[thaumasiotes]

Formal species are focused in the regions where formal biologists work. Outside of those regions, people don't care.

This paper appears to define the new species by physical characteristics, although it also remarks that differential characteristics within the new species "are regarded as intraspecific variation for the time being".

This isn't a question that people approach with any kind of rigor.

Compare the recent paper ( https://www.cell.com/current-biology/fulltext/S0960-9822%282... ) finding that, despite obvious phenotypic differences, snail darters are "not a species but a subpopulation of the Stargazing Darter" because the authors couldn't find an obvious genetic difference.† Whatever your view of speciation is, it can't accommodate both papers.

† The claim that they must not be a "species" loosely implies that a genetic difference doesn't exist, or that what difference does exist "doesn't count". That second option is not a scientific claim. The first option is possible - it might be that, if you dropped eggs from other stargazing darters into the waters inhabited by snail darters, those eggs would develop into snail darters, with the phenotype being driven by environmental input. But I don't think that's especially likely. The phenotypic difference is more likely evidence that there is a genetic difference, and we just can't see it.