Justifications for the Treatment of Abies

Infra-Abies delineations follow the combined nuclear, plastid, and morphological study of Xiang et al. (2018). Section-level classifications follow more targeted studies.

Section Abies

The Eastern Mediterranean Complex: The taxa A. bornmuelleriana and A. equi-trojani are frequently considered to be synonymous with the latter as the accepted name, but there is evidence that they are distinct taxa. Handel-Mazzetti named them at the same time in 1925 from distinct geographical regions; therefore my classification here treating A. equi-trojani as a subordinate taxon follows the genetic data in Hrivnak et al. (2017) establishing it as a recent offshoot of A. bornmuelleriana. Coode and Cullen (1965) also considered these taxa to be distinct, and at the species level. Hrivnak et al. (2017) also provide evidence that A. x olcayana (putative A. bornmuelleriana x A. equi-trojani) is not a hybrid, but a recent evolutionary offshoot within A. bornmuelleriana s.l., much like A. equi-trojani. I adopt this treatment here, since it is clearly a distinct regional/ecological form worthy of conservation. Hrivnak et al. (2017) establish a close relationship between the above taxa and A. nordmanniana. They are maintained at the species level here to capture their variation, but there appears to be an argument for including them as subordinate subspecies/varieties under A. nordmanniana. Hrivnak et al. (2017) provide strong supporting data for Abies cilicica and Abies cilicica ssp. isaurica. The latter is quite rare and of major conservation concern. It is in North America, but it would be cool to acquire new genetics.

The Balkans Complex:

The taxa Abies alba, Abies cephalonica, and their putative hybrid A. borisii-regis are present in the Balkans, the latter as a putative stabilized hybrid. Krajmerova et al. (2016) provides data indicating that A. borisii-regis is a product of recent introgression resulting from contact between these two species, and is not a monophyletic stabilized hybrid species but rather a variable and complex hybrid swarm. Bella et al. (2015) also provide data showing that A. borisii-regis is genetically intermediate. Needle volatiles share the same tendency: clustering by species with A. borisii-regis intermediate (Nikolic et al. 2021). Despite its variable nature and hybrid origin, I record the name as A. borisii-regis here since it generally behaves as a stabilized hybrid species.