Wedelia trilobata (L Bangladesh J. Plant Taxon. 17(1): 109-111, 2010 (June) - Short communication © 2010 Bangladesh Association of Plant Taxonomists MICRASTERIAS TORREYI BAIL. VAR. NURULISLAMII AZIZ VAR. NOV. (CHLOROPHYCEAE) FROM BANGLADESH ABDUL AZIZ Department of Botany, University of Dhaka, Dhaka 1000, Bangladesh Keywords: Micrasterias torreyi Bail. var. nurulislamii Aziz var. nov.; Desmid; Green alga; Bangladesh. Substantial works have been carried out on desmids of Bangladesh (Islam, 1970; Islam and Haroon, 1980; Islam and Begum, 2004; Islam and Irfanullah, 2006). These include 51 species of Micrasterias Ag. in addition to many species and varieties of different genera (Ahmed et al., 2008). Of the reported species of Micrasterias, 18 species, 22 varieties and 11 forma are new to science. The author came across a taxon of Micrasterias collected from a freshwater body which showed similarities and dissimilarities with M. doveri Biswas var. curvata (Krieger) Thomasson 1960, M. rotata (Grev.) Ralfs ex Ralfs and M. torreyi Bail. var. sachlanii Scott et Prescott 1961. Thorough studies revealed some characteristics which are unique and thus described as a new variety of M. torreyi Bail. in this paper. Class: Chlorophyceae; Order: Zygnematales; Family: Desmidaceae Micrasterias torreyi Bail. var. nurulislamii* Aziz var. nov. (Figs. 1&2) Cellulae quasi ovalis, 280-310 µm longa, 210-220 µm latus ad isthmus, longitude- latitudo rationes 1.33-1.41. Semicellula cum 26 lobulis, lobus axiales columnararis, 95- 100 µm longa, fere 47 µm latus ad basim, 35 µm proximus apicem. Chloroplasto lobus ad parietilobulis aptum, uni in quoque semicellula; pyrenoids 10-12 in quoque chloroplasto. Cellula parieti subtiliter verrucatus omnino. Cells oval, 280-310 µm long, 210-220 µm broad giving length-breadth ratio that varied from 1.33 to 1.41, with deep isthmus (31 µm). Each semicell heavily incised, lateral lobes divided into six lobes of order III, which is further divided into 12 lobules of order IV with two spines in each. Thus, there are 26 lobules in each semicell. Basal half portion of each lobe near the isthmus is parallel to the transverse axis, while others are radial to slightly convergent to poles. Axial lobes 95-100 µm long, columnar, about 47 µm broad at the base, 35 µm broad near the tip giving the length-breadth ratio that varied from 2.11 to 2.33. Cell wall with fine warts all through. Chloroplast single in each semicell and lobed with 10-12 pyrenoids. Each lobe of the chloroplast corresponds to one lobe of the semicell. *The verietal epithet has been chosen after National Professor Dr. A.K.M. Nurul Islam who worked a lot on desmids and a pioneer on algal taxonomic researches in Bangladesh. 110 AZIZ Locality: Ati-panchdana Beel, Dhaka, 15 Janurary 1998. Holotype: Photomicrographs, Figs. 1-2. Note: The present material resembles Micrasterias torreyi var. sachlanii Scott and Prescott 1961 by having 26 lobules in each semicell and curvature of lobules but in the present organism length-breadth ratio of the axial lobe is much lower (2.11-2.33) giving a robust nature and that it does not project so much beyond the adjacent lobules. Islam and Haroon (1980) described a new var. dacchense of Micrasterias torreyi (by mistake the name M. doveri var. dacchense was given; personal communication National Prof. A.K.M. Nurul Islam). The new var. dacchense Islam et Haroon differs from the type by having two supra-isthmal median processes in each semicell. The present material resembles M. doveri var. curvata (Ling and Tyler, 2000) by 1.32 length-breadth ratio of cells and slightly by curvature of lobules, but the number of lobules is only 18 and axial lobes are more or less uniform in diameter from base to apex. M. rotata (Grev.) Ralfs ex Ralfs resembles the present material by having 26 lobules in each semicell and warted cell wall, but differs by cell shape, convergence of lobules and the shape of axial lobes (Růžička, 1981). However, in M. torreyi var. sachlanii, cell wall is without warts, base of the axial lobes are as wide as the tip giving length-breadth ratio that varied from 3.22 to 4.00. On the other hand, in the present organism cell wall is with warts, the axial lobes are much wider at the base appearing columnar, length-breadth ratio varied from 2.11 to 2.33 and supra-isthmal median processes are absent, the features distinct enough to consider it as the new variety under Micrasterias torreyi Bail. Figs. 1 & 2. Micrasterias torreyi Bail. var. nurulislamii Aziz var. nov. 1. a cell; 2. a semicell enlarged, warts present on cell wall. Inset in the upper left is a part of the lobe enlarged showing warts. Bars = 30 µm. MICRASTERIAS TORREYI VAR. NURULISLAMII VAR. NOV. 111 Acknowledgement Sincere gratitude is due to Prof. Syed Hadiuzzaman, Department of Botany, University of Dhaka, for Latin diagnosis of the taxon. References Ahmed, Z.U., Begum, Z.N.T., Hassan, M.A., Khondker, M., Kabir, S.M.H., Ahmad, M., Ahmed, A.T.A., Rahman, A.K.A. and Haque, E.U. (eds.) 2008. Encyclopedia of flora and fauna of Bangladesh. Vol. 3. Algae, Chlorophyta (Aphanochaetaceae-Zygnemataceae). Asiat. Soc. Bangladesh, Dhaka. 812 pp. Islam, A.K.M. Nurul. 1970. Contributions to the knowledge of desmids of East Pakistan. Part 1. Nova Hedwigia 20: 903-983. Islam, A.K.M. Nurul and Begum, A. 2004. Desmids from some selected areas of Bangladesh. I. Genus Micrasterias Ag. Bangladesh J. Plant Taxon. 11(2): 1-14. Islam, A.K.M. Nurul and Haroon, A.K.Y. 1980. Desmids of Bangladesh. Part 1. Nova Hedwigia 65(4): 551-604. Islam, A.K.M. Nurul and Irfanullah, H.M. 2006. Hydrobiological studies within the tea gardens at Srimangal, Bangladesh. V. Desmids (Euastrum, Micrasterias, Actinastrum and Cosmarium). Bangladesh J. Plant Taxon. 13(1): 1-20. Ling, H.U. and Tyler, P.A. 2000. Australian freshwater algae (exclusion of diatoms). Bibliotheca Phycologica 105: 1-643. Růžička, J. 1981. Die Desmidiaceen Mitteleuropas. Band 1, Lieferung 2. E. Schweizerbart’sche Verlagsbuchhandlung, Stuttgart. pp. 293-736 + Tafel 73. Scott, A.M. and Prescott, G.W. 1961. Indonesian desmids. Hydrobiologia 17: 1-132. Thomasson, K. 1960. Some planktonic Staurastra from New Zealand. Bot. Notiser 113: 225-245. (Manuscript received on 6 May 2010; revised on 22 May 2010)