Submitted Ph.D. thesis to Dr. R.M.L. Avadh University, in Botany Discipline. The research was carried out under the supervision of Dr. D.K. Upreti, Scientist, NBRI, Lucknow. Topic of the thesis is “Revisionary studies of Lecanora s. lat. from India”.

Sumary:

During the last five decades of past century a large number of macrolichens (foliose and fruticose) from India were revised or monographed. At present information on the occurrence of 697 species of macrolichens (crustose, suamulose, placodioid) of India belonging to 71 families is available. On the other hand, in contrast to macrolichens, microlichens from India are insufficiently revised or even investigated. Often descriptions from the century back publications were only information for several taxa. Most of such taxa belong to the lichen families Lecanoraceae and Lecideaceae. Awasthi in keys of microlichens of India has not keyed out Lecanora species, as the data according to the present concept of the genus were not available. The information on Indian Lecanora was scattered and a large number of specimens of the genus were lying unidentified in the lichen herbarium of National Botanical Research Institute, Lucknow (LWG). Thus there was an urgent need for the revision of the genus and consolidation of the information available so far on the species of Lecanora from India.

The lichen genus Lecanora Ach., is characterized by the crustose to effigurate or squamulose thallus containing Trebouxioid phycobiont, lecanorine apothecia and colourless simple ascospores which are small to medium sized. Lecanora is one of the largest genera with 600 species in the world, out of which 76 species are represented in India. It is a heterogeneous genus and widely distributed from Arctic, Antarctic to subtropical regions.

Lecanora sensu stricto includes species with crystals in the amphithecium, containing atranorin, filiform conidia and with or without algal cell in amphithecium. Lecanora sensu lato includes Lecanora sensu stricto and all the other species under the genus Lecanora.

Lichen genus Lecanora has two subgenus, Lecanora subgenus Lecanora with purely crustose forms and Lecanora subgenus Placodium with crustose to squamulose or placodioid forms. According to the modern concept of lichen classification, the lichen genus Lecanora belongs to family Lecanoraceae, suborder Lecanorineae, order Lecanorales, group Bitunicate Ascohymenials, subclass Euascomycitidae and class Ascomycetes.

The revisionary studies on lichen genus Lecanora sensu lato in India is based on the observation of more than 1500 specimens housed at LWG. The lichen herbarium LWG is richest in the South East Asia, holding more than one lakh specimens belonging to about 1500 species and representing all the phytogeographic regions of India. It includes personal herbarium of Dr. D.D. Awasthi (AWAS), lichen herbarium of Lucknow University (LWU) which have been transferred to LWG on permanent loan basis, thousands of exsiccate materials and also several voucher specimens deposited by various workers. The fresh collection for the present study of Lecanora were also made from Himachal Pradesh, Sikkim, Uttaranchal and few localities of Karnataka, Tamil Nadu and Uttar Pradesh.

The taxa were investigated following the modern concept of the genus. All the available information on the genus Lecanora from India is consolidated. The Lecanora specimens were identified by studying their morphology, anatomy and chemistry. The chemistry of the specimens was performed by colour spot tests (with usual reagents K, C, PD), thin layer chromatography (TLC) and high performance liquid chromatography (HPLC) for few specimens. All the taxonomical characters needed for the identification of species are discussed.

The identity of the specimens were confirmed by matching them with type specimens, exsiccate materials housed at LWG or consulting experts (Lumbsch, T.H., University of Essen, Germany).

The description and discussion of different species are given. The list of different chemical compounds has also been provided. The key to segregate different species is given. The taxonomic treatment includes full citation of the literature, basionym, synonyms, type collection and taxonomic description (including Latin diagnosis and etymology in case of new species, morphology of thallus and apothecia, anatomy of apothecia, chemistry, habitat, altitude, distribution and list of specimens examined). Each species is compared with similar taxa and the difference is discussed. 

The revisionary studies on lichen genus Lecanora sensu lato in India revealed the occurrence of 76 species from India. A total of five species are described as new to science, 20 are new records while 37 taxa are excluded for the country and the reason for the exclusion is discussed,

New species:

1.      Lecanora caesiousa S. Nayaka and D. Upreti

2.      L. leuteomarginata S. Nayaka and D. Upreti

3.      L. palniensis S. Nayaka and D. Upreti

4.      L. sorediferous S. Nayaka and D. Upreti and

5.      L. subpraesistens S. Nayaka and D. Upreti

New Records:

Excluded species:

Out of 76 species of Lecanora sensu lato 12 belongs to Lecanora subgenus Placodium while remaining 64 belongs to subgenus Lecanora. Within the subgenus Lecanora the subfusca group is dominating with 57 species, followed by varia group, represented by L. intricata, L. polytropa, L. saligna, L. sambuci and L. varia while dispersa group has only two species such as L. albescens and L. dispersa. The subgroups of subfusca group, coronulans, pallida and marginata are represented by eight, seven and one species respectively while remaining 41 species belongs to subgroup subfusca.

The Western Himalayas exhibit the maximum diversity of Lecanora with 66 species among the eight lichenogeogrphical regions of India. The Western Ghats, Eastern Himalayas and Central India with 31, 20 and 18 species respectively are the regions having moderate number of Lecanora species. The Gangatic Plain, Eastern Ghats and Deccan Plateau, Western Dry region and Andaman Nicobar Islands exhibit scarce to poor diversity of Lecanora with 10, nine, six and two species respectively.

Among the different states Uttaranchal scores highest of 50 species followed by Himachal Pradesh with 42 species and Tamil Nadu by 25 species.

            The taxa of Lecanora are substrate specific. A total of 45 species found growing on bark (corticolous), 27 on rock, boulders, stones (saxicolous) while L. chondroderma, L. gypsacea and L. himalayae were found either on moss (muscicolous) or soil (terricolous). L. dispersa has a wide niche and grows on nutrient rich soil, bark and soil. The type of the substratum is one of the important criteria for segregation of different groups and taxa in Lecanora. The name of the host plant is not mentioned on the herbarium packets thus it gives very less scope to discuss the host specificity of different taxa. However, by field experience and observation of the samples of bark in the herbarium it is clear that Lecanora prefers to grow on rough bark. The rough bark helps in retaining the moisture for longer duration, easily trapping the lichen spores and provides better niche for establishment. The major host plants in the Gangatic plain and Central India are Mangifera indica and Shorea robusta, in coastal areas the coconut trees, in Eastern Himalayas Cryptomeria and Michelia trees, and in Western Himalayas Quercus, Pinus and Cedrus trees are mostly the rough barked trees. The Western Ghats has a great diversity of host plants and their names are rarely mentioned on the herbarium packets.

            The altitude plays an important role in the distribution of Lecanora. The maximum number of Lecanora taxa prefers to grow in temperate regions and the most favourable altitudinal range is between 2001-2500 m. L. allophana, L. cinereofusca, L. cinereofusca var. himalayensis, L. indica, L. muralis var. dubyi, L. muralis var. muralis, L. perplexa, L. queenslandica, L. subimmersa and L. sulphurescens are the taxa having a wide altitudinal range (Table 3). Among the 12 placodioid Lecanora, 11 exhibit their restricted distribution in temperate regions of Himalayas while only L. indica distributed in other parts of the country. Most of placodioid Lecanora prefers to grow in sub-alpine to alpine regions or in cold desert and mostly on rock. The species L. andina, L. fuscococcinea and L. intumescens are mainly tropical in distribution. The availability of wide range of altitude along with substratum is few of the reasons for high diversity of Lecanora in Western Himalayas, Western Ghats and Eastern Himalayas.

            To study the distribution of Indian Lecanora vis-à-vis the world five distribution patterns can be recognized (Table 3); 1. cosmopolitan (C) - with world wide distribution, 2. restricted (R) – restricted in distribution to one major region, such as Australia, Africa, Europe, North or South America, northern or southern hemisphere, 3. semi- restricted (SR) – distributed in mainly in one or two adjacent regions, 4. endemic (E) – confined to India, and 5. new species (N) – presently known from India. L. campestris ssp. gulmargia, L. cinereofusca var. himalayensis, L. fimbriatula and L. indica are endemic to India while five new species described are presently known only form their type locality except L. palniensis which is also known from 2-3 localities in south India only. A total of 19 taxa were cosmopolitan in distribution, 29 are restricted in distribution while 18 were semi restricted in their distribution.

Lecanora is always found growing in association with other lichens and bryophytes. However, strict association between any species and group could not been established. The associated species varies from habitat to habitat. In tropical regions the corticolous Lecanora are found growing with the members of Physciaceae (Physcia, Heterodermia, Phaeophyscia), Graphidaceae and rarely with Parmeliaceae. In moist, humid and shady areas the bryophytes (leafy liverwarts and moss), Collema, Leptogium are the common associates. In drier areas Arthonia, Buellia, Chrysothrix accompany Lecanora. In the evergreen forests of Western Ghats Graphidaceous, Pyrenocarpous and Thelotremataceous lichens grow along with Lecanora. The temperate climate such as Western Himalayas supports the good growth of Parmelioid lichens (Bulbothrix, Everniastrum, Hypotrachyna, Parmotrema, Punctelia, Rimelia, Relicina) that usually grow along with Lecanora. The species of Usnea, Ramalina are occasionally found growing with Lecanora. In temperate and sub alpine region the twigs of Barberis, Pyracantha crenulata bushes hosts the luxuriantly growth Buellia, Caloplaca, Heterodermia, Ramalina, Usnea and Parmelioid lichens along with Lecanora. On the cultivated trees species of Lecanora usually grows along with Candelaria, Heterodermia, Punctelia and Physcia.

The saxicolous species of Lecanora on open, exposed rocks grows along with species of Buellia, Lecidea, Staurothele, Verrucaria and Caloplaca while the shady rocks supports Collema, Heterodermia, Leptogium, Physcia and Parmelioid lichens. The rocks are the major substratum for the lichens in sub alpine and alpine regions. All most all the placodioid Lecanora are found growing in this climate. The different species of Lecanora grow together along with the species of Aspicilia, Acarospora, Caloplaca, Rhizocarpon, Rhizoplaca, Staurothele, Xanthoria, Xanthoparmelia and Verrucaria

            It is too early to predict the affinities of Indian Lecanora with other phytogeographic regions of the world, since not many revisionary studies on the genus are available throughout the world. The different lichenogeographical regions of the India such as Western Ghats, Western Himalayas and Eastern Himalayas does not show any specific affinities with the adjacent or neighbouring phytogeographic regions of the world. However, Lecanora of India in general shows its affinity towards the Australian, European, North American and partly Eastern Asian elements. The Lecanora taxa of Western Himalayan regions have their affinity towards those of Northern Hemisphere including Europe, Canada and Arctic.

            L. argentata collected on 1^st Dec. 1947 from Port Caming, West Bengal by D.D. Awasthi is the oldest herbarium that have been observed during the study and it has been repeatedly collected thereafter. Except for L. albescens, L. chondroderma, L. dispersa, L. intricata, L. sambuci and L. varia, all the other taxa are collected repeatedly or collected in recent times. Since most these species are widespread and cosmopolitan in distribution and can not be considered as extinct from India. They could not been recollected since the exact locality and habitat of the species were untraceable. None of the Lecanora taxa falls under any IUCN category.