W&M ScholarWorks Reports 1981 Ontogenesis and phylogenetic interrelationships of parasitic flatworms Boris E. Bychowsky Follow this and additional works at: https://scholarworks.wm.edu/reports Part of the Aquaculture and Fisheries Commons, Marine Biology Commons, Oceanography Commons, Parasitology Commons, and the Zoology Commons Recommended Citation Bychowsky, B. E. (1981) Ontogenesis and phylogenetic interrelationships of parasitic flatworms. Translation series (Virginia Institute of Marine Science) ; no. 26. Virginia Institute of Marine Science, William & Mary. https://scholarworks.wm.edu/reports/32 This Report is brought to you for free and open access by W&M ScholarWorks. It has been accepted for inclusion in Reports by an authorized administrator of W&M ScholarWorks. For more information, please contact [email protected]. /J,J:>' :;_~fo c. :-),, ONTOGENESIS AND PHYLOGENETIC INTERRELATIONSHIPS OF PARASITIC FLATWORMS by Boris E. Bychowsky Izvestiz Akademia Nauk S.S.S.R., Ser. Biol. IV: 1353-1383 (1937) Edited by John E. Simmons Department of Zoology University of California at Berkeley Berkeley, California Translated by Maria A. Kassatkin and Serge Kassatkin Department of Slavic Languages and Literature University of California at Berkeley Berkeley, California Translation Series No. 26 VIRGINIA INSTITUTE OF MARINE SCIENCE COLLEGE OF WILLIAM AND MARY Gloucester Point, Virginia 23062 William J. Hargis, Jr. Director 1981 Preface This publication of Professor Bychowsky is a major contribution to the study of the phylogeny of parasitic flatworms. It is a singular coincidence for it t6 have appeared in print the same year as Stunkardts nThe Physiology, Life Cycles and Phylogeny of the Parasitic Flatwormsn (Amer. Museum Novitates, No. 908, 27 pp., 1937 ), and this editor well remembers perusing the latter under the rather demanding tutelage of A.C. Chandler. Bychowskyrs paper remained unknown to most parasitologists, however, for many years, and it is largely due to W.J. Hargis, Jr.ts careful husbanding through trans­ lation of Bychowskyrs monograph on monogenetic trematodes that his earlier work has commanded the interest which it deserves. In his 1957 work Bychowsky very briefly summarizes the content of his 1937 article and goes on to state (A.I.B.S. translation, W.J. Hargis, Jr., ed., 1961, p. 564), nThe views expressed are completely held by us also at the present time.n He names several Soviet para­ sitologists who have accepted his opinions in whole or in part, but also describes at length the objections of D.M. Fedotov. In truth, Bychowskyrs system is not widely used, and apparently has not been widely accepted elsewhere, as a glimpse at any general parasitology text will show. Part I of the 1937 paper is of interest to specialists in monogeneans, principally; Parts II-V are of more general interest. It is not necessary for one to agree fully with any given section, ~.g. to accept the basis of his monogene system in full, in order to appreciate the subsequent arguments. It is in the hope of allowing a fair treatment by a larger audience that this translation is given. The present editor will make a single objection and a proposal and be done with it. This has to do with the taxon, Cercomeromorphae, here given Superclass status by Bychowsky. Not only is the term horribly non-euphonious, but (2) as originally employed by Janicki, it indicated a different concept, and (3) a number of the forms included therein do not possess a cercomer, though, to be sure, they do bear the posterior larval hooks characteristic of this group. Here and now is proposed the name, ONCOPHOREA, for the concept which includes those parasitic flatworms having larvae which develop hooks in a character­ istic manner and of a characteristic type, and bear them posteriorly. The translators have employed the transliteration system of the U.S. Department of Commerce, National Bureau of Standards, Joint Publications Research Service. The editor has changed several names, e·.5I.· Bychowsky, Sinitsin, Janicki, to the spelling which is most tamiliar to Western readers, and more specifically used by the Index Catalogue of Medical and Veterinary Zoology. Obvious misspellings ii Izvest. Akad. Nauk SSSR, Seriia Biol. IV:l353-1383 (1937). ONTOGENESIS AND PHYLOGENETIC INTERRELATIONSHIPS OF PARASITIC FLATWORMS by B.E. Bychowsky Zoological Institute of the Academy of Sciences USSR On the basis of studies of the development of monogenetic trematodes, it is possible to establish that their current system is artificial. In this connection, the author attempts to develop a system for monogenetic trematodes not only on the basis of comparative anatomy, but also on the basis of ontogenesis. At the same time, the development of a new system of flatworms is the result of the above propositions. INTRODUCTION The purpose of this report is to establish relationship among individual groups of parasitic flatworms, namely, among monogenetic trematodes (Monogenea), digenetic trematodes (Digenea), tapeworms proper (Cestoda), and the so-called Cestodaria group (AMPHILINIDAE and GYROCGTYLIDAE). The attempt to establish the above-mentioned re­ lationships is made to a variable degree for different groups. The main point of this report is the establishment of phylogenetic re­ lationship in the Monogenea, not only for the entire group as a whole, but also for the individual families which are members of this group. We feel that another important point is our attempt at clarifying the phylogenetic position of the GYROCOTYLIDEA group which until very recently has been puzzling in many respects. On the basis of phylogenetic considerations stated below, we consider it possible to suggest a new system for parasitic flatworms which is essentially different in many respects from the generally accepted current system. The significance of the solution of these problems lies, un­ doubtedly, not only in the fact that they shed some light on the obscure points of taxonomy and in the fact that these solutions provide us with a clue for understanding the evolutionary process within the studied group, but also in the fact that these solutions make it possible for us to clarify correctly a number of problems of the biology and development of parasitic flatworms. The solution of the latter is quite often extremely important for answering purely practical questions connected with therapeutic, biological and preventive measures for controlling parasitic worms and diseases caused by them. Investigations of the phylogeny of lower organisms are hindered greatly by the fact that there is no direct evidence of their evolution, i.e. paleontological remains. This fact makes it necessary 1 to pay even more attention to the data of comparative anatomy and comparative embryology. However, it should be mentioned here that the embryological evidence of phylogenetic interrelations of para­ sitic flatworms is not given sufficient attention at the present time. Moreover, as it will be shown further in this paper, em­ bryological materials have not been used at all for monogenetic trematodes. For parasitic animals, a certain criterion of their phylo­ genetic relationships, in addition to the above-mentioned ones, can also be aspects of specificity with respect to the host (Fuhrmann's rule for the Cestoda; Bychowsky's rule for the Monogenea) and data on the paleontological antiquity of the host in connection with the parasite's specificity. However, the utilization of the latter purely "parasitological!! criteria of phylogeny is extremely difficult and very often may lead to completely erroneous conclusions, because the rates of the evolutionary processes of the host and of the parasite may be entirely different: a parasite could change considerably more slowly.on an extremely rapidly evolving host, or vice versa, which, undoubtedly, will significantly obscure the picture-ana will hinder the correct utilization of the indicated criteria. It is to be supposed that the presence of a very specialized group as parasites on a definite and very ancient host group still does not permit us to say with a sufficient degree of confidence that the group of para­ sites is also very ancient. However, such deductions are made quite frequently. As an example, we can cite Fuhrmann's view regarding phylogenetic interrelations within the Subclass Cestoda. Fuhrmann writes: TTFor establishing the phylogeny of the Cestoda, we have at our disposal the data on the incidence of various orders of the Cestoda among the vertebrates. For example, Tetraphyllidea (with the exception of aberrant PROTOCEPHALIDAE and MONTICELLIDAE), as well as Tetrarhynchidea (exception- one species), live only in selachians. Pseudophyllidea are not present in primitive selachians, but occur in marine teleosts and are common in fresh-water fish and land vertebrates. Cyclophyllidea parasitize only birds and mammals and occur rarely in reptiles and amphibians. On this basis, it is easy to conclude that tapeworms of them ost ancient vertebrates ( selachians) are the most primitive, and not Pseudophyllidea, as is asually accepted." It should be mentioned here, that in calling Tetraphyllidea "the most primitive", Fuhrmann means that it is equivalent to TTthe most ancient, 11 which is indicated by the phylogenetic scheme presented by him later. However, this is absolutely inadmissible, because the most ancient forms do not have to be necessarily the most primitive (it seems to us that quite frequently it is just the opposite). The example cited above shows the nature