COUCH: DISEASES AND PARASITES OF PENAEID SHRIMPS 



staining studies and lifecycle studies are more 

 complete. 



Reports by Chatton (1911), Chatton and Lwoff 

 (1935), Debaisieux (1960), and Bradbury (1966, 

 1973) have demonstrated the common occurrence 

 of apostomes on Crustacea that occupy ecological 

 niches near that of the pink shrimp. The present 

 species has not been found associated with mortal- 

 ity in shrimp, although severe infestations may 

 cover much gill surface and blackened areas of 

 infested gills are found. Species of two known 

 apostome genera, Synophyra and Terebrospira, 

 cause considerable damage by penetrating the 

 cuticle of their crustacean hosts (Chatton and 

 Lwoff 1926; Bradbury 1974). 



R. M. Overstreet (pers. commun.) has found 

 similar cysts on gills of brown and white shrimp, 

 and Feigenbaum (1973) reported cysts similar to 

 those described above on gills of Penaeus 

 brasiliensis from Biscayne Bay. The cysts of apos- 

 tomes could be confused with the loricae of species 

 of Lagenophrys, Care should be taken to distin- 

 guish them. Loricae of Lagenophrys spp. have 

 apertures surrounded by liplike structures (Couch 

 1973). 



Order Scuticociliatida Small 1967 

 Genus Parauronema Thompson 1967 

 Parauronetua sp. 



An undescribed species of ciliate was observed 

 in the hemocoel of protozoeal, mysid, and juvenile 

 stages of living, moribund, and dead brown shrimp 

 from a mass mortality which occurred at a com- 

 mercial shrimp hatchery^ during April 1974. In a 

 sample of 139 larvae examined, 28.8% were in- 

 fected by the ciliate (Tables 1, 2). The ciliate is 

 ovoid to pyriform in shape, ranging in length from 

 23.6 to 31.6 ;u.m, and in width from 9.2 to 12.2 ju.m 

 (Figures 24, 25). It has a uniform body ciliature 

 originating from longitudinal kineties (Figure 25) 

 as revealed by Protargol silver staining. 



The ciliate was observed swimming about in 

 hemolymph of infected shrimp larvae and 

 juveniles. Often the affected shrimp were still 

 alive and active, but several that were dead or 

 quite moribund contained ciliates. John Corliss 

 (University of Maryland) tentatively identified 

 the ciliate as a species of Parauronema. More 

 studies are required in order to name this ciliate. 



^Mortality was that reported on preceding pages (under virus 

 section). Several microorganisms were associated with this mor- 

 tality. 



Apparently the ciliate causes mechanical injury 

 in infected shrimp by replacing and dislodging 

 tissues. I have been unable to determine from lim- 

 ited observations whether or not the ciliate is his- 

 tophagous. In some shrimp the ciliates were 

 numerous enough to fill the entire hemocoel and 

 abdomen. The fact that living shrimp larvae were 

 infected by the ciliates strongly suggests that the 

 ciliate probably contributes to pathogenesis and 

 mortality and that it is an opportunistic invader 

 following initial breaks in the host's defense 

 mechanisms due, possibly, to the presence of other 

 pathogenic microorganisms {the Baculovirus and 

 a flagellate to be described next). Tables 1 and 2 

 show the relationship of prevalence of ciliate with 

 virus and flagellate in a sample of young brown 

 shrimp from a stock suffering mortality. 



Subclass Suctoria Haeckel 1866 



Order Suctorida Claparede and Lachmann 1858 



Family Ephelotidae Kent 1881 



Genus Ephelota Wright 1858 



Ephelota sp. 



Protozoeal and mysid stages of brown shrimp 

 were found infested on a single occasion with an 

 undescribed species of Ephelota. The larval 

 shrimp were examined in March. Each larva had 

 from one to seven individual Ep/ze/ota sp. attached 

 to their cuticles usually on the pleural plates or on 

 the telson. The suctorian possesses a characteris- 

 tically striated attachment stalk and a trophont 

 with both suctorial and prehensile tentacles. 

 These Protozoa were not abundant enough to 

 cause embarrassment to the larval shrimp. 



Subphylum Sarcomastigophora 



Honigberg and Balamuth 1963 

 Class Zoomastigophorea Calkins 1909 

 Order Kinetoplastida Honigberg 1963 

 Suborder Trypanosomatina Kent 1880 

 Family Trypanosomatidae Doflein 1901 

 Genus Leptomonas Kent 1880 

 Leptornonas sp. 



An undescribed species of flagellate was as- 

 sociated with the mass mortality of brown shrimp 

 larvae (see Baculovirus and Parauronema sec- 

 tions) (Figure 26). This form is tentatively as- 

 signed to the genus Leptomonas based on sub- 

 sequently described characteristics. The flagellate 

 was studied alive (bright field and phase contrast), 

 fixed, and stained with Harris' hematoxylin and 



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