Proposal (664) to South American Classification Committee

 

Treat Stephanoxis lalandi as consisting of two species

 

 

Effect on SACC:  This would treat the subspecies loddigesii as a separate species from Stephanoxis lalandi.

 

Background: Our current Note reads as follows:

 

27. The southern subspecies loddigesii was formerly (e.g., Cory 1918, Pinto 1937) considered a separate species from Stephanoxis lalandi, but Peters (1945) treated them as conspecific.  Cavarzere et al. (2014) provided evidence that loddigesii merits species rank.  Del Hoyo and Collar (2014) also independently treated them as separate species based on plumage differences.  Proposal badly needed.

 

 

New information: Cavarzere et al. (2014) compiled and synthesized essentially everything known concerning the taxonomy and nomenclature of Stephanoxis.  As they pointed out, treatment of as a subspecies of is based on a Peters’ opinion that was not based on any explicit rationale:

 

“Early on, the two taxa were recognized as distinct species by most authors (e.g., Salvin, 1892; Ihering & Ihering, 1907; Cory, 1918; Pinto, 1938).  However, Peters (1945), without any reasoned argument, considered Stephanoxis loddigesii as a subspecies of S. lalandi, a treatment that has been followed ever since (e.g., Pinto, 1978, Schuchmann, 1999; Grantsau, 2010).”

 

The two are allopatric; their ranges are separated by a 160 km gap in São Paulo.  The males differ in multiple plumage characters, among which there is no overlap in plumage characters.  Here is the fantastic painting by Rolf Grantsau in Cavarzere et al. that illustrates the differences:

 

 

 

         The females also differ in multiple characters:

 

 

         Cavarzere et al. (2014) used the following rationale for treating the two as separate species under the BSC:

 

“In addition, body adornments commonly assumed to be important for sexual selection in males (crest, throat colouration) differ between Stephanoxis populations, the differences of which are determined not only by colouration, but by a clear geographic pattern as well. These observations are even more evident than in pairs of some hummingbird taxa which are undoubtedly considered as separate species, such as the Emeralds Violet-capped Thalurania glaucopis/Fork-tailed Woodnymph Thalurania furcata, warranting specific status to Stephanoxis subspecies also under the Biological Species Concept (Mayr, 1942, 2000).”

 

         Del Hoyo & Collar (2014), using the Tobias et al. numerical taxonomy scheme for assigning species rank, also independently elevated loddigesii to species rank.

 

Analysis and Recommendation: I strongly concur with the rationale presented by Cavarzere.  These two differ to a greater extent in plumage than do most allopatric sister taxa of hummingbirds ranked as species.  In my opinion, by any reasonable standard of comparative degree of phenotypic divergence for allotaxa, these should be treated as separate species.  They differ as much or more from each other than do the Oxypogon subspecies we recently elevated to species rank.  My only questions are why Peters lumped and why they have remained lumped for so long.  In my opinion, burden of proof in a case like this clearly falls on treatment as conspecific, and so I recommend a YES on this one.

 

English names: Cavarzere et al. (2014) used “Purple-crested Plovercrest” for loddigesii and “Green-crested Plovercrest” for S. lalandi.  Del Hoyo & Collar (2014) used “Violet-crowned Plovercrest” and “Green-crowned Plovercrest”, respectively.  I like Cavarzere et al.’s use of “crest” because the color really does extend to the crest, not just the crown, and it emphasizes the most conspicuous feature of the genus.  On the other hand, one could consider “-crested” redundant with respect to “Plovercrest”.  As for Violet vs. Purple, I am uncertain; perhaps someone with direct access to specimens can assess which is more appropriate.  I suspect we will need a separate proposal on English names, perhaps with a hybridization of the competing names.

 

Lit. Cit.

CAVARZERE, V., L. F. SILVEIRA, M. F. DE VASCONCELOS, R. GRANTSAU, AND F. C. STRAUBE.  2014.  Taxonomy and biogeography of Stephanoxis Simon, 1897 (Aves: Trochilidae).  Papéis Avulsos de Zoologia 54: 69–79.

 

Van Remsen, December 2014

 

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Comments from Zimmer: “YES.  The plumage distinctions are pronounced for males, subtle for females, the two replace one another geographically, with a pronounced gap in São Paulo, and to my ears, there are some vocal differences as well, although this has not yet been quantified.  This was another unjustified Peters-lumping, and I think the burden of proof really should fall on those that would follow Peters.  I guess English names will be left for a separate proposal.  Ted Parker used to refer to these as "Purple-breasted Plovercrest" (lalandi) and "Black-breasted Plovercrest" (loddigesii), which are nice names given that the difference in breast color between the two species is usually pretty striking.  S. lalandi has the median breast stripe very wide (nearly covering the entire underparts) and brilliant, bright purple, whereas S. loddigesii has a noticeably narrower dark median stripe, that appears blackish (or midnight blue) in most light, but with more purplish-blue margins.  Crest color is more discretely different (although probably not as eye-catching as the differences in the breast color and pattern) although to my ears, it is somewhat redundant to use "crest" twice in the same English name (e.g. Green-crested Plovercrest).  Despite this, I would favor using Green-crested and Purple-crested or Emerald-crested and Violet-crested as opposed to the same color modifiers paired with ‘crowned’.”

 

Comments from Cadena: “YES. Differences appear striking and the proposed split is consistent with how we acted on the Oxypogon case.”

 

Comments from Pacheco: “YES. Completely agree with the proposal. A clear case of unjustified lumping that needs to be reversed.”

 

Comments from Areta: “YES. Marked consistent morphological differences and distribution patterns support the split.”

 

Comments from Robbins: “YES for treating these two very distinct taxa as species.  Very nice figure by Grantsau! The English names used by Parker seem quite appropriate.”

 

Comments from Jaramillo: “YES – This looks straightforward to me. With regards to English Names, I will wait for a proposal as it seems that there are multiple options. I do suggest we agree to what purple actually looks like, as the plate makes the breast look more blue than purple to me…but that is of course a painting, not the real thing.”