Latitudinal, habitat and substrate distribution patterns of freshwater ascomycetes in the Florida Peninsula

Abstract

Freshwater ascomycetes are important decomposers of dead woody and herbaceous debris in aquatic habitats. Despite evidence of their ecological importance, latitudinal, habitat and substrate distributional patterns of freshwater ascomycetes are poorly understood. In this study, we examined the latitudinal and habitat distributional patterns, and substrate recurrences of freshwater ascomycetes by collecting dead submerged woody and herbaceous debris in lentic and lotic habitats at five selected sites along a north-central-south, temperate-subtropical latitudinal ecotone in Florida. One hundred and thirty-two fungal taxa were collected during the study. Seventy-four were meiosporic and 56 were mitosporic ascomycetes, while two species were basidiomycetes. Canonical analyses of principal coordinates (CAP) and Sørenson's similarity index of species based on presence/absence data revealed a high turnover in species composition between the northern and southern sites, indicating a change in species composition along the temperate-subtropical latitudinal ecotone of the Florida Peninsula. Results from the ordination analysis indicated that freshwater ascomycete community composition is not significantly different between lentic and lotic habitats in Florida. The geographically broadly distributed species and species commonly found in Florida occurred in both habitats, whereas a number of new or rare species occurred in either lentic or lotic habitats, but not both. The same freshwater ascomycete species did not necessarily occur on both woody and herbaceous debris; of the 132 taxa collected, 100 were reported only on woody debris; 14 species occurred exclusively on herbaceous debris; and 18 species were found on both woody and herbaceous debris in lentic or lotic habitats. Implications of data from this study to the conservation and knowledge of biodiversity for freshwater ascomycetes is discussed.

Freshwater ascomycetes: Wicklowia aquatica, a new genus and species in the Pleosporales from Florida and Costa Rica

“…Methods for collection, isolation, morphological characterization, and illustration of freshwater ascomycetes used in this study are described by Shearer et al (2004) and Raja et al (2009). The holotype and additional specimens are deposited in the Herbarium of the University of Illinois at Urbana-Champaign (ILL).…”

“…During studies of freshwater ascomycetes along a latitudinal gradient through North and Central America, an unusual bitunicate fungus was found on submerged wood and herbaceous material in Florida (as F76 in Raja et al 2009) and on submerged wood in Costa Rica. Morphological characters such as presence of a globose, immersed to erumpent pseudothecium with a pseudoparenchymatous peridium, interascal tissue of cellular pseudoparaphyses, fissitunicate asci, and thin-walled, hyaline, one-septate ascospores with a gelatinous sheath are characteristics of taxa in the order Pleosporales (Dothideomycetes).…”

Diversity patterns of leaf-associated aquatic hyphomycetes along a broad latitudinal gradient

“…Furthermore, very few studies have focused on aquatic fungal diversity patterns at large spatial scales (Ho et al 2001;Arnolds 2007;Raja et al 2009). Based on a compilation of data extracted from the literature, Shearer et al (2007) concluded that the species richness of aquatic hyphomycetes in streams appeared to exhibit maxima in temperate rather than tropical climates, and suggested that this pattern might be driven by more varied ecological niches in temperate climates, resulting from stronger seasonality than in the tropics.…”

Fungal diversity on submerged wood in a tropical stream and an artificial lake

“…There are many reports on freshwater fungi from both lentic and lotic habitats in different areas (Raja et al 2009;Cai et al 2002Cai et al , 2006Nikolcheva et al 2005;Pascoal and Cássio 2004;Rajashekhar and Kaveriappa 2003;Tsui et al 2001aTsui et al , b, 2003Sivichai et al 2002Sivichai et al , 2000Ho et al 2001;El-Hissy et al 2000;Hyde and Goh 1999;Raviraja et al 1998) and much has been written on the subject .…”