Date of this Version
Illinois Biological Monographs (July 1927) 11(3):
Contributions from the Zoological Laboratory of the University of Illinois (1928) Number 323.
Representatives of the genus Corallobothrium from American fish have never been described. Marshall and Gilbert (1905) report two members of this genus taken from Ameiurus melas (black bullhead) caught in the lakes at Madison, Wisconsin. La Rue (1914) refers to an undescribed species of Corallobothrium encysted in the livers of A. melas and A. nebulosus (common bullhead) from the Illinois River. Ward (1918) noted the presence of a species of Corallobothrium in lctalurus punctatus (channel-cat) at Milford, Nebraska. Aside from these incidental references, the American literature contains no information on this interesting group of fish tapeworms.
The acquaintance of the writer with these cestodes began during the summer of 1925 while a survey of the parasites of fish from the rivers and lakes in the upper Mississippi and Missouri basin was in progress (Essex and Hunter, 1926). At that time cestodes belonging to Corallobothrium were found in the following hosts: A. meiurus melas, Leptops olivaris (mud-cat), and Ictalurus punctatus.
At the suggestion of Dr. Henry B. Ward an intensive study was begun in the spring of 1926 on the species of Corallobothrium infesting I. punctatus. As the investigation progressed it came to assume three distinct phases: (1) taxonomy and morphology; (2) seasonal occurrence; (3) lifecycle. It was discovered that two new species of Corallobothrium were represented in my collections. These two species are described and named in the present paper. No work having been reported previously on the seasonal occurrence of any fish tapeworm in America, an effort was made to obtain all possible information on this phase of the problem. This study has shed some light on the biological relations between the parasites and their hosts. Up to this time only a few experimental investigations on the life-cycle of fish cestodes have been reported by European workers and none whatever by workers in America. Since such studies are of especial biological significance, and since complete information on the developmental history of fish parasites is of great assistance to fish culturists in their efforts to combat parasitic diseases among fish, all data that I have secured on this phase of the investigation are presented in this paper.
1. An intensive study has been made of two new species of Corallobothrium. Both species are parasitic in Ictalurus punctatus, Ameiurus melas, and Leptops olivaris. Woodland's proposal (1925) to delete the genus Corallobothrium has not been accepted. The genus has been retained and the two new species have been designated as Corallobothrium giganteum and C. fimbriatum. A description is given of the adult anatomy of each parasite. The scolex of C. giganteum is subject to wide variation. Amphitypy occurs in the arrangement of the interovarial organs of both species. A new role has been suggested for the excretory system.
2. Particular attention has been paid to the degree of infection and seasonal occurrence of these cestodes in Ictalurus punctatus. Among 130 adults of this species nearly 70 per cent harbored one or the other of these cestodes or both. The adult parasites occurred only from spring to fall but the plerocercoid stage was present in the final host throughout the year.
3. The life-cycle of each cestode was studied experimentally. Infection was produced in Cyclops serrulatus and C. prasinus by feeding eggs of Corallobothrium giganteum. Positive results were obtained by feeding the eggs of C. fimbriatum to Cyclops bicuspidatus, C. serrulatus, and C. prasinus. The complete development of both parasites in the first intermediate host has been described. The procercoid of Corallobothrium giganteum reached maturity in the Cyclops by the twelfth day after the Cyclops had been exposed to the eggs. The development of the procercoid of Corallobothrium fimbriatum required from 12 to 14 days.
4. Observations on the feeding habits of Cyclops reveal that organic debris and cercaria are eaten and that protozoa are consumed in large numbers.
5. Cyclops infected with mature procercoids of Corallobothrium fimbriatum were fed to minnows (Notropis blennins). Larvae were recovered from the body-cavity of the minnows 3 days after feeding. Sections of an infected minnow showed the presence of the larvae in the intestine, within the coelom, and in the musculature.
6. Ictalurus punctatus measuring from 2 to 3 inches in length were found to harbor adult Corallobothrium fimbriatum.
7. Cyclops infected with the procercoids of Corallobothrium fimbriatum were fed to minnows. The minnows were fed to Ameiurus melas and the larvae of Corallobothrium fibriatum were recovered from the intestine of A. melas.
8. The evidence indicates that catfish may be infected with Corallobothrium fimbriatum either by ingesting infected Cyclops or by feeding on infected minnows.
9. A comparison of Bothriocephalid and Proteocephalid development indicates a close relationship between the two groups.