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Taxonomic revision of Lycopodiaceae P. Beauv. ex Mirb. of the Pan-Himalaya

Nawal Shrestha, State Key Laboratory of Systematic and Evolutionary Botany, Institute of Botany CAS, China


Lycopodiaceae are ancient, homosporic vascular plants with an estimated 400 species in the world. The taxonomic status of the genera and species belonging to this family has been a long standing dispute among taxonomists chiefly due to its simple morphology and alternative interpretation of morphological characters. With regard to taxonomy of Himalayan Lycopodiaceae, there have been very few studies carried out until now. The studies so far in the Himalayan region have focused more on floristic surveys and enumerations. Although, the species diversity of Himalayan species of Lycopodiaceae was assessed on a fragmentary basis by many taxonomists, none of them covered all of the Himalayas and therefore, the studies were inadequate. Keeping in view the insufficient knowledge on Himalayan Lycopodiaceae, detailed taxonomic revision was undertaken in the present work. The study is an attempt to assess species diversity of Lycopodiaceae in the Pan-Himalayan region using evidences from morphology, anatomy and ecology.

The results indicated that plant height, width of branchlets, density of leaves, leaf shape and size, phyllotaxy, leaf margin are the most important character in delimiting taxa in this family. Some mircromorphological characters (eg. leaf epidermal cells, stomata, etc.) are too useful in segregating problematic taxa. The size of sporangium, its outline and depression at the point of attachment varies between species. Sporangia are either reniform or circular in outline with varying degree of grooves. Species of Lycopodium have comparatively thinner sporangial walls than Huperzia. Gemmae are a common feature of terrerstrial species of Huperzia and almost absent in epiphytic forms. Although, sporangial and gemmae characters are not unique to individual species, they are useful in segregating groups. There is great variation in the organization of stele in different species and are useful in segregating taxa. Diversity is highest among the terrestrial as well as epiphytic species of Huperzia. Lycopodiaceae species richness in the Himalaya has a pronounced peak at 2000 m and decreases in both directions which is primarily caused by climatic factors rather than hard boundaries.

The present study has reported 38 species from the Himalaya. Huperzia is represented by 28 species, Lycopodium by 9 species and Lycopodiella by 1 species in the Himalaya. Fifteen species (14 Huperzia + 1 Lycopodium) are endemic to China. Five sections have been proposed for Huperzia with two new combinations and five species have been synonymised. Based on our analysis of morphological with climatic data and ecological niche modeling, four species were recognized in Huperzia serrata complex. The results, however, do not support the recognition of other infraspecific taxa previously recognized under H. serrata. The present work is the first comprehensive account of the Himalayan species of Lycopodiaceae and the results, although approximate, have provided a clear insight of the species diversity in the Himalayan region. It has also paved the way for future morphological and/or molecular studies for this family.

I would like to acknowledge the support received from IAPT for this study. Funds were particularly utilized in field trips to South China and Nepal.

Publications

  • Shrestha N. and Zhang X.C. (2014) Re-circumscription of Huperzia serrata complex in China using morphological and climatic data. Journal of Systematics and Evolution. doi:10.1111/jse.12120.
  • Shrestha N., Xing F.W., Qi X.P., Yan Y.H. and Zhang X.C. (2014). Huperzia nanlingensis (Lycopodiaceae), a new terrestrial firmoss from southern China. Phytotaxa 173 (1): 73–79. doi:10.11646/phytotaxa.173.1.6.
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