Proposal (1089) to South American Classification Committee

Establish English names for the species within former Rhynchocyclus olivaceus (Olivaceous Flatbill)

This is a quick proposal to establish English names for the two species we voted to recognize within formerly broadly defined Olivaceous Flatbill in SACC proposal 1054. Keep in mind that additional data might produce additional splits in the complex. For now, we agreed to split it into two species, R. aequinoctialis and R. olivaceus. Under that taxonomy, R. aequinoctialis includes nominate aequinoctialis (widespread in western Amazonia from eastern Colombia south through eastern Ecuador, eastern Peru, and western Brazil to northern Bolivia), as well as five other subspecies in northwestern South America and eastern Panama (tamborensis, jelambianus, flavus, mirus, and bardus), leaving the remaining taxa in R. olivaceus (namely, nominate olivaceus of the Atlantic Forest, guianensis of the Guianan Shield region, and sordidus from south of the Amazon in eastern Brazil).

EBird (and AviList) went ahead and split these without SACC endorsement, and the English names used in eBird are Western Olivaceous Flatbill and Eastern Olivaceous Flatbill (no hyphens).

I see little hope in finding “better” names for these species, which differ mainly in voice and occupy broad regions not amenable to finer geographic names. I also strongly support keeping the group name “Olivaceous Flatbill” to retain the link these two allospecies; without the context of a group name, a name like “Western Flatbill” makes no sense. That “Western” is a translation of aequinoctialis is helpful in tying the English and scientific names. So, our names would be Western Olivaceous-Flatbill and Eastern Olivaceous-Flatbill, with hyphens as per SACC guidelines. A YES vote endorses those, and a NO vote means you have a better set of names and are willing to do a SACC proposal for them.

Van Remsen, July 2026

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Vote tracking chart:

https://www.museum.lsu.edu/~Remsen/SACCPropChart1044+.htm

Comments from Donsker: “Record me as a firm YES for Western and Eastern Olivaceous-Flatbill.”