500111-13 The Micranthes nelsoniana aggregate M. insularis, M. nelsoniana, M. porsildiana
Geography: Asian (N/C) - amphi-Pacific-Beringian.
Notes: Zhmylev: The name Micranthes punctata (as Saxifraga) was applied to this aggregate (subsect. Rotundifoliatae) until recently when it was found to be the valid name for a species previously known as M. redowskiana (Pugsley 1936b; Webb 1964). European and North American authors have regarded M. nelsoniana in a broad sense and have distinguished up to eight subspecies within it (e.g., Calder and Savile 1960; Webb 1964; Hultén 1968a; Scoggan 1978c; Webb and Gornall 1989). Russian botanists have usually regarded these entities as species (e.g., Siplivinsky 1976; Rebristaya 1984; Khokhrjakov 1985; Kharkevicz 1989).
Based on the pubescence of the inflorescence, the entities of M. nelsoniana s. lat. can be divided on two groups (Zhmylev 1995): plants with only short glandular hair in series Aestivalis (Zhmylev) and plants with long glandular and non-glandular hair in series Reniformes (Zhmylev). Among the arctic entities, M. nelsoniana including ["aestivalis"] belongs to series Aestivalis, whereas M. porsildiana and M. insularis belong to series Reniformes. Transition forms between these groups are very rare, e.g., Saxifraga [Micranthes] xtolmachevii (see Excluded taxa).
Elven: The options are three: (a) One wide Micranthes nelsoniana with several races as in many North American treatments (e.g., Brouillet and Gornall 2007; Brouillet and Elvander 2009a); (b) two species, representing Zhmylev's two series, with races; or (c) two series with several species and some races as in Zhmylev's treatment. Two arguments in favour of the last-mentioned option are that the ranges of the taxa vary from sympatry to allopatry, not indicating a simple situation of allopatric or parapatric geographical races with transitions, and that transitions seem to be rare or restricted even where taxa closely co-occur (as do M. nelsoniana s. str. and M. porsildiana, sometimes within sites). In addition to the taxa listed to reach the Arctic, two more reach the non-arctic parts of southern Alaska: M. pacifica and M. charlottae. We accept Zhmylev's proposal of several species.
Higher Taxa
- Micranthes [5001,genus]