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Volume 37 Number 4 Volume 38 Number 1 Volume 38 Number 2

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ScienceAsia 38(2012): 1-12 |doi: 10.2306/scienceasia1513-1874.2012.38.001


Phenetic study of the Microsorum punctatum complex (Polypodiaceae)


S. Petchsria,b, T. Boonkerda,b,*, B.R. Baumc

 
ABSTRACT:     Microsorum punctatum (L.) Copel. is a widespread species of ferns. It is distributed in the tropics and subtropics of Asia and Africa from sea level to about 2800 m elevation. At present, the taxonomic status and boundary of this species is still uncertain due to the great variation in frond form, size, and venation patterns. These variations depart from previous systematic treatments, so this species group was proposed as a species complex worth investigating. Cluster analysis and canonical discriminant analysis were performed on 694 herbarium specimens deposited at BCU, BKF, BM, K, B, L, and P and consisting of 20 taxa of Microsorum punctatum complex. Twenty-five quantitative and 31 qualitative characters were employed. Cluster analysis separated these 20 taxa into seven groups, viz. M. thailandicum, M. membranaceum, M. musifolium, M. glossophyllum, M. siamense, M. steerei, and M. punctatum. The seven cluster groups are discussed. From a canonical discriminant analysis using the 20 taxa as priori groups, it can be concluded that M. siamense, M. thailandicum, M. membranaceum, and M. musifolium are obviously distinct taxa, while characteristics of M. glossophyllum and Pleopeltis megalosoides are mixed and should be proposed as the same species. Likewise, specimens of M. steerei, P. tonkinense, and P. playfairii should be recognized as M. steerei. Moreover, the specimens of the species previously recognized as the other 10 synonyms of M. punctatum are not distinct from M. punctatum and are treated here as members of M. punctatum. The four most important characters that have separated the seven species are stipe length, density of sori, number of sori rows between adjacent secondary veins, and diameter of sori. These quantitative characters, together with some qualitative characters were coded into a database using Descriptive Language for Taxonomic Analysis (DELTA) software. An identification key to species of the Microsorum punctatum complex was then created using the associated program INTKEY. The differentiation between the taxa studied is discussed.

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a Biological Sciences Program, Faculty of Science, Chulalongkorn University, Bangkok 10330 Thailand
b Department of Botany, Faculty of Science, Chulalongkorn University, Bangkok 10330 Thailand
c Agriculture & Agri-Food Canada, Eastern Cereal and Oilseed Research Centre, Ottawa, Ontario, K1A 0C6, Canada

* Corresponding author, E-mail: Thaweesakdi.B@chula.ac.th

Received 4 Jul 2011, Accepted 15 Feb 2012