New Species of Thelypteridaceae from India, Ceylon and Burma

Abstract

The object of the present communication is to describe two species of ferns of the family Thelypteridaceae discovered by Dr. Chandra during field work in India, and also two species represented by specimens noted by me in the Kew Herbarium. This family, comprising in all about one thousand species, almost all tropical, presents many complex problems both of taxonomy and nomenclature. I have been studying the Old World species for the past three years with a view to writing an account of the family in Flora Malesiana. I hope to present a new conspectus of genera, mainly Malesian, at a later date. I must however present a brief explanation of the generic names here adopted. It is generally admitted that the treatment of this family by Copeland in his Genera Filicum (1947) is unsatisfactory. He did not distinguish genera clearly and included them, with other groups not nearly related to them, in his family Aspidiaceae. The fact that natural species-groups within Thelypteridaceae have not yet been clearly distinguished has led various authors to conclude that the only satisfactory arrangement is to include all species in one genus Thelypteris. I believe however that it is possible, though difficult, to recognize species-groups, and that some of them should have generic rank; also that some generic names adopted by Copeland should be used with different circumscriptions. Copeland used the generic name Cyclosorus Link to include a very wide range of species. But that generic name was originally based on one species, C. gongylodes (Schkuhr) Link, a pantropic swamp-fern of similar habit to the temperate Thelypteris palustris Schott. It appears to me that the majority of species of Copeland's Cyclosorus are not at all closely related to the original species, and that they should have other generic names. Sphaerostephanos was established in 1839 by John Smith and applied only to a species with elongate sori; but it seems to me very clear that the original species is closely related to many others in Malesia which have round sori, and as it is the oldest name available for them I am adopting it with a wider circumscription. Here it is used for an Indian species which has hitherto never been fully described; Bory gave it a name in 1833, but his description was brief and has been misinterpreted. Dr. Chandra re-discovered the species, and by chance I recently discovered Bory's original specimens in the Paris Herbarium.