Marasmius koae to the substrate. The fruit body has no distinctive taste or odor. The thin-walled spores are somewhat fusoid (spindle-shaped) to elongated ellipsoidal in shape, smooth, hyaline (translucent), and measure 12–14.5 by 4–4.8 μm. The basidia (spore-bearing cells) are club-shaped, four-spored, and clamped, measuring 24–28 by 7–9 μm. The species is endemic to Hawaii, where it has been found growing in dense groups on the rotting wood of koa ("Acacia koa"). Collections have been made only in the Koa/Ohia Montane Wet Forest on Kauaʻi island. Marasmius koae Marasmius koae is a species of agaric fungus in the Marasmiaceae family. Newly described
Hakalau Forest National Wildlife Refuge numerous deep gulches. Rainfall decreases to about at elevations above , where majestic koa ("Acacia koa") and red-blossomed ōhia lehua ("Metrosideros polymorpha") trees form a closed-canopy forest. Further upslope, above , rainfall decreases to or less and native forest merges into abandoned pastureland where alien grasses and weeds, introduced as forage for cattle, are the dominant vegetation. Since 1989, over 400,000 koa, ōhia, and other native plants have been planted in this area as part of the refuge's reforestation program. The Pua Akala Cabin, located within the refuge, was nominated to the National Register of Historic Places in August 2008.