The current taxonomical situation here is untenable as Leucodermia currently only contains a single species described there without an available name in Heterodermia but the rest of the species placed in Leucodermia by those authors who accept it are still in Heterodermia.

This situation should be rectified in either of two ways:

1) Moving to fully accept the taxonomy of Mongkolsuk et al. (2015) with all of the segregates (and perhaps also Kondratyuk et al. (2021) who describe the 'Heterodermia obscurata'-group of the former authors as Klauskalbia gen. nov.)

2) Maintaining Heterodermia in its broad sense, merging the current Leucodermia into it, and leaving Leucodermia guzmanii as an "orphaned" species within it

I would personally favour option 2 as option 1 leaves Heterodermia heterogenous as Mongkolsuk et al. leave some groups unnamed and additionally it seems there are genetic problems with the segregates. Kondratyuk et al. with rather preliminary data recover Heterodermia s.l. as monophyletic but Polyblastidium not so. De Souza, Aptroot & Spielman (2022), also with preliminary data find even more chaos:

The focus of this paper is on species, not on deeper nodes in the phylogeny. However, species are classified in genera, and the generic division of the group is in flux and as yet unsettled. In order to test the validity of the split genera and to some extent our species concept, we sequenced 18 of our more recent specimens (see Supplementary Material Table S1 & Fig. S1, available online) and added these results to publicly available sequences. In the cladogram constructed from ITS only, four of the five groups found by Mongkolsuk et al. could be recognized (see Supplementary Material Fig. S1). In a concatenated tree based on ITS and mtSSU, the pattern is much less clear, and in fact none of the groups, and none of the split genera are monophyletic. It is not a good sign when the more information that is added, the more confused the pattern becomes, and in any case Heterodermia s. str. is paraphyletic. Therefore, we do not accept the split genera introduced by Mongkolsuk et al., who also did not present any cladograms supporting their division.

Compared to this, the trouble of having one or a few "orphaned" species in the taxonomy seems much preferrable to me, though I must admit that I am personally generally a lumper to the greatest extent that monophyly and morphological coherence will allow and also dealing with only European species I do not encounter the great diversity that might leave tropical workers wanting for smaller genera.

In iNat currently the type species of the genus, Leucodermia leucomelos, is accepted as a synonym of Heterodermia leucomelos. Therefore the genus Leucodermia is a synonym of Heterodermia. We should not have the genus simply as a parent for an uncombined species. Our 'standard' is to move Leucodermia leucomelos under Heterodermia and then synonymise the parent genus into Heterodermia. It is a common situation with many hundreds of similar orphaned species in iNat.