02512nas a2200289 4500008004100000245014300041210006900184300001200253490000800265520158500273653002601858653002501884653002501909653002601934653001901960100001901979700002201998700002202020700001902042700001802061700002102079700001502100700001902115700001802134700001902152856005102171 2014 eng d00aAquastella gen. nov.: a New Genus of Saprolegniaceous Oomycete Rotifer Parasites Related to Aphanomyces, With Unique Sporangial Outgrowths0 aAquastella gen nov a New Genus of Saprolegniaceous Oomycete Roti a544-5580 v1183 a

The oomycete genus Aquastella is described to accommodate two new species of parasites of rotifers observed in Brooktrout Lake, New York State, USA. Three rotifer species – Keratella taurocephala, Polyarthra vulgaris, and Ploesoma truncatum – were infected, and this is the first report of oomycete infection in these species. Aquastella attenuata was specific to K. taurocephala and Aquastella acicularis was specific to P. vulgaris and P. truncatum. The occurrence of infections correlated with peak host population densities and rotifers were infected in the upper layers of the water column. Sequencing of 18S rRNA and phylogenetic analysis of both species placed them within the order Saprolegniales, in a clade closely related to Aphanomyces. The Aquastella species were morphologically distinct from other rotifer parasites as the developing sporangia penetrated out through the host body following its death to produce unique tapered outgrowths. Aquastella attenuata produced long, narrow, tapering, finger-like outgrowths, whilst A. acicularis produced shorter, spike-like outgrowths. We hypothesize that the outgrowths serve to deter predation and slow descent in the water column. Spore cleavage was intrasporangial with spore release through exit tubes. Aquastella attenuata produced primary zoospores, whereas A. acicularis released spherical primary aplanospores, more typical of other genera in the Aphanomyces clade.

10aAquastella acicularis10aAquastella attenuata10aConvergent evolution10aPhylogenetic analysis10aSaprolegniales1 aMolloy, D., P.1 aGlockling, S., L.1 aSiegfried, C., A.1 aBeakes, G., W.1 aJames, T., Y.1 aMatitsky, S., E.1 aWurdak, E.1 aGiamberini, L.1 aGaylo, M., J.1 aNemeth, M., J. uhttp://dx.doi.org/10.1016/j.funbio.2014.01.007