largemouthed black bass vs largemouth black bass

largemouthed black bass and largemouth black bass both are nouns.

Word	Noun	Adjective	Verb	Adverb
largemouthed black bass	Yes	No	No	No
largemouth black bass	Yes	No	No	No

As nouns, largemouthed black bass and largemouth black bass are synonyms defined as:

largemouthed black bass and largemouth black bass: a large black bass; the angle of the jaw falls behind the eye

Other synonyms of largemouthed black bass include largemouth, largemouth bass, largemouthed bass, Micropterus salmoides.

largemouthed black bass (noun)	largemouth black bass (noun)
a large black bass; the angle of the jaw falls behind the eye	a large black bass; the angle of the jaw falls behind the eye