Hypostomus dlouhyi, a new species of mailed catfish from Paraguay (Pisces, Siluriformes, Loricariidae). -Hypostomus dlouhyi sp. nov. is described from the Yguazü River basin, Caaguazü and Alto-Paranâ departments, Paraguay. Morphological caracters are discussed, and the species is compared with other species of the genus, especially those recognized in the Paraguay-Parana River System.

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H. aspilogaster, H. limosus (Eigenmann & Eigenmann, 1888) e H. regani. Säo apresentadas urna chave, descricöes e ilustracöes de todas as espécies.

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We give the first (as far as we know) complete description of the boundary of the Milnor fiber for some non-isolated singular germs of surfaces in C 3 . We study irreducible (i.e. gcd (m, k, l) = 1) non-isolated (i.e. 1 ≤ k < l) Hirzebruch hypersurface singularities in C 3 given by the equation z m − x k y l = 0. We show that the boundary L of the Milnor fiber is always a Seifert manifold and we give an explicit description of the Seifert structure. From it, we deduce that: 1) L is never diffeomorphic to the boundary of the normalization.2) L is a lens space iff m = 2 and k = 1.3) When L is not a lens space, it is never orientation preserving diffeomorphic to the boundary of a normal surface singularity.

A new Hypostomus species is described from the rio Cuiabá, upper rio Paraguay basin, Mato Grosso State, Brazil. The new species is distinguished from all other Hypostomus species, with exception of young specimens of H. latifrons, by the presence of a wide dark transverse bars on laterals of body and fins; and conspicuous dark vermiculations on abdominal region. From H. latifrons it differs by having just one pre-dorsal plate surrounding supraoccipital bone and by the maintenance of the dark saddles in adults. Added to the other fish species recently described from the upper rio Paraguay basin, this work helps to highlight that the region still functions as a potential source of new species.Uma espécie nova de Hypostomus é descrita do rio Cuiabá, bacia do alto rio Paraguai, Estado do Mato Grosso, Brasil. A espécie nova é diagnosticada de todas as outras congêneres, com exceção de H. latifrons, pela presença de amplas barras escuras transversais nas laterais do corpo e nadadeiras, e pelas conspícuas vermiculações escuras na região abdominal. De H. latifrons ela difere por ter somente uma placa pré-dorsal margeando o osso supraoccipital e pela manutenção das barras escuras transversais nos adultos. Somada a outras espécies de peixes recentemente descritas na bacia do alto rio Paraguai, este trabalho demonstra que a região ainda funciona como uma fonte potencial de espécies novas.