Proposal (1069) to South American Classification Committee

Recognize new species of Tinamus/Crypturellus

Morais et al. (2025) have described a new species of tinamou as Tinamus resonans from the isolated Cerro do Divisor in Acre, western Amazonian Brazil; although it is clearly in the Crypturellus clade, the authors followed Bertelli et al. (2025) in using Tinamus for Crypturellus, based on strict priority:

“The genus Tinamus Hermann, 1783 was recently redefined by Bertelli et al. (2025), who restored its priority for the clade historically referred to as Crypturellus Brabourne & Chubb, 1914. Following their treatment, we here consider all species phylogenetically allied with Tinamus soui Hermann, 1783 as belonging to Tinamus.”

This issue will be addressed in a separate proposal. In my opinion, this case illustrates exactly why the Code has the Prevailing Usage provision. For the purposes of this proposal, the name SACC would be Crypturellus resonans, pending results of the separate proposal.

This new tinamou population was first detected vocally on the Cerro do Divisor by Fernando Godoy in October 2021. The authors first obtained photos (see below) and then obtained 3 specimens, all females, deposited at the Museu Nacional, Rio de Janeiro. The population as far as is known is restricted to the slopes of the Cerro:

“The species was observed exclusively on the steep forest floor within a narrow transitional zone between 310 and 435 m a.s.l., representing a gradient between submontane and stunted forest. This habitat is characterized by an exceptionally dense and widespread mat of fine roots and leaf litter, forming a continuous network over nutrient poor, quartzitic sandstone soil (Mendonça et al. 2020, 2023), through which the tinamou moves and forages. At all surveyed sites, the species was found in sympatry with Thamnophilus divisorius, which in Brazil was previously known only from its type locality, Morro Queimado.”

Sonograms were published in the paper, but the recordings are apparently not available online.

Tissue samples were collected and stored at Museu de História Natural do Ceará and INPA, but have not been analyzed.

The authors compared the plumage and voices to those of other Crypturellus but did not quantify those comparisons but simply asserted that they were diagnostic and let the photos and sonograms speak for themselves:

“Diagnosis: This species differs from all other Tinamidae by presenting, at least in females (the three individuals whose sex could be determined were female), a distinctive dark slate-colored crown, which extends into a prominent stripe down the hindneck and into the post-ocular region, forming a conspicuous facial mask (Fig. 1 and 2). The ferruginous coloration of the breast places it near the T. variegatus/brevirostris group, from which it is readily distinguished by its uniform brownish-gray dorsum lacking any barring, a condition otherwise shared only with T. soui. It can be further separated from T. soui by its ferruginous breast, neck, and cheeks and the presence of white on the lower belly. Its vocalization is unique and therefore diagnostic among the vocalizations attributed to other Tinamidae. As described below, it is distinguished by its overall structure and note modulation.”

Discussion and recommendation: This is a remarkable new discovery! Congratulations to the authors. The bird is strikingly distinctive in plumage and as far as I can tell, voice. I recommend a YES

English name: Morais et al. proposed “Slaty-masked Tinamou” to highlight its most distinctive phenotypic feature (see photos). I see no reason not to go with this, but if anyone objects, speak out and be prepared to propose a substantially “better” name.

References:

MORAIS, L. A., M. A. CROZARIOL, F. I. GODOY, R. A. A. PLÁCIDO, AND M. A. RAPOSO. 2025. A new species of Tinamus (Aves: Tinamiformes) from the western Amazon, Brazil. Zootaxa 5725: 279–291.

Van Remsen, December 2025

Note from Tom Schulenberg: audio recordings of resonans at

https://media.ebird.org/catalog?birdOnly=true&sort=rating_rank_desc&taxonCode=sddtin1&mediaType=audio

Vote tracking chart:

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

Comments from Robbins: “YES. Wow, amazing discovery of an obvious very distinct tinamou. An emphatic Yes for acceptance.”

Comments from Lane: YES. This is a shockingly obvious new species from a group that has relatively little morphological distinction among its members! I am a bit surprised that the authors did not make an effort to review the online documentation of tinamous from the Divisora, or they would have been able to include this recording from Peru by Tom Schulenberg in 2005: https://macaulaylibrary.org/asset/235615
but that's neither here nor there in accepting the species to the SACC list.”

Comments from Bret Whitney (who has Remsen vote): “YES to this highly distinctive new species. Nomenclatural issues surrounding the genus aside, the description is excellent, well-documented and nicely presented. If anyone wants to hear some of the distinctive vocalizations and view some video, including the locality of discovery and the lead author’s comments, go to YouTube and search “dodó brasileiro”.”

Comments from Zimmer: “YES. Plumage and voice are both unique within the family, so this is an easy one as far as I’m concerned. Several species within this genus are sexually dimorphic in plumage, so I am curious as to whether this one is. All 3 specimens are females, but I don’t see any indication of field observations of any individuals that differed in appearance from the type series. Congratulations to all involved on a remarkable find!”

Comments from Thomas Valqui (guest voter): “YES. I would say it seems safe to say it is a new species. The video is particularly convincing although it really is one short song only. The size seems also to be quite different from soui, as mentioned previously.”

“I was hoping there would be some DNA to look at sister taxa before deciding. I heard it was already done, but apparently not made public. They also mention they have regular soui from nearby, although no pictures or recordings. So there seems to be a lot of evidence to make a very strong case, but not much material to validate the evidence.

“Anyway, not fully convinced, but I would vote for it being a new species.”