Juniperus monticola compacta ≠ Juniperus zanonii
Plants of the World Online lists Juniperus monticola f. compacta Martínez and Juniperus compacta (Martínez) R.P.Adams as synonyms of Juniperus zanonii R.P.Adams. This is an obvious error which I explain below:
- Martínez described Juniperus monticola with three forms (compacta, monticola and orizabensis) as a subalpine to montane, dense-leaved juniper with small bluish cones and arched branches. J. m. compacta was described as a prostrate shrub that grows above the tree line on the volcanoes of the Trans-Mexican Volcanic Belt.
- Later, similar plants were discovered near the summit of Cerro El Potosí, in Nuevo León. These were assumed to be J. monticola f. compacta as well.
- In 2007, R.P.Adams et al. published their analysis of genomic data and the composition of the essential oils of what they had assumed was Juniperus monticola f. compacta from Cerro El Potosí. They found out that it differed quite a bit from J. m. f. monticola, but failed to compare it adequately with the J. m. f. compacta that Martínez had originally described. This led to the form being elevated to species rank as Juniperus compacta, encompassing the populations of the Trans-Mexican Volcanic Belt as well as from Cerro El Potosí and Sierra Mojada (Coahuila).
A few years later, R.P.Adams realized his misapplication error, retracted and began using the name J. monticola f. compacta sensu Martínez again, while separating the Nuevo León and Coahuila populations as J. zanonii.
A summary of how different authorities treat this complex and my proposal about how iNat should treat it is as follows:
The whole discussion leading up to this realization can be found here. I have since deleted the taxonomic swap where the discussion took place, as I had proposed a change that I now see is wrong.
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@bouteloua @loarie @socogonzalez
Muy bien @bodofzt
I would suggest to accept, for now, the three forms of Juniperus monticola. It is still necessary a study of the group, with additional tools, to decide if J. monticola "f. compacta" and "f. orizabensis" should be considered as synonyms of J. monticola or not.
Juniperus monticola "f. monticola" are erect shrubs or trees up to 10 m growing in pine-oak forests and coniferous forests, whereas the "forma compacta" are decumbent shrubs forming mats at the alpine timberline. Of course, this may remind of "ecotypes", but there are also many cases of related species that have that pattern of morphological and ecological separation. So, lets hope that somebody will study the group and provide information to decide the status of those forms.
What baffles me is that, on its page for J. m. orizabensis, PoWO only cites one source that does accept the taxon and no sources that do not accept it! Like Tropicos, PoWO probably took that info from the wildly inconsistent "Catálogo taxonómico de especies de México", which only lists the type as valid for all three forms. This catalog in turn cites Farjon's conifer database as its source, a checklist that is also out-of-date — for example, it cites J. zanonii as a synonym of J. monticola...
Having already observed J. m. monticola at two locations —El Chico and Peñón del Rosario— and J. m. compacta at three —Nevado de Colima, Telapón/Tláloc and Malinche—, I'd love to visit Sierra Negra, find some junipers and post them. Hope to go there soon. :)
@bodo, sería genial si en las próximas poblaciones que revises te traes una muestrita en silica (1 gr) y un voucher. No se si Bob Adams quiera ver el grupo, pero ojalá alguien en México se animara a abordarlo.
¡Procuraré hacerlo! Saludos, Soco :)
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