I’d like to canvas curator opinion about the use of the iNat species complex rank.
The curators guide includes …
o Species complex is monophyletic (i.e. sibling groups of species)
o Complex is recognized in the literature
o A named subgenus, section, or series does not already exist for the group …
Modern phylogenetic analysis in my group, the fungi, often uncovers cryptic species-level diversity within taxa that were historically treated under a single name. Often these cryptic species reflect biogeographical divisions, but not always.
In addition, we quite often find that taxa that are grouped into tight clades, where morphological distinctiveness may, or may not distinguish species in the clade, i.e. closely related species are sometimes morphologically indistinguishable and at other times (surprisingly) they have clear/stable differences.
I’m sure there are other groups where the same issues arise.
So my questions are these:
Do you think that ‘species complex’ should be applied to both these cases? Or only the first where morphology alone does not easily separate the (phylogenetic) species? And then what about ‘mixed bags’?
If you include the latter situation, where morphology can be quite different between closely related species, then ‘species complex’ can easily become a means of labelling clades. Is that appropriate or not?
What level of evidence is required to justify the introduction of a complex?
a. Does the ‘complex’ need to be quoted in multiple peer reviewed publications (by different authors), or just used on the web somewhere?
b. Does a source need to explicitly refer to a (cryptic) complex, or does the use of words like ‘the xxxx group of species’ count as a valid proxy for the term species complex?
Can an iNat species complex stand alone in the iNat hierarchy with just the nominate species as a subordinate taxon (so it can at least be used for observations) or do all the relevant taxa need to be included as subordinates?
If introduction of a complex requires all iNat subordinates to be included then good practice would be to ensure that primary cited sources not only mention/introduce the complex, but also establish the boundaries of the complex and enumerate the species within it. i.e. it would not be adequate to reference a work that uses the complex name but does not define what it is (which is why it might stand alone).
I have clear opinions on all these questions but I’m willing to change my views, and the way I curate, depending on the consensus.