7105 Douglasia Lindl.
- Lindl., Quart. J. Sci. Lit. Arts 2: 385 (1827) nom. cons..
Notes: Korobkov (PAF proposal) considered Douglasia a narrowly circumscribed North American genus with the arctic representatives D. arctica and D. beringensis, whereas he assigned the Eurasian species to Androsace, including Douglasia ochotensis and also the North American D. alaskana. The Russian point of view as to Androsace and Douglasia is referred by Kelso et al. (1994).
Kelso: I am very strongly opposed to subsuming Douglasia (or parts of it) into Androsace, for a number of reasons. Although the odd species D. alaskana is quirky, the other species, and also the segregate genus Vitaliana in the European Alps, fall out nicely. Subsuming them, especially piecemeal as Korobkov has done, just blurs what are otherwise definite patterns. This position, by the way, has been accepted also by the most recent treatment of Androsace as a whole, see Smith and Lowe (1997). They had much experience with a global view of the genus.
Aside from the morphological differences, we now have molecular and anatomical evidence that shows differentiation of the groups and which support placement of the odd species D. (A.) alaskana into Douglasia rather than Androsace. This work is Anderberg and Kelso (1996). Abstract: "We investigated the differences in endosperm cell wall thickening in three genera of Primulaceae: seven species of Douglasia, 28 species of Androsace representing the four sections of the genus, and the single species of the genus Vitaliana. Endosperm cell walls have irregular wall thickenings and narrow constrictions and characterize all Douglasia species and Vitaliana, whereas evenly thickened cell walls without constrictions were found in the endosperm of Androsace (and Primula). The endosperm character supports the monophyly of Douglasia and Vitaliana and we discussed the phylogenetic implications of this conclusion." Note that D. alaskana was included in the study and fell clearly into the Douglasia type. So, too, did D. ochotensis, whereas A. chamaejasme fell into the Androsace type.
In conjunction with my colleague Elena Conti, Zürich, we also have unpublished molecular data from chloroplast sequences that clearly separates Androsace and Douglasia (using A. sempervivoides and D. beringensis) into different clades!
Elven: The ongoing work Kelso referred to is now published. Trift et al. (2002) concluded from cpDNA evidence that "Douglasia is a derived relative of Androsace". The division between Androsace and Douglasia is drawn according to Kelso's proposal. In a later study, Schneeweiss et al. (2004) supported Douglasia in Kelso's concept but with some demarcation problems vs. Androsace. See the discussion by Kelso (2009b).