SOME FRESHWATER PHYTOPLANKTON AS NEW REPORTS AND ONE NEW FORMA FROM BANGLADESH

Eight newly recorded taxa of freshwater phytoplankton from Bangladesh have been described in the present paper. Of these, 3 species are from Cryptomonadales, 2 species from each of Volvocales and Euglenales and one species from Chromulinales. In addition one new forma of Pediastrum duplex Meyen var. duplex fa. nagdaensis M.A. Alfasane, M.S. Islam & M. Khondker fa. nov. (Chlorococcales) has also been described in this account. Introduction Recently a series of papers have been published where many taxa from different classes have been described and illustrated (Khondker et al., 2007a, b, c; 2008a, b; 2009). During the present study on some recent collections from different parts of the country planktonic algae of different orders have been found to occur which, could not be recorded earlier from the areas selected or any other parts of Bangladesh. So these could be considered as new records for Bangladesh. The recorded species belonged to the genera Chlamydomonas and Pyramidomonas under Volvocales, two taxa of Trachelomonas under Euglenales, Epicystis under Chromulinales and the rest three belonged to Chroomonas, Rhodomonas and Cryptomonas under Cryptomonadales. Pediastrum duplex var. duplex fa. nagdaensis M.A. Alfasane, M.S. Islam & M. Khondker fa. nov. under Chlorococcales is described as new to science. Materials and Methods Samples for the present paper were collected from 4 different places in Bangladesh. One of them is Buriganga River (near to Sikdar Medical College, Hazaribagh), Dhaka metropolis. In this place, the sampling station (Station 1) is located in the mid-part of the river. The second one is a polluted ditch of village Nagda, Narayanganj. Two other sampling stations are located in two domestic ponds of Pirojpur and Barisal districts (Khondker et al. 2006). Samples were obtained by sieving 100 L of sub-surface water through a plankton net having a mesh aperture of 20 μm. The concentrated plankton sample in the bucket of the plankton net were taken in a screw caped glass vial and fixed with Lugol's solution. Corresponding author. E-mail: mujaddade@yahoo.com Ansar Academy, Shafipur, Gazipur, Bangladesh.


Introduction
Recently a series of papers have been published where many taxa from different classes have been described and illustrated (Khondker et al., 2007a, b, c;2008a, b;2009).During the present study on some recent collections from different parts of the country planktonic algae of different orders have been found to occur which, could not be recorded earlier from the areas selected or any other parts of Bangladesh.So these could be considered as new records for Bangladesh.The recorded species belonged to the genera Chlamydomonas and Pyramidomonas under Volvocales, two taxa of Trachelomonas under Euglenales, Epicystis under Chromulinales and the rest three belonged to Chroomonas, Rhodomonas and Cryptomonas under Cryptomonadales.Pediastrum duplex var.duplex fa.nagdaensis M.A. Alfasane, M.S. Islam & M. Khondker fa.nov.under Chlorococcales is described as new to science.

Materials and Methods
Samples for the present paper were collected from 4 different places in Bangladesh.One of them is Buriganga River (near to Sikdar Medical College, Hazaribagh), Dhaka metropolis.In this place, the sampling station (Station 1) is located in the mid-part of the river.The second one is a polluted ditch of village Nagda, Narayanganj.Two other sampling stations are located in two domestic ponds of Pirojpur and Barisal districts (Khondker et al. 2006).
Samples were obtained by sieving 100 L of sub-surface water through a plankton net having a mesh aperture of 20 µm.The concentrated plankton sample in the bucket of the plankton net were taken in a screw caped glass vial and fixed with Lugol's solution.
Organisms were photomicrographed with the help of a Nikon Optiphot, UFX-11A microscope fitted with a Nikon FX-35WA camera, Japan.

Taxonomic enumeration
A total of eight taxa of freshwater phytoplankton have been identified as new reports for Bangladesh and one taxa has been described as new to science.The illustrated taxonomic descriptions of these taxa are given below.and O. Ettl] (Fig. 1) (Huber-Pestalozzi, 1961, 159, 28: 139;Dillard, 1989, 16  Notes: This new forma differs from the typical by being smaller in colony diameter and length-breadth ratio of central and peripheral cells.In the type, peripheral cell length 1.42 times more than breadth, in the central cells it is nearly double (Huber-Pestalozzi, 1983).In this new forma, length and breadth ratio of both peripheral and central cells are 1.07 and 0.83, respectively.
Type locality: The sample was collected from a polluted ditch located in the village Nagda, Narayanganj, Bangladesh, Z max = 1.7 m, A = 1600 m 2 .The ditch receives effluents from the nearby industries.