A novel microhabitat for parasitic copepods: a new genus of Ergasilidae (Copepoda: Cyclopoida) from the urinary bladder of a freshwater fish.

An endoparasitic copepod is reported from the urinary bladder of a fish for the first time. Endoparasitic copepods on fish hosts are extremely rare and the impact of colonization of this novel microhabitat on the biology of the parasite is discussed. This curious association was reported from two different host families of Neotropical freshwater fishes, Erythrinidae and Cichlidae, collected from the Cristalino River, a tributary of the Araguaia River, in Brazil. The copepod is fully described using light and scanning electron microscopy. Urogasilus brasiliensis n. g., n. sp. represents a new genus and species of the family Ergasilidae and can be distinguished from other genera by its unique tagmosis, in which the fourth and fifth pedigerous somites and the genital double-somite are all fused to form an elongate trunk. The anal somite is the only free abdominal somite present. The pattern of leg segmentation is also unique, with legs 1 to 3 each having a 2-segmented endopod and leg 4 reduced to a single seta. The discovery of ovigerous female ergasilids in the urinary bladder of a fish is novel and this discovery represents a good model for further studies on the adaptations to an endoparasitic lifestyle.

New and previously described species of Urocleidoides (Monogenoidea: Dactylogyridae) infecting the gills and nasal cavities of Hoplias malabaricus (Characiformes: Erythrinidae) from Brazil.

During an investigation of the biodiversity and structure of parasite communities among native populations of the erythrinid fish Hoplias malabaricus (Characiformes) from 7 rivers in Brazil, the following monogenoidean (Dactylogyridae) species were found: Urocleidoides malabaricusi n. sp., Urocleidoides naris n. sp., Urocleidoides cuiabai n. sp., Urocleidoides brasiliensis n. sp., and Urocleidoides eremitus Kritsky, Thatcher, and Boeger, 1986. Specimens considered as a new genus of Dactylogyridae were also found. The new species are mainly distinguished from the other 14 species of Urocleidoides in the general morphology of their copulatory and anchors/bar complexes. These new species and the new dactylogyrid genus are described, as well as supplemental observations and new illustrations of U. eremitus are provided. The present findings expand the known geographical distribution of species of Urocleidoides to southeastern and midwestern Brazil. A high speciation of this genus in the tropics is hypothesized, and it is briefly discussed.

[Parasitism of Hoplias malabaricus (Bloch, 1794) (Characiformes, Erythrinidae) by Quadrigyrus machadoi Fábio, 1983 (Eoacanthocephala, Quadrigyridae) at a pond, Aguaí, State of São Paulo, Brazil]. / Parasitismo de Hoplias malabricus (Bloch 1794) (Characiformes, Erythrinidae) por Quadrigyrus machadoi Fábio, 1983 (Eoacanthocephala, Quadrigyridae) de uma lagoa em Aguai, Estado de São Paulo, Brazil.

The parasitism of trahira, Hoplias malabaricus, by the acanthocephalan Quadrigyrus machadoi was studied. Fish were collected at a pond located on Palmeiras Farm (21 degrees 59'19''S, 47 degrees 12'04''W), municipal district of Aguaí, São Paulo, Brazil, during the period of January, 2002 to May, 2003. Among the 64 specimens analyzed, 56 (prevalence=87.5%) were infected with three to 573 specimens of Quadrigyrus machadoi (mean intensity=119.0+/- 120.6 and mean abundance=104.1+/-119.4). Most of the parasites were found in the mesenterium as cystacanths. Some fish contained adult female parasites in the intestine, but gravid females were not verified. Parasite indices were analyzed in relation to the biological parameters of sex and standard length of the trahira, as well as with regard to the dry and the rainy periods defined for the area. No differences in parasite indices between sexes were found. The smaller specimens were the most extensively infected and had higher intensities of infection than fish of greater lengths. No seasonal variations in prevalence, mean intensity of infection and mean abundance values were found. The health of the fish was not influenced by the presence of parasites, as shown by the relative condition factor.