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FISHKRY BULLETIN OF THE FISH AND WILDLIFE SERVICE 



Grand Isle, La. Jacobs (1912) made physiological 

 studies on four unidentified species of cOiates in- 

 festing sea urchins in the vicinity of the former 

 Biological Laboratory of Carnegie Institution at 

 Dry Tortugas, a group of islands located approx- 

 imately 60 miles west of Key West, Fla. Powers 

 (1933 and 1935) studied about 13 species of ciliates 

 (including those observed by Jacobs) at Tortugas, 

 describing and naming 6 new ones. He described, 

 also, one new flagellate. More recently, Wichter- 

 man (1940, 1942, and 1942a) described 3 new cUi- 

 ates from an oligochaete and 1 on coral, all at 

 Tortugas. He observed in the same oligochaete 

 host an unidentified gregarine. BuUington (1931, 

 1935, 1939, 1939a, and 1940) made a series of 

 studies on 15 free-living ciliates at Tortugas, a 

 dozen of which were new species, and observed 

 many unidentified ones as well. Noland (1937) 

 studied 18 species of free-living ciliates, 6 of which 

 were new, at Bass Biological Laboratory, Engle- 

 wood, Fla. Schaeffer (1926) has been the chief 

 student of the amoebae. He made a series of 

 studies which culminated in a lengthy paper on 

 taxonomy of the amoebae with description of 23 

 (?) new species from Tortugas and Key West, 

 Fla. Hopkins (1931) made life history studies on 

 2 of the same amoebae at Tortugas and 1 myce- 

 tozoan. Apparently, Prytherch (1938, 1940) made 

 the first noteworthy observations on a sporozoan 

 of the Gulf of Mexico. He observed Nematopsis 

 in oysters from Lake Barre and vicinity in Louisi- 

 ana to Mobjack Bay, Va., and described the first 

 member of the genus known in American waters. 

 Later, Sprague (1949, 1950, 1950d, and this paper) 

 studied 7 sporozoan parasites, 6 of them new, of 

 mollusks and decapod Crustacea along the Louisi- 

 ana coast. Mackin et al. (1950) described a 

 sporozoan (?) parasite, Dermocystidium marinum,^ 

 of widespread occurrence in oysters along the 

 Gulf coast. Most of the other Protozoa consid- 

 ered here have been mentioned only casually in 

 the literature or called to the attention of the 

 writer in personal correspondence. 



DISTRIBUTION OF PROTOZOA 



Most of the known Protozoa of the Gulf of 

 Mexico have been reported as new species. 



3 Taxonomic posirion of Dermocytifidium was rather uncertain. In 1952 

 Ray found that this microorganism is a fungus (Ray, Samray M., 1952, A 

 Culture Technique for the Diagnosis of Infections with Dermocyslidiuin 

 mnrinum Mackin, Owen and Collier, in Oysters, Science lir>- 360-3C1). 



These and the previously known ones have usually 

 been reported only from particular localities. 

 Not much about their general distribution, there- 

 fore, seems to be known. We may reasonably 

 suppose, however, that certain generalizations 

 about distribution of free-living Protozoa else- 

 where in the world may give us some idea about 

 the expected distribution of those known in the 

 Gulf since particular species generally tend to 

 occur wherever the particular conditions favoring 

 their life processes e.xist. Pertinent remarks on 

 distribution of free-living forms can be found in 

 Calkins' (1933, pp. 25-26) book on biology of 

 Protozoa. 



The distribution of parasitic Protozoa is neces- 

 sarily limited to that of their hosts. The hosts 

 themselves are not generally so widely distributed 

 as are the free-living Protozoa, one reason being, 

 perhaps, that the means of dispersal available to 

 them are somewhat more limited. Furthermore, 

 distribution of parasitic Protozoa is not neces- 

 sarily so extensive as that of their hosts, since 

 environmental conditions tolerated by the latter 

 may be unfavorable to the former. Protozoa 

 with alternation of hosts (such as many of the 

 Sporozoa) are further limited in distribution, 

 since the definitive and intermediate hosts, both 

 necessary for survival of the parasite, may not 

 have the same range of adaptability to different 

 habitats. While the host species living in geo- 

 graphical isolation have been undergoing evolu- 

 tionary divergence their parasites have likewise 

 diverged to give rise to separate varieties and 

 species. In view of these considerations, the 

 parasitic Protozoa occurring in the Gulf of Mexico 

 are less likely to be identical with species found in 

 similar habitats elsewhere than are the free-living 

 ones. To phrase the same idea in positive terms, 

 one would expect, a priori, to find that many of 

 the parasitic Protozoa in the Gulf of Mexico are 

 new ones. The limited information we have 

 about them, in fact, tends to support that con- 

 clusion, since the overwhelming majority of them 

 have been previously unrecorded species. The 

 noteworthy exceptions were some of the ciliates 

 observed by Powers (1935) in sea urchins; about 

 half of them had previously been described at 

 Bermuda and Beaufort, North Carolina. With 

 one or two exceptions, as far as the writer knows, 

 each of the parasitic species known in the Gulf of 

 Mexico has been observed only in one or few 



