INaturalist has 5 requirements to create a species complex: https://www.inaturalist.org/pages/curator+guide#complexes
I think all 5 of these are essential, but I’m curious how literally to interpret “Complex is recognized in the literature”.
I argue below that closely related insect species, in the literature suggested to be monophyletic and separated only by male genitalia, should be represented as identifiable units in the iNat taxonomy when further ID is impossible. Overly narrow interpretations of the requirement that a species “complex” is explicitly erected in the literature may hurt iNaturalist users, and I don’t see their purpose. Below, I discuss the case of North American Rivellia as an example of a widespread question.
The vast majority of the Rivellia from North America belong to the pallida/imitabilis or colei/quadrifasciata groups, which cannot be identified further photographically; females cannot be identified without DNA. Namba (1956) suggests the monophyly of these two species groups, although this was before scientists conceived of “monophyly” as an explicit term.
This species group has no name in the historical literature: why would taxonomic experts erect a “species complex” for a group of only 2 species? Just label the females “Rivellia pallida or imitabilis,” give them their own tray in the collection, and report them as such! Only with three or more species would a “species group” formal designation serve a purpose. Thus, a well-recognized species group could exist in every museum collection for hundreds of years but never be formally recognized in the literature.
According to the current iNat taxonomy, observations of these Rivellia flies must be left at genus. Yet this creates a big problem for someone trying to get a sense for the species found in their area. The two groups Rivellia colei/quadrifasciata and Rivellia pallida/imitabilis cannot be identified further and form the vast majority of Rivellia observed in North America, but are completely unrepresented in an observation search (or thus by the AI): https://www.inaturalist.org/observations?place_id=1&subview=grid&taxon_id=132237&view=species
I don’t think every set of similar species should get its own place in the iNat taxonomy. However, it seems reasonable that two cryptic sister species should be recognized, even if historical literature never bothered to specifically use the words “group” or “complex” to describe them. These terms are only slowly starting to appear in entomology, and many branches of insect taxonomy haven’t been touched by experts in a century.
Since I’ve done the research, I’d like to create Rivellia pallida/imitabilis and colei/quadrifasciata as ‘complexes’ in the iNaturalist taxonomy. Does anyone object or agree?
Thanks for your feedback!