Chaftee 1 the Compeehensive Taxonomic Accouht of The
Total Page：16
File Type：pdf, Size：1020Kb
CHAFTEE 1 THE COMPEEHENSIVE TAXONOMIC ACCOUHT OF THE UCHEM 6ENfUS GSAPfflSiFMMhY eEiAFHlDACEAE) FEOM MDIA. Taxonomic Account Graphis Adans. ex Miill. Arg. Mem. Soc. Phys. Geneve, 29(8): 28, 1887. The genus Graphis is characterized by: crustose, corticolous, or rarely saxicolous or foliicolous thallus; lirelline, elongate, simple to irregularly branched ascomata; simple, unbranched paraphyses; unitunicate asci with apical pore apparatus; colourless and transversely septate ascospores with lenticular cell lumina. Photobiont a green alga (generally Trentepohlia). The name Graphis was first proposed by Adanson (1763) in his treatise "Families des Plantes" for accommodating a few species of lichens known at that time. However, Linnaeus (1753) in his "Species Plantarum" had included them under Lichen scriptus while Acharius included them in Opegrapha. Acharius (1810) in his "Lichenographia Universalis" has divided Opegrapha into three genera Arthonia, Opegrapha and Graphis where Graphis is characterized by an elongate apothecium immersed in the thalline margin. Miiller Arg. (1880, 1882) in his series "Lichenoligische Beitrage" has utilized spore characters in the segregation of genera. Taking Graphis (sensu Acharius) with hyaline, transeptate spores he formulated three more genera Graphina with hyaline muriform spores, Phaeographis with brown, transeptate spores and Phaeographina with brown, muriform spores. The name Graphis given to the genus by Adanson has been retained with all the diagnostic characteristics universally accepted, are sensu Miiller Arg. (1882). Exciple characters have traditionally formed the backbone of species delimitation in Graphidaceae. In addition, almost all subgeneric taxa are based on excipular characters. Many of these characters according to Wirth & Hale (1978) appear to be quite variable and unreliable. Although a system of ascospore based genera in the family established by Muller Arg is still in use, the in appropriateness of Zahlbruckner's ascospores concept had long been recognized and several Hchenologists (Santesson 1952; Wirth & Hale 1978; Staiger & Kalb 1999) stated it as an unnatural and artificial system and therefore needs to be revised. As opined by Liicking (2003), the concept now presented by Staiger (2002) is indeed revolutionary. Although Graphis, Phaeographis and Phaeographina still exist, these genera are no longer what they used to be. Graphis now comprises species with a carbonized excipulum and hyaline, both transversely septate and muriform ascospores, while Phaeographis unites taxa with non-carbonized excipula and brownish, transversally septate or muriform ascospores. In addition, no less than 16 genera, described more than a century ago and long forgotten by most Hchenologists, have been reinstated, and two further genera are newly established. However, Staiger's treatment of Graphidaceae is different because it terminates an artificial arrangement already accepted for too long. The taxonomic concept applied by Staiger, chiefly based on excipular structures and supported by ascomata morphology, hamathecium structure, ascospore type, and secondary chemistry. Graphis is the largest genus in the family Graphidaceae claiming c. 300 species (Kirk et al. 2001), which are cosmopolitan but occurring more abundantly in the tropics. Several Hchenologists have contributed to the knowledge of the genus Graphis. However, noteworthy contributions in recent years include the publications recording 49 species from Brazil (Redinger 1934, 1935), 14 species from Mexico (Wirth & Hale 1963), 17 species from Japan (Nakanishi 1966), 27 species from Dominica (Wirth & Hale 1978), 5 species from Florida (Harris 1995). More recently, 6 species have been described from Japan (Nakanishi «fe Harada 1999, Nakanishi et al. 2002), 74 species from India by Indian Hchenologists (Awasthi 2000) and 4 species were added from Australia (Archer 1998, 2001). Recently, on account of the occurrence of spiny periphysoides and /or periphyses, seven species previously described under Graphis have now been placed in the genera Acanthothecis and Fissurina (Staiger & Kalb 1999). To summarise, the most important works on Graphis, particularly those concerning India, are as follows: Awasthi (1965), in his "Catalogue of lichens from India, Nepal, Pakistan and Ceylon" enumerated 36 species of Graphis which were recorded in the 19* and the early 20"" centuries by various lichenologists viz. Belanger (1838), Leighton (1869), Stirton (1879), Nylander (1867, 1891, 1900), Jatta (1905) and Rasanen (1952) based on the collections of European botanists or naturalists from India. Lichenological studies in India were resumed by the work of Dr. D.D. Awasthi in the early forties of the last century and little later by Dr. P.G. Patwardhan and their associates. Consequently, several species were described and reported by Indian lichenologists. As such 33 species of Graphis were recorded and published in various scattered publications [Awasthi & Singh, K. (1975) Awasthi & Singh, S. (1977), Patwardhan & Kulkami (1976, 1979), Kulkami (1977), Nagarkar & Patwardhan (1982), Singh, K. (1984), Singh, A. (1994), Singh, K.P. & G.P. Sinha (1994) and Makhija et al. (1992)]. Awasthi (2000), in his recent publication the "Lichenology in Indian subcontinent" listed 74 species of Graphis so far known from India. In the present work I have recorded 137 species and 8 varieties oi Graphis from India, which includes 11 new records to India, 48 new species, and 7 unnamed species. In the present treatment, I have preferred to key all the species under the genus Graphis sensu Mtiller Arg. (1882). After understanding the new concept presented by Staiger (2002), the species now placed in Graphis will be revaluated for their correct placement in the new system before the publication. Description of the Region (Geographical Extent, Topography, Climate, and Vegetation) Although the vast area of India encompasses a broad range of phytogeographic areas, thousands of years of human habitation and severe population have so altered the natural vegetation that primary forests are thought to exist only on small areas in hilly regions of northern, eastern and southern India and the sparsely populated but increasingly settled and exploited Andaman and Nicobar Islands in the Bay of Bengal. Only about one sixth of the subcontinent is now forested, and areas that have retained their climax vegetation after shifting cultivation practices of the past are exceedingly rare and under great pressure, being mostly confined to isolated pockets of tropical evergreen and semi evergreen forest in northeastern India and monsoon forest in the Western Ghats (Kendrick 1989). The 3.27 million km^ of subcontinental India harbor so great a variety of biomes that they can be only grossly defined by reference to the three major relief regions and the south west monsoon of summer. Where the relief blocks the southwest monsoon, regions in the rainshadow exhibit a tropical dry deciduous or torn forest vegetation. Such is the case for the great Deccan Plateau. On the other hand in Northeastern India, lying thwart the air flow and at the junction of the Himalayas and the Eastern Hills that trend into Burma, the hill station of Cherrapunji on the southern slopes of the Khasi Hills records more than 11 m of rain a year, whilst Shilong, only 54 km away, receives only about 2.15 m of annual rainfall. Thus the description of the region that follows can only hint at the great complexity and diversity of the subcontinent. To the north and arcing southeastward, tower the young Himalayan peaks, formed in the upper tertiary when geosynclinic deposits were compressed, folded and upraised by the northward movement of the Deccan block from the ancient continent of Gondwana. The eastern Himalayas rise from the Brahmaputra valley through a zone of swamp forest that gives way from about 200 m to 800-900 m to broad-leaved tropical evergreen rainforests, topped by subtropical grasslands and subtropical forests up to about 1800 m and succeeded by temperate forests to about 3500 m. The Eastern Himalaya region has provided a gateway for the migration of plants and is considered a meeting ground of the Indo-Malaysian and Sino-Japanese floras. The Eastern Hills, running in a northeast-southwest direction, are a series of ranges, averaging 1500-1800 m. which divide India from Burma and support tropical evergreen forests. The Brahmaputra, or Assam, Valley is the corridor that links Arunachal Pradesh to the rest of India. The vegetation is very varied and interesting. Tropical wet evergreen forests comprising species of Dipterocarpus, Syzygium, Artocarpus, Mesua and Aguillaria and bamboos occur in eastern and Southern Assam. Tropical semi evergreen forests comprising species of Phoebe, Dysoxylon, Termimlia, Michelia etc. occur in foothills of Assam. The Assam Plateau, in a pocket between Bangladesh and Burma, is a fragment of the Deccan block and is broken by the Garo, Khasi and Jaintia Hills averaging 1200-1800 m in height. Rainfall on the south facing slopes is among the heaviest in the world and the humidity supports the growth of dense tropical evergreen forests. The dominant soil type is acrisol, very low in nutrients and subject to much erosion. In the west, below the icy peaks and high plateaus of the Himalayas lies the heavily formed intermontane basin, the Vale of Kashmir. Himalayan conifers of tropical and subtropical types grow on the slopes of Kashmir. Paralleling the mountain wall to the south are the low lands