3. Development of Dogielius Bychowsky 



The genus Dogielius appears to be the closest to Dactylogyrus 

 and differs from the latter mainly in the structure and location of the middle 

 hooks of the attaching apparatus (Fig. 147). They lie in one plane surface, 

 are oriented with their points toward each other, and at the place of the 

 transition of the point into the base part of the hook there is a characteristic 

 "displacement" toward the interior so that the point is sharply delineated 



fronn the base part. In 1936 while de- 

 scribing the genus Dogielius (D. forceps 

 Bychowsky) for the first time, we said 

 on the subject: "We know that the differ- 

 ence in the shape of the middle hooks 

 serves as a good systematic character of a 

 species, but in addition to that, the 

 difference has a completely different 

 qualitative meaning in this case. Actually, 

 as a rule the differences lead to a larger 

 or smaller development of certain parts, 

 principally of the same hook. . . . Here 

 also we have a difference connected 



with a change of the shape of the hook 

 which stands independently of larger or 

 smaller developments of the separate 

 parts and apparently which appears 

 during the early stages of ontogenesis. . . , 

 and consequently, its middle hooks 

 (Dogielius forceps Bychowsky) already 

 differ from those in Dactylogyrus in the 



OJmm 



Fig. 147. Dogielius forceps 

 Bychowsky, general view of 

 the worm from the gills of 

 Schizothorax pseudakaaiensis 

 issykkuli Berg from the Tsku 

 (Kazak Republic of SSSR). 



early stages of development. " These 

 suppositions were fully substantiated 

 later during the research in 1944 on a 

 second type of Dogielius. This type (D. 

 planus Bychowsky) was discovered by us 

 on Schizothorax intermedius Macdelland 



in the river Varzob near Stalinbad; its 

 development was studied rather completely by us with the exception of the 

 earliest stages, as we were unable to obtain egg-laying. 



The youngest (known, nobis) larvae of Dogielius (Fig. 148, A) 

 have the head end still with two lobes. The edge hooks numbering 14 are 



0. 016 - 0. 017 mm in length with a well-developed terminal little hook and 

 basal part of the handle. The later terminates in a sphere-shaped widening 

 corresponding to the proximal part of the handle. Further growth of the 



158 



