Based on this discussion: iNat link, NaturaLista link.
T. huegelii C.Lawson was published two years before T. mucronatum Ten., so it should be the accepted name based on the Principle of Priority. In fact, it appears thus on TPL (albeit citing a contradicting source!). Nevertheless, the community decided that we use T. mucronatum as a nomen conservandum, and relegate T. huegelii as a synonym, based on the long-standing tradition of the former and the obscurity of the latter.