Proposal (#239) to South American Classification Committee
Remove Melanopareia from the Rhinocryptidae and create family Melanopareiidae
Background: The phylogenetic position of the suboscine genus Melanopareia, currently placed in the family Rhinocryptidae, has long been controversial. Cory & Hellmayr (1924) placed Melanopareia in the Formicariidae (= Thamnophilidae), but Wetmore (1926) transferred it to the Rhinocryptidae on the basis of evidence that now appears weak. This placement was adopted in subsequent classifications (e.g. Meyer de Schauensee) and has remained unaltered until present time.
Some morphological characters (e.g. brightly colored plumage, concealed white interscapular patch in some species, oscine-like anatomy of stapes of the inner ear, straight humerus, pterylography, rather long tail) set Melanopareia aside all other Rhinocryptids, whereas other characters (e.g. lachrymal bones that are partly fused with the ectethmoid bones) are typical of the tapaculos (see Feduccia and Olson 1982). Sick (1985) described the eggs of M. torquata as antbird-like, and Ridgely and Tudor (1994) noted that in external appearance, behavior, and vocalizations, species of Melanopareia are "decidedly untapaculo-like (more resembling antbirds)".
New Information and Analysis: Two recent phylogenetic studies employing mitochondrial and nuclear DNA data (Irestedt et al. 2002, Chesser 2004) show quite clearly that Melanopareia is only distantly related to other genera currently placed in the Rhinocryptidae. In fact, although the position of Melanopareia could not be established with certainty by any of these studies, both of them indicated that the genus represents a deep branch with no obvious close relatives within the Furnarii. This led Irestedt et al. (2002) to suggest that Melanopareia should be excluded from the Rhinocryptidae and placed in a new family, Melanopareiidae. Chesser (2004) did not make any specific taxonomic recommendations.
The conclusion that Melanopareia does not belong in the Rhinocryptidae has not been incorporated into our current classification probably because taxon sampling in the studies mentioned above was not deemed sufficient to test the monophyly of the Rhinocryptidae rigorously and/or because the affinities of Melanopareia remain unclear. Regarding the first concern, I believe that the available data are sufficient to show that Melanopareia is not a member of a monophyletic group formed by the Rhinocryptids that have been sampled so far (Rhinocrypta, Pteroptochos, Scytalopus - note the inclusion of the genus that gives the name to this family). The question of whether other "problematic" genera (e.g. Psilorhamphus, Teledromas) belong in Rhinocryptidae or not is a different one that clearly needs work to be solved satisfactorily, but this should not prevent us from taking a first step towards making the Rhinocryptidae a monophyletic group.
The second concern (i.e. the uncertainty in the position of Melanopareia within the Furnarii) is a bit more troubling. However, it should be noted that the uncertainty relates really to whether Melanopareia is the sister group to the rest of the Furnarii or if it is more closely allied to particular groups, such as the Thamnophilidae. In other words, there is no indication in the studies of Irestedt et al. and Chesser that Melanopareia might form a clade with other Rhinocryptids.
Results to be presented in a forthcoming publication by R. Moyle et al. based on analyses of c. 4000 bp of sequence of the nuclear RAG-1 and RAG-2 regions are consistent with those of earlier studies in showing Melanopareia to be a long branch that is only distantly related to the Rhinocryptidae, now represented by many more genera (Myornis, Eugralla, Scytalopus, Pteroptochos, Schelorchilus, Liosceles, Acropternis, Rhinocrypta, and Teledromas). The exact position of Melanopareia is still not resolved by this new data set, but it is now clear that this genus lies outside a strongly supported clade that includes some "Formicariidae" (i.e. "Grallaridae" and Formicariidae sensu stricto, see proposal 235), the Furnariidae, and the Rhinocryptidae.
In sum, phylogenetic evidence indicates strongly that maintaining Melanopareia in the Rhinocryptidae is untenable. This is already clear from two published studies, which should be sufficient to support a taxonomic change. The still unpublished study by Moyle et al. is mentioned here only to confirm that conclusions of earlier studies were well substantiated.
Recommendation: Possible alternatives mentioned in the current version of the SACC website are to place Melanopareia in the new family Melanopareiidae as suggested by Irestedt et al. (2002), or to list it as Incertae Sedis. The latter option would imply hoping that the relationships of this enigmatic genus will be resolved at some point and that once this is done, the genus could be placed in one of the families we already recognize. I do not think this is the best alternative. For one, it seems that establishing the position of Melanopareia is a very difficult phylogenetic problem that may turn out to be unsolvable with any degree of confidence even in the long run because the genus is a very long branch connected to other long branches by quite short internodes (this is clear in RAG trees kindly provided by R. Moyle). Thus, if we take this route, the genus may remain perpetually listed as Incertae Sedis, a "rank" that I personally find rather frustrating.
In addition, tree topologies and branch lengths clearly show that Melanopareia is even more distinct phylogenetically from other Furnarii families than these families are from each other (e.g. Rhinocryptidae vs. Formicariidae sensu stricto). This, coupled with the uniqueness of Melanopareia in many respects (plumage, internal anatomy, etc.), suggests that placing the genus in its own monogeneric family is the best possible alternative. Therefore, I recommend voting YES to creating the new family Melanopareiidae. Note that in many ways, the case of Melanopareia in the Furnarii resembles that of Oxyruncus in the Tryanni, a case in which it was decided to place this taxon in a monotypic family. If the proposal passes, the position of the Melanopareiidae in the linear sequence of the Furnarii should be noted to be uncertain.
C. Daniel Cadena (in consultation
with Rob Moyle), August 2006
Comments from Robbins: "YES. Although based on what has been published I would simply support treating Melanopareia as Incertae Sedis. However, given that Rob Moyle's unpublished data are consistent with the published data and he supports the recognition of Melanopareidae (pers. comm..), then I support that arrangement. Nonetheless, if the rest of the Committee is hesitate to make this change until the Moyle et al. data are published, then I would support that decision."
Comments from Stiles: "YES. Melanopareia is off on its own, and a monotypic family may be the most logical way to recognize this, as no close relatives have been identified so far and the genus is clearly misplaced in the Rhinocryptidae. Actually, Daniel´s alternatives are not incompatible since two questions are involved: at what rank to recognize the distinctness of Melanopareia, and where to put it? The most sensible way to resolve this seems to me to be to place it at the end (or the beginning??) of the Furnarii as "Melanopareiidae, family incertae sedis".
Comments from Zimmer: "YES. Data seem clear, and conform with morphological, vocal and ecological distinctions. I like Gary's suggestion of placing the new family as Incertae Sedis until further resolution is possible."
Comments from Jaramillo: "YES - Melanopareia in the tapaculos never made sense, and certainly no one I have ever talked to regarding this subject felt comfortable with the arrangement as it stood. But then I could say the same about Teledromas for example. But as Daniel mentions, those remaining questions need not be resolved before acting on Melanopareia. I am comfortable with creating a family Melanopareiidae for the group, incertae sedis leaves me unsatisfied. I would rather create Melanopareiidae and then change that arrangement as appropriate when new data becomes available."
Comments from Pacheco: "YES. Por coerência com a decisão em voga no CBRO, sou favorável à adoção de Melanopareiidae. O posicionamento da presente família, evidentemente, está por ser estabelecida."