talabanoides is the chief host of this species. It is impossible to say 



anything definite regarding the occurrence of the other species of fishes 



which were indicated until secondary findings substantiating the data of d. 223 



Chauhan are made. Our certain suspicion toward the data reproduced is 



caused by the fact that in the works of Chauhan there are, as we will show 



later, a number of dubious indications about hosts of separate parasites 



(see pages 227, 228 and others), 



Gyrodactylus arcuatus arcuatus, which was encountered many 

 times by different researchers, was first described by us from Pygosteus 

 pungitius (L. ), and Gastrosteu s aculeatus L. (Gasterosteidae, Gastero- 

 steiformes). In addition to that , the special subspecies --Gyrodactylus 

 arcuatus gerdi Bychowsky from Eleginus navaga (Pall. ) and G. arcuatus 

 proximus Kutikowa from Boreogadus saida (Lep. ) (Gadidae, Gadiformes), 

 were discovered (Bychowsky, 1933b). The two last subspecies are closer 

 to each other than to the typical species, which is undoubtedly connected to 

 their occurrence on representatives of one family (standing far from the 

 family which G. arcuatus arcuatus parasitizes). The transfer of the latter 

 to the fishes which are far removed from the initial host is probably linked 

 with the relative phylogenetic youth of the species, and because of that-- 

 with a weaker adaptation to the host. This is also underlined by the cir- 

 cumstance that the given species is encountered both in fresh and in 

 marine waters --on the transitory just as on the truly fresh water or purely 

 marine hosts, (Bychowsky and Poljansky, 1953; Shulmann and Shulmann-- 

 Albova, 1953). 



Benedenia melleni was first described by MacCallum from 

 the New York Aquarium, "from the eyes of Sphaeroides annulatus, 

 Chaetodipte rus faber, Angelichtyes isabelita, Pomacanthus arcuatus, 

 etc. " (MacCallum, 1927). The author supposed that this parasite was p^ 224 



carried to the aquarium with the first of the above-mentioned species of 

 fishes from California, that is, of Pacific Ocean origin and that it trans- 

 fered to the other hosts only in the artificial conditions. However, this 

 does not correspond to reality. Thus, Jahn and Kuhn (Jahn and Kuhn, 1932) indicated 

 that according to the opinions of the workers in the New York Aquarium 

 at the time when B. melleni appeared in the aquarium there were no 

 Sphaeroides annulatus in it and that the parasite mentioned was brought 

 and is brought into the bodies of water not by fishes of the Pacific Ocean 

 but from the Atlantic Ocean- -from West India (from the region of the 

 Bahama Islands). At the present time one can consider it fully sub- 

 stantiated that B. melleni was discovered on a number of fishes in the 

 region of Bimini Island in natural conditions (Nigrelli, 1947). At the 

 present time B. melleni is known from the following fishes in natural 

 artificial bodies of water r^ 



244 



