INDIAN CHEILANTHOID FERN - A NUMERICAL TAXONOMIC APPROACH

Twenty one species belonging to five genera (viz. Aleuritopteris Fēe, Cheilanthes Sw., Doryopteris J. Sm., Notholaena R. Brown, Pellaea Link.) of the Indian cheilanthoid ferns were studied to develop the new data set of micromorphological details viz. epidermal cells, stomatal morphotypes, venation pattern and spore ultrastructre. Cluster analysis was performed by using the twostate of multiple characters that separate the genus Aleuritopteris from Cheilanthes at the Eucladian distance of 5.1, though completely linked with other closely related genera, viz. Doryopteris, Notholaena and Pellaea. The taxonomic conundrum lies within these genera was resolved with numerical taxonomic study.


Introduction
Cheilanthoid ferns form an evolutionary group with the strong tendency to be confined in the three large continental/archipelago land areas of America, Africa and Asia-Malaysia.The centre of diversity of the genera is in America and especially in Mexico, where about 100 species form the richest xeric fern flora in the world (Tryon and Tryon, 1982).In India, the distribution range is very wide from the altitudinal variations of plains (100m) to the slopes and small pockets of Himalaya (3000 m.), Nilgiri and Palni hills of South (Nayar, 1962;Dixit, 1984;Pande and Pande, 2003;Sen and Mukhopadhyay, 2011).The group is characterized by the sporangia on the abaxial side of the lamina, covered or not by a marginal pseudoindusium without veins, sporangia approximate in sori or soral lines, stipes at the base with one vascular bundle, sometimes with two, lamina farinose or efarinose, stems with scales, rarely with hairs, base chromosome no.n=29 or 30 (Nayar, 1962;Tryon and Tryon, 1990).
Cheilanthes and Aleuritopteris are old and phylogenetically problematical genera (genus 'arduum' of Fee) generally included among the gymnogrammeoid or placed in the Cheilanthaceae (family nov.) by Nayar (1962) or Pteridaceae (Tryon and Tryon, 1982;Smith et al., 2006).Difficulties in identifying discrete generic boundaries among the cheilanthoids have long been attributed to convergent evolution driven by adaptation to arid environment (Tryon and Tryon, 1973).The workers frequently echo the comment on that "there is an obvious need for the development of new data which will give a better insight into the evolutionary lines within the group" (Tryon and Tryon, 1973).And the workers of molecular systematics also inferred for the genus Cheilanthes that "it needs redefinition" (Smith et al., 2006).Among cheilanthoid ferns the depositions of farina are used widely to delineate section Aleuritopteris (presence of farina) from section-Cheilanthes (absence of farina) though it breaks at the wider geographical scales (Nayar, 1962;Khullar, 1994).But the potential adaptive significance of the farina has made it a trait of evolutionary interest.
To redefine Aleuritopteris and Cheilanthes and also to regenerate new character sets to resolve the ambiguity of their generic status our present study is attempted to focus mainly the micromorphological characters.On the basis of the multiple dataset of two character-state, taxa were clustered to establish the interrelationships that exist among them.

Materials and Methods
Detail list of specimens studied are mentioned in the Table 1.For cluster analysis of the 21 taxa studied as many as 9-two state characters (i.e.characters which exist in two alternative forms or states i.e. either present or absent for generic segregation (Table 2); for 12 spp. of Aleuritopteris, 43-two state characters (Table 3) and for 6 spp. of Cheilanthes 42-two state characters (Table 4), were taken into account to prepare the data matrix.Responses of each taxon to each of these characters were coded in a data matrix as '1' and '0' respectively for two alternative states i.e. presence or absence.The data thus recorded were further utilized in finding the overall similarities or rather the distance between taxa and putting them in clusters using the concept of 'Euclidean Distance' for measuring distance and 'Complete Linkage' for amalgamation or linkage.Statistical analysis was performed using Statistica-6 (Sneath and Sokal, 1973).
Images of the standard character-sets used for the analysis were taken in Leica QWIN 80 microscope and Scanning Electron Microscope, Model No. Japan Hitachi 530.

Results and Discussion
The morphometric study was performed to delineate the taxa of the cheilanthoid fern at the generic and infrageneric level.For numerical taxonomic study the suitable characters used at the generic level are mentioned in the Table 2.For clustering at the infrageneric level used characters are mentioned in Table 3 (Genus Aleuritopteris) and Table 4 (Genus Cheilanthes) respectively.Figure 4(A-I) and Fig. 5(A-K) shows the contrasting character states as stated in Tables 2-4.Previously, all the works performed by various workers (Nayar, 1962;Tryon and Tryon, 1982;Khullar, 1994) have given much importance to the farina character, which is a potential synapomorphy and have some evolutionary interest (Sigel et al., 2011).But, the wholesome approach of character is giving a better clue of separation at both the generic and infrageneric level (Sen, 2014).The works at the molecular phylogeny also found some dispute for this group when the regional basis of works was performed (Gastony andRollo, 1995, 1998;Zhang, 2007).
On the basis of phenetic study of the 5 genera, close relation or affinity with each other was noticed.The genus Aleuritopteris Fee and Notholaena R. Brown form a group and Doryopteris J. Sm and Pellaea Link.form another group; these two groups are allied with each other and form a broad group with Cheilanthes Sw.One important ambiguity which persisted so long regarding the generic segregation of Aleuritopteris from Cheilanthes gets some clear clue from this phenetic study in that they are quite apart from each other in phenogram but are linked.The characters as mentioned by Fraser-Jenkins and Dulawat (2009) to distinguish the genus Cheilanthes from Aleuritopteris, are narrow stipe scale and narrow leaf segment, which are very vague as is evident from our numerical data enlisted (Table 2).
To categorise the infrageneric taxa, phenetic study resolves some ambiguity.Placement of C. subvillosa Hook.under the genus Cheilanthes is also corroborated by our study as the taxon possesses similarity in generic characters with Cheilanthes.The placement of its synonym Aleuritopteris subvillosa (Hook.)Ching under the genus Aleuritopteris by Fraser-Jenkins and Dulawat ( 2009) is however not in conformity with the present study.The placement of the genera Hemionitis L., Parahemionitis Panigrahi and Pityrograma Link.with cheilanthoid group of ferns (Fraser-Jenkins and Dulawat, 2009) must not be supported as their taxonomic positions were clarified earlier by Smith et al. (2006) on the basis of morphology as well as molecular taxonomy in other subfamilies Hemionitidae and Taenitidae respectively.Cluster analysis at infrageneric level Cluster analysis of Aleuritopteris spp.

Phenetic study Cluster analysis at generic level
A. argentea (AAR) and A.subargentea (ASR) have the nearest relation as is revealed from complete linkage at the Euclidean Distance of c.2.8.At the level of the linkage Distance of 3.5 as many as 8 clusters can be recognized of which 4 are with solitary OTUs (Operational taxonomic Unit), viz. A. rufa (ARU), A. chrysophylla (ACH), A. formosana (AFO), A. subdimorpha (ASD).However, at the Linkage Distance of 4.5 three large clusters are recognizable, viz.AAL, AAN, ARU; AAR, ASR, ACH, ABI, ADO, AFO; ABU, AGR, ASD.The relatedness of the last two clusters mentioned is greater than with the first cluster which is clearly expressed at the distance of 4.7.However all the OTUs under study, although individually distinct, are linked ultimately at the Ed of 4.8 because of their moderate overall similarity.The dendrogram based on phenetic study clearly revealed the interrelationships of five Indian genera of arid region.Despite of their homoplasy of characters (Tryon and Tryon, 1973;Sen and Mukhopadhyay, 2014;Sen, 2014) they can be separated, though linked, clearly by using a multiple sets of characters.Present study is the first report describing the correlation between the cheilanthoid ferns of India at generic and infrageneric level and also establishes the generic segregation of Aleuritopteris and Cheilanthes by doing numerical taxonomic study.