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L'auteur étudie les principaux représentants européens du genre Tyromyces. Se basant sur des caractères d'ordre divers, caractères morphologiques et anatomiques du carpophore et du mycélium, oxydases, polarité et comportement nucléaire, il montre l'hétérogénéité de ce genre. Il propose son éclatement en trois genres : genre Leptoporus avec L. mollis, type du genre Leptoporus, genre Tyromyces avec T. chioneus et kmetii, et genre Spongiporus qui comprend de nombreuses espèces à spores allantoïdes, germant au laboratoire avec difficulté, et présentant un comportement nucléaire normal du mycélium ; T. wynnei est transféré dans le genre Heteropus. A l'occasion de ce travail, une nouvelle espèce est décrite : Spongiporus luteocaesius. Les espèces nouvellement récoltées en France sont les suivantes : Tyromyces kmetii, Spongiporus guttulatus, lowei, undosus, et Heteroporus wynnei. Tyromyces kmetii non connu d'Amérique a été récolté par l'auteur en Louisiane. Enfin des interfertilités montrent ou confirment l'identité de récoltes américaines et européennes notamment pour Spongiporus stipticus, undosus et Tyromyces spraguei.

Seines are simple and effective fish collection gears, but the net mesh size influences how well the catch represents the fish communities. We designed and tested a hybrid seine with a dual-mesh bag (1/4 00 and 1/8 00 ) and compared the fish assemblage collected by each mesh. The fine-mesh net retained three times as many fish and collected more species (as many as eight), including representatives of several rare species, than did the coarser mesh. The dual-mesh bag permitted us to compare both sizes and species retained by each layer and to develop species-specific abundance correction factors, which allowed comparison of catches with the coarse-mesh seine used for earlier collections. The results indicate that a hybrid seine with coarse-mesh wings and a fine-mesh bag would enhance future studies of fish communities, especially when small-bodied fishes or early life stages are the research focus.

Biodiversity is responsible for important ecological processes like productivity and ecosystem stability, and rare species are a major component of biodiversity. Rarity increases a species' vulnerability to disturbances and also makes them difficult to study. Globally, species of freshwater systems are some of the most threatened, and evaluation of rare freshwater species and their habitats is needed to help preserve natural flexibility and ecological function. We conducted an analysis of full fish communities of the upper St. Lawrence River and its major US tributaries, with the goals of determining species locations and abundances, associated environmental conditions, the distribution of distinct fish assemblages across the landscape (with emphasis on communities supporting rare species), and potential threats. From 2009 to 2015, the US Geological Survey (USGS) and Saint Regis Mohawk Tribe (SRMT) worked together using standardized methods to collect community samples within 4 different aquatic realms (shallow and deep lentic, and small and large lotic systems) and determine species-specific fish abundances, frequencies of occurrence, and associated habitat signatures and spatial distributions. Distinct fish assemblages and associated habitat conditions were objectively identified by multivariate and hypothesis-testing methods. We used a geographic information system (GIS) to spatially associate habitat, biotic, and landscape attributes within each stream reach throughout the study area, facilitating quantification of distribution patterns. Comparisons with historical data provided estimates of loss or gain of threatened and endangered species (T&E) colonies. We developed a disturbance index to highlight potential threats to aquatic species. More than 140,000 fishes of 87 species were collected from a total of 1140 sample sites, covering 278 stream reaches, including the endangered Notropis anogenus (Pugnose Shiner), and threatened Hiodon tergisus (Mooneye), Etheostoma pellucidum (Eastern Sand Darter), and Acipenser fulvescens (Lake Sturgeon). We identified 50 distinct fish assemblages differing in species composition, abundance, and/or diversity, but only 13 of those assemblages included a T&E species. The rareness, extent, and patchiness of fish assemblages created a mosaic of fish communities across the landscape, from headwaters to the mainstem of the St. Lawrence River. Comparisons with historic surveys showed a stable number of T&E species colonies or an increase for some species. The geographic distribution of multimetric disturbance index values showed where combinations of disturbances to fish habitats might affect rare fish species and aquatic communities in the region. The species-habitat associations and fish assemblage distributions can be used for evaluation of species, communities, or habitats that may need protection or restoration.

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