scarcely linked with Perciformes. It is more likely that ancestors of 

 Gyrodactylidae were already encountered in times when Perciformes 

 were not yet separated, i.e., earlier than the upper Cretaceous period. 



Capsalidae are biologically similar to Gyrodactylidae thanks 

 to the ability to transfer in the adult state from one fish to another under 

 favorable conditions. They are undoubtedly the primary parasites of 

 Perciformes. Only two subfamilies of the six are not encountered in 

 these fishes. These are the Entobdellinae which will be nmentioned 

 later (see page 316 ) and Nitzschiinae examined earlier (see page 307 ). 

 As we have already indicated the peculiarity mentioned above allowed 

 Capsalidae to spread widely not only on related but also on very distant 

 groups. 



Diclidophoridae are encountered basically on Perciformes. 

 At the same time four genera are peculiar only to them (Choricotyle, 

 Cyclobothrium , Pedocotyle , and Echinopelma) , one is encountered both 

 on Perciformes and Macruriformes ( Diclidophoropsis ) and two are not 

 peculiar to Perciformes (Diclidophora and Heterobothrium). Morpho- 

 logical analysis of Diclidophoridae (see page 431 ) shows that primary 

 forms close to Diclidophoropsis which later produced more specialized 

 genera were primary for this group. In this connection, it would have 

 been possible to suppose that the prinnary Diclidophoridae parasitize 

 Macruriformes; however, this is contradicted by all the data about 

 distribution and morphological peculiarities of the order Mazocraeidae 

 as a whole. Diplectanidae are encountered almost exclusively on 

 Perciformes (6 genera and 33 species from 8 genera and 35 species) 

 and are also their primary parasites. Finally, Microcotylidae in- 

 disputably are primary parasites of Perciformes. Of the 15 genera, 

 12 are encovmtered in these fishes and only three which clearly descend 

 from the genera encountered on Perciformes, are discovered on fishes 

 of other orders. At the same time a few separated, individualized 

 species of genera peculiar basically to Perciformes became adapted 

 to parasitizing the fishes of other orders. We have already spoken 

 about all these cases (see pages 311 and 313). 



As a whole, the fauna of Monogenoidea of Perciformes can 

 be characterized as being very rich and basically linked in its origin 

 with Percifornnes with the exception of a few families which became 

 secondarily adapted to parasitizing them (Gyrodactylidae, part of 

 Dactylogyridae and Mazocraeidae). At the same time, the faxina of 

 Monogenoidea of Perciforines gave rise to numerous groups which 

 became distributed on a number of orders of fishes whether linked or 

 not linked with them phylogenetically. In the second case this took 

 place mainly in connection with the peculiarities of the ecology of the 



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