Proposal (176) to South American Classification Committee
Split Pionus seniloides from Pionus tumultuosus
Background. These two taxa were treated as distinct species by Peters (1937). Given that Peterson generally lumped on a massive scale, this is surprising. O'Neill & Parker (1977) noted that the two taxa appeared to differ only in degree of saturation of the reddish pigment, a typical mode of differentiation among New World parrots. However, they did not formally propose to lump the two taxa.
This step was taken by Collar (1997:463), who stated: "Race seniloides often regarded as a separate species, but differences between them slight and superficial, appearing more appropriate for subspecific separation." Dickinson (2003: 202) also lumped them, citing only O'Neill & Parker (1977) in footnote 4.
On the other hand, Forshaw (1978:524-25) and Fjeldså & Krabbe (1990:214-215) kept the two taxa as distinct species, the latter authors stating: "A more detailed mapping of distribution and variation n[orth] of the Carpish Mtns. is needed in order to state whether this taxon intergrades with the White-capped P[arrot], and should in fact include it as ssp." Ridgley & Greenfield (2001: 288-89) also kept P. seniloides as a distinct species, although they stated that if intergradation between the two taxa occurred in n. Peru, this would justify lumping them.
The fact remains that there are no known intergrades between the two taxa. Furthermore, there is no gradation within each taxon: that is, it is not the case that birds close to the range of the other taxon approach the other taxon more in coloring than do birds at the other end of the taxon's range, as might be expected if we are dealing with subspecies.
In the circumstances, I consider that the decision to lump the two taxa was premature and that they are better retained as distinct species.
I also note that Chrysotis albifrons Bonaparte, 1845, Atti di Società Italiana di Scienze Naturale e museo civico de Storia Naturale, Milano, 6, p. 404. (Colombia) is an earlier name applying to P. seniloides. Salvadori (1891: 330) lists Bonaparte's 1845 name in the synonymy of Pionus seniloides with (nec Sparrm.). However, Psittacus albifrons Sparrmann, 1788, the basis of Amazona albifrons, does not preoccupy Bonaparte's name, either by primary or secondary homonymy. To preserve stability, it is necessary to declare Chrysotis albifrons Bonaparte, 1845 a Nomen oblitum and Psittacus seniloides Massena & Souancé,1854 a Nomen protectum under ICZN 23.9.1-2 (1999: 28).
That Pionus seniloides (Massena & Souancé,1854) and Pionus tumultuosus (Tschudi, 1844) be treated as distinct species.
Collar, N. J. (1997), Family PSITTACIDAE(Parrots), Pp.280-479 in del Hoyo, J., Elliott, A. & Sargatal, J. (eds.), Handbook of the Birds of the World, 4, Lynx Edicions, Barcelona.
Dickinson, E. C. (ed.) (2003) The Howard and Moore Complete Checklist of the Birds of the World. Revised and enlarged 3rd edn, Christopher Helm, London.
Fjeldså, J. & Krabbe, N. (1990) Birds of the High Andes. Zoological Museum, University of Copenhagen, Copenhagen.
Forshaw, J. (1978), Parrots of the World, 2nd edn., Lansdowne Press, Melbourne.
O'Neill, J. P. & Parker, T. A. III (1977), Taxonomy and range of Pionus seniloides in Peru. Condor 79, (2), 274.
Ridgley, R. S. & Greenfield, P. J. (2001) The Birds of Ecuador: Status, Distribution and Taxonomy. Cornell University Press, Ithaca, N. Y.
Salvadori, T. (1891) Catalogue of the Birds in the British Museum, vol. 20, Psittaci, Trustees of the British Museum (Natural History), London.
John Penhallurick, May 2005
Comments from Zimmer: "YES. Although the morphological differences between these taxa are not particularly impressive, the absence of any real evidence of intergradation, combined with an absence of any published analysis to support the lump is enough to sway me, at least until such time as evidence to the contrary is published."
Comments from Robbins: "NO. Given that our current treatment has seniloides as a subspecies, and we have no new information, I vote "no" until the time comes that we have information that can guide us into making a more informed decision."
Comments from Stotz: "NO. Whether seniloides and tumultuous should be lumped or split is an open question. However, this proposal makes several comments that are erroneous in making it seem like this is a recent change. It says "However, they [O'Neill and Parker 1977] did not formally propose to lump the two taxa." In fact, they did formally suggest that the two taxa be lumped, saying 'We believe, in the absence of evidence to the contrary, that the two forms of Pionus under discussion do not differ enough morphologically or ecologically to warrant being retained as separate species.' It can't get much clearer than that. This treatment was adopted by Hilty and Brown in 1986, so it didn't have to wait for Collar to be adopted. I doubt that Forshaw 1978 had seen the 1977 paper, but I don't have it in order to check.
"In terms of the lack of intergradation, I would just note that there is a gap of 150 km between the northernmost tumultuosus and the southernmost seniloides, so the lack of known intergrades does not in itself suggest anything to me. I have to agree with Mark on this one. In the absence of new information, I don't see a good argument for upsetting our status quo."
Comments from Silva: "NO. We need more information about the putative contact zone between these two taxa."
Comments from Jaramillo: "NO - In the absence of a new analysis, keep them as they are. Although my hunch tells me that there are two species here, the lack of information from the intervening zone is a key missing piece of data."
Comments from Nores: "YES. Aunque las diferencias en plumaje no son tan grandes, son aparentemente suficientes como para separarlos. La única contra que yo veo es lo sugerido por Ridgely y Greenfield de que hubo intergradación en el N de Perú. Si fuera así, habría que juntarlas.”