FOUR NEW VARIETIES OF THE FAMILY ARACEAE FROM BANGLADESH

Four new varieties belonging to four species and three genera of the family Araceae are being described and illustrated from Bangladesh. The new varieties are: Colocasia fallax Schott var. purpurea H. Ara & M.A. Hassan , Colocasia oresbia A. Hay var. stolonifera H. Ara & M.A. Hassan , Rhaphidophora calophyllum Schott var. violaceus H. Ara & M.A. Hassan and Typhonium trilobatum (L.) Schott var. fulvus H. Ara & M.A. Hassan. The morphological diagnostic characters of each new variety and comparison with its closest one are provided. Detailed taxonomic description along with other relevant information are provided for easy recognition of the new aroid taxa.


Introduction
The family Araceae de Juss. is represented by 3,645 species globally under 144 genera (Boyce and Croat, 2011). In Bangladesh, the family consists of 27 genera and 109 species of which 81 species are wild and 29 are cultivated (Ara, 2016).
For revisionary work on the monocot family Araceae of Bangladesh the first author has made an extensive field survey throughout the country since 1988 and collected a good number of specimens. While examining the specimens, we came across some characteristically interesting unidentified specimens closest to Colocasia fallax Schott, C. oresbia A. Hay and Typhonium trilobatum (L.) Schott which were collected from different forests and homestead areas of Bangladesh. Moreover, some specimens of Rhaphidophora Hassk. collected from different forest areas of Moulvibazar district were found to be closest to R. calophyllum Schott. But differs from a number of characters. The flowering and fruiting samples of these specimens were preserved for identification in Bangladesh National Herbarium (DACB), Dhaka. The rhizomes of these specimens were also grown in the garden of Bangladesh National Herbarium (BNH), Dhaka; First author's rooftop garden at Khilgaon, Dhaka and in the Botanical Garden of the University of Dhaka. These interesting specimens were later critically examined and compared with the identified specimens of Colocasia fallax Schott, C. oresbia A. Hay, Rhaphidophora calophyllum Schott and Typhonium trilobatum (L.) Schott available at BK, BKF, BM, CAL, DACB, K, DUSH (Dhaka University Salar Khan Herbarium), HCU (Herbarium of Chittagong University), BCSIRH (Herbarium, Bangladesh Council for Scientific and Industrial Research) and BFRIH (Herbarium, Bangladesh Forest Research Institute). Besides, consultation of relevant literature (Wallich, 1829(Wallich, -1849Roxburgh, 1832;Wight, 1843Wight, -1845Hooker, 1893;Jackson, 1893Jackson, -1955Prain, 1903;Engler andKrause 1908, 1920;Engler, 1920;Heinig, 1925;Hu, 1968;Rao and Verma, 1976;Nicolson, 1976Nicolson, , 1979Nicolson, , 1987Nasir, 1978;Nicolson and Sivadasan, 1981;Mayo, 1985;Karthikeyan et al., 1989;Hay, 1993Hay, , 1996Noltie, 1994;Sriboonma et al., 1994;Sookchaloem, 1995;Liu and Huang, 1996;Mayo et al., 1997;Toha, 2000;Hetterscheid and Boyce, 2000;Wang et al., 2002;Warasy and Alam 2009;Heng et al., 2010)  The major morphological and cytological differences between two varieties of Colocasia fallax Schott are outlined in Table 1. A. Hassan differs from its closely related variety Colocasia oresbia A. Hay var. oresbia by its tuber character (up to 7.0 cm long and 4 cm in diameter); presence of white small stolon; leaf shape ovate-sagittate (up to 52 cm long and 36 cm in diameter); number of inflorescence in groups of up to 3 and male zone c. 5.5 cm long.
Flowering and fruiting period: August to October. Ecology: Grows on the hill slopes as under growth.  The major morphological differences between two taxa of Colocasia oresbia A. Hay are outlined in Table 2. A. Hassan differs from its closely related Rhaphidophora calophyllum Schott var. calophyllum by the length of petiole (3.5-6.0 cm) and peduncle (8.5-20 cm long); length and colour of the spathe blade that is 5.5 cm long and the colour is dark violet (outside) and light creamy pinkish (inside) and length of the spadix is 3.5-4.0 cm.
Flowering and fruiting period: April-September. Ecology: Subtropical and tropical rain forests. Distribution: North-Eastern part of Bangladesh, Moulvibazar district (within greater Sylhet).
Etymology: The variety is named after violet colour of its spathe.  The major morphological differences between two varieties of Rhaphidophora Hasskarl. are outlined in Table 3.  Bengali name: Ban kachu. Perennial herb, tuber c. 5 cm long, c. 4 cm in diameter. Petiole 15-55 cm long, c. 0.8 cm in diameter, green. Leaf paired, blade usually deeply trilobed, anterior lobe ovate-lanceolate, to c. 18.0 cm long, c. 9.5 cm in diameter, posterior lobe c. 18 cm long, c. 8 cm in diameter, green. Inflorescence paired. Peduncle c. 4 cm long, c. 1 cm diameter, green. Spathe c. 17 cm long, tube and blade separated by a strong constriction; tube c. 3 cm long, outside green, inside light green; blade c. 14 cm long, c. 8 cm in diameter at the middle, outside dark green, inside light purple, tip of the spathe twisted up to 4 cm. Spadix shorter than spathe, c. 11 cm long; female zone c. 1 cm long, c. 1 cm in diameter, flowers congested; sterile zone between female and male zone 2.3-2.5 cm long, the lower 0.8-1.0 cm densely covered with staminodes, the remainder naked, cream colour, longitudinally grooved; male zone cylindrical, c. 1.6 cm long, c. 1.0 cm in diameter; base and top oblique, flowers congested; appendix very shortly stipitate, stipe c. 1 mm long, elongate conical, c. 6.5 cm long, c. 1.3 cm in diameter at the base, pale purple, top acute, base crenulate or multifurcate, producing a strong unpleasant smell at female anthesis. Ovaries cylindrical, c. 1 mm long, c. 1 mm in diameter, yellowish green, unilocular, with one basal ovule; stigma sessile, large, discoid, with a central depression, 0.8 mm in diameter, 0.2 mm long, densely shortly papillose, light yellowish cream. Staminode filiform, c. 1.5 cm long, c 0.3 mm in diameter, creamy white or light yellowish, curled.
Flowering and fruiting period: April-November. Chromosome number: 2n = 18 (Warasy and Alam, 2009 Etymology: The variety is named after light yellowish cream colour of its stigma.  The major morphological and cytological differences between two taxa of Typhonium trilobatum (L.) Schott are outlined in Table 4.

Conservation status:
The new variety is located in a single locality in the wild and therefore, the status of this new variety is EN (Endangered) (IUCN, 2017).