Proposal (974) to South American Classification Committee

Change the names of Tolmomyias flycatchers from “Flycatcher” to “Flatbill”

With the current proposal (SACC 973) on the English names of two species of Tolmomyias, now is clearly the time to also consider the group name for Tolmomyias.

For stability, I am opposed to changing English names unless there are justifiable reasons. This is one such case for which there are justifiable reasons, in my opinion.

Our current classification treats all Tolmomyias flycatchers under the group name “Flycatcher”, e.g. “Yellow-olive Flycatcher”. The issue is that past and other current classifications have called them “Flatbills”, e.g. “Yellow-olive Flatbill”, as in their sister genus Rhynchocyclus, for which “Flatbill” is universally used.

The history of the issue is outlined below; the taxonomic history is interwoven with English name usage. This may not be comprehensive but is sufficient, I hope, to cover the main points:

1. Starting with at least Ridgway (1907), the Middle American species now in Tolmomyias were known as “Flat-bills.” This makes sense because Ridgway treated them as members of Rhynchocyclus, which were (and always been) known as Flatbills.

2. As noted in SACC 973, Cory & Hellmayr (1927) described a new genus, Tolmomyias, with the following diagnosis: “Similar to Rhynchocyclus, but bill relatively smaller and narrower, subterminal phalanx of middle toe entirely free from outer toe, and edge of outer web of outermost primary not roughened.“ They included in Tolmomyias all the current taxa that we do, but also included Ramphotrigon megacephalum, which at that time was placed in Tolmomyias. Cory & Hellmayr continued to use ”Flat-bill” as the group name and also expanded it to include Ramphotrigon, a genus that Ridgway did not deal with (other than in a key in which, by the way, he correctly ascertained its relationship to Sirystes and other genera that we now know is correct, contra Cory and Hellmayr).

3. Zimmer (1939; Studies of Peruvian birds No. 33) transferred megacephalum from Tolmomyias to Ramphotrigon without providing rationale. Nonetheless, this was subsequently supported by Lanyon’s (1988) work on syringeal morphology, and followed by all subsequent genetic analyses, including Harvey et al. (2020).

4. Eisenmann (1955) was the first one to introduce “Flycatcher” for Tolmomyias. He called the two Middle American Tolmomyias species “Flycatcher” and restricted “Flatbill” to Rhynchocyclus with the following note:

“Unlike true Rhynchocyclus, whose breeding behavior is like Pipridae, Tolmomyias behaves normally (Skutch, Ibis 1953; 4, 33-34). As these genera may not be closely allied, it seems best to reserve the name “Flatbill” to the aberrant Rhynchocyclus.”

Fair enough, but wrong on, at least on the relationships. Harvey et al. (2020) confirmed that they are sister genera, although the split is old (est. 14 mya). So, Ridgway was correct in inferring a relationship from their phenotypes, as was usually the case.

5. Meyer de Schauensee (1966, 1970), who acknowledged Eisenmann’s help with English names, also called all species in Tolmomyias “Flycatchers” and retained “Flatbill” for Rhynchocyclus but also called all the Ramphotrigon species “Flatbills”, thus following Cory & Hellmayr (but not Ridgway) in assuming from their morphology that they were closely related (by placing them adjacent in his linear sequence). Thus began the “polyphyletic” use of the formerly “monophyletic” Flatbill: Lanyon’s (1988) data on syringeal morphology showed that Rhynchocyclus and Rhynchocyclus were distantly related, and Harvey et al. (2020) confirmed that they these two genera not even in the same subfamily.

6. “Flycatcher” for Tolmomyias became entrenched by its use in subsequent influential literature (e.g., AOU 1983, 1998; Hilty 1986; Ridgely & Gwynne 1989 Panama; Stiles & Skutch 1989 Costa Rica; Sibley & Monroe 1990, Ridgely & Tudor 1994; Fitzpatrick-HBW 1994; Howell & Webb 1995 Mexico, etc.).

7. Ridgely & Greenfield (2001; Ecuador book) restored the name “Flatbill” for Tolmomyias, with the following justification:

“We have reverted to the group name of ‘flatbill’ for all members of the genus Tolmomyias. This name was used long ago in Birds of the Americas (pt. 5) and is surely more useful than considering this group as yet another tyrannid genus bearing the group name ‘flycatcher’.”

8. “Flatbill” was then used by Hilty (Birds of Venezuela 2003), Ridgely & Tudor (2009; Field Guide to Songbirds of South America), del Hoyo & Collar (2016; BLI), IOC, and presumably others. However, NACC and SACC continued to use “Flycatcher’, as did Kenefick et al. (2007; Trinidad-Tobago), Schulenberg et al. (2007; Peru), Dickinson & Christidis (2014; Howard-Moore), Herzog et al. (2016; Bolivia), <check Pearman-Areta 2020 Argentina>, and many others

In summary, Flatbill was the one and only name for Tolmomyias from 1907 to 1955 (48 years), Flycatcher the only name in widespread use from 1955 to 2001 (46 years), and after 2001, both were in use.

I favor a YES on this proposal because:

1. Flatbill was the original and only name in the literature for a half-century.

2. It correctly signals its relationship to sister genus Rhynchocyclus.

3. As noted by Ridgely & Greenfield, “Flycatcher” is fairly useless.

4. It makes finding suitable new English names for future splits in the sulphurescens and assimilis groups easier because of a dramatic reduction in the number of “Something Flatbills” vs. the dramatically larger number of “Something Flycatchers” (including Old World families). There are 79+/- species in the Tyrannoidea with the group name Flycatcher.

5. It’s already in widespread use in several frequently used sources, so we would not be introducing an unfamiliar, novel name.

6. There is some chance that the Rhynchocyclus-Tolmomyias might someday be recognized as a separate family from Tyrannidae. I the phylogeny of Harvey et al. (2022) you can see that these two are separated on a very long branch that at least merits treatment at the subfamily or tribe level. Calling them all Flatbills would be a nice way to mark them not just as sisters but as a separate lineage (except for the Ramphotrigon problem).

Van Remsen, May 2023

Vote tabulation: https://www.museum.lsu.edu/~Remsen/SACCPropChart864+.htm

Comments from Stiles: “I am quite willing to revert to Flatbill for Tolmomyias, so YES; This fits with the phylogeny, simplifies the e-name problems for further splits, and is not inaccurate (the bills in this genus are more flattened than those of most other small tyrannids of similar aspects, and in most species of this genus, the mandibles are notably whitish, which might enhance the impression of flatness (?).”

Comments from Hilty (voting for Claramunt): “YES, I would prefer ‘Flatbill,’ because of all the reasons discussed. The sister relationship of Tolmomyias and Rhynchocyclus is particularly compelling because this now sets these genera apart from the hordes of ‘other flycatchers.’ Also, note that I also used ‘Flatbill’ in 2021 Birds of Colombia.”

Comments From Dale Dyer (voting for Remsen): “YES. I vote for Flatbill for all the reasons given, and add that Flatbill was used in Birds of Belize and Birds of Costa Rica.”

Comments from Lane: “YES to changing Tolmomyias to "Flatbill" ... it took me a while to come around to this when Ridgely and Greenfield brought it back, but I see considerable value to it. Most importantly it will be helpful when looking forward to the mega-splits that are inevitable within several of the species in the future. In addition to the phylogenetic relationship with Rhynchocyclus, and the accuracy in describing the bill morphology, using "Flatbill" rather than "Flycatcher" for the members of the genus will result in a much wider field of potential names that would risk more redundancy with "Flycatcher".

Comments from Marshall Iliff: “You didn't ask, but I'll just lodge a *strong* vote of support for the proposal to use Flatbill for all Tolmomyias for all the reasons you lay out in your excellent arguments here. I think Flatbill is fairly well entrenched for Tolmomyias for followers of the IOC and BirdLife list, and I think the importance of finding alternatives to avoid overuse of "flycatcher" for so many Tyrannids (and other families in Eurasia!) really helps with ability for birders to understand, identify, and relate to this hyper-diverse Neotropical family. As you know, I support the same moves for Trochilids (using alternatives to "hummingbird" when possible/sensible. I would go further to suggest that we might want to think about a potential solution for the Ramphotrigon, although I am not sure what that might be.”

Comments from Gary Rosenberg (voting for Del-Rio): “YES to changing “Flycatcher” to Flatbill - for Tolmomyias. I have resisted this for a long time as I thought it would add to unnecessary confusion - given “Flycatcher” has been used in field guides for so long - but if the original name was “Flatbill”, then it makes sense to me to change back to that usage - especially since much of the world, and many guides, has already adopted the use Flatbill.”

Comments from Schulenberg (voting for Robbins): “Enthusiastic YES to 'Flatbill'. I don't think that every genus of tyrannid needs its own English group name, but even so, chipping away at the number of birds named simply 'Flycatcher' serves a good cause.”

Comments from Jaramillo: “YES. The name is useful in the field, as well as informative relative to understanding relationships with the other birds named flatbill in the family. I do think that any time we can change a "flycatcher" to something else is good given that flycatcher tells you nearly nothing about the bird, often is incorrect ecologically (for the ones that eat fruit), and definitely is incorrect taxonomically given that muscicapids are the "real" flycatchers. Both of these issues are entrenched and accepted so they are not really a problem, but when we can shift from flycatcher to something else, it is worthwhile in my opinion.”

Comments from Zimmer: ”A very strong YES! As some of you know, I’ve been working on redefining species-limits within the Tolmomyias sulphurescens complex for more than 20 years (manuscript 75% completed, pending completion of broadly sampled vocal analysis), during which, I’ve constantly mulled over what English names I was going to recommend for the various splits. I long since came to the conclusion that the only way to achieve meaningful English modifiers for a group in which all members are extremely similar in plumage was to use modifiers that reflect distributional and habitat distinctions, but even with that, the only way those name choices would be helpful, would be to change the group name from the ubiquitous and overly broad “Flycatcher”, to the narrower, and more taxonomically informative “Flatbill”. As others have noted, we may want to rethink the group name for Ramphotrigon, and reserve “Flatbill” for Rhynchocyclus and Tolmomyias – a grouping that is on the precipice of becoming much more speciose.”