atrata, atratum
Clothed in black

atratus
In mourning clothes

atrialba
Black & white (black cap, white to grayish gills)

atriavellaneus
Grey and pink

atricapillus
Without a hairy cap

atricapillus
Black haired (brown fibrils on stalk)

atro-olivacea
Black olive

atroalboides
Resembling atroalbus

atrobadius
Black & reddish brown (blackish red cap)

atrobrunnea
Blackish brown (cap reddish brown to blackish brown)

atrocaerulea
Bluish black cap

atrocinereum
Black-ashy

atrodisca, atrodiscum
Black disc (cap black or dark gray at center)

atrofolia
Black leaves (gills)

atrofuscus
A black blackish-brown

atrogleba
Black clod

atromarginatus
Possessing black margin (gill edges)

atropuncta
Black spotted

atropurpurea, atropurpureum
Purple black (cap dark red with black center)

atropurpureus
Dark purple

atrorubens
Dark red

atrorufa
Dark red

atrosanguineus
Dark blood

atrosquamosum, atrosquamosus
Black scaly

atrostipitatum, atrostipitatus
Black stalk

atrotomentosus
Black woolly

atroviolaceum
Blackish violet colored

atrovirens
Dark green

atroviride, atroviridis
Blackish green

attenuata, attenuatus
Narrowed, tapered

augeana
Pertaining to Augeos (uncleaned stable for 30 years, odor)

augustus
Majestic

aurantia
Orange

aurantiaca, aurantiacum
Reddish orange

aurantiacus
Bright orange

aurantiellum
Somewhat reddish-orange

aurantiisiccescens
Becoming orange and dry

aurantio-olivaceum
Olive green colored

aurantio-turbinatus
Cone or top shaped and golden as an orange

aurantiobasis
Reddish orange base