Comprehensive checklist of algal class Chlorophyceae (sensu Fritsch, 1935) for Uttar Pradesh, India, with updated taxonomic status

: Uttar Pradesh is an active center for algal research in India, but regional checklists are not available. Checklists of algae reported from class Chlorophyceae (sensu Fritsch, 1935) are presented here, with taxonomic status updated per AlgaeBase. The checklist covers algae from 17 types of habitats and includes 749 species, 166 varities and six forma, belonging to four phyla, 11 classes, 26 orders, 64 families and 161 genera. Charophyta is the dominant phylum with 519 infrageneric taxa (species, varities, forma), while Chlorophyta is represented by 389 taxa. Zygnematophyceae is the dominant class with 465 infrageneric taxa under two orders, six families and 29 genera. Chlorophyceae has 305 infrageneric taxa under five orders, 33 families, and 76 genera. Cosmarium is the most speciose genus with 163 taxa, followed by Oedogonium (79) , Spirogyra (72), and Closterium (54). Our study revealed that of 75 districts in Uttar Pradesh only 40 are explored for algae, with Prayagraj and Lucknow recording 266 and 144 taxa respectively.


INTRODUCTION
Algae are defined as "oxygenic photosynthesisers other than embryophyte land plants" by Cavalier-Smith (2016). They are predominantly aquatic photosynthetic organisms, and are the major primary producers. Algae are ubiquitous in distribution and occur in a wide variety of shapes and sizes. Fristch (1935) classified algae into 11 classes under the plant kingdom, mostly based on the pigments, reserve food and flagella. Modern classification uses few kingdoms and several phyla (Ruggiero et al. 2015). Although Fristch's classification is obsolete, it is still popular and followed by many authors. AlgaeBase (www.algaebase.org, Guiry & Guiry 2019) currently lists 155,155 species and infraspecific taxa, under 15 phyla and 54 classes. According to Guiry (2012) there are 72,500 species of algae in the world, of which >20,000 are diatoms. From India so far 7,411 taxa of algae are known, which is 15% of the total Indian flora (Mao & Dash 2019).
Freshwater algal studies in India date back 170 years, when Griffith (1849) first reported species of Chara from West Bengal. Several workers thereafter explored the algal flora of different water bodies across India. Uttar Pradesh, the fourth largest and most populous state of India, lies between the geo-coordinates 23.866-30. 416N and 77.05-84.15E. The state covers a geographical area of 2,40,9228 km 2 and is divided into 75 districts. Himalayan foothills form the northern border, and the state is largely covered by plains characterized by hard rock strata and plateaus. About 7% (16,826 km 2 ) of the geographical area is covered by forests, which include tropical thorn forest, deciduous and semi-evergreen. A total of 5,712 km 2 is protected under 24 wildlife sanctuaries, three tiger reserves and one national park. The Ganga, Yamuna, Ramganga, Gomti, Ghaghara, Gandak, Chambal, Betwa, Ken, and Son are some of the major rivers flowing through Uttar Pradesh. The state has at least 36 prominent lakes and numerous ponds. It is notable that 11 wetlands of the state are declared as wildlife sanctuaries of which eight are recognized as Ramsar sites. Uttar Pradesh has a humid subtropical climate with four seasons; temperature ranges from 42°C in summer to 7°C in winter. Annual rainfall ranges from 650 to 1,000 mm. The state has been an active center of algal research in India for nine decades, indicated by numerous publications and descriptions of several novel taxa. However, the algal enumerations published from Uttar Pradesh are scattered and a compiled list is not yet available. The aim of the present study is to prepare comprehensive checklist of algal flora for Uttar Pradesh state. Since a large number of studies are available with total taxa exceeding 2,000, the checklist is split in to several publications. Class Chlorophyceae (sensu Fritsch 1935) is presented here, with updated taxonomic status of all taxa.

MATERIALS & METHODS
The present checklist is based on an extensive review of literature involving over 126 research papers, 10 books, monographs and chapters, 18 dissertations and Ph.D. theses deposited at various universities and research institutes. The entire list is appended as a bibliography. Taxa identified up to species, variety or forma level are included. Taxonomic identities of the taxa were checked on AlgaeBase (www.algaebase.org). Taxa are arranged alphabetically (Table 1) and their heirarchial position is provided separately ( Table 2). AlgaeBase is followed for arranging taxa as per their hierarchy, which in turn mostly follows the classification system proposed by Ruggiero et al. (2015). A map of Uttar Pradesh indicating the districts explored for Chlorophyceae is provided in Figure 1.

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Noor; Spirogyra hyalina var. gracilis (Hassall) Kützing; and S. reservoiraensis R.N.Singh. The study revealed that phylum Charophyta is most dominant in Uttar Pradesh with 519 infrageneric taxa (species, varieties, forma) under four classes, six orders, 10 families, and 37 genera. Whereas Chlorophyceae is the most diverse phylum with 389 infrageneric taxa under four classes, 17 orders, 51 families, and 120 genera (Table 2). Among the 11 classes Ulvophyceae of phylum Chlorophyta is diverse with six orders followed by Chlorophyceae and Trebouxiophyceae with five orders each. However, Zygnematophyceae of phylum Charophyta is the most dominant class with maximum infrageneric taxa totaling up to 465 under two orders, six families, and 29 genera. It is followed by Chlorophyceae with 305 infrageneric taxa under five orders, 33 families, and 76 genera. Order Chlamydomonadales of phylum Chlorophyta is the most diverse in the state with 17 families, 27 genera, and 61 species and varieties, followed by Sphaeropleales with nine families, 33 genera, and 112 species and varities. Desmidiaceae (phylum Charophyta) is the diverse family with 16 genera and 277 species and varieties, followed by Hydrodictyaceae with nine genera and 21 taxa, and Chaetophoraceae with seven genera and 29 species and varieties. Cosmarium is the most speciose genera with 163 taxa followed by Oedogonium (79), Spirogyra (72), Closterium (54) while several genera had less than five taxa.
It is observed that algal samples were collected from as many as 17 habitats including ditches, tanks to river. Among them maximum number of Chlorophycean algae belonged to ponds with 621 taxa, followed by lakes (394 taxa) and river (236 taxa). The study revealed that out of 75 districts in Uttar Pradesh, algal exploration has been carried out only in 40 districts ( Figure 1). The district Prayagraj (= Allahabad) recorded the maximum number of taxa (266 nos.) followed by Lucknow (144 nos.), Gonda (141 nos.), and Saharanpur (139 nos. It is clear from the study that 35 districts of Uttar Pradesh are either unexplored or the literature unavailable. The major algal research centres in Uttar Pradesh are mostly located in Banaras Hindu University, Varanasi; University of Allahabad, Allahabad; University of Lucknow and CSIR-NBRI, Lucknow. Therefore, much attention was paid to easily accessible region in and around Allahabad, Lucknow, and Prayagraj while other districts are neglected. Among unexplored districts Lakhimpur, Siddarth Nagar, and Maharajganj are in the Tarai region of the state, which are wetter regions due to mansoon flooding. The district Sonbhadra located in the south-east of Uttar Pradesh is a biodiversity rich part of the state but so far no records of algae available from here. The south-western part of Uttar Pradesh can be considered as potential region under explored for algal flora. This region consists of districts such as Agra, Eath, Etawah, and Kannauj with wetlands declared as protected areas such as Patna Wildlife Sanctuary, Sarasai Nawar Wetland, Lakh Bahosi Sanctuary, National Chambal Wildlife Sanctuary, and Sursarovar Sanctuary. Currently, one each species is reported from Agra and Kannauj districts.

CONCLUSION
The enumeration of 921 taxa under phylum Chlorophyta covering only 40 districts of Uttar Pradesh in the present study is certainly remarkable indicating the presence of rich diversity of this phylum in the state. It can be noted that earlier studies by Gupta et al. (2012) and Suseela et al. (2015) have estimated low number of algae from the state. This rich diversity may be due to the presence of numerous small and large water bodies with diverse physico-chemical characteristics and seasonal variations. Floristic exploration in the unexplored areas of the state could be an important step towards unraveling the true representation of the algal wealth in the state.