branchiopodan vs branchiopodous

branchiopodan is a noun but branchiopodous is not a noun.

Word	Noun	Adjective	Verb	Adverb
branchiopodan	Yes	Yes	No	No
branchiopodous	No	Yes	No	No

As adjectives, branchiopodan and branchiopodous are synonyms defined as:

branchiopodan and branchiopodous: of or relating to or characteristic of the subclass Branchiopoda

Other synonyms of branchiopodan include branchiopod.

branchiopodan (noun)	branchiopodous (noun)
aquatic crustaceans typically having a carapace and many pairs of leaflike appendages used for swimming as well as respiration and feeding

branchiopodan (adjective)	branchiopodous (adjective)
of or relating to or characteristic of the subclass Branchiopoda	of or relating to or characteristic of the subclass Branchiopoda