding molt. 



Among the extensive collections of the subgenus 

 Litapenaeus that I have examined, no females of 

 either P. occidentalis of P. vannamei carrying 

 spermatophores were found. Four impregnated 

 females of P. stylirostris and two of P. schmitti in 

 the National Museum of Natural History, Smith- 

 sonian Institution, constituted the only material 

 at my disposal when this study was initiated. 

 After several unfruitful attempts to collect sper- 

 matophore-bearing females in various localities 

 throughout the range of the Pacific species, I ob- 

 tained such specimens of the three in the Gulf of 

 Panama in March 1973. 1 caught an additional one 

 of P. occidentalis in the same month off 

 Buenaventura, Colombia. In the fall of 1974, Billy 

 R. Drummond sent me three impregnated females 

 of P. stylirostris which had been collected off 

 Costa Rica, and recently Harold H. Webber 

 brought me eight spermatophore-bearing females 

 of P. stylirostris and five of P. vannamei from the 

 same area. The study of the spermatophore of the 

 Atlantic P. setiferus was based largely on one 

 female carrying a complete spermatophore and 

 three additional ones in which paired masses of 

 sperm embraced by winglike processes were 

 present on sternite XIII; these specimens had 

 been caught in the waters of North Carolina, and 

 were made available to me by Austin B. Williams. 

 Recently, further observations were made on four 

 impregnated females, two from Apalachicola Bay, 

 Fla., and two from off Texas, given to me by 

 William H. Clark, Jr. and Kenneth N. Baxter. 



The spermatophores of the various species are 

 similar (herein described as when in position on 

 the female), each consisting basically of a roughly 

 semicylindrical hardened sperm sac enclosing a 

 columnar sperm mass (spermatozoa within a vis- 

 cous fluid) surrounded by a thick "sheath" (King 

 1948) of gelatinous substance (Figure lA, B). The 

 sac usually bears an anterolateral aliform process, 

 the wing, and is produced caudally or 

 caudolaterally, in a flange. A lateral flap, variable 

 in width and consistency, extends both along the 

 sac and the flange, or only along the latter, usually 

 attached to a firm, elongate blade, and a hardened 

 but plastic dorsal plate is present on the 

 posterodorsal surface of the spermatophore. 

 Finally, a glutinous material always lies against 

 the flange, adhering to the mesial side of the flap. 



These various accessories associated with the 

 sperm sac presumably help to anchor the sperma- 

 tophores to the female. 



The wall of the sperm sac consists of three 

 somewhat distinct longitudinal regions: a thick, 

 opaque ventral wall, a mostly thin and translucent 

 lateral wall, and an entirely translucent dor- 

 somesial wall. The heavy ventral wall is produced 

 in a longitudinal mesial lapel, clearly delimited by 

 a line along which the ventral and dorsomesial 

 walls meet. The above terminology is consistently 

 employed in the descriptions that follow. 



During copulation, two closely attached sper- 

 matophores, which are here referred as the com- 

 pound spermatophore, are transferred to the 

 female (Figure IC). Immediately after expulsion 

 from the paired terminal ampullae of the male, 

 each spermatophore joins its mate firmly along the 

 dorsomesial walls of the sacs, thus forcing the 

 mesial lapels to project ventrally from the con- 

 tiguous ventral walls (Figure ID). These walls, 

 becoming strongly convex when the compound 

 spermatophore is anchored to the thelycum, are 

 responsible for the podlike appearance of the con- 

 joined paired sacs, which constitute a median 

 double structure referred to below as the geminate 

 body. 



If the posterior part of the thorax of live mature 

 males is compressed, the spermatophores are 

 readily expelled through the gonopores situated 

 mesially on the coxae of the fifth pereopods. It 

 then may be observed that the spermatophores 

 leave the ampullae with the anterior end foremost, 

 the surface facing the sternum of the male being 

 the same as that which, through a rotation, comes 

 to lie against the thelycum. Consequently, as 

 Kishinouye (1900) first indicated, the right and left 

 spermatophores on the female originate in the 

 corresponding right and left terminal ampullae of 

 the male. Observations by Hudinaga (1942) on 

 Penaeus (Marsupenaeus) japonicus Bate 1888, 

 demonstrated that copulation takes place in a head 

 to head position, the sternum of the male pressing 

 against that of the female. Previously, 

 Burkenroad (1934) and later King (1948) presented 

 hypotheses concerning the transfer of the sper- 

 matophores to the thelycum, taking into account 

 the probable utilization of the petasma-ap- 

 parently so well fitted to lodge the compound 

 spermatophore— and the pereopods. No satisfac- 

 tory explanation, however, has been advanced as 

 to how a rotation of the spermatophore through 

 180° around its longitudinal axis, is accomplished. 



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