Taxonomic checklist of the pteridophytes of Rajkandi Reserve Forest , Moulvibazar , Bangladesh

Pteridophytes growing in the Rajkandi Reserve Forest of Moulvibazar district were indentified and a total of 52 species belonging to 30 genera of 20 families have been documented. The family Pteridaceae with nine species was found to be the largest, which was followed by Polypodiaceae with seven, Tectariaceae with six and Thelypteridaceae with five species. The genus Pteris with six species was found as the largest, which was followed by Tectaria with five and Bolbitis, Lygodium and Selaginella, each with 3 species, and the rest of the genera consisted of two or one species. Most of the species were recorded from the woodlands and three species, viz., Tectaria chattagramica and Cyathea gigantea enlisted in Red Data Book of Bangladesh (Khan et al., 2001), were found as common in this reserve forest.


INTRODUCTION
Pteridophytes are an important component of the flora, biodiversity, natural habitats and ecosystems of many areas.A good number of species of this plant group are used as ornamentals and medicinals (Nayar, 1957;Benerjee and Sen, 1980;Dhiman, 1998;Dixit, 1974Dixit, & 1975;;Hodge, 1973;Kaushik, 1998;Singh, et al., 1989).Many pteridophytes occurring in Bangladesh are also reported as ethno-medicinally useful (Uddin, et al., 1998;Uddin, et al., 2008;Sarker and Hossain, 2009).However, the pteridophytes of this country have not yet been fully assessed and their status is not yet clear.This plant group has been excluded from most of the floristic studies conducted in Bangladesh and still demand attention for their taxonomic documentation.Prain (1903) was the first who enumerated 98 species of fern from the then East Bengal including the present political boundary of Bangladesh.The report of Prain (1903) did not provide data on the species composition and exact distribution of the pteridophytes in particular areas and forests.In last eleven decades, the nomenclature and taxonomic position of many pteridophytic taxa have also been changed.After the independence of Bangladesh, a very few studies on pteridophytic flora have been done (e.g., Pasha and Mallick, 1980;Pasha and Chakraborty, 1984;Pasha, 1985;Mirza and Rahman, 1997;Uddin and Pasha, 1997;Uddin, 2001;Uddin et al., 2001;Uddin and Hassan, 2012).Recently, Siddiqui et al. (2007) compiled 195 species of pteridophytes from Bangladesh.Most of these works were based mainly on survey of available literatures and examination of deposited voucher specimens at different herbaria.Recently, Hossain et al. (2015) have published a checklist of the pteridophytes of Bangladesh Sunderbans.Information on species composition and diversity of the pteridophytes of most of the areas of this country, especially of the protected areas, are still lacking.Therefore, there is a great scope and need for exploring this plant group in their natural habitats of Bangladesh.
The Rajkandi forest, composed of ca.2450 hectares of land, is one of the tropical semievergreen forests of this country which falls within the Indo-Burma hot-spot of biodiversity.The Reserve Forest of Rajkandi was declared as a protected area in 1915 by the government of British India.This forest is currently being maintained under the three beats, namely Adampur, Kamarchara and Kurma beats of Rajkandi Forest Range of Sylhet Forest Division (Sayma et al., 2009).The topography of Rajkandi Reserve Forest is undulating with slopes and hillocks that range from 10 to 50 m in elevation (Rizvi, 1970).The hills are generally low and gently sloping, dissected by numerous valleys, separated by ridges and rising some 50 m above them (Anon, 2006).These hillocks are scattered and interspersed with numerous streams flowing through the forest that form a scenic topography of Rajkandi Forest.Soil of this forest area ranges from clay loam to pale brown, is acidic (pH 5.0) in nature and clay loams in the hills (Anon, 2006).The Rajkandi Reserve Forest seems to harbor a rich flora, species diversity and enormous genetic resources in its diverse habitats and ecosystems, but this forest is not yet explored floristically.Hence, the floristic study of the pteridophytes extant in Rajkandi reserve forests was carried out as the first step in generating the base-line taxonomic information on the pteridophytic flora of this forest for helping the sustainable conservation and management activities there.

MATERIALS AND METHODS
The Rajkandi Reserve Forest, one of the protected areas of Bangladesh lying between the 24º12´-24º17´N and 91º51´-91º55´E, is situated in northeast area of Kamalganj upazilla which is located in the southern part of Moulvibazar district.The tropical monsoon prevails in the area with average annual rainfall of 3931 mm (BBS/UNDP, 2005) and 90% of the total rainfall occurs in the period between June-September.The average maximum temperature of the study area is 30.7ºCduring May to July, whereas, the average minimum temperature is 30.7ºCduring November to March (BBS/UNDP, 2005).The mean relative humidity is rather high and usually remains between 69-95% throughout the year (Anonymous, 1986).Soil of Rajkandi forest area ranges from clay loam to pale brown, is acidic (pH 5.0) in nature and clay loams in the hills (Anonymous, 2006).Standard herbarium methods and techniques were followed (e.g., Jain and Rao., 1977;Hyland, 1972) in collection, processing, drying and preservation of plant specimens.The representative herbarium specimens were examined at the Bangladesh National Herbarium (DACB), Dhaka University Salar Khan Herbarium (DUSH) and Jahangirnagar University Herbarium (JUH).The specimens were identified by consulting Clarke (1880), Holttum (1968Holttum ( , 1991)), Siddiqui et al. (2007) and Smitinand and Larsen (1975;1989).The relevant type images of pteridophytes available in the web pages of different international herbaria (e.g., K, BM, P) were also matched.The voucher specimens have been preserved at DACB and JUH.Nomenclatural information of each taxon was verified following Flora of China (1995China ( -2013) ) and the nomenclatural data bases of IPNI ( 2008) and TROPICOS (2010).The families have been arranged according to the classification system of Pichi (1977).The genera and species under each family have been arranged alphabetically.The valid name of each taxon is mentioned with full original citation, followed by the basionym and synonym/s (if available).

RESULTS AND DISCUSSION
A total of 53 species belonging to 30 genera of 20 families of pteridophytes have been found in Rajkandi Reserve Forest.Considering Siddiqui et al. (2007), the Rajkandi Reserve Forest harbors 26.66 percent of the pteridophyte species of Bangladesh and hence, it can be concluded that this reserve forest is an important area for harboring the pteridophytes of this country.In respect to the size of land area, the species composition of the pteridohytes of Rajkandi Reserve Forest seems higher than that of few other protected areas of Bangladesh.For example, 41 fern species were recorded from Rampahar and Sitapahar (Uddin and Hassan, 2012) and 24 species from Sundarbans (Rahman et al., 2016).Two species of pteridophytes occurring in Rajkandi Reserve Forest, viz., Cyathea gigantea, and Tectaria chattagramica, have been enlisted as LR (cd)-(Lower risk, conservation dependent) and DD (Data deficient) respectively in Red Data Book by Khan et al. (2001).But these been commonly found in this reserve forest with normal natural regeneration.
Throughout the forests of Rajkandi, woodlands were found as the most common habitats that harbored a total of 25 species, which was followed by stream bank harboring 13 species, the scrub jungles nine species, grass land five species, valley four species, marginal lands three species and aquatic habitat two species.It indicates that the pteridophytic species of the study area were variable in preferring their habitats.In Rajkandi Reserve Forests, most of the natural habitats were found to be disturbed in different extents, mainly due to various anthropogenic activities and weak forest management.As the pteridophytes are very susceptible to habitat disturbances, therefore, their natural habitats should be conserved through the effective and sustainable conservation programs.
authorities of the following herbaria for allowing consulting their libraries and using their herbarium materials, viz.Bangladesh National Herbarium (DACB) and Dhaka University Salar Khan Herbarium.

Fig. 1 .
Fig. 1.Map showing the location of Rajkandi forest range in Kamalganj, Moulvibazar, Bangladesh This study was based on a thorough taxonomic inventory comprised of 25 field trips conducted in different seasons of 2010-2015 throughout the Rajkandi Reserve Forest.Standard herbarium methods and techniques were followed (e.g.,Jain and Rao., 1977;Hyland, 1972) in collection, processing, drying and preservation of plant specimens.The representative herbarium specimens were examined at the Bangladesh National Herbarium (DACB), Dhaka University Salar Khan Herbarium (DUSH) and Jahangirnagar University Herbarium (JUH).The specimens were identified by consulting Clarke (1880),Holttum (1968Holttum ( , 1991)),Siddiqui et al. (2007)  andSmitinand and Larsen (1975; 1989).The relevant type images of pteridophytes available in the web pages of different international herbaria (e.g., K, BM, P) were also matched.The voucher specimens have been preserved at DACB and JUH.Nomenclatural information of each taxon was verified following Flora ofChina (1995China ( -2013) )  and the nomenclatural data bases of IPNI (2008) and TROPICOS (2010).The families have been arranged according to the classification system ofPichi (1977).The genera and species under each family have been arranged Mirza and Rahman (1997)-date nomenclature, plant habit, ecology and the examined representative specimens collected from different forest beats of Rajkandi forest range, Kamalganj, Moulvibazar has been mentioned below.Marselia aegyptica wall.(1829).Terrestrial herb, rhizomes creeping.In rice fields, ditches.In Bangladesh it occurs in cox's Bazar, Dhaka, Rajshahi, Rangpur and Manikganj.Representative specimen: Adampur, 30 Jun 2015, Kamrul 2261 (JUH).Marsilea quadrifolia L. Sp.Pl.2: 1099-1100 (1753).Marselia europa Desv.(1827).Terrestrial herb, rhizomes creeping.In rice fields; on moist soil.In Bangladesh it occurs throughout the country.Representative specimen: Adampur, 30 Jun 2015, Kamrul 2260 (JUH); M.A. Rahim, 2603 (JUH).Among the total 52 pteridophyte species recorded from Rajkandi Resrve Forest, 50 were found in Adampur beat, which was followed by 27 and 18 species, respectively in Kurma and Kamarchara beat and 17 species were commonly found in these three beats.These data indicate that the Adampur beat harbors most of the pteridophytes of Rajkandi forest range.A total of 46 species were found as terrestrial.Only five species were epiphytic and two species were aquatic.The family Pteridaceae with nine species, Polipodiaceae with seven, Tectariaceae with six and Thelypteridaceae with five species constitute 51.92% of total fern flora of the area, whereas, remaining sixteen families constitute 48.08%.Pteris with six species was found as the largest genus, which was followed by Tectaria with five and Bolbitis, Lygodium and Selginella, each with 3 species.The rest of the genera were consisted of two or one species each.Uddin and Pasha (1997)recorded 16 fern allies,Mirza and Rahman (1997)listed 161 species of fern and fern allies andSiddiqui et al. (2007)compiled 195 species of pteridophytes from Bangladesh.