No abstract

Trophonts of a parasitic dlnoflagellate were obtalned from the gills of feral and cultured red drum Sciaenops ocellatus and aquarium-housed sebae clownflsh Amphiprion clarku, Imperator Pomacanthus imperator, mandann goby Pterosynchiropus splend~dus and flame angelfish Centropyge loriculus. After incubation of tomonts, dinospores were studied by scanning electron microscopy.Dinospores have a plate pattern and tabulation of PO, cp, X. 4 ' , l a , 7 " , 6 to 8?c, ?S, S"', 2"", which are similar to that of the free-living Peridiniales. The parasite is tentatively identified as Amyloodinium cf. ocellatum. Most descriptions of parasitic dinoflagellates rely only on the morphology of the trophont. However, despite the fact that some past studies have questioned the validity of using dinospores in making taxonolnic classifications because of their plastic and unstable morphological characteristics, dlnospore characterization is critical Traditionally, dinospores of parasitic dinoflagellates have been described as unarmored (naked) and have been considered to have gymnodinioid, gyrodinioid or cochlodinioid forms. Ultrastructural f~xation techniques used for A. cf. ocellatum revealed the presence of thin plates arranged in Kofoldlan series. Such plates could be more prevalent in other dlnoflagellate species than has been previously ~ndicated, and existing taxonom~c-classification schemes may need to be emended. Dinospores of other parasitic dinoflagellates should be reevaluated for the presence of similar diagnostic characteristics.

Dinoflagellates can be classified both botanically and zoologically; however, they are typically put in the botanical division Pyrrhophyta. As a group they appear most related to the protistan ciliates and apicomplexans at the ultrastructure level. Within the Pyrrhophyta are both unarmored and armored forms of the dominant, motile flagellated stage. Unarmored dinoflagellates do not have thecal or wall plates arranged in specific series, whereas armored species have plates that vary in thickness but are specific in number and arrangement. In armored dinoflagellates, the plate pattern and tabulation is a diagnostic character at the family, subfamily, and even genus levels. In most cases, the molecular characterization of dinoflagellates confirms the taxonomy on the basis of external morphology; this has been demonstrated for several groups. Together, both genetic and morphological criteria are becoming increasingly important for the characterization, separation, and identification of dinoflagellates species. Pfiesteria and Pfiesteria-like species are thinly armored forms with motile dinospore stages characterized by their distinct plate formulae. Pfiesteria piscicida is the best-known member of the genus; however, there is at least one other species. Other genetically and morphologically related genera, now grouped under the common names of "Lucy," "Shepherd's crook," and cryptoperidiniopsoid, are being studied and described in separate works. All these other heterotrophic dinoflagellate groups, many of which are thought to be benign, co-occur in estuarine waters where Pfiesteria has been found.

Dinoflagellates can be classified both botanically and zoologically; however, they are typically put in the botanical division Pyrrhophyta. As a group they appear most related to the protistan ciliates and apicomplexans at the ultrastructure level. Within the Pyrrhophyta are both unarmored and armored forms of the dominant, motile flagellated stage. Unarmored dinoflagellates do not have thecal or wall plates arranged in specific series, whereas armored species have plates that vary in thickness but are specific in number and arrangement. In armored dinoflagellates, the plate pattern and tabulation is a diagnostic character at the family, subfamily, and even genus levels. In most cases, the molecular characterization of dinoflagellates confirms the taxonomy on the basis of external morphology; this has been demonstrated for several groups. Together, both genetic and morphological criteria are becoming increasingly important for the characterization, separation, and identification of dinoflagellates species. Pfiesteria and Pfiesteria-like species are thinly armored forms with motile dinospore stages characterized by their distinct plate formulae. Pfiesteria piscicida is the best-known member of the genus; however, there is at least one other species. Other genetically and morphologically related genera, now grouped under the common names of "Lucy," "Shepherd's crook," and cryptoperidiniopsoid, are being studied and described in separate works. All these other heterotrophic dinoflagellate groups, many of which are thought to be benign, co-occur in estuarine waters where Pfiesteria has been found.

Protistan parasites associated with a disease syndrome in tropical fish from the lower east coast of Florida to the upper Florida Keys were investigated. One of these pathogens inducing mortality in aquariumheld French angelfish Pomacanthus pant and gray angelfish Pomacanthus arcuatus is Rrooklynella hostilis. This cyrtophorine ciliate was isolated from the gills and examined for the first time with scanning electron microscopy.