John L. Crites

Population biology of Camallanus oxycephalus Ward and Magath, 1916 (Nematoda: Camallanidae) in white bass in western Lake Erie.

The distribution and abundance of the nematode Camallanus oxycephalus infecting white bass, Morone chrysops, in western Lake Erie was studied for over 2 years. Infection was generally more frequent and of higher intensity in large fish. The frequency distributions of nematode abundance in all segments of the fish population followed the negative binomial distribution. The data show seasonal cycles in population structure, site selection, intensity of infection, maturation, and reproduction. Infection occurs during July and August with a resulting peak in population density; during late summer and autumn, mortality, probably density-dependent, reduces the population by 30 to 60%; surviving worms are eliminated at 1 year of age. Growth and development of female worms is arrested from November to April, then proceeds at a rapid rate until the worms release their larvae and die. This growth pattern is probably related to temperature but may also involve host hormone cycles. The dispersal period of the nematode coincides with the annual maximum density of the intermediate host, a cyclopoid copepod,and is interpreted as an adaptation which increases the probability of successful transmission. Because the number of larvae produced by each female worm is a function of body volume, natural selection has favored rapid spring growth and attainment of large body size relative to the male worm. Both seasonal timing in the life cycle and the number of larvae produced are important factors in determining the abundance of this and perhaps other parasites. Evidence is presented suggesting that fluctuations of environmental parameters may disrupt the timing of transmission and alter the distribution and abundance of the parasite. It is hypothesized that the magnitude of such changes in parasite abundance may be related to the complexity of the host-parasite system.

TRIAENOPHORIASIS IN LAKE ERIE WHITE BASS, Morone chrysops1

The pseudophyllidean tapeworm, Triaenophorus nodulosus, was found in 51% of the adult white bass, Morone chrysops, sampled from western Lake Erie during the summer of 1973. Prevalence of infection with Triaenophorus increased with size and age of fishes. This worm is responsible for the disease triaenophoriasis, which is grossly characterized by large, white cysts, dark-brown “streaks” and hemorrhages in the liver. Microscopically, there is an acute inflammatory response, necrosis of liver parenchyma, squamous metaplasia, fibrosis and displacement of liver tissue as the tapeworm grows. Many plerocercoids were necrotic and surrounded by a dense tissue. The pathophysiology of extensive liver obstruction needs to be investigated as well as its effect upon infected fish populations.

Heliconema brooksi n. sp. (Nematoda: Physalopteridae) from the Ophichthid Eel Ophichthus gomesi in the Gulf of Mexico

Heliconema brooksi n. sp. is described from the shrimp eel, Ophichthus gomesi, in Mississippi Sound. This species is distinguished from other members of the genus by possessing in the male 40 or more tessellated longitudinal ridges, a spicule ratio averaging 1:10.6, 4 precloacal papillae, and 6 postcloacal papillae. Females have a protruding vulvular flap. Both sexes have a prominent sclerotized cardium. Heliconema brooksi is morphologically most closely related to Heliconema heliconema. A juvenile worm from the white shrimp, Penaeus setiferus, in the same locality may be the infective stage.

Renal coccidiosis in interior Canada geese, Branta canadensis interior Todd, of the Mississippi Valley population

Kidneys from 309 Interior Canada geese from three locations in the Mississippi Flyway were examined for renal coccidia. Oocysts and/or young zygotes of Eimeria sp. were found in 6.8% of goose kidneys sampled. Only one type of renal coccidian oocyst was observed. Significantly more immature geese were infected than adults; however, there was no significant difference observed between the prevalences of infection in male and female birds. A host cellular response to zygotes and oocysts was noted in the majority of infected adult geese. Heavily infected kidneys were hypertrophic with minute foci on the surface of the organ. Histological examinations showed large numbers of unsporulated oocysts accumulated in distended collecting tubules, resulting in pressure necrosis to adjacent tissue and urate retention. Zygotes were observed in the cytoplasm of tubule cells and extracellularly in interstitial tissue. Infected tubule cells were characterized by the peripheral location of the nuclei, cytoplasmic basophilia, and cellular hypertrophy. This is the first report of an Eimeria sp. in the kidneys of Canada geese of the Mississippi Valley population.

CUCULLANUS PALMERI N. SP. (NEMATODA: CUCULLANIDAE) FROM THE BATFISH OGCOCEPHALUS NASUTUS IN THE GULF OF MEXICO

Cucullanus palmeri n. sp. is described from the shortnose batfish, Ogcocephalus nasutus, in the Gulf of Mexico. This species is anatomically most similar to Cucullanus gendrei but differs from it in having a shorter esophagus and longer tail. Males differ in having a smaller gubernaculum and a different arrangement of a lateral caudal papilla. Cucullanus palmeri is readily distinguished from Cucullanus lophii, also from a lophiform fish host in that the deirids and excretory pore are not posterior to the posterior end of the esophagus like in C. lophii.

Ctenascarophis lesteri n. sp. and Prospinitectus exiguus n. sp. (Nematoda: Cystidicolidae) from the Skipjack Tuna Katsuwonus pelamis

Two cystidicolid nematodes, Ctenascarophis lesteri n. sp. and Prospinitectus exiguus n. sp., are described from the skipjack tuna, Katsuwonus pelamis, from Fiji, New Caledonia, Marquesas Islands, New Zealand, Papua New Guinea, and Puerto Rico. The former species differs from Ctenascarophis gastricus, the only other member of the genus, by having comb rows extending farther posterior than two-thirds the body length, to the anus in the female; it also has differently distributed spines on each comb, with a maximum of 32 rather than 8. The male has 7 rows of precloacal longitudinal crests; 3 pairs of precloacal, 1 pair adanal, and 6 pairs postcloacal papillae; and a spicule ratio of 1:3.4-1:5.0. The latter species differs from Prospinitectus mollis, the only other species in the genus, by being less than one-half as long, 3.5-5.9 mm long; with a proportionally longer esophagus; fewer spines per spine ring, a maximum of 49 compared with 100; deirids that lack spinules; males with an unornamented precloacal cuticle as well as a different number and distribution of caudal papillae, 2 precloacal and 7 postcloacal; and a smaller spicule ratio, 1:4 rather than 1:5-1:7.

A redescription of Eustrongylides tubifex (Nitzsch 1819) Jägerskiöld 1909 (Nematoda: Dioctophymatidae) from mallards (Anas platyrhynchos).

Eustrongylides tubifex (Nitzsch 1819) Jägerskiöld 1909 is redescribed from six male and 10 female adult specimens from experimental infections in mallards (Anas platyrhynchos). Our redescription is compared with that of Jägerskiöld (1909) and those of the Russian investigators Kontrimavichus and Bakhmeteva (1960) and Karmanova (1968). Our redescription differs in the ranges of total body length, esophageal length, maximum width, spicule length and vagina length. The cuticular fringe and inner rim of small papillae of the male bursa are shown to be definitive species characters. A key to the species of Eustrongylides is included.

Rhigonema thysanophora sp. n. (Nematoda: Rhigonematidae) from the Millipede, Euryurus erythropygus Brandt, 1841

Rhigonema thysanophora sp. n. (Nematoda: Rhigonematidae) is described from Euryurus erythropygus Brandt, 1841. This is the first species in this genus to be recorded from a polydesmid millipede in North America. The other recognized species in the genus are listed and the characters which separate the new species from others in the genus are elucidated. The specimens used for this report were removed from the posterior part of the intes- tine, the intestinal-rectal valve, and from the anterior part of the rectum of the polydes-