Monstera Leaves Curling Up. Keep in mind that after a leaf develops it will not change. I do this about once a week.
As discussed earlier root rot due to overwatering can manifest in dark brownblackish spots on Monstera leaves. As a tropical plant your Rhaphidophora tetrasperma naturally enjoys a good deal of humidity. I live in a dry area so the humidity in my house is normally below 20.
Mine does that when its starting to dry up and needs a watering.
If the leaves of your Monstera are curling your plant is most likely under-watered. One way you can remedy this is to use a water filtration system. Young plants have leaves that are completely solid and that have no slits or holes. My monstera seems generally happy and produced 2 new leaves a couple of weeks ago.