FISHERY BULLETIN: VOL. 76, NO. 1 



in the relative sizes of their bothridia, bulbs, and 

 post-bulbosal regions." 



The genus differs from Prochristianella in the 

 morphology of the blastocyst; species of the latter 

 genus having a division between anterior and 

 posterior portions, with large granules contained 

 in the anterior division of the blastocyst. These 

 worms apparently do not harm their hosts sig- 

 nificantly. 



Pa rachriitia nella heterotnegaca nth lis 

 Feigenbaum 1975 



The most recent species to be described is from 

 Penaeus brasiliensis from Biscayne Bay. Twenty 

 percent of this shrimp were infected with fewer 

 than 1.5 worms occurring in each infected shrimp. 

 Corkern ( 1970) found an average of 2.3 specimens 

 of P. dimegacantha per infected brown shrimp 

 from Galveston Bay, Tex. Prevalence data from 

 Corkern's work shows 239^ brown shrimp infected, 

 a figure close to that of Feigenbaum's (1975) 20% 

 for P. heteromegacanthus. Tentacle hook ar- 

 rangements in P. heteromegacantha differed from 

 those in P. monomegacantha and P. dimega- 

 cantha. 



Family Renibulbidae Feigenbaum 1975 1 



Genus Renihiilhiis Feigenbaum 1975 

 Renihulhus penaeus Feigenbaum 1975 



To date, this species was found in 14.3% ofPen- 

 aeus brasiliensis examined from Biscayne Bay. 

 The short kidney-shaped bulbs in the scolex of this 

 cestode set it apart from other trypanorhynchan 

 cestodes in penaeid hosts. No organ site of infec- 

 , tion was given by Feigenbaum (1975) for this 

 worm, and no pathogenesis was indicated. 



Unknown Cestode Larva 



Hutton et al. (1959), Kruse (1959), Overstreet 

 (1973), Feigenbaum (1975), and I have found a 

 small pyriform cestode larval stage ( Figure 33a, b) 

 commonly in the intestine of penaeid shrimps 

 from the Gulf and Atlantic coasts of Florida. This 

 worm also is found in large numbers in several 

 tissues of infected shrimp, namely, the muscles 

 and hemocoel. The worm possesses a large an- 

 terior sucker and many refringent calcareous cor- 

 puscles in its body, and is approximately 0.61 to 

 0.81 mm long by 0.12 to 0.22 mm wide. Large 

 numbers of this worm may occlude the intestinal 



lumen or cause perforation of the intestinal wall. 

 Several hundred larvae have been counted in a 

 single shrimp. Hosts, to date, include Penaeus 

 duorarum, P. aztecus, P. setiferus, and P. 

 brasiliensis. 



Nematodes 



Phylum Aschelminthes Grobben 1910 

 Class Nematoda (Rudolphi 1809) Cobb 1919 

 Superfamily Ascaridoidea 



(Railliet and Henr> 1915) 

 Genus Thynnascaris Dolfus 1933 

 Thynnascaris sp. 



Overstreet (1973) reported that the nematode 

 larvae identified by Kruse (1959), Hutton et al. 

 ( 1959), and Corkern ( 1970) as Contracaecum sp. in 

 penaeid shrimps should be considered species of 

 Thynnascaris. Norris and Overstreet (1976) have 

 found that at least two species occur in penaeid 

 shrimps in North America. Characteristics of this 

 genus are short intestinal caecum and longer ven- 

 tricular appendix combined with the position of 

 the excretory pore near the nerve ring. Figures 34 

 and 35 are photomicrographs of Thynnascaris sp. 

 recovered from hepatopancreas and cephalo- 

 thorax of Penaeus duorarum near Pensacola. I 

 have not found it commonly in shrimp from west 

 Florida, but Overstreet (1973) reported that 

 Donald Norris of his laboratory found up to 31% of 

 white and brown shrimp from Mississippi Sound 

 and adjacent waters infected during summer 

 months. Thynnascaris sp. juveniles measure 1.02 

 to 2.40 mm long by 0.06 to 0.10 mm wide." 



Overstreet (1973) reported two specimens of 

 Spirocamallanus pereirai Olsen 1952, in the intes- 

 tine of Penaeus setiferus from near Biloxi, Miss. 

 These were third stage larval nematodes which 

 measured 1.00 mm long by 0.03 mm wide. Over- 

 street suggested that the shrimp may serve as a 

 paratenic host and that copepods may serve as a 

 more common source or vector for this nematode 

 which normally matures in fishes. 



Several species of free-living nematodes, com- 

 monly found in shrimp habitat, have been re- 

 ported as facultative commensals or inquilines of 

 penaeids. Shrimp may take these worms in larval 

 stages when they feed on detritus or bottom or- 

 ganisms in nature or in artificial ponds. Speci- 

 mens of Leptolaimus sp. and Croconema sp. have 

 been found by Overstreet (1973) in brown and 

 white shrimps from Mississippi. Other than phys- 



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