DIVERSITY AND DISTRIBUTION OF THE THELYPTERIDACEAE (POLYPODIOPSIDA) IN PAKISTAN

The present taxonomic study of Thelypteridaceae (Polypodiopsida) in Pakistan is based on the study of fern specimens in 15 herbaria in Asia, Europe and USA. A total of six genera and eight species are recognized; a key, detailed description of species, distribution in Pakistan and worldwide, ecology, and a list of specimens examined from Pakistan are provided


INTRODUCTION
Thelypteridaceae Ching ex Pic.Serm. is a large family of pteridophytes which is represented by two subfamilies, 37 genera and approximately 1200 species worldwide (PPG I 2016;Fawcett and Smith 2021).Some authors prefer to treat all the species under a broad concept of Thelypteris Schmidel (e.g.POWO; Fraser-Jenkins 2014;Fraser-Jenkins et al. 2016).Members of the Thelypteridaceae range from temperate to tropical regions, achieving greatest diversity in tropical humid forest environments, in both montane and lowland habitats.The foundation of the taxonomy in the family Thelypteridaceae is based on cytological and morphological studies (Ching 1940;Holttum 1982).Within the last two decades, a series of molecular phylogenetic studies have improved our understanding of the evolutionary relationships within the family, enabling taxonomic refinements (Smith and Cranfill 2002;He and Zhang 2012;Rothfels et al. 2012;Almeida et al. 2016;Patel et al. 2019a;Fawcett et al. 202l;Fawcett 2022).The taxonomic treatment here follows the circumscription of the family Thelypteridaceae, which recognizes separate genera (Fawcett and Smith 2021).
Previous studies have included species lists of the Thelypteridaceae of Pakistan, but did not provide detailed descriptions or keys.Stewart (1972) reported seven species from various localities of Pakistan; Fraser-Jenkins (1992;2014) listed all eight known species from Pakistan from specimens collected or seen in herbaria, providing regional distribution for seven of them; Nakaike and Malik (1992;1993) reported six species from Azad Jammu and Kashmir, Abbottabad, Kohistan, Mansehra and Peshawar districts; Iltaf et al. (2012) documented three species from Punjab province, Pakistan; Fraser-Jenkins et al. (2016) listed all the Pakistan species with detailed synonymy and taxonomic comments, also giving their global range.Shah et al. (2019) investigated the spore morphology of five species from Malakand division, Pakistan; Attaullah et al. (2020) reported one species from Utror valley, district Swat, Pakistan.Irfan et al. (2022a) documented the floristic diversity and chorotype analysis of the seven species of Thelypteridaceae in Pakistan.Khullar et al. (2022) documented the detailed taxonomy, habitat, distribution, and specimens examined of sixteen species of Thelypteridaceae from Jammu and Kashmir.Recently Fraser-Jenkins et al. (2023) described and illustrated the detailed specimen-lists of seven species from districts Buner, Swat, and Shangla, in Khyber Pakhtunkhwa province, Pakistan.At the present time, a relatively small proportion of herbarium specimens of Thelypteridaceae from Pakistan have been digitized, which necessitates study of physical herbarium specimens.
The aim of the present study is to provide an account of the Thelypteridaceae in Pakistan, with updated taxonomy, including synonymy, a key to genera and species, detailed morphological descriptions and distributions both within Pakistan, and globally, for the eight known species.

MATERIALS AND METHODS
The present study is based on specimens deposited in the herbaria of Asia, Europe and USA, including BM, CAL, DD, HUP, ICP, ISL, K, KUH, MO, MUZU, NY, PFI, PMNH, RAW, TNS (acronyms according to Thiers 2023).All the images of type specimens were accessed through the JSTOR Global Plants project database (https://plants.jstor.org).Many fern specimens collected from Pakistan, including type specimens at BM, CAL, DD, ISL, K, KUH, PFI, PMNH, NY and RAW were carefully examined.Extensive lists of specimens examined provided by C.R. Fraser-Jenkins have corroborate our findings, and reflect the same patterns of diversity and distribution.Different parameters, including correct name, locality, altitude, habitat, distribution, collector's name, year, voucher specimen-number and herbarium acronym were documented.Descriptions of the species are based on morphological and taxonomic characters of specimens examined from Pakistan.Definition of terms follows the glossary by Lellinger (2002).Distribution data for Pakistan is based on specimens deposited at the above herbaria.(Retz.) Copel., Gen. Fil. 144. 1947;Stewart (1957Stewart ( , 1972)); Nakaike and Malik (1993); Haq et al. (2022); Irfan et al. (2022a, b) Fig. 1 A-D

Distribution and ecology. Christella multiauriculata
Punetha is terrestrial on banks of water courses at an elevation of 1000-2000 m, found rarely, and distributed in Asia (Bangladesh, India, Nepal, and Pakistan).Initially considered a synonym of Christella dentata by Fraser-Jenkins (2008), he later recognized it as a distinct species (Fraser-Jenkins et al. 2016).This species is characterized by most fronds tapering downwards towards the stipe; lamina beneath with rather dense distinctive stalked white glands; veinlets pale, well raised beneath; veinlets varying from 1.5-2.5 pairs anastomosing below the sinus.
Distribution and ecology.Menisciopsis penangiana (Hook.)S.E.Fawc.& A.R.Sm. is terrestrial in mountains in moist temperate forests at an elevation of 1000-2000 m found infrequently, and is distributed in Asia (Bhutan, China, India, Myanmar, Nepal and Pakistan).This species has been treated in Pronephrium, however, phylogenetic data have shown that it is distantly related to Pronephrium s.s.(Fawcett et al. 2021).
Distribution and ecology.Phegopteris connectilis (Michx.)Watt is terrestrial near streams among bushes at an elevation of 1400-2000 m found infrequently, and distributed in Asia (Bhutan, China, Georgia, Japan, Nepal, Pakistan, Russia, and Turkey); Europe (widespread); and North America (Canada and USA).We follow Fraser-Jenkins et al. (2016), in recognizing Phegopteris connectilis, however, it is possible that the plants in Pakistan are more closely related to Phegopteris tibetica Ching than they are to the Canadian type of Phegopteris connectilis.Phegopteris tibetica is poorly characterized, and no material was available for study.Study of the Phegopteris connectilis complex has revealed cytological and taxonomic complexity in the group (Matsumoto 1982;Patel et al. 2019b), and further study of this widespread complex is needed.Description.Plants 48-60 cm tall, rhizome long creeping, horizontal to suberect, hairy and scaly; fronds remote, stipe stramineous, hairy; leaves monomorphic, dying back in winter, clustered, laminae herbaceous, green, drying dark green, abaxially hairy, pinnatepinnatifid, lanceolate, oblong, base slightly tapering, acuminate at apex; rachis diameter 2 mm, hairy, brownish; pinnae 6.5 × 1.4 cm, opposite, sessile, proximal pinnae smallest, lanceolate to triangular; veins hairy visible on both surfaces, lateral veins may be simple or forked.Sori round, submarginal, suborbicular, 3-7 pairs per pinnule, borne on middle of ultimate veins, indusiate, indusia yellow-reddish and hairy, sporangia having 1-3 hairs below annulus, spores monolete and elliptic.

DISCUSSION
The Thelypteridaceae in the flora of Pakistan are predominantly of South East Asian and Sino Himalayan affinity, but also shares elements with Africa (e.g., Ampelopteris prolifera) and hosts a southern extension of a circumboreal taxon (Phegopteris connectilis).The diverse and varied climates of Pakistan host 168 taxa of lycophytes and ferns (Fraser-Jenkins 2014;Irfan et al. 2022a), many of these adapted to arid environments.The Thelypteridaceae tends to be most diverse in humid, tropical montane areas, and its occurrence in Pakistan is limited to eight species, which correspond to those recognized in earlier studies (Stewart 1945(Stewart , 1957(Stewart , 1967(Stewart , 1972(Stewart , 1982;;Fraser-Jenkins 1992, 2014).The species in Pakistan were previously collected by well known botanists mainly from the Himalayan range in Azad Jammu and Kashmir, Hazara and Malakand division, while some localities are still not explored.Fewer species occur in the Hindu-Kush and Karakorum ranges due to relatively low precipitation.Some interesting pteridophyte rich localities in Pakistan are Sharan Forest, Kagan valley, Saiful-Maluk Lake, Neelam valley, Kalam valley, Malam Jaba, Murree hills, Shahi and Binshahi, Hunza valley, Bara Gali, Nathiya Gali, Donga Gali, Meranjani, Gadoon valley and Shangla pass.Four species are shared with the Sino-Himalayan region, while two species have S.E.Asian affinities, and two species are cosmopolitan.
Most of these species are widespread, and their populations are globally stable, and not of conservation concern.Five species are collected infrequently, but Glaphyropteridopsis erubescens is common, and Christella dentata is abundant.In contrast, Christella multiauriculata is rare and localized, and may be of conservation concern.The lack of digitized specimens from Pakistan has made it a challenging group to study.For example, only three specimens of Thelypteridaceae from Pakistan were available in GBIF as of Oct. 24, 2022, necessitating visits to herbaria to examine specimens in person.Our hope is that providing a key, detailed description of species and fine-scale distribution records will facilitate exploration and discovery of biodiversity in Pakistan.