Summary

The Western Ghats of the Indian peninsula constitute one of the 34 global biodiversity hotspots along with Sri Lanka, on account of exceptional levels of plant endemism and by serious levels of habitat loss (Conservation International, 2005). It straddles through the states of southern Gujarat, Maharashtra, Goa, Karnataka, Tamil Nadu and Kerala, practically forming an unbroken relief dominating the west coast, for almost 1600 km from the mouth of river Tapti to the tip of South India. The complex physiography of the rugged mountain chain, the  general elevation varying from 400-500 m to exceptionally high peaks exceeding over 2500 m, especially in the Nilgiris and Anamalais, and rainfall ranging from 1000-6000 mm are major reasons for rich biodiversity and high endemism. There are about 2015 endemic flowering plant taxa in Peninsular India, of which about 1600 are confined to the Western Ghats (Chandran et al. 2010). The overall latitudinal and altitudinal gradients, rainfall patterns brought in by the South-West and North-East monsoons, reduction in number of rainy months progressively towards northern latitudes and towards the leeward side of mountains and variations in soils and rocks coupled with over three millennia of vegetation changes caused by humans have resulted in a mosaic of ecological islands, niches and refugia favouring with varied degrees of endemism that reach highest in rare stands of relic forests having conservation histories since time immemorial.
Several studies have been carried out on flowering plants of Western Ghats. However, the lower vascular plants, and in particular pteridophytes did not receive much attention. Pteridophytes including ferns and fern-allies (Lycophytes) are the earliest of the vascular plants on the earth that heralded the arrival of an advanced vascular system – xylem for water and phloem for food transport respectively. They grow luxuriantly in moist tropical and temperate forests from sea level to the high mountains. The pteridophytes among the vascular plants with about 12, 000 species are next only to the angiosperms in the world. More than 1200 species of pteridophytes have been reported from India (Dixit, 1984; Chandra, 2000). However, due to the presence of many doubtful species this seems to be an overestimate and hence, the actual number of pteridophytes species are estimated to be 900-1000 (Chandra et al. 2008). Undulating terrains of Western Ghats hills are habitats for about 320 species of pteridophytes (Dudani et al. 2011).

Prospecting for rare vegetation and their specific kinds of habitats, based on flowering plant communities, might lead to the discovery of some rare ferns as well. For instance Cyathea crinita Copel., an Endangered tree fern is found only in the cooler shola and other high altitude (>1500 m) evergreen forests of southern Western Ghats especially alongside shaded streams (IUCN, 2012). Similarly, Lycopodium wightianum (Wall.  ex Hook. & Grev.) Holub, a South Indian species, considered to be Near-threatened (Chandra et al. 2008), has its specific habitats in higher altitudes (1800-2400 m) on exposed slopes and grasslands (Manickam & Irudayaraj, 1992).
While studying some of the exclusive, threatened, swamps overgrown with wild nutmeg trees (Myristica swamps), in the Kathalekan forest of Uttara Kannada in central Western Ghats,  several sensitive fern species were found in association with rare community of evergreen trees like Myristica magnifica Bedd. (Endangered), Dipterocarpus indicus Bedd. (Endangered), Gymnacranthera canarica (King) Warb. (Vulnerable), Syzygium travancoricum Gamble(Critically endangered), Semecarpus kathalekanensis  Dassapa & Swaminath (newly discovered tree species of mango family, assigned to Critically Endangered status) and scores of other canopy and understory endemic flowering plants.  Mention may be made of South Indian endemics like, Bolbitis subcrenatoides Fras.-Jenk., B. semicordata (Bak.) Ching and others like the tree fern Cyathea gigantea (Wall. ex Hook.) Holttum, Pteris quadriaurita Retz., Leptochilus axillaris (Cav.) Kaulf, etc. Among the many climax forest relics, Kathalekan (Kathale = dark; kan = sacred forest) relic forest in Uttara Kannada District, of Central Western Ghats in Karnataka is with the repository of rare biotaevident from 35 species of amphibians from an area of 2.25 km² (Chandran et al. 2010).
Cyathea nilgiriensis Holttum, a South Indian endemic tree fern (Fraser-Jenkins, 2008) was seen growing in the deep shade of the swampy forest of Kathalekan in the Uttara Kannada. This is a new report of its distribution anywhere from north of 14° latitude in the Western Ghats. The tree ferns of the genus Cyathea belong to the family Cyatheaceae which has 241 species and 4 hybrids distributed throughout the mountainous regions of the world (Khare & Srivastava, 2009). India has 11 species of Cyathea (Dixit, 1984) of which C. nilgirensis was listed ‘Endangered’ (IUCN, 1998), but subsequently brought into the category of ‘Least Concern’ (IUCN, 2012).

Chandra et al. (2008) have carried out extensive work on the distribution and nomenclature of pteridophytes in India and  consider the threat categorization by IUCN of the pteridophytes of India are based on often erroneous names, taxonomic misunderstandings, and insufficient studies on distribution. This has necessitated a fresh look on this subject. As Chandra et al’s is a convincingly good approach towards threat categorization, until a revision happens in IUCN’s Red Listing of Indian pteridophytes and as a lone population of few individuals of  C. nilgirensis  survives precariously in the threatened swamps of Kathalekan in Uttara Kannada, the northernmost range of its distribution in the Western Ghats, we felt it reasonable to endorse its Near Threatened status.  

Image 1. Kathalekan Sacred grove in Uttara Kannada District, Karnataka

The fern is also, notably,  listed in the Appendix-II of CITES (Convention of International Trade in Endangered Species of Wild Fauna and Flora) (Sanjappa & Lakshminarasimhan, 2011). It is distributed in restricted pockets in the shaded and damp streamside forests of Kerala, Karnataka, Tamil Nadu and Andhra Pradesh. It was reported from Kemmangundi and Charmadi Ghats of Chikmagalur district, Mercara – Bhagamandala – Talacauveristretch in Kodagu district and in Sakleshpur and Devalkere in Hassan district (Rajagopal & Bhat, 1998) and now from south of Uttara Kannada, Central Western Ghats.  In Kathalekan the species exists precariously, with merely four individuals left, obviously the last relics of what would have been once a primeval forest before the introduction of agriculture and forestry operations by humans.