rhietidiadelphus, with the ie spelled out
heard as rhietidiadelphus
spelled rhytidiadelphus
The sound is right and the letters are not: rhytidiadelphus.
What the ear did
Somebody heard rye and reached for the English spelling of it. The Greek upsilon leaves no room.
R-H-Y-T-I-D-I-A-D-E-L-P-H-U-S
The full entry for rhytidiadelphus covers the name itself.