Helminths Of Fish Research Articles

Notes on Tetraphyllidean Cestodes from the Atlantic Coast of North America, with Descriptions of Two New Species

The genus Rhinebothrium Linton, 1890 (Tetraphyllidea: Phyllobothriidae) is redefined and considered valid. Rhinebothrium spinicephalum sp. n. and R. lintoni sp. n. are described from the southern stingray, Dasyatis americana Hildebrand and Schroeder. The phyllobothriid, R. maccallumi Linton, 1924, and the oncobothriid, Acanthobothrium tortum (Linton, 1916), are redescribed. Discovery of a hermaphroditic specimen of Dioecotaenia cancellata (Linton, 1890) indicates that the dioecious character of these cestodes is not absolute. Until recently, little has been done to clarify or contribute to the knowledge of the elasmobranch cestode fauna from the western North Atlantic since the work of Linton. Linton's descriptions of helminths of teleost and elasmobranch fishes frequently are too inadequate for accurate identification. Furthermore few of Linton's type specimens are available and, of those that are, many have faded and partially disintegrated. Linton (1890) described the genus Rhinebothrium to accommodate species resembling Echeneibothrium, a genus common to the eastern North Atlantic and Mediterranean Sea, but lacking a myzorhynchus (rostellum). He included four species in this genus. Among Linton's descriptions only two dealt with species of Echeneibothrium. One (E. austrinum Linton, 1924) is considered inadequately described, and the second (E. vernetae; syn. E. variabile Beneden sensu Linton, 1889) was redescribed as a new species by Euzet (1956a). The validity of the genus Rhinebothrium has been questioned by Wardle and McLeod, 1952; Young, 1956; Yamaguti, 1959; and Alexander, 1963; and is considered as synonymous with Echeneibothrium. However, Baer (1961) and Williams (1966) have provided evidence that Rhinebothrium may be distinct from Echeneibothrium. Recent collections of elasmobranch cestodes from the Atlantic Coast and Chesapeake Bay have disclosed two new species of Rhinebothrium and sufficient material to better define the morphology of R. maccallumi Linton, 1924. Cestodes designated as Rhinebothrium cancelReceived for publication 18 September 1969. latum by Linton (1890) were recovered from two cow-nosed rays, Rhinoptera bonasus (Mitchill). Schmidt (1969) examined specimens of this cestode from a single cow-nosed ray and found their morphology unlike that of any other family in the order Tetraphyllidea. Due to the unusual characters of these cestodes, among which Schmidt cites their separate sexes, he designated Dioecotaenia cancellata (Linton, 1890) gen. et comb. n. and proposed the new family Dioecotaeniidae. My recovery of a hermaphroditic specimen of Dioecotaenia indicates that the dioecious character of these cestodes is not absolute. This paper also describes in detail Acanthobothrium tortum (Linton, 1916), an oncobothriid recognized as a member of Acanthobothrium by Southwell (1925) and briefly redescribed by Baer and Euzet (1962). MATERIALS AND METHODS Elasmobranchs were collected during the summers of 1967 and 1968 in Atlantic coastal waters from New Jersey to Chesapeake Bay, Virginia. Through the cooperation of the Virginia Institute of Marine Science, hosts were collected in trawling nets, or with hook and line. Specimens of Acanthobothrium tortum, donated by Dr. R. J. Goldstein, Emory University, were collected at the Cape Haze Marine Laboratory, Sarasota, Florida. Helminths were fixed in situ or removed from the spiral valve, studied alive, and fixed without pressure in alcohol-formol-acetic acid (AFA) at room temperature. Whole mounts were stained with Ehrlich's acid hematoxylin or Mayer's paracarmine, cleared in methyl salicylate, and mounted in Permount. Frontal and transverse serial sections were stained in Heidenhain's iron hematoxylin and eosin. Drawings were made with the aid of a camera lucida and microprojector. All species were compared with available specimens from the USNM Helminthological Collection. Measurements

相模湾産魚類の寄生蠕虫類-I

相模湾産魚類の寄生蠕虫類-I

Intestinal Helminths of Fish from Basswood Lake, Superior National Forest, Minnesota

Intestinal Helminths of Fish from Basswood Lake, Superior National Forest, Minnesota

The Effects of Low Temperatures on Larval Cestodes and Other Helminths in Fish

Our knowledge of the resistance of larval cestodes and other helminths to low temperatures has been derived mainly from the efforts of European investigators. In Russia, Titova (1955) employed two temperatures, -6? and -18?C, to determine the freezing time required to kill plerocercoid larvae of Diphyllobothrium latum L. in pike (Esox lucius). Her findings suggest that the time of freezing required to kill the larvae is roughly proportional to the weight of the fish. For example, at -6?C, 7 days of freezing were required to kill larvae in a 9 kg fish, whereas only 2 days were needed to accomplish similar results in a 700 gm fish. The Italian workers Scolari and Monzini (1954), using yellow perch (Perca fluviatilis) of comparatively uniform weight (70 gm), were able to kill encysted plerocercoid larvae of Diphyllobothrium latum by exposing the hosts to the following temperatures: 0?C for 20 days, -5?C for 72 hours, -15?C for 8 hours, -40?C for 2 hours. These findings led the writer to attempt to determine the survival capabilities during subjection to various low temperatures of some of the larval helminths occurring in fresh-water fishes of Alaska. Such determinations would le of interest for two reasons. (1) Knowledge of the comparative effect of temperature, limited to 1 species at present, would be extended to include several species of Diphyllobothrium, 1 of Triaenophorus, and ascarids (Porrocaecum sp.). (2) The information might prove useful to public health workers interested in preventing fish tapeworm infections among the Eskimos of central and western Alaska. These peoples habitually consume raw or partially cooked fishes carrying the larvae of these tapeworms. In a recent study of enteric infections in the Bethel-Napaskiak area, Fournelle and Wallace (1958) found ova of Diphyllobothrium spp. in about 30 per cent of the human stool specimens examined, while a similar investigation by Rausch (unpublished data) at Hooper Bay in 1957 showed approximately the same rate of infection. Since it is generally suspected by medical investigators, both in this country and Europe, that tapeworms compete with their hosts for certain nutrients, such as vitamin B12, the development of a preventive measure which would destroy the larval cestode in fishes used as foods would be of particular value for the native peoples of western Alaska. This investigation included the following hosts and their helminth larvae: blackfish (Dallia pectoralis Bean), Diphyllobothrium dalliae Rausch and Triaenophorus sp.; whitefish (Coregonus lavaretus pidschian (Gmelin)), Diphyllobothrium sp.; red salmon (Oncorhynchus nerka (Walbaum)), Diphyllobothrium ursi Rausch; rainbow smelt (Osmerus dentex Steindachner), Diphyllobothrium osmeri von Linstow and Porrocaecum sp.; rainbow trout (Salmo gairdneri Richardson),

Observations on the Seasonal Occurrence of a Pseudophllidean Tapeworm Infecting the Alimentary Tract of Lepomis macrochirus macrochirus Raf. in Albermarle County, Virginia

In an investigation of the helminths of fresh-water fish from ponds in Albemarle County, Virginia, the presence of a pseudophyllidean tapeworm infecting Lepomis macrochirus macrochirus Raf. was recorded. The parasite was recovered from the intestine and pyloric caeca of the fish host. The worm was assigned to the genus Bothriocephalus Rudolphi, 1808, on the bases of the nature of the scolex and the arrangement of internal organs in the proglottids. It resembles B. rarus Thomas which was described from the newt, Trituris viridescens Raf. (Thomas, 1937). Little information regarding the seasonal occurrence of parasites is available in the existing literature. Most investigators are concerned with the number and types of parasites present in the host; few attempt to establish any correlation between the extent of infection and seasonal regularity. This correlation is especially significant when applied to a parasite that requires an intermediate host which in itself displays a periodicity of occurrence. It is possible, then, to correlate the seasonal variability of the worm with its degree of maturity within the host.