Proposal (652) to South American Classification Committee

 

Transfer Porzana flaviventer and Porzana spiloptera to Laterallus

 

Our current footnotes summarizes the situation:

 

15. Porzana flaviventer has been placed by some authors (Olson 1970, 1973) in a separate genus Poliolimnas, along with P. cinereus of the East Indies and Australasian region, but see Mees (1982) as cited by Walker (1998).  Slikas et al. (2002) showed that it is not closely related to Old World P. cinereus, but rather is sister to Anurolimnas + Porzana.  Therefore, Dickinson & Remsen (2013) resurrected the monotypic genus Hapalocrex for this species.  Garcia-R. et al. (2014) found that it was sister to a group of species currently placed in Laterallus; however, these species are not sister to the type species (melanophaius) for the genus Laterallus.  Proposal badly needed.

16. Porzana spiloptera has been placed by some authors (e.g., Hellmayr & Conover 1942, Meyer de Schauensee 1970, Blake 1977) in the genus Laterallus, the genus in which it was described, but see and Ripley (1977) and Storer (1981).  However, Garcia-R. et al. (2014) found that it is the sister species to Laterallus jamaicensis.  Proposal badly needed.

 

         Garcia-R. et al. (2014) produced a phylogeny for the Rallidae based on a fairly large analysis of DNA sequence data, both mitochondrial and nuclear, largely compiled from GenBank etc.  Their taxon sampling was fairly good for a family that is cosmopolitan and difficult to collect: 70 species in 22 of 33 extant genera.  Below is the relevant section of their tree:

 

 

 

Clearly, neither flaviventer or spiloptera are close to true Porzana, which is another part of the tree – see the lower part of the tree above.  The type species for Laterallus is melanophaius; therefore, to maintain our Laterallus as monophyletic, everything branching from that node needs to be included in Laterallus, including spiloptera and flaviventer.  The problem is that this also includes extralimital Coturnicops, so it will be interesting to see whether NACC and others are willing to do this.  To retain Coturnicops, two new genera will have to be resurrected (presumably Hapalocrex for the group containing flaviventer, and Creciscus Cabanis for the group containing jamaicensis).

 

Recommendation: I have none and will sit back and see what all of you think, especially in terms of voice.  A broad Laterallus that includes Coturnicops might be too heterogeneous, although in terms of relative depth of nodes, it would match up fairly well with true Porzana.  A NO vote would mean that we would follow this with a proposal to treat these taxa in four genera.  The logistic problem with that is that placement of levraudi, spilonota, leucopyrrhus, and xenopterus, i.e. half of the South American taxa, will have to be inferred from non-genetic data, so one could argue that a broad Laterallus would be safer until those taxa are sampled.

 

Literature Cited (also see SACC Biblio):

 

GARCIA-R, J. C., G. C. GIBB, AND S. A. TREWICK.  2014.  Deep global evolutionary radiation in birds: diversification and trait evolution in the cosmopolitan bird family Rallidae.  Molecular Phylogenetics and Evolution 81: 96–108.

 

Van Remsen, October 2014

 

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Comments from Stiles: “YES. At least until more complete taxon sampling has been conducted, a broad Laterallus seems reasonable, although this means subsuming Coturnicops therein as well.

 

Comments from Stotz: “YES  I think we are probably better off with fewer genera in this part of Rallidae rather than more.  Certainly the original ideas on relationships, and then the attempts to fix those relationships have been a miserable failure based on the tree.  I am completely comfortable with Coturnicops noveboracensis in Laterallus.”

 

Comments from Nores: “YES, although it could also be to treat these taxa in three genera: 1) resurrect Creciscus (Sharpe 1894) for spiloptera and jamaicensis; 2) Coturnicops; and 3) Porzana, including flaviventer.

 

Comments from Zimmer: “YES.  I think recognizing a broader Laterallus is the way to go (even though that means including Coturnicops).  Based on the tree, we would have to broaden Laterallus anyway, or, else, do something with jamaicensis, and the latter course, taken alone, would not resolve the problem with flaviventer and spiloptera, nor would it take into account the fact that we don’t have genetic data for several species of putative Laterallus, as mentioned by Van in the proposal.  Better to dump them all in Laterallus, at least until we have the benefit of broader taxon-sampling among the SA crakes, and can see how everything settles out.”

 

Comments from Robbins: “YES, I’m fine with a broader defined Laterallus that includes Coturnicops. By choosing this course of action we also may preclude making additional changes that might be precipitated by the inclusion of missing taxa, i.e., taxa that might be embedded in an unexpected way in this clade.  Also, if we do this it would seem to be consistent in generic treatments that we should consider melanops as a Porzana (see proposal 651).”

 

Comments from Areta: “NO. I think that taxon sampling needs to be more comprehensive to make this decision. Several problems arise when trying to accommodate the phylogeny into a classification:

 

1) the inclusion of Laterallus viridis and Anurolimnas viridis in the same clade (=genus in this case) demands a taxonomic change, as otherwise they would both have the same name.

 

2) lack of sampling of Laterallus leucopyrrhus, L. levraudi and L. xenopterus makes it unsafe to assume that they will all fall in the same clade, given their similarities in vocalizations and plumage to different members of Laterallus and even Anurolimnas. It is already surprising enough to find that several species that appeared to be closely related based on voice and plumage are not so closely related, that I don't trust first impressions anymore (and that is what we would be doing by assuming that unsampled members will fall where we expect them to fall).

 

3) The Cresiscus are vocally and morphologically a very coherent group, and presumably spilonota will also fall here.

 

4) We have no idea of where Coturnicops notatus fits this scheme, while vocally Coturnicops noveboracensis is millions of years away from other Laterallus.

 

“In sum, the chances of having to undo an all-encompassing, highly uninformative and eco-morpho-vocally very diverse Laterallus are big, and until natural history and phylogenetic data have been put together in a densely sampled study, lumping a diverse array of birds in a single genus (without even sampling several!) doesn't seem to be the best choice.

 

“We are clearly approaching a better taxonomy of rails and the work by Garcia et al. is a great contribution, but until rail phylogeny has been fully solved (or nearly so), changes might not give us both good information contents and stability as desired in any classification.”

 

Comments from Cadena: “NO. The thread of proposals derived from the fine García et al. paper reflect that our historical intuition on what rail genera should be based on overall phenotypic similarity was fraught with problems because several genera turned out not to be monophyletic. I thus feel uncomfortable in assuming that half of the South American species of "Laterallus", which have not been sampled, will fall in the same clade as the rest of the taxa. Like Nacho, I think that we need more data here.”

 

Comments from Jaramillo: “NO. As noted “To retain Coturnicops, two new genera will have to be resurrected (presumably Hapalocrex for the group containing flaviventer, and Creciscus Cabanis for the group containing jamaicensis).” I am more comfortable doing this given the present knowledge. The inclusion of other Laterallus in the analyses will likely create clearer patterns of relationships and may even shift some of the birds in the current tree, maybe? Yet Coturnicops seems to me a valid genus, as does Creciscus. Clearly the unsampled spilonota is a Creciscus based on voice; jamaicensis likely needs to be split given vocal differences between northern and southern populations, so eventually we will obtain a much more “robust” and informative Cresciscus that matches both plumage and vocal similarities in the members. I would not want this, nor Coturnicops subsumed into a broad Laterallus even with what we know currently.”

 

Comments from Remsen:  “NO.  After reading through all of the comments, it is clear that there are no good options here.  The choices are basically to (1) retain these two in a genus in which we are certain they do not belong, or (2) create additional problems.  I favor the former because option 2 is almost certainly only a temporary solution until all Laterallus are sampled, and thus I favor maintaining stability until we have all the data.”