Proposal (713) to South American Classification Committee

 

Merge Pseudoscops clamator into Asio

 

Background: Pseudoscops clamator has been included in the genus Asio Brisson 1760 (type: A. otus), Pseudoscops Kaup 1848 (type: P. grammicus), or in its own genus Rhinoptynx Kaup 1851(type: R. clamator). The classification used in by SACC follows the recommendation of Olson (1995). He examined the osteology of Asioninae owls, and suggested that otus, capensis and flammeus shared a derived morphology that included a higher cranium dome in lateral view and a more triangular skull outline in dorsal view. He suggested restricting Asio to these three “more advanced” forms. Species clamator and grammicus shared a presumed more primitive condition with more prominent frontal bones. The overall similarity between these two species led Olson to unite them in the genus Pseudoscops, which has priority over Rhinoptynx.

 

New Information: Wink et al. (2008) inferred the phylogeny of owls using a combination of cytochrome b and RAG-1 sequences. The Asioninae clade is fairly well resolved, with strong support for most clades. Although the tree is not complete (A. stygius and two African species are missing), the result already indicates that Olson’s “advanced” forms—otus, capensis and flammeus—do not form a monophyletic groups because clamator is sister to otus with 98% ML bootstrap support and a Bayesian posterior probability of 1.

 

 

Analysis and Recommendation: While I agree with Olson (1995) regarding skull similarities and differences, the molecular phylogeny of Wink et al. (2008) is a more reliable assessment of relationships. Maintaining clamator in a separate genus makes Asio paraphyletic and the simplest solution is to place clamator back into Asio. The binomen Asio clamator was in regular use during the 1990s (e.g., Sibley & Monroe 1990, König et al. 1999, Marks et al. 1999). Rhinoptynx will enter the synonymy of Asio. If grammicus is sister to clamator, as Olson (1995) suggested, Pseudoscops can also be merged into Asio, but the taxonomic status of Pseudoscops does not need to be considered by SACC since P. grammicus is out of the SACC region.

 

Literature Cited:

OLSON, S. L. 1995. The genera of owls in the Asioninae. Bulletin of the British Ornithologists’ Club 115(1):35-39.

WINK, M., A. A. EL-SAYED, H. SAUER-GÜRTH, & J. GONZALEZ. 2009. Molecular phylogeny of owls (Strigiformes) inferred from DNA sequences of the mitochondrial cytochrome b and the nuclear RAG-1 gene. Ardea 97(4):581-591.

 

Santiago Claramunt, March 2016

 

 

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Comments from Remsen: “YES.  Although better sampling of taxa, genes, and individuals would obviously be desirable, I think this is sufficient evidence for merging Pseudoscops and Rhinoptynx into Asio.”

 

Comments from Stiles: “YES. Strong genetic support clearly places clamator in Asio. This is our question, and NACC should deal with generic status of grammicus, which morphologically seems the likely sister species of clamator, although genetic evidence is currently lacking.”

 

Comments from Areta: “NO. The easy alternative would be to place everything in Asio. However, without sampling of the type of Pseudoscops [i.e., grammicus] we cannot make an informed decision. Taxon sampling is not satisfactory: note that only 4 out of 7 recognized species were sampled, and the situation gets worst when subspecies of very-widespread taxa are considered. Even if Olson was wrong regarding species-level relationships, this does not mean that Pseudoscops must go. Vocally and structurally, grammicus and clamator are similar, whereas capensis and flammeus are morphologically and structurally similar (although differing notably in vocalizations). Prima facie, three groups appear to be recognizable: the whistling grammicus and clamator, the open grassland and short- eared capensis and flammeus in a separate clade, and the low-pitched single-hooting forest species (otus and I would also say stygius). I am not even close to suggesting where the unsampled abyssinicus and madagascariensis would fall. So, based on natural history data, preliminary interpretations regarding morphological similarities, and lack of more compelling phylogenetic data I'd rather keep the distinctive clamator in a genus different from the type Asio otus, either in Pseudoscops (if sister to grammicus) or in Rhinoptynx (if distantly related to the core Asio). Asio as a genus seems to hide more than what it shows, and I like cohesive genera.”

 

Comments from Pacheco: “NO. Given Nacho's comments, I prefer to be cautious and wait for broader coverage in the molecular analysis of this group of owls.”

 

Additional comments from Claramunt:I wanted to emphasize that merging clamator into Asio is the easiest solution AND the only solution available at the moment! Nacho’s suggestion of splitting these owls into three genera is interesting but implementation of that classification will need to wait until further studies are published, in particular, a phylogeny with higher taxon sampling and a formal description of a new genus for the “flammeus group”, because the type of Asio is A. otus, and there does not seem to be a genus name available for the flammeus group. We have to work with the evidence at hand. Taxon sampling in Wink et al. (2009) is not complete but is nonetheless sufficient to demonstrate that clamator is embedded into Asio. A “No” on this proposal would perpetuate an erroneous classification in which clamator is portrayed to be out of the group formed by otus, flammeus, stygius, and other owls currently in Asio (i.e. a non-phylogenetic classification).”

 

Comments from Jaramillo: “YES. I understand and feel Nacho’s point, this seems like a step back in some respects as Asio might better be separated into various groups. The call structure however, could be due to acoustical convergence due to habitat type? Or perhaps not. On the other hand, Santiago makes the point that I am voting on. Right now, there is no way to defend retention of Pseudoscops given that we know it is something embedded in what we understand to be Asio. So maybe in the future this genus can be divided again, once we have more information, but with today’s information we cannot leave Pseudoscops as is.”

 

Additional comments from Areta: “I disagree in that this is THE only solution available at the moment. The argument put forward by Santiago is inherently circular: because what is at stake is the concept of Asio, available evidence does not indicate per se that clamator is "embedded" within Asio, but rather is embedded within one possible and generous definition of Asio. Importantly, a closer relationship between grammicus and clamator has not been falsified, and thus there is nothing solid against usage of Pseudoscops clamator or even Rhinoptynx clamator as names. The problem, as I see it, is making a change with meager data. Is it better to change to something that might be wrong or inaccurate or to stick to our present treatment, which could likewise be wrong or inaccurate? I am concerned by stability in this case: if we put everything into Asio and later evidence indicates that it makes much more sense to put this species in Pseudoscops or Rhinoptynx we would have added the usage of a different name without solid reasons. Fitting everything into Asio when half of the species and less than half of the taxa have been sampled seems risky to me. But, as I said before, it is the easy solution to embrace a fully phylogenetic classification which nonetheless needs to assume that the addition of the other >50% of taxa in "Asio" will not change how we conceive the genus.”

 

Additional comments from Claramunt: “There is nothing circular in my reasoning; it follows from the basic principle of modern taxonomy adopted by our SACC in which supraspecific taxa should be monophyletic. If clamator is kept as Pseudoscops, then Asio remains paraphyletic. Taxon sampling in Wink et al. (2008) is sufficient for demonstrating the paraphyly of our Asio because we have flammeus in Asio but clamator is more closely related to Asio otus, the type of the genus Asio. The hypothetical alternative envisioned by Nacho requires information that we do not have now; it would require a minimum of one publication describing a new genus for flammeus and defining the phylogenetic position of stygius and grammicus. Therefore, maybe sometime in the future there will be other alternatives, including the one envisioned by Nacho, but right know, that alternative is just speculation. On the other hand, our flawed current taxonomy can be corrected by merging clamator into Asio. I also wanted to emphasize that this change has minimal effects on stability because Asio clamator has been used more often than Pseudoscops clamator (for example, a search in Google Scholar results in 284 references citing Asio clamator versus 142 references citing Pseudoscops clamator).”

 

Comments from Robbins: “YES, based on the evidence at hand, there is only one conclusion that can be made: clamator should be placed in Asio.

 

Comments from Zimmer: YES.  I am wholly sympathetic to Nacho's line of reasoning, and his arguments regarding three apparent groups within the species under consideration are compelling, and agree with my field experience with the taxa in question (and by the way, abyssinicus, at least, would seem pretty clearly to group with otus and stygius on vocal, morphological and natural history grounds).  I do think that the vocal characters separating these "groups" are not quite as simple as presented -- clamator also hoots (much like the typical hoots of otus and stygius), and stygius routinely gives piercing whistles (much like the typical calls of clamator) -- so the vocal distinctions may be less of repertoire and more of frequency of use or context.  But that is neither here nor there.  With regard to the proposal, setting aside the very real problems of incomplete taxon-sampling, the Wink et al. (2009) paper presents us with a situation in which clamator is clearly embedded with Asio, as we currently understand it (whether or not our understanding is correct).  It seems preferable to correct what we know to be wrong, at least within our current understanding of Asio, than to wait to do anything until such time as more taxa have been sampled and we have (perhaps) a greatly revised understanding of Asio.  I look forward to revisiting this question in the (hopefully) not-too-distant future, when we have more data involving more taxa within this group, by which time I suspect Nacho's assessment of structure within Asio will have gained much more traction.  Like Nacho, I too prefer more internally cohesive genera.”

 

Comments from Cadena: “YES. I hear Nacho's points, but I think it is clear that otus, clamator, capensis, and flammeus form a clade within which clamator is sister to otus. This calls for a change in classification to make Asio monophyletic, and the simplest solution is to merge clamator into Asio. More complete sampling will undoubtedly reveal details about relationship in this clade that are not apparent right now, but that would not necessarily result in further changes in classification assuming all these taxa will be members of this same clade. One thing that bothers me a bit with the Wink et al. data set is that three of the taxa relevant to the issues discussed here were sampled from captive animals. I don’t know anything about hybridization in owls in captivity, but given problems related to hybridization in other groups in which material from captive animals was used in taxonomy (e.g. cracids), I always wonder about why do researchers not use material from animals collected in the field.”

 

Additional comments from Pacheco: “YES.  I will change my vote here to Yes.  After carefully rereading I am now convinced that the Santiago's suggestion is a step forward.”