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Desmids from Some Selected Areas of Bangladesh: 3. Genus Staurastrum Meyen (2)

A.K.M. Nurul Islam
Department of Botany, University of Dhaka, Dhaka-1000, Bangladesh

Nasima Akter
Department of Botany, University of Dhaka, Dhaka-1000, Bangladesh

Abstract/ Executive Summary:

The paper deals with 13 taxa belonging to Desmid genus Staurastrum Meyen from some selected areas of Bangladesh. Of these, eight taxa are new records for Bangladesh and two taxa are new to science.

Keywords: Desmids, Staurastrum, Bangladesh

Location: Kaliganj Railway station, Gazipur district, Bangladesh

Start Date: 00-01-1989

End Date: 00-12-1989

Program Area: Conservation and Biodiversity

Commodity: Algae

Objectives:

To identify the Desmids from some selected areas of Bangladesh: 3. Genus Staurastrum Meyen (2)

Methodology:

Staurastrum excavatum West & West var. spinosum Islam and Akter var. nov. Cell medium-small, with distinct notch-like median constriction; broader than long; cell length without process 11.5 µm; mid-diam. without processes 10.3 µm, with processes 37-54 µm; isthmus 5.2 µm; differs from the typical by its shorter length and greater breadth, and with one large spine at the basal angles of each semicell; additional spines are present on the cell wall and the processes are relatively longer; top view is somewhat twisted; apex with distinct depression. Specimen studied: Collection No. KG2, Collected from a ditch near the Kaliganj Railway station, Gazipur district, on 12 September 1989. Cellulis medio-parvus, cum mediano incisura distinctus; aspectus apicalis aliquantum tortus; membrana cellulis spinosus; apicalis cum dipressio distinctus; cellulis sine processibus 11.5 µ m longis; medio-diam. sine processibus 10.3 µ m, cum processibus 37-54 µ m; isthmus 5.2 µ m; varieties a typo divergens a longitudo brevis; diametro latus, et unus spina ad angulis basalis et semicellulis; membrana cellulis spinosus. *St. indentatum West and west fa. minus Scott & Prescott. In cell shape and ornament this form is similar to the typical form, but is much smaller and with shorter processes; cell length 34-37 µm; mid-diam at base without processes 17.1 µm; with processes 59-62.5 µm; isthmus 5.7-7.1 µm; a form with two large spines at the apex of the semicell; arms more or less horizontal. Specimens studied: Collection No.KG3, from a rice-field near the Kaliganj Railway station, district Gazipur; collected on 4 November, 1989; common in the collection. St. leptocladum var. cornutum West & West Cell L. without spines 36.9 µm; L. with processes 38.8 µm; mid-diam without processes 17.1 µm, with processes 82.4 µm; isthmus 7.1 µm; the process are horizontally elongted; dentatum at the base of each semicell present. Specimen studied: Collection No. KG2, from a rice-field near the Kaliganj Railway station, Gazipur district, on 12 September 1989. *St. leptocladum Nordst., var. smithii Grönblad. In shape and size it fits well with this variety as shown by Förster (1969, Pl. 38: 1) from Brazil. His illustrations of the same taxon in 1974 are little different; cell length without spine 39.8 µm; mid diam. without processes 17.1 µm, and with processes 85.2 µm; isthmus 5.7 µm broad. Specimen studied: Collection No. KG3, from a rice-field near Kaliganj Railway station on 4 November, 1989. *St. pinnatum Tumer var. simplex Turner. Cell small, broader than long; cell length with spines 30 µm; mid-diam. without process 20.5 µm, with process 47.5 µm; isthmus 11.5 µm; it is somewhat smaller than the typical. Specimen studied: Collected from a ditch near Kaliganj Railway station, Gazipur district, on 14 August 1989; common in the collection. *Staurastrum subjavanicum Islam and Akter sp. nov. Cell medium-large, broader than long, with prominent depression/incision at middle; each semicell with 3-radating arms/processes, apical 2 horizontal and the third process developed from almost the mid-region of the semicell, straight but twisted at the base; process margins serrated; apical margin with bifurcated spines, 2 bigger spines one at each apical corner and 4 small spines in between; at the apex; top view triangular with asymmetric arrangement of the central arm; cell length with spines 57 µm; mid-diam. without processes 25.5 µm; with processes 96.5 µm; isthmus 14.2 µm broad; bifurcated spines are present at the base of each arm/process. Staurastrum subjavanicum Islam and Akter sp. nov. Cellulis medio-grandis, latus quam longior, medianus incisura/depressus nonprofundus; semicellulis cum triprocessus, 2-apicalis horizontalis, tertius irregularis, basalis tortus; marginem processus serratis; marginem apicalis cum medio spinis bifidus ad centralis, et unus spina in quoque angulis apicalis; cellulis 57 µ m longis cum spinis; medio-diam. sine processes 25.5 mm, cum processus 96.5 µ m; isthmus 14.2 µ m latus; bifid spinis in quoque basalis ad processus. *St. tetracerum Ralfs. Cell length without processes 8.9 µm; mid-diam. without processes 7.7 µm, with processes 19.2 µm; isthmus 3.8 µm; in shape and size it is similar to Sierra Leone material shown by Gönblad et al. (1968).

Source of Information: Bangladesh J. Plant Taxon. 13(1): 41-47, 2006 (June)

Article Link (Online Journal):

Funding Source:

Budget:

Total Budget (Tk.) :

Achievement/Findings:

The latter paper dealt with the genus Staurastrum Meyen, in which 30 taxa belonging to it have been described. In the present instalment further addition of 13 taxa belonging to the same genus, not included in the previous paper, have been made. Of these taxa included here, eight taxa are new records for Bangladesh and two taxa are new to science. The new taxa and new records are marked by the asterisk (*) in the text.

Knowledge Management: Journal