Proposal (202) to South American Classification Committee
Reinstate Pipromorpha
for the rufous Mionectes
Proposal: This proposal is for the reinstatement of the genus Pipromorpha
for the rufous Mionectes species, M. oleagineus, M.
macconnelli and M. rufiventris. This is a taxonomic chestnut with
over 100 years' vintage of controversy. If this change were sanctioned, I
understand that M. oleagineus may need revert to P. oleaginea to
reflect the change in gender of the genus, though a nomenclatural expert could
perhaps be consulted on this matter were the proposal to pass.
Taxonomic History:
Mionectes species fall into two rather distinct groups:
two green-and-yellow Andean species (M. olivaceus and M.
striaticollis) and three rufous lowland species (M. oleagineus, M.
macconnelli and M. rufiventris). Various of these taxa include a
number of morphologically and possibly vocally distinctive races that may in
time prove to deserve species rank (pers. obs.).
The rufous species, Mionectes oleagineus, M. macconnelli,
and M. rufiventris have for much of their taxonomic history been
placed in the genus Pipromorpha.
Mionectes and Pipromorpha were merged at
some point in the 1800s (per Traylor, 1977, though I have not been able to
locate the original reference). Ridgway (1907) proposed reinstating Pipromorpha,
a key feature in his view being the presence of modified primaries in true Mionectes,
versus their absence in Pipromorpha. Todd (1921) followed this treatment
in a review of the Pipromorpha. Van Rossem (1938), however, later
proposed merging Pipromorpha with Mionectes, based on the
dubious proposition that some Pipromorpha also have modified ninth
primaries. Zimmer (1941) considered that there was "little evidence of the
suggested reduction in width of the ninth primary in Pipromorpha in
comparison with the tenth although single specimens [of Pipromorpha]
have a slight sinuation of the inner margin that reduces the width of the
feather a little at that point". Zimmer (1941) thus suggested continuing
to recognize Pipromorpha: "Two distinct patterns of coloration are
presented, each involving more than one species. In Mionectes, the
greatest modification occurs in the subexternal primary; in Pipromorpha the
outer primary is most strongly modified In Mionectes, there often is a
pronounced sexual difference in size markedly less obvious than in Pipromorpha."
This approach was followed by most authors (e.g., Phelps &
Phelps 1950a, Meyer de Schauensee 1970 & 1978, Wetmore, 1972) until Traylor
(1977)'s major phylogeny of the Tyrannidae. Traylor suggested that the two
genera be merged, arguing that: "different shapes of the 9th primaries in
adult males is a trivial character in a family where in a single genus such as Pseudocolopteryx,
three species have different sets of primaries and the fourth has them all
normal". Lanyon (1988), studying syringeal morphology and the nasal
septum, found Mionectes and Pipromorpha to be identical
structurally and together to show morphological features unique among the
Tyrannidae. He concurred with Traylor's proposal.
Traylor (1977) proposed dispensing with 36 Tyrannidae genera.
Almost all of the changes he proposed have been followed without much comment
in the modern literature. However, the merger of Pipromorpha with Mionectes
has remained controversial. Snow & Snow (1979) maintained Pipromorpha
(not citing Traylor) in a discussion of the evolution of lek behaviour in the Pipromorpha.
Hilty & Brown (1986) and Hilty (2003) each note "formerly in the
genus Pipromorpha" alongside the relevant species accounts.
Ridgely & Tudor (1994) refer to the rufous Mionectes as
"former Pipromorpha" or "true Pipromorpha"
(even in the plates) with the green Mionectes "true Mionectes".
Collias (1997) refers to "Mionectes (including Pipromorpha)".
Fitzpatrick (1980) refers to "Mionectes (includes Pipromorpha)".
Chesser (2004) refers to "Mionectes / Pipromorpha". These
publications taken as a whole and the long history of use of the genus prior to
Traylor suggest an awareness of the existence of an alternative generic
treatment among those interested in Neotropical birds and, arguably, some
suspicion over Traylor's lump.
Similarities and differences between Mionectes and Pipromorpha:
Morphology and biology
In addition to cranial and syringeal morphology, other
similarities between Mionectes and Pipromorpha include general
proportions, a largely frugivorous diet (rare among the Tyrannidae), foraging
strategy (see Fitzpatrick, 1980) lack of rictal bristles (also rare among the
Tyrannidae), general size and general proportions, understorey foraging and
primary or mature secondary forest habitat. Mionectes and Pipromorpha
both make doomed (roofed) nests, as do other Pipromorphinae* such as Leptopogon,
Corythopis and Hemitriccus (Collias, 1997).
[* The Pipromorphinae is
often used as a subfamily name to describe Mionectes and Pipromorpha (e.g.
Wolters, 1977; Sibley & Ahlquist 1985a; Collias, 1977; Chesser, 2004)
together with other closely related genera. A recent molecular study suggests
that the Pipromorphinae includes Leptopogon, Hemitriccus, Todirostrum and
Corythopis as well as Mionectes / Pipromorpha (Chesser,
2004).]
As noted by Zimmer (1941), suggestions that the genus Pipromorpha is
supported only by differences in the modification of the ninth primaries (e.g.
Traylor, 1977) are an exaggeration. Other differences between the two groups are
summarised in the table below (compiled from leading literature sources, e.g.
Zimmer, 1941, Hilty & Brown, 1986, Ridgely & Tudor, 1994 and fairly
extensive personal field experience with all but one of the species
involved):
Mionectes |
Pipromorpha |
Modified ninth primary |
No modified ninth primary |
Streaked underparts |
No streaked underparts |
Yellowish underparts |
Rufous or orange underparts |
White postocular patch |
No white postocular patch |
Greenish or bluish head |
Grey/rufous head |
Greenish back |
Brownish back |
Andean range (also ranging into Central America) |
Non-Andean (lowland) range |
Notable sexual dimorphism (size) |
Much less sexual dimorphism (size) though see
Snow & Snow (1979) on small wing size differences |
Typically larger in all dimensions than Pipromorpha (bill,
wings, tail, tarsus) |
Typically smaller in all dimensions than Mionectes(bill,
wings, tail, tarsus) |
Generally silent and inconspicuous
(per Hilty & Brown, 1986; Ridgely & Tudor, 1994 etc.). I have only
heard a true Mionectes call on a handful of occasions, despite it
being one of the most abundant genera at almost every forest site I have
studied in Colombia over the last 10 years or so. |
Call not infrequently. Pipromorpha can
regularly be located through field observations following a call. |
When calling, have quiet, thin "wiry" or
"hummingbird-like" calls (summarised in Hilty & Brown, 1986;
Ridgely & Tudor 1994). |
"Twittering" or
"furnariid-like" calls (summarised in Ridgely & Tudor 1994). |
Rarely make "wing-flashing" movements (per
Ridgely & Tudor, 1994) |
Frequently make "wing-flashing"
movements (Snow & Snow, 1979; Ridgely & Tudor, 1994) |
May not be lek-forming (see further below); lek-forming is
at least very rare |
All frequently lek
forming (see further references and discussion below) |
Molecular data
Chesser (2004) included M. (P.) oleagineus material in his
molecular study but no true Mionectes. Bates & Zink (1994)
included M. olivaceus in their analysis but no Pipromorpha.
Neither of these studies suggests paraphyly of the genus, both studies showing
a relatively close relation between Mionectes/Pipromorpha and Leptopogon,
for example. I am not aware of any molecular study that has included
representatives of both Pipromorpha and true Mionectes groups.
Morphology, biogeography and behaviour each suggest strongly that the species
in current Mionectes fall into two quite distinct groups and that
greater Mionectes are rather different from other Tyrannidae. Whether
the Pipromorpha/Mionectes separation should be recognized at the
genus level is a question of degree. It is questionable whether the depth of
the Mionectes/Pipromorpha node would be particularly
illuminating. No one has ever doubted that (i) "true Mionectes";
(ii) "Pipromorpha" and (iii) greater Mionectes are each
monophyletic.
Vocalizations
Vocalizations are rather distinct between the two groups. The true
Mionectes are generally silent. When they do call, they give
"thin", "wiry" or "hummingbird-like" calls. Pipromorpha
call regularly, linked with their lekking behaviour. Their calls are more
twittering or furnariid-like, i.e. louder with a somewhat more liquid quality
to them (above all described in Ridgely & Tudor, 1994 and other recent
reference works). Although syringeal structures are similar (Lanyon, 1988), it
seems likely that some vocal tract differences exist as between the two groups,
giving rise to these different call qualities.
Behaviour - lekking
The Pipromorpha are all lek-forming, being the
only Tyrannids confirmed to exhibit such behaviour (Snow & Snow, 1979;
Wescott & Smith 1994; Fixo & Aleixo 1997). Pipromorpha at
such leks frequently call and engage in wing-raising behaviour. Snow & Snow
(1979) suggest that wing-raising may be to show off male wing emarginations,
one of few sexual differences among Pipromorpha. Snow & Snow (1979)
considered the evolution of lek-forming in the Tyrannidae to be restricted to
the Pipromorpha. There is, however, a report of a congregation of male M.
olivaceus observed in Panama (noted in Ridgely & Tudor, 1994). It may
be that the very thin vocalizations made by the green Mionectes make
any lek sites (if any do exist) difficult to detect. However, the lack of
reports of lekking behaviour, a frequent interest of ornithological researchers
where found, in two widespread species amounts to a somewhat "deafening
silence". Further, lek-related behaviour common in Pipromorpha such
as frequent wing-raising and vocalisations (Snow & Snow, 1979) are observed
only very rarely in true Mionectes (e.g. Ridgely & Tudor, 1994).
Whether true Mionectes do not lek at all or instead present some
retarded/vestigial version of the Pipromorpha lek, this clear
behavioural difference between the two groups amounts to additional grounds for
the recognition of two genera. Much has been written of the unique evolution of
lek behaviour within the Tyrannidae by Pipromorpha (e.g. Snow &
Snow, 1979; Wescott & Smith 1994; Fixo & Aleixo 1997) and it would seem
perhaps appropriate to recognise this feature at the genus level. The
lek-forming behaviour of the Pipromorpha makes the name [=
"Manakin-shape"] particularly apt for this group.
Conclusion: This proposal may lie close to the border of
what people conceive a genus to be in ornithology. Whilst going against almost
all recent taxonomic treatments, I would recommend reinstating Pipromorpha
for the rufous Mionectes (= "YES" vote) on the basis of
external morphology, range, behaviour and voice. I'll leave the last words to
Zimmer (1941) as his views on this topic still make a great deal of sense
today: "Possibly these features ought to be held as of no more than
subgeneric value but the two groups are easily distinguished and I prefer to
maintain their generic separation."
References (not on SACC list):
Bates J.B. & Zink R.M. 1994. Evolution into the Andes:
molecular evidence for species relationships in the genus Leptopogon. Auk 111(3):
507-515.
Capparella, A. & S. M. Lanyon. 1985. Biochemical and
morphometric analyses of sympatric Neotropical sibling species, Mionectes
macconnelli and M. oleagineus. Ornithol. Monogr. 36:
347-355.
Collias N.E. 1997. Of the origin and evolution of nest building by
passerine birds. Condor 99(2): 253-270.
Fitzpatrick, J.W 1980. Foraging behaviour of Neotropical tyrant
flycatchers. Condor 82: 43-57.
Pixo M.A. & Aleixo A. 1997. Lek behaviour of the gray-hooded
flycatcher. Condor 100: 726-731.
Snow B.K. & Snow D.W. 1979. The Ochre-bellied Flycatcher and
the evolution of lek behaviour. Condor 81: 286-292.
Todd W.E.C. 1921. Studies in the Tyrannidae I. A revision of the
genus Pipromorpha. Proc. Biol. Soc. Wash. 34: 173-192.
Wescott D.A. & Smith J.N.M. 1994. Behaviour and social
organisation during the breeding season in Mionectes oleagineus, a
lekking flycatcher. Condor 96(3): 672-683.
Wolters H. 1977. Die Vogelwarten der Erde. Vol. 3. Paul
Parcy, Hamburg & Berlin.
Thomas
Donegan, February 2006
___________________________________________________________________________________________
Comments from Remsen: "YES. This is clearly a
matter of taste, not science (because sister status seems unquestionable), but
to my taste, the differences between these two groups warrant treatment as
separate genera, as outlined above by Donegan. I have never liked the merger
and have to force myself to call the Pipromorpha 'Mionectes.'"
Sister genera yes, but congeners, no."
Comments from Stiles: "NO. Here, I disagree - the
differences cited by Donegan are by no means as clear-cut as he suggests. To
begin with, in my experience at least Mionectes olivaceus does have leks -
exploded leks to be sure, but definitely leks! On its song perch, a male will
wing-flick much as does oleagineus. There are numerous suboscine genera in
which different species do or do not lek, or lek in different ways (v. gr.,
exploded vs. compact). Regarding primary emargination, there is enough
variation among the races of oleagineus to convince me that this character
is hardly of generic value. The Costa Rican races of
oleagineus show distinct dimorphism in this feature as well as being larger and
more dimorphic in body mass, compared to the Colombian races. The songs do
differ, but again, such characters are often subject to intense sexual
selection, and phenotypic responses to this selection can be striking."
Comments from Nacho Areta: "I think that Thomas overstates the differences between Pipromorpha
and Mionectes and overlooks similarities (e.g., by comparing each body
part coloration he increases the number of characters suggesting differences).
Both build spectacular mossy pensile nests different from other tyrants
(including those in a light version of Pipromorphinae) and are frugivores which
makes them quite distinctive. I disagree with the statement that true Mionectes
are vocally inactive and that they rarely or never lek. Actually, it seems to
be that both activities are related: lekking Mionectes olivaceus can
be among the most continuous singers I have ever heard in the field. Also,
lekking birds are at audible distance from each other which I would not
considered an expanded lek (distance is sometimes less than 8m between
displaying males). Finally, Mionectes are not absolutely "Andean"
with at least a subspecies of olivaceus extending into the northern
cordillera of Venezuela. And, for that matter, birds in the Pantepui cannot be
considered strictly "lowland".
"I think that ecological and behavioral
similarities are sound enough to keep both taxa as subgenera and to retain for
both the genus Mionectes (which I
think describes their riverine nesting habits)."
Additional comments from Thomas Donegan: "A few small points on the two comments above. First, on
Gary’s comments on emarginations, I quote Snow & Snow’s proposition that
Pipromorpha wing-raising is to draw attention to this feature, but do
not state this to be a difference between the two groups (note: this is not in
table) nor is this suggested. Secondly, on exploded or non-exploded M.
olivaceus leks, it is interesting to hear confirmation that these do
exist (given the lack of published work on this and the fact I had not noted it
myself). I stated in the proposal that true Mionectes calls
are thin which may make any leks difficult to detect - which seems most likely
to have been the case. Thirdly, nesting, foraging, frugivory and all the other
similarities between these groups mentioned by Nacho and Gary are cited,
referenced and noted in the proposal. On nests specifically, the Collias
article cited notes the Pipromorpha/Mionectes nests to be of the
same structure, as mentioned. However, it does not draw attention to
similarities between Pipromorpha / Mionectes vs. other
Pipromorphinae. Though I do not doubt what Nacho says and indeed, find it very
interesting, I am not sure that lack of knowledge of (presumably) unpublished
data amounts to overlooking similarities! I tried, whilst putting the case for
this split, to cite and discuss or at least mention all the
available evidence and alternative treatments. A white-wash is certainly not
intended! Finally, on the range question, M. olivaceus of course
extends into lowland regions, particularly away from the equator (as noted for
M. olivaceus in C America in the proposal). And M. (P.) oleaginea and
(I understand) M. (P.) macconnelli extend into the Andean
foothills, where they are fully sympatric with "true Mionectes at
multiple sites (in Colombia from 100 to about 500-1000m across most of the
Andean foothills on both slopes). (There are of course lots of species in the
same genus that are sympatric, Tangara being perhaps the best
example). This proposal is, as Van Remsen states, a matter of taste. To my
mind, the very different external morphology and voices of these forms place
them into two separate groups that it is helpful to recognise at the genus
level (even if we discount lekking). Throughout the tortuous history of the
group, some have taken this view whilst others have taken the contrary view,
which is why a proposal and a consensus is needed. Debate is good and it is
pleasing to see this proposal provoking comment and a better understanding of
the group."
Comments from Stotz: "NO. I agree with Van in
every way, except the conclusion. I still think of the Pipromorpha as Pipromorpha
rather than Mionectes. But they are clearly sisters, although not
intermingled. Given that, the question is are we better served by lumping or
splitting. Given my preference for the status quo in the absence of compelling
arguments to the contrary, I think I view the nearly 30 years post-Traylor as a
significant period that should only be overturned for strong reasons. Also
given that there are only 5 species in the genus, we would be creating very
small genera for no obvious reason. If genetic analysis showed that they were
not sister (or if there were any suggestion from other studies of that), or
showed a long branch between Mionectes (sensu stricto) and Pipromorpha,
I would be willing to split. In the absence of that, I can't see what we
gain."
Comments from Zimmer: "YES. This is a tough one.
On the one hand, each of the two groups is quite uniform (in plumage and vocal
characters) when considered separately, and quite different when viewed in the
context of the other group. On the other hand, Doug's points are well taken.
Assuming that the two groups (Mionectes and Pipromorpha) are one
another's closest relatives, then I guess it comes down to what each of us
perceives a genus to be. To my thinking, the species in each group are so much
more similar to one another than any one of them is to any member of the other
group, that the two groups really fit my concept of genera. I might also add
that I think the vocal differences between these two groups are even greater
than suggested in the proposal summary, and although I don't doubt for a minute
the testimony that the two Mionectes species can be persistent
vocalists, I find it hard to believe (based on my field experience with all of
the species) that they come anywhere near being as persistently and
conspicuously vocal as the Pipromorpha. I vote YES."
Comments from Robbins: "NO. As Gary correctly
points out, this proposal does not accurately reflect morphological and
behavioral data for the taxa involved. In addition to Mionectes lekking,
the summary of plumage characters in Donegan's table overemphasizes differences
between these two groups: there is considerable variation in size within and
among Mionectes, and both groups have various degrees of ventral
streaking. I vote "no" until there are appropriate genetic data to
indicate that these two groups are as genetically differentiated as are other
similar appearing tyrannid taxa that we consider generically distinct."
Comments from Silva: "YES. Hard decision, but I
will vote for yes because the differences that were pointed out as well as
because the distribution pattern that is well distinct (lowland vs. highlands).
It will be nice to have a molecular phylogeny of this group as there are enough
samples of them in most of the museums."
Comments from Pacheco: "YES. Difícil decisão. Porém, diante das incertezas e da
falta de um argumento robusto para asseverar o desmembramento do grupo em dois,
voto pela manutenção do tratamento vigente."
Comments from Nores: "YES, aunque como puede deducirse de las diferentes opiniones
emitidas al respecto, las diferencias no son tan marcadas como para pensar en
algo definitivo. Yo veo ambos grupos bastante diferentes, particularmente en lo
que se refiere al color. El color predominantemente rufo en el cuerpo es poco
frecuente en Tyrannidae, y con pocas excepciones, es una característica
genérica. Es el caso de Neopipo, Terenotriccus, Miyophobus, Pyrrhomyias,
Myiotheretes, Cnemarchus, Hirundinea, Neoxolmis, Cassiornis y Attila. En
los pocos casos que no es así, Myiarchus semirufus, Pachyramphus castaneus,
Rhytipterna holerythra, no difieren marcadamente del resto, son sólo más
rufos. En Mionectes y Pipromorpha los colores son muy
diferentes: los primeros amarillos o verdosos muy rayados y los otros rufos muy
poco rayados. Además, es notable el parche blanco detrás del ojo presente
en Mionectes y ausente en Pipromorpha."
Comments from Jaramillo: "YES - I do think it is a
matter of taste, but I am compelled by the vocal differences between the two groups.
As separate groups the two genera are quite uniform and easily defined, I think
it is less so when lumping the two under Mionectes. I find it more
informative to keep Pipromorpha separate from Mionectes, than to
lump them all under one genus."