 The holotype of Protomycena is a single fruit body without any associated structures , preserved in a piece of clear light yellow polished amber approximately 4 @.@ 5 – 2 @.@ 5 cm ( 1 @.@ 77 – 0 @.@ 98 in ) wide . The pileus is 5 mm ( 0 @.@ 2 in ) in diameter and has a convex shape , sporting a raised central region ( an umbo ) . The pale flesh appears yellowish in the amber , and is smooth and glossy , changing to <unk> and slightly translucent towards the margin . The pileus margin is <unk> and slightly flared . The gills on the underside of the pileus are broadly attached ( <unk> ) to the top of the stipe , and distantly spaced — between six and eight gills extend completely from the pileus margin to the stipe . These full @-@ length gills are <unk> with <unk> ( short gills which do not reach the edge of the stipe from the pileus margin ) of varying lengths . The pileus is centered on the curved stipe , which is smooth and cylindrical , measuring 0 @.@ 75 mm ( 0 @.@ 030 in ) thick by 10 mm ( 0 @.@ 39 in ) long . The stipe lacks a ring and <unk> . The mushroom is preserved with a small liquid and gas @-@ filled bubble , possibly originating from the mushroom itself , which indicates the amber to be very solid and well @-@ sealed . 
