Does the r double?
stress-doubleA doubled consonant would mark a short stressed vowel, and neither of the syllables in front of the stress here is short or stressed.
heard ascorriaceous
spelledcoriaceous
saidko-ree-AY-shus
No. coriaceous, one r.
There is no stress on the first syllable to support a doubling. Corium has one r and so does everything built on it.
Also on this leaf
coriaseus coriaseous coriaceus coreaceous ceriaceous
All six are on the same page. All 6 spellings of coriaceous.