Revision of Aplanopsis, Pythiopsis, and ‘subcentric’ Achlya species (Saprolegniaceae) using 18S rDNA and morphological data

The Evolutionary Phylogeny of Oomycetes—Insights Gained from Studies of Holocarpic Parasites of Algae and Invertebrates

“…For oomycetes, most molecular studies have used the sequences of either the nuclear-encoded SSU (Dick et al, 1999;Spencer et al, 2002), large ribosomal subunit (LSU) genes (Riethmu¨ller et al, 1999(Riethmu¨ller et al, , 2002Petersen and Rosendahl, 2000;Leclerc et al, 2000) or associated internal spacer region (ITS) sequences (Cooke et al, 2000), or the mitochondrial-encoded cytochrome c oxidase subunit II (cox2) gene (Hudspeth et al, 2000;Cook et al, 2001;Thines et al, 2008). Phylogenetic sequence data for the oomycetes is still far from complete, and the current analyses should be viewed as work in progress.…”

“…All genera in the water mold order the Saprolegniales form a well-defined clade (Dick et al, 1999;Riethmu¨ller et al, 1999;Petersen and Rosendahl, 2000;Leclerc et al, 2000;Inaba and Tokumasu, 2002;Spencer et al, 2002). On the basis of their study, Dick et al (1999) proposed creating a new family within the Saprolegniales called the Leptolegniaceae, in which he subsequently placed the genus Aphanomyces (Dick, 2001).…”

“…When greater numbers of taxa were included in the phylogenetic analyses, it became apparent that the two largest and most familiar water mold genera Achlya and Saprolegnia did not form monophyletic taxa but had representatives scattered in several different ''genus-level'' clades (Leclerc et al, 2000;Tokumasu, 2002, Spencer et al, 2002). It is now clear that the traditional generic classification of the Saprolegniaceae based on the pattern of zoospore discharge does not accurately reflect the underlying phylogenetic relationships in this family (Riethmu¨ller et al, 1999;Inaba and Tokumasu, 2002;Spencer et al, 2002). Even in such a well-known genus as Saprolegnia, the application of molecular methods has proved problematic because many currently recognized taxa seem to be polyphyletic on ITS trees (Hulvey et al, 2007).…”

Evidence of parasitic Oomycetes (Peronosporomycetes) infecting the stem cortex of the Carboniferous seed fernLyginopteris oldhamia

“…We retain the name Oomycetes because of its wider currency in the mycological and plant pathological communities. Oomycetes are an ancient group, but their evolutionary history is mostly inferred from molecular phylogenetic studies of living species [3][4][5][6][7][8][9][10][11][12][13][14][15][16]. Bhattacharya et al [17] suggested a mean age for the split between Oomycetes and Bacillariophyta of 936 Ma (range: 1150 -770 Ma).…”

First record of Pythiopsis cymosa de Bary (Saprolegniales: Oomycota) from freshwater fish in Brazil

“…The description of the isolate of P. cymosa obtained in this study agrees with the original description of the taxon and displays morphological characteristics reported by Coker (1923) (Figure 1a-f). Spencer et al (2002) consider Pythiopsis monotypic consisting of only one subeccentric species, P. cymosa. Most of P. cymosa oospores are spherical and the wall is smooth, and each oogonium almost always contains only one subeccentric oospore (Figure 1a-d).…”