the official record-keeper of these changes?

Iris Cohen schreef
For flowering plants it is Index Kewensis.

+ + +
No, there is no official record-keeper, which was what the Battle of St
Louis (1999) was about. De facto the Index Kewensis (online as www.ipni.org)
serves as record-keeper for newly published names. But do see the Mini FAQ

I assume Matelea was named for a Mr (possibly Mrs) Matele, likely to be
French.
PvR