Reaching Consensus on Contested Regional Species ID

Recently, Aetobatus (eagle ray) identifications in the Galapagos have been revised from A. laticeps to A. ocellatus based on an unpublished phylogenetic capstone project. From what I’ve read, species within the genus are highly variable in appearance, so molecular data is necessary to determine species, and the paper notes that there hadn’t previously been any molecular studies in the Galapagos. The genus also has a history of inconsistent classification, with some sources listing A. narinari as a synonym for A. laticeps, and thus the species present in the Galapagos.

I don’t have an issue with assigning A. ocellatus to observations in the Galapagos in this case given the paucity of local data for the genus, but it raised questions on the burden of proof for changing IDs when regional species ID is contested. How are the results of an unpublished study weighed against information provided by taxonomic authorities listed on the curator’s page, which I assume only revise species distributions based on published studies (e.g. Eschmeyer’s Catalog of Fishes still lists A. ocellatus as the species present in the Galapagos)? As it stands, the majority of Aetobatus observations in the Galapagos are bumped up to the genus level. While many will likely eventually reach species, I can foresee substantive differences in approach depending on whether one chooses to follow taxonomic authorities and published studies exclusively, or if any emergent information is considered sufficient to change the regional assignment for observations within the genus.

Has this topic been addressed before in the forum?

2 Likes

It may be best to wait on reflecting the document in IDs until it is published in some form, allowing more review. The document also says it’s “not a publication,” and that “Future research is recommended where higher resolution molecular markers are used to determine relationships within A. ocellatus on the islands.”

Overall though what you’re asking can sometimes be a debatable gray area. iNat curation changes (since some taxa need to be added before it’s possible to ID them) are supposed to be based on authoritative sources which are often academic publications or books, although also include some websites (see iNat Help documents and related forum topics). Sometimes in cases of recent, uncertain, or debated revisions identifiers explain what species they think an observation is by commenting instead of IDing. In other cases I’ve seen identifiers use disagreeing IDs to reflect a specific taxonomic interpretation where multiple exist.

3 Likes

In general, for issues with curation of specific taxa, it would be best to raise a flag on the taxon in question and start a discussion with comments there. Many curators or users who might be familiar with certain taxa are likely not on the forum, and this will create a record of the discussion and any taxonomic changes that other iNat users can then reference.

8 Likes

I would think that users could be tagged and the ID changed once the paper is published, but taxonomic decisions usually don’t get set in stone until it is published. The data seems pretty convincing that A. ocellus is the species in the Galapagos, as the closest relative genetically to the Galapagos specimens is the Atlantic species and not the Eastern Pacific spotted eagle Ray (A. laticeps). If the Galapagos ones were all really laticeps, then all three species would need to be lumped (again)!

The paper’s result looks very robust that the Galapagos species cluster with R. ocellatus in that gene, but keep in mind that it is only one gene (the mitochondrial genome) out of thousands of genes. There are many cases where the mitochondrial genes have relationships that don’t match the species relationships shown by the majority of other genes, so the case might not be closed on this one.

4 Likes

I’m commenting here knowing nothing about ray taxonomy, but it seems to me that the ideal route is to identify these observations to the genus level for now because:

  1. It sounds like there is no clear way to identify them to species from a photo (e.g., identifications must be assumptions based on location), and

  2. There is a lack of consensus on which taxa occur around the Galapagos

My opinion would be that we need at least one of those issues to be resolved before confidently assigning species level IDs.

2 Likes

Yeah genus is best. More because while the Indo-Pacific one might live there, but the eastern Pacific species might also live there sympatric with it (unsampled or rarer). I would think it would be an easy swim for an eastern Pacific A. laticeps to swim to the Galapagos!

1 Like

It should be mentioned (again) that there is no agreed upon number of nucleotide differences that distinguish one species from another.
Might this be another case of systematics being used interchangeably with (and mucking up) taxonomy?

1 Like

Issues such as this should typically be discussed via taxon flags. My personal opinion as a curator is that IDs should be based on information published in peer-reviewed studies. However, I also believe that there are always exceptions to the rules, which is why it’s good to establish consensus via taxon flag discussions.

2 Likes

This is very true. It’s risky to make conclusions about species relationships based on a single mitochondrial gene. Mitochondrial introgression can cause misleading results.

3 Likes

That’s because splitters need the flexibility to describe new species in every publication, no matter the degree of differences.

1 Like