Proposal (26) to
Elevate Automolus paraensis to species rank
Effect on South American CL: this proposal would split Automolus infuscatus (Olive-backed Foliage-gleaner) into two species: A. infuscatus and A. paraensis.
Background: To my knowledge, paraensis has never been considered a full species. It is found in eastern Amazonian Brazil, south of the Amazon, from R. Madeira east to Maranhão. In terms of plumage and morphology, this form does not stand out, however, from other subspecies currently included in A. infuscatus.
New information: Zimmer (2002) concluded that paraensis warranted recognition as a separate species from A. infuscatus based primarily on vocal characters. He analyzed recordings of about 95 individuals from across the range of A. infuscatus, including all four described subspecies and including about 30 individual paraensis, from near-extremes of its distribution. The only weak-point in the sampling is that only 3 individuals from 1 locality were available for the subspecies badius. He also examined about 300 specimens from throughout the range of infuscatus, including good samples from all five component taxa.
The taxon paraensis is diagnosable based on plumage characters, but it is really no more distinctive than the other taxa in question. In terms of measurements, the five taxa generally differ significantly from one another in one or more characters, but none can be diagnosed by any single measurement.
In vocalizations, however, paraensis differs substantially from the other four in each of the four characters considered (general loud-song type, note structure, note length, and calls): "paraensis differed strikingly and consistently in all aspects of its vocal repertoire from all other subspecies in the complex." In contrast, differences among the other four were nonexistent or minor, although some consistent but slight call note differences among some of them. Zimmer noted that that paraensis was more similar vocally to A. leucophthalmus lammi of NE Brazil than to any subspecies of A. infuscatus (but that is another project ).
Recommendation: I recommend a YES on this proposal. Although sampling could always be improved and playback trials would be great, in my opinion the vocal differences between paraensis and infuscatus are greater or better documented than those between roughly 25 other pairs of ovenbirds currently treated as separate species. It seems to me that the burden of proof after Zimmer's analysis would fall on those who would continue to treat paraensis as a subspecies of A. infuscatus.
English name: Zimmer recommended "Para Foliage-gleaner" for A. paraensis; in the absence of distinguishing plumage features, this seems fine to me ad appropriate. Zimmer recommended leaving the English name of infuscatus unchanged (Olive-backed Foliage-gleaner) rather than concocting a new one to distinguish it from the older, broader infuscatus; I agree with this, given that even with paraensis split out, A. infuscatus still occupies the vast majority of Amazonia.
Zimmer, K. J. 2002. Species limits in Olive-backed Foliage-gleaners. Wilson Bull. 114: 20-37.
Van Remsen, 19 May 2003
Comments from Zimmer: "Obviously a "YES" vote on this one. Sample sizes even larger after my most recent Brazil trip to Carajas; all vocalizations of that population consistent with recordings of paraensis from elsewhere in the range, and completely different from other populations of infuscatus."
Comments from Stotz: "If we could only get everybody to publish such evidence to support splits."