Proposal (832) to South American Classification Committee

A. Recognize the new genus Cryptopezus for “Hylopezus nattereri” and B. transfer H. berlepschi, H. fulviventris, and H. dives to Myrmothera

Background:

The current taxonomic organization of the genera Hylopezus, Myrmothera, and Grallaricula is not congruent with the phylogenetic history of the group. Consequently, it is necessary to redefine their generic boundaries while avoiding the erection of highly heterogeneous non‐diagnosable taxa and minimizing the number of required taxonomic changes. Our assessments of phenotypic variation in combination with their phylogenetic reconstruction suggest that the four monophyletic groups identified by us (Figure 1) are suitable units to be treated as separate genera.

Grallaricula represents a phenotypically cohesive group of species, and we consider than any generic change involving any species of Grallaricula is unwarranted. This cohesiveness is also shown by their preference for forested habitats along Neotropical mountain systems and some of their life history traits such as nesting and breeding (Greeney, 2008; Greeney & Jipa, 2012; Krabbe & Schulenberg, 2003; Robbins, Krabbe, Ridgely, & Molina, 1994). Therefore, here, we recommend the maintenance of Grallaricula as currently defined.

Ridgway (1909) erected the genus Hylopezus with H. perspicillatus as its type species, and a couple of years later H. dives and H. macularius were allocated therein (Carriker, 1910; Ridgway, 1911). However, Cory and Hellmayr (1924) and Peters (1951) rejected this genus and maintained their members in Grallaria. In the most recent and currently accepted genus‐level taxonomic revision of the Grallariinae (now treated as the family Grallariidae), Lowery and O’Neill (1969) resurrected and redefined the genus Hylopezus, to which they allocated five species: H. perspicillatus, H. macularius, H. fulviventris (including dives), H. berlepschi, and H. ochroleucus, including nattereri from the Atlantic Forest.

In its original description, Pinto (1937) diagnosed Grallaria nattereri as a species distinct from Grallaria ochroleuca on the basis of longer tarsi and overall plumage differences. However, in the brief text of the description of the holotype, he acknowledged that “in the future it might prove to be subspecifically related to G. ochroleuca.” In fact, only 2 years later, Naumburg (1939) treated nattereri as a subspecies of G. ochroleuca and its status as subspecies was maintained throughout most of the 20th century (Meyer de Schauensee, 1970; Peters, 1951; Pinto, 1978), when it was elevated to full species on the basis of vocal, plumage, habitat, and distributional differences (Krabbe & Schulenberg, 2003; Whitney, Pacheco, Isler, & Isler, 1995).

New Information:

A comprehensive molecular phylogeny of lowland antpittas in the genera Hylopezus and Myrmothera indicated that Hylopezus, as currently defined, is paraphyletic with respect to Myrmothera and Grallaricula. Specifically, both species now placed in Myrmothera, Hylopezus dives, Hylopezus fulviventris and Hylopezus berlepschi form a strongly supported clade that is sister to a clade comprised by Hylopezus perspicillatus, Hylopezus auricularis, Hylopezus ochroleucus, Hylopezus whittakeri, Hylopezus paraensis, Hylopezus macularius, and Hylopezus dilutus. Furthermore, Hylopezus nattereri is sister to a clade glade grouping Myrmothera, Hylopezus, and Grallaricula, representing the most divergent lineage in this complex. Our approach to assess diagnosability and define generic boundaries among these taxa integrates phylogenetic relationships with morphological and acoustic traits. Given that phenotypic and ecological differences do not warrant merging H. nattereri into any other genus, and because there is no generic name available for H. nattereri, we proposed a new genus for this Atlantic Forest endemic lineage, Cryptopezus gen. n. (Carneiro et al. 2019). We also redefined generic limits in Myrmothera and Hylopezus to have a taxonomic classification concordant with their phylogenetic relationships.

FIGURE 1. Reconstruction for antpittas estimated from multilocus dataset (species tree) using *Beast. Bars indicate 95% highest posterior densities of divergence dates. The mean estimated dates are shown above nodes. Bayesian posterior probability (PP) support for nodes is indicated by coded circles according to the figure legend. IV = Quaternary. Images of antpittas species are adapted from Krabbe and Schulenberg (2003) and the Handbook of Birds of the World Alive. (Retrieved from Carneiro et al. 2019)

Given the obtained topology, several plausible taxonomic arrangements will avoid non‐monophyletic genera:

First, all species currently placed in Grallaricula and Hylopezus could be merged into a broadly defined Myrmothera due to its nomenclatural priority. This option is unwarranted because it would render a highly heterogeneous genus and would require a considerable number of taxonomic changes.

Second, species currently placed in Hylopezus, with the exception of H. nattereri, could be merged into Myrmothera while retaining Grallaricula as it is and erecting a new genus for H. nattereri. This option is also unwarranted because it would render a fairly heterogeneous Myrmothera and it would lead to numerous taxonomic changes after transferring species from Hylopezus to Myrmothera.

Third, to maintain Grallaricula genus unaltered, to transfer H. berlepschi, H. fulviventris, and H. dives into Myrmothera, to keep H. perspicillatus, H. auricularis, H. ochroleucus, H. macularius, H. dilutus, H. whittakeri, and H. paraensis in Hylopezus; and to recognize the new genus Cryptopezus for “Hylopezus nattereri”. This third possible arrangement will not only reflect more accurately phylogenetic relationships in the group, but also produce diagnosable taxa while minimizing the number of required taxonomic changes. Any further splitting would lead to taxonomically inflated classifications, which would be undesirable from the point of view of the stability of the International Code of Zoological Nomenclature (ICZN, 1999).

Literature Cited:

Carneiro, L. Bravo, G. A, Aleixo, A. (2019). Phenotypic similarity leads to taxonomic inconsistency: A revision of the lowland's antpittas. Zool Scr. 48:46–56. https://doi.org/10.1111/zsc.12324

Carriker, M. A. Jr (1910). An annotated list of the birds of Costa Rica including Coco Island. Annals of the Carnegie Museum, 6, 314–915.

Cory, C. B., & Hellmayr, C. E. (1924). Catalogue of birds of the Americas and adjacent islands in Field Museum of Natural History. Pt. III. Pteroptochidae — Conopophagidae — Formicariidae. Field Museum of Natural History, Zoological Series, 13(3), 1–369.

Greeney, H. (2008). The breeding biology of Grallaria and Grallaricula antpittas. Journal of Field Ornithology, 79, 113–129. https://doi. org/10.1111/j.1557-9263.2008.00153.x

Greeney, H. F., & Jipa, M. (2012). The nest of Crescent‐faced Antpitta Grallaricula lineifrons in north‐east Ecuador. Bulletin of the British Ornithologists' Club, 132(3), 217–220.

ICZN [International Commission on Zoological Nomenclature] (1999). International code of zoological nomenclature, 4th ed. London, UK: International Trust for Zoological Nomenclature.

Krabbe, N. K., & Schulenberg, T. S. (2003). Family Formicariidae (Ground‐Antbirds). In J. del Hoyo, A. Elliott, & D. Christie (Eds.), Handbook of the birds of the world (Lynx Edicions) Vol. 8 (pp. 682– 731). Barcelona, Spain: Lynx Edicions.

Lowery, G. H., & O’Neill, P. O. (1969). A new species of antpitta a from Peru and a revision of the subfamily Grallariinae. The Auk, 86, 1–12.

Meyer de Schauensee, R. (1970). A guide to the birds of South America. Wynnewood, PA: Livingston Publishing Co.

Naumburg, N. E. M. B. (1939). Studies of birds from eastern Brazil and Paraguay, based on a collection made by Emil Kaempfer. Bulletin American Museum of Natural History, 76, 231–276.

Peters, J. L. (1951). Check‐list of birds of the world (7th Volume). Cambridge, MA: Museum of Comparative Zoology.

Pinto, O. M. O. (1937). Grallaria ochroleuca Pelzeln prova ser ave diversa de Myioturdus ochroleucus Wied. Boletín Biológica N. S., 3(5), 6–7.

Pinto, O. M. O. (1978). Novo catalogo das aves do brasil; 1a Parte aves não Passeriformes e Passeriformes não Oscines, com exclusão da família Tyrannidae. São Paulo, Brasil: CNPq.

Ridgway, R. (1909). New genera, species and subspecies of Formicariidae, Furnariidae, and Dendrocolaptidae. Proceedings of the Biological Society of Washington, 22, 69–74.

Ridgway, R. (1911). The birds of North and Middle America. Bulletin of the United States National Museum, 50(5), 1–859.

Robbins, M. B., Krabbe, N., Ridgely, R. S., & Molina, F. S. (1994). Notes on the natural history of the Crescent‐faced Antpitta. Wilson Bulletin, 106, 169–173.

Whitney, B. M., Pacheco, J. F., Isler, P. R., & Isler, M. L. (1995). Hylopezus nattereri (Pinto, 1937) is a valid species (Passeriformes. Formicariidae): Ararajuba, 3, 37–42.

Lincoln Carneiro, May 2019

Note from Remsen on voting procedure: Vitor Piacentini informed me that there may be a problem with the name Cryptopezus as an available name (comments to follow), so let’s structure the voting as Part A. Cryptopezus, and Part B. Transferring species to Myrmothera.

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Comments from Stiles: “YES to transferring the mentioned species to Myrmothera and to naming a new genus for nattereri. However, because Cryptopezus is preoccupied, I think it’s up to Carneiro to propose a replacement name.. for now, call it “genus to be renamed” (much as we did for Elliotia for the same reason).”

Comments from Robbins: “This should be divided into two proposals given that Cryptopezus is apparently not available. That should be sorted out and a new proposal created. Thus, “No” to that element. “YES” to the transfer of berlepschi, fulviventris, and dives to the genus Myrmothera based on the genetic data.”

Comments from Zimmer: (A) “YES” to erecting a new genus for H. nattereri, based upon the phylogeny presented by Carneiro et al 2019, which establishes nattereri as sister to a clade which contains all of the other species currently recognized in Hylopezus, as well as all of Myrmothera and Grallaricula. However, given the raised possibility that “Cryptopezus” may not be available, I think that Gary’s suggestion (“genus to be renamed”) is a good one until Carneiro proposes another name. (B) “YES” to the third option presented in the Proposal, which is to maintain the cohesive Grallaricula as it is currently constituted, and to transfer berlepschi, fulviventris and dives into Myrmothera, while maintaining the other species in Hylopezus. Some of these moves make sense to me on the basis of vocal characters, natural history, morphology, etc., whereas others are not particularly intuitive, but such a rearrangement does at least conform to the relationships revealed in the phylogeny, and does so in the least objectionable and destabilizing way in my opinion. I would be opposed to any restructuring that diluted the cohesion and distinctiveness of Grallaricula, and the heterogeneity that would result from lumping everything else into an expanded Myrmothera would result in a less informative, overly heterogeneous grouping.”

Comments from Areta: “A. YES to the idea of placing nattereri in its own genus (a surprising but solid result), pending on the resolution of whether Cryptopezus is available or not. This being said, and until this is solved, we would need to put nattereri somewhere.

“B. YES to moving dives, berlepschi and fulviventris to Myrmothera.”

Comments from Claramunt: “A NO. Need to wait until there is a name available for nattereri. Indeed, the name Cryptopezus was proposed in an on-line appendix, thus not properly published under ICZN rules, thus not available. Also, I would like to see how well supported is the position of nattereri as a basal lineage. It is definitely supported by the mitochondrial dataset but nuclear trees are not shown.

“B. YES. I think the proposed solution is reasonable.”

Comments from Stotz: “A. YES and NO. I think that H. nattereri needs to be moved out of Hylopezus, but we need to make certain there is an available name. I think in other cases when we were certain a species was misplaced in its current genus, but didn’t have an alternative genus to place it in, we’ve used double quotes around the generic name, so, while we wait for a clear generic name, would could call it “Hylo[ezus” nattereri.

“B. YES. This treatment seems the clear best choice given the phylogenetic tree and the degree of morphological distinctiveness in the group.”

Comments from Pacheco: “A. NO. The treatment of nattereri in genus apart although evidenced needs to wait for a validly proposed name.

“B. YES. To relocate dives, berlepschi and fulviventris to Myrmothera.

Comments from Bonaccorso: “A. YES, move nattereri to its own genus whenever a name is available; but I do not agree with using the double quotes on “Hylopezus” since most non-taxonomists will be confused. I think we should urge Carneiro et al. to do a proper description (as Santiago says, according to ICNZ rules) so the issue is solved as soon as possible, without further confusion.

“B. YES to transfer H. berlepschi, H. fulviventris, and H. dives to Myrmothera.”

Comments from Remsen (5 Apr. 2020): “Gustavo Bravo informed me today that Cryptopezus now registered in ZooBank: http://zoobank.org/References/533674EE-6734-4B37-A7D1-30523E62016A

Comments from Jaramillo: “A YES – As I understand it Cryptopezus is now available, or did I get this wrong? If so, then yes move nattereri to Cryptopezus.

“B YES – Specifically to transferring berlepschi, fulviventris and dives into Myrmothera.”

Additional comments from Robbins: “A. YES. Given that Cryptopezus has been verified as an available name, I support placing the genetically distinct (very long branch) nattereri in that genus.”

Additional comments from Stiles: “A. YES. With Vitor's approval, I will vote YES to accept Cryptopezus.”

Additional comments from Claramunt: “With the name registered in Zoobank and reported in the publication, the name has been made available, I change my vote to YES.”