New distribution data on Plagiomnium undulatum var. madeirense T. J. Kop. Sergio
When undertaking a revision of the Bryales for the Iberian Flora, herbarium specimens of Plagiomnium undulatum (Hedw. T.J.Kop. from the LISU herbarium were revised. Some specimens corresponded to the variety Plagiomnium undulatum var. madeirense T. J. Kop. C. Sergio. Further material of P. undulatum from various herbaria (BM, COI and H) were revised and some specimens were also found to correspond to P. undulatum var. madeirense. The taxonominc status of P. undulatum var. madeirense at a molecular level is uncertain as genetic differences between the two varieties are ambiguous but morphological differences, based mainly on the difference in median cell size, support the division of P. undulatum into the two taxa (Stech Sim Sim, 2006) According to Koponen Sergio (2001) the var. madeirense is distinguished by the larger size of its median leaf cells (width and length) which ranges from 25 40628 65 (80) mm. In this variety, the cells are also more irregular in size with patches of very large cells (frequently .30645 mm) sometimes present whereas in the variety undulatum, cells are usually homogenous in size. In material studied, the leaves were longly decurrent as indicated by Koponen Sergio (2001) The plants are generally larger in appearance .8 cm compared to 3 8 cm in var. undulatum) including the leaves, although this is not a reliable character as large plants with long leaves that were revised from the Azores also correspond to P. undulatum var. undulatum. The variety madeirense occupies a similar habitat and substrate as P. undulatum var. undulatum; both are found in humid forest areas, usually by a water source (e.g. ponds) or running water (e.g. streams and waterfalls) on rocks or predominantly on banks (Koponen Sergio, 2001) P. undulatum var. madeirense was originally described from the island of Madeira in 2001 (Koponen Sergio, 2001) and was subsequently found in the Azores in 2009 (Stech et al. 2009) Revised material from BM that corresponded to P. undulatum var. madeirense has led to an extension of its distribution range southwards to Morocco and to Tenerife in the Canary Islands (Figure 1) By contrast, P. undulatum has a wider distribution and is present not only in Macaronesia but also temperate Europe, North Africa, and the Near East (Koponen, 1980) It is found in most provinces of the Iberian Peninsula (Fuertes, 2010) From a distributional perspective, bryophyte species depend mainly on biogeographical and geological events, which are reflected in the diverse bryoflora of the Iberian Peninsula, Macaronesia, and North Africa (Allorge, 1947; Sergio, 1990) Other species clearly representing a similar distribution pattern as P. undulatum var. madeirense are Homalia lusitanica Schimp. (He, 1997) and Sematophyllum substrumulosum (Hampe. E. Britton, the latter considered a signal species for climate change in Europe (Sergio et al. 2011) P. undulatum is reported in North Africa (Koponen, 1980) but we suggest that some specimens may correspond to var. madeirense and it probably covers a wider distribution than is currently known. Further studies, especially from Spain and Macaronesia, are needed and will be important to interpret the actual distribution pattern of this Plagiomnium.