Eight species of fishes from rivers of Northern Portugal were examined for cestodes but only one, Barbus barbus bocagei (Steindachner), was infected: river Este (4 of 12 infected, 1,1,4 adult and 37 juvenile cestodes found respectively), Lima (1 of 8 infected, 1 juvenile cestode), Paiva (1 of 5 infected, 57 juvenile cestodes) and Sousa (1 of 13 infected, 1 adult cestode). The cestodes were Caryophyllidea. The fan-shaped scolex had very shallow incisions, with the scolex separated from the hindbody by a neck. The first vitelline follicles started a considerable distance anterior to the testes, with some vitelline follicles along the lateral margins of the cirrus sac, uterine coils and H-shaped ovary. The uterine coils extended forward to the posterior half of the cirrus sac. Transverse transmission electron microscope sections showed cortical vitelline follicles and medullary testes validating Lytocestidae. These features identify Khawia baltica Szidat, 1941, described from tench Tinca tinca (L.) in East Prussia and subsequently reported from barbel B. barbus and T. tinea in Russia, This is a new host and first record from Portugal and western Europe, thus extending the known range of distribution of K. baltica.
Microhabitat use in the endangered cyprinid species spirlin Alburnoides bipunctatus and accompanying species was examined in three water courses of Slovakia to determine the species’ environmental requirements as a basis for informing conservation policy and management. In all three rivers, water velocity, water depth and substratum character were central features of spirlin microhabitat use, regardless of year or season of sampling, with only limited variation in microhabitat associations as a function of time of day. Clear differences in microhabitat use and intra-specific associations during development were observed in two of the rivers. In particular, a shift in velocity preference towards faster flowing waters appears characteristic of spirlin during their larval and juvenile development, and possibly also that of gudgeon Gobio gobio, European minnow Phoxinus phoxinus, and chub Leuciscus cephalus, which are all species that may be significantly associated with young spirlin. Disproportionate use of deeper waters tended to increase with age in spirlin, and in gudgeon and barbel Barbus barbus, but spirlin preference for substratum was less uniform, with affinities ranging from indifference to strong preference. This contrasts the clear preferences for sand in gudgeon and for cobbles in European bullhead Cottus gobio. Of particular importance to young-of-the-year (YOY) spirlin are lentic zones with some sort of ligneous debris – habitat also used by YOY gudgeon and minnow. Contrary to previous reports elsewhere, spirlin did not avoid in-stream vegetation where present, and in one river it was preferred by YOY and 1+ spirlin. To avoid declines in spirlin and accompanying stream-dwelling species, such as reported elsewhere in Europe, river management in water courses such as these should be limited to the rehabilitation of regulated sections to achieve a natural, heterogeneous channel character.
Based on light and scanning electron microscopical studies, three new, one already known and one not identified species of the nematode genus Rhabdochona Railliet, 1916 are reported from the intestine of freshwater fishes in Dzanga-Sangha Protected Areas (Congo River basin), the Central African Republic: Rhabdochona (Rhabdochona) centroafricana sp. n. from Barbus miolepis Boulenger, R. (R.) marcusenii sp. n. from Marcusenius greshoffii (Schilthuis), R. (Globochona) paski Baylis, 1928 from Phenacogrammus aurantiacus (Pellegrin) (new host record), R. (G.) tricuspidata sp. n. from Raiamas christyi (Boulenger) and Rhabdochona (G.) sp. (only females) from Epiplatys multifasciatus (Boulenger). Rhabdochona centroafricana is mainly characterised by the length of the left spicule (333 µm) and the presence of the operculum bearing a conspicuous gelatinous formation on one of egg poles, R. marcusenii by the length of the left spicule (453-486 µm) and the presence of a single broad filament on one egg pole only and R. tricuspidata by the body with marked cuticular ornamentations and deirids branching into three prongs. A key to valid species of Rhabdochona parasitic in fishes of Africa is provided.