[Taxacom] Glacial survivals

[Algologia]

In the 70's and 80's, when algal biogeography was 
the product of taxon distribution, few might have 
thought that the boundary between the warm and 
cold temperate regions on each side of the North 
Atlantic (cf. Bot. mar. 22: 389, 1979) might 
reflect the limit of the latest glaciation, or 
that the apparent lack of palaeoendemics on the 
northern coast of Europe and Scandinavia might be 
due to massive extinction. In the light of new 
geological considerations (see Taxon 52: 417-450. 
2003),  this overlap seems now apparent and the 
search for glacial survivals has been actualized. 
The results remain modest however, so far the 
distributional range of most macroalgae is 
notoriously uncertain. The Scandinavian Ceramium 
tenuicorne (Kützing) Waern (Ceramiales, 
Rhodophyta) was pointed out as a putative glacial 
survival, providing that this species does not 
belong to the European C. strictum sensu Harvey 
(see Taxon l.c.), and several other taxa known 
only from Scandinavia (e.g. Pterothamnion 
spinescens, Scagelothamnion pusillum var. 
droebachiense, and several Ceramium species) 
await closer examination. While the lack of 
palaeoendemics in Scandinavia and Northern Europe 
remains to be falsified, the finding of two 
unique corallines (Rhodophyta) on the northern 
periphery of glaciation (NW Spitsbergen and East 
Novaja Zemlja) (Nordic J.Bot. 24: 469-499. 2007), 
supports the extinction scenario but also 
indicates the presence of a richer Arctic flora, 
at least for that algal group.

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