A new cucullanid nematode, Dichelyne mexicanus sp. n., is described from the intestine of three species of fishes, Agonostomus monticola (Bancroft) (Mugilidae, Perciformcs) (type host), Ictalurus balsanus (Jordan et Snyder) (Ictaluridac, Siluriformes) and Cichlasoma beani (Jordan) (Cichlidae, Perciformes), from three rivers (la Maquina River, Veracruz; Chontalcoatlán River, Guerrero and Santiago River, Nayaril) in central Mexico. This species is characterised by the absence of a ventral sucker in the male (subgenus Dichelyne) and it differs from its congeners mainly in possessing very unequal and dissimilar spicules (left 0.465-0.768 mm and right 293-548 mm long), an asymmetrical gubernaculum, and two intestinal caeca. Another cucullanid nematode, Cucullanus cabaUeroi Petter, 1977, is reported from Dormitator maculalus (Bloch) (Eleotridae, Perciformes) from the La Palma and La Maquina Rivers and Balzapote stream, Veracruz, being briefly described and illustrated; this represents a new host record. Findings of D. mexicanus and C. cabalteroi represent a new record of cucullanid nematodes from fishes in Mexican fresh waters.
Species of the cnidarian genus Henneguya Thélohan, 1892 (Myxosporea: Myxobolidae) are histozoic parasites commonly found in freshwater and, more rarely, in marine fish. The development of these parasites in fish tissues includes the formation of plasmodia within which occurs the sporogony originating spores with two caudal processes, which are usually randomly distributed within the plasmodia. In this report the authors present some cases of non-random distribution of the spores of six species of Henneguya within their plasmodia. Two different patterns of non-random distribution were found based on a literature survey. These patterns and their origin are discussed. Apparently this non-random distribution of the spores is due to both internal and external factors.
The present study was designed to determine the influence of temperature and the addition of potassium dichromate solution (K2Cr2O7) on the efficiency of sporulation of Eimeria bovis (Zublin, 1908), a coccidian species most commonly diagnosed in European bison Bison bonasus (Linnaeus). Sporulation under conventional conditions (2.5% dichromate solution, 23 °C) was completed on the fourth day of incubation (control), whereas the oocyst development took two days more at the temperature of 18 °C, and two days less at 28 °C. Additionally, experimental sporulation of E. bovis at the temperature of 23 °C in the environment of sterilised tap water (without any preservation) took 9 days more compared to control. Finally, oocyst development took 16 weeks when the faces were stored in the refrigerator (3-5 °C) without any special additives. Overall, our results indicate that K2Cr2O7, besides the temperature, plays a crucial role in the process of sporulation of oocysts under laboratory conditions, as the longest delay in sporogony was observed when the faeces were stored without any other additives in the temperature of the refrigerator., Anna M. Pyziel, Aleksander W. Demiaszkiewicz., and Obsahuje bibliografii
The development of the nematode Syncuaria squamata (Linstow, 1883), a gizzard parasite of cormorants, was experimentally studied in the ostracod Notodromas monacha. After the eggs of this nematode have been swallowed by the ostracod, the toothed first-stage larvae of the parasite are released and penetrate through the intestinal wall into the haemocoel of the crustacean. Before attaining the infective third stage, the larvae moult twice in the body of the intermediate host (9-11 and 13-15 days after infection at water temperatures of 20-22° C). The fishes Alhumaides hipunctatus, Noemacheilus barbatulus, Oncor-hynchus mykiss and Poecilia reticulata were for the first time recorded as suitable experimental paratenic hosts of S. squamata third-stage larvae in which a slight growth of larvae may occur. The first recorded natural paratenic host of this nematode was tench, Tinca tinea, originating from a South-Bohemian pond where cormorants occur. Paratenic hosts are apparently the main source of S. squamata infection for cormorants.
The nematode parasite Huffmanela huffmani Moravec, 1987 (Trichosomoididae) infects swimbladders of fishes in the family Centrarchidae. Only fish collected from the upper San Marcos River (Texas) have been found infected with H. huffmani eggs with a prevalence of 90%. Hundreds of thousands of H. huffmani eggs have been observed in these fish but only a few specimens of adult worms have ever been found. The San Marcos River arises from springs along the Balcones Fault Zone in San Marcos, Hays County, Texas. The restriction of the parasite to the upper San Marcos River and the high prevalence of the parasite eggs in centrarchids would seem to enable one to solve the life cycle of H. huffmani but this has proved false. Here, the insights and experiments used to help define some of the aspects concerning the life cycle of this enigmatic parasite are described. This study of H. huffmani includes a description of the habitat, the known limits of geographic distribution of the parasite, possible dispersal processes, egg characteristics, the testing of a possible intermediate host, Palaemonetes antrorum (Benedict) (Decapoda: Palaemonidae), and the effects of the digestion process on H. huffmani eggs.
The eggs of most dactylogyrid and diplectanid monogeneans that infect Acanthopagrus australis are tetrahedral. The adults of larger species deposit more eggs per worm on average in 24h in vitro: Lamellodiscus major (31.7 eggs) = Allomurray-trema rohustum (31.6 eggs) > Haliotrema spariensis (9.6 eggs) > Lamellodiscus squamosus (3.2 eggs). The eggs of L. squamosus (55.9 pm) and H. spariensis (56.4 pm) are smaller than those of L. major (66.1 pm) and A. robustum (63 pm). These eggs are normally shed into the water column. On the other hand, the eggs of Lamellodiscus acanthopagri are a modified T-shape (97.6 pm) and are attached to the gills by a sclerotised, thom-like filament. 1’he parasite can auto-infect the host, but has a low fecundity (0.05 eggs), possibly to prevent lethal parasite burdens.