Proposal (860) to South American Classification Committee
Create an
English name for Sclerurus obscurior
Effect on SACC: This would
create an English name for the South American forms that we have voted to treat
as a separate species from Middle American Sclerurus mexicanus. Importantly, this is likely a temporary name,
because all sentiment from previous proposals (SACC 603, SACC 752) indicates that we think
that broadly defined S. obscurior contains multiple species that
will be recognized as such with publication of additional data.
Background: See proposals cited
above. The bottom line is that we have
voted to recognize a minimal 2-way split that recognizes the two northern,
Middle American forms (nominate mexicanus with pullus) as a
separate species from the largely South America forms, for which the oldest
name is S. obscurior.
This
is a unusual situation because: (1) one of the daughter species, Sclerurus
mexicanus, is exclusively Middle American, thus under NACC purview, and so
our role is advisory only, and (2) all evidence so far strongly suggests that the
two daughter species, Middle American and South American, both consist of two
or more species that would be recognized if more published data were
available. Thus, whatever we decide here
likely represent temporary “place-holder” English names with limited
longevity. Therefore, I don’t see a
reason for putting too much effort into this – it’s just something we have to
do to move one step forward by implementing the minimal 2-way split. Perhaps more important is thinking ahead in
our choices for the temporary names for the consequences for the eventual names
(see Cooper & Cuervo 752 for possibilities).
I
recommend looking at the map in SACC 752 as a starting point. Our split breaks the two species in E. Panama,
where pullus and obscurior meet.
Because
all component taxa have been treated historically as a single polytypic
species, S. mexicanus, that was not given a composite name until Meyer
de Schauensee (1966) [or more likely Eisenmann 1955 – but I don’t have
access to my copy to check- can someone check] called it Tawny-throated
Leafscraper (subsequently modified to Leaftosser). Ridgway (1911) and Cory & Hellmayr (1927)
provided English names for each subspecies but not for the composite species; those
names (with Sclerurus or Leaf-scraper as “last” names) were:
S. m. mexicanus: Mexican
S. m. pullus: Dusky
S. m. anomalus: Panama (now treated as synonym of pullus)
S. m. obscurior: Pacific
S. m. andinus: East Andean
S. m. peruvianus: Peruvian
S. m. macconnelli: Guianan
S. m. mexicanus: Mexican
S. m. bahiae: Bahia
In
anticipation of future splits, I suggest that these names are off limits to
prevent confusion when some or all of these are elevated to species rank. Also, “Tawny-throated” needs to be retired
for our informal SACC guideline of avoiding use of parental name for a
phylogenetic daughter (and NACC’s now formal guidelines currently under our
consideration).
That
doesn’t leave much to work with. I don’t
see any consistent plumage differences between the two groups. In the absence of alternatives, my limited
imagination sees only two possibilities: Northern vs. Southern, and Middle
American vs. South American. I lean
slightly towards Middle American and South American as providing more
information. With respect to congeners,
broadly defined S. obscurior has the largest range of any South American Sclerurus
(as does broadly defined mexicanus for Middle America). The bad aspects of either pair of names are
too obvious to elaborate. Given that
either set will likely have a mercifully short shelf-life, I recommend we not
get too worked up about the pros and cons.
That said, if anyone has a better suggestion, please come forth in your
comments.
Given
my own very slight lean, let’s make the voting as follows: YES = “Middle
American” and “South American”, and NO = “Northern” and “Southern” (or
something else). Our suggestions for S.
mexicanus would be advisory-only.
Van Remsen, June 2020
Comments
from Jaramillo:
“NO. Use North American and South American instead of Middle American. I think
North American is formally more correct than Middle American.”
Comments from Zimmer: “YES. Van’s reasoning that these
names are almost certainly “placeholders” is well taken, and therefore, the
idea that the English names used by Ridgway and Cory & Hellmayr should be
held in reserve in anticipation of future splits makes perfect sense. Given that what we are currently dealing with
is a two-way split, with one daughter restricted to Middle America and the
other, with a range that is 99% restricted to South America, suggests to me
that the proposed names of “Middle American Leaftosser” and “South American
Leaftosser” are the way to go.”
Comments from Schulenberg: “YES, I can't wait for AOS NACC and SACC to get to the end point of the
species-level classification for this group. Middle American and South American
are lame, but I'll vote for them for now, since that's easier than proposing
novel, equally lame names that - we hope - will not have a long shelf life
anyway.”