Department of Biology, Southern Oregon University, Ashland, Oregon 97520, USA.
Mycologia. 2010 Jan-Feb;102(1):93-107. doi: 10.3852/07-190.
A species of Psathyrella (Basidiomycota) with true gills has been observed fruiting underwater in the clear, cold, flowing waters of the upper Rogue River in Oregon. Fruiting bodies develop and mature in the main channel, where they are constantly submerged, and were observed fruiting over 11 wk. These mushrooms develop underwater, not on wood recently washed into the river. Substrates include water-logged wood, gravel and the silty riverbed. DNA sequences of the ITS region and a portion of the ribosomal large subunit gene place this fungus in Psathyrella sensu stricto near P. atomata, P. fontinalis and P. superiorensis. Morphological characters distinguish the underwater mushroom from previously described species. Fruiting bodies have long fibrillose stipes with small diameter caps. Immature stages have a thin veil that is soon lost. Gills lack reddish edges. Cystidia are ventricose with subacute apices. Spores were observed as wedge-shape rafts released into gas pockets below the caps. Underwater gills and ballistospores indicate a recent adaptation to the stream environment. This particular river habitat combines the characteristics of spring-fed flows and cold, aerated water with woody debris in shallow depths on a fine volcanic substrate. Based on molecular and morphological evidence we conclude that the underwater mushrooms are a new species, Psathyrella aquatica. This report adds to the biodiversity of stream fungi that degrade woody substrates. The underwater environment is a new habitat for gilled mushrooms.
已在俄勒冈州罗格河上游清澈、寒冷、流动的水域中观察到一种具有真正菌褶的离褶伞属（担子菌门）物种水下果实。生殖体在主河道中发育和成熟，那里它们不断被淹没，并观察到果实超过 11 周。这些蘑菇在水下发育，而不是在最近被冲入河流的木材上。基质包括水logged 的木材、砾石和含沙的河床。ITS 区和核糖体大亚基基因部分的 DNA 序列将这种真菌置于离褶伞属中，靠近 P. atomata、P. fontinalis 和 P. superiorensis。形态特征将水下蘑菇与以前描述的物种区分开来。生殖体具有长而纤细的纤维状菌柄和小直径的菌盖。未成熟阶段有一层很薄的面纱，很快就会消失。菌褶没有红色边缘。囊状体为宽斗状，顶端稍钝。观察到孢子呈楔形筏子释放到菌盖下方的气袋中。水下菌褶和掷孢子表明其对溪流环境的近期适应。这种特殊的河流栖息地结合了泉水流和冷、充气水的特点，以及在细火山基质上的浅深度 Woody 碎片。基于分子和形态学证据，我们得出结论，水下蘑菇是一种新物种，即 Psathyrella aquatica。本报告增加了降解木质基质的溪流真菌的生物多样性。水下环境是菌褶蘑菇的一个新栖息地。
