Unfortunately, there isn't any official Wiki that lists the different transformations.
If you can read code, i'd recommend checking out the github repository.
Otherwise, asking here is the best way to get answers.
See Below for the remaining Metamorphs:
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Note: Mutations that occurred before you obtain Genetic Memory don't count towards unlocked Transformations. If you already have the body part that you are looking to unlock, you'll need to re-transform that part. (By overwriting it, then re-transforming the body part)
1 Skin (Chitin, was able to get it 1st playthrough but never since in NG+)
Chitin (Sweet/Black Gossamer from Spiders) - Just keep trying and you'll get it
1 Face (between Spider and Dragon)
Fox face (Unlocked via foxberries from the Tel'Adre bakery)
1 Tongue (between Snake and Dragon)
Demon Tongue (Have snake tongue, and Incubus Draft/Succubus Milk from demons)
1 Eyes (under Snake, next to Elf)
Raiju Eyes (Lightning Gem/ Mast. with buff)
2 Ears (next to Cow, above Fox; under Orca, next to Elf)
Elfin Ears (Sweet/Black Gossamer from Spiders)
Raiju Ears (Lightning Gem/ Mast. with buff)
5 Tails (Kitsune 7-9; below Lizard; top row center between Salamander and Mantis)
Fox tail (Single) - (FoxJewel from Kitsune, or Foxberry from Tel'Adre bakery)
Kitsune 7-9 (FoxJewel + Perk 'Ninetails Kitsune of Balance') - Requires Player to have 9 fox tails, and to have permanently unlocked both 9-tails perks via ascension
Goat tail (Infernal Elixir from Evangeline)
1 Legs (between Snake and Demon).
Demon(Female) (Succubus Milk from Demons)