Desmidiales

Staurodesmus convergens (EHRENB. ex RALFS) TEILING   Synonym: Arthrodesmus convergens EHRENB. ex RALFS  Cells are wider than long, the cell halves have elliptical shapes. The cell halves are laterally covered with large inward bent spines. The central cuts are strongly broadened towards the periphery.  Dimension: Length 35 – 55 µm, width 50 – 80 µm (including spines) Ecology: In acidic to medium acidic fens. Occurrence: Ubiquitous common  

Staurodesmus convergens (EHRENB. ex RALFS) TEILING   Synonym: Arthrodesmus convergens EHRENB. ex RALFS  Cells are wider than long, the cell halves have elliptical shapes. The cell halves are laterally covered with large inward bent spines. The central cuts are strongly broadened towards the periphery.  Dimension: Length 35 – 55 µm, width 50 – 80 µm (including spines) Ecology: In acidic to medium acidic fens.

Xanthidium armatum (BREB.). RABENH. ex RALFS The cells are 1.5 times longer than wide and rectangular in shape. The cell halves are octagonal with 6 pairs of furcated processi. In the center of the cell halves is a star shaped branched processus. The cell terminations are broadly truncated. The central cuts are deep and strongly broadened towards the periphery.  Dimension: Length 100 – 140 µm, width 120 – 180 µm Ecology: As acidophilic alga common in acidic sphagnum bogs. Occurrence: Ubiquitous 

Xanthidium armatum (BREB.). RABENH. ex RALFS The cells are 1.5 times longer than wide and rectangular in shape. The cell halves are octagonal with 6 pairs of furcated processi. In the center of the cell halves is a star shaped branched processus. The cell terminations are broadly truncated. The central cuts are deep and strongly broadened towards the periphery.  Dimension: Length 100 – 140 µm, width 120 – 180 µm Ecology: As acidophilic alga common in acidic sphagnum bogs. Occurrence: Ubiquitous 

In phase contrast the massive layer of mucilage around the algal filament is clearly visible. On the lower right another filament of H. dissiliens stands perpendicularly providing an apical view which shows the stelloid form of chloroplasts. The scale bar indicates 50 µm.   Collected from bottom sediments of a tiny pond at the island of Hiddensee (Baltic Sea, Germany). Images were taken using Zeiss Standard with Olympus C7070 CCD camera.

Cosmarium turpinii BREB. var. eximium WEST & G. S. WEST  The cells are only a little longer than wide and sexangular in shape. The cell halves are strongly tapered towards the flat, weakly emarginated cell ends. The central cut ist closed and right-anglularly opened at the outside end. The cell wall wears rows of warts. In the center of each cell half there is a clearly visible hemispheric bump. Dimension: Length: 60 – 70 µm, width: 50 – 60 µm Ecology: Sometimes in plancton of lakes and ponds.  Occurrence: Ubiquitous in temperate zones. 

Cosmarium turpinii BREB. var. eximium WEST & G. S. WEST  The cells are only a little longer than wide and sexangular in shape. The cell halves are strongly tapered towards the flat, weakly emarginated cell ends. The central cut ist closed and right-anglularly opened at the outside end. The cell wall wears rows of warts. In the center of each cell half there is a clearly visible hemispheric bump. Dimension: Length: 60 – 70 µm, width: 50 – 60 µm Ecology: Sometimes in plancton of lakes and ponds.  Occurrence: Ubiquitous in temperate zones. 

Closterium lunula (MÜLL.) NITSCH ex RALFS The cells are 6-8 times longer than wide, almost straight, whereas the dorsal side is somewhat more strongly curved than the ventral side. The cell ends are broadly rounded off and sometimes curved a little backwards. In the terminate vacuoles there are numerous tiny cristals. The cell wall is lightly striated.  Dimension: Length 500 – 900 µm, width 60 – 100 µm  Ecology: Very tolerant concerning living conditions, in acidic and alcaline waters of all kinds often abundant. Occurrence: Ubiquitous. 

Closterium lunula (MÜLL.) NITSCH ex RALFS The cells are 6-8 times longer than wide, almost straight, whereas the dorsal side is somewhat more strongly curved than the ventral side. The cell ends are broadly rounded off and sometimes curved a little backwards. In the terminate vacuoles there are numerous tiny cristals. The cell wall is lightly striated.  Dimension: Length 500 – 900 µm, width 60 – 100 µm  Ecology: Very tolerant concerning living conditions, in acidic and alcaline waters of all kinds often abundant. Occurrence: Ubiquitous. 

Staurastrum bicorne HAUPTFL. The cells including their protrusions are appr. 1.3 times wider than long. The cell halves are bell-shaped and have a little swelling on the base. The cell arms are straight or small inward curved with one pair of pricks each at the ends. Along the cell ends the cell wall is covered with a row of warts with multiple apices.  Dimension: Length 60 – 70 µm, width 10 – 100 µm  Ecology: Sporadic in the Alps in medium acidic zones of moorlands and mountain lakes. Occurrence: Ubiquitous, mainly in colder climes (among others in Alaska, the Arctic, Newfoundland). 

Staurastrum bicorne HAUPTFL. The cells including their protrusions are appr. 1.3 times wider than long. The cell halves are bell-shaped and have a little swelling on the base. The cell arms are straight or small inward curved with one pair of pricks each at the ends. Along the cell ends the cell wall is covered with a row of warts with multiple apices.  Dimension: Length 60 – 70 µm, width 10 – 100 µm  Ecology: Sporadic in the Alps in medium acidic zones of moorlands and mountain lakes. Occurrence: Ubiquitous, mainly in colder climes (among others in Alaska, the Arctic, Newfoundland). 

Cosmarium obsoletum (HANTSCH) REINSCH.var. minus (MESSIK.) KRIEG. & GERLOFF The cells are almost as long as wide and broadly elliptical in shape. The central cut is deep. The cell halves are semicircular and broadly rounded off at the basis, with a bulge-like thickened cell wall. The central constriction is deep. Scattered over the cell wall are closely packed pores.  Dimension: Length 36 – 40 µm, width: 34 – 36 µm Ecology: Sporadic up to rather rare in moorlands of medium acidity.  Occurrence: Only known from Austria and Switzerland hitherto.  

Cosmarium obsoletum (HANTSCH) REINSCH.var. minus (MESSIK.) KRIEG. & GERLOFF  The cells are almost as long as wide and broadly elliptical in shape. The central cut is deep. The cell halves are semicircular and broadly rounded off at the basis, with a bulge-like thickened cell wall. The central constriction is deep. Scattered over the cell wall are closely packed pores.  Dimension: Length 36 – 40 µm, width: 34 – 36 µm Ecology: Sporadic up to rather rare in moorlands of medium acidity.  Occurrence: Only known from Austria and Switzerland hitherto. 

Micrasterias thomasiana ARCHER var. notata (NORDST.) GRÖNBLAD. Length 200 - 240 µm, width 170 - 210 µm. Common in marsh areas and forest ponds both in lowlands and in alpine regions, considerably more frequent than the type variety of species Micrasterias thomasiana.

Micrasterias thomasiana ARCHER var. notata (NORDST.) GRÖNBLAD  Length: 200 – 240 µm, width: 170 – 210 µm.   Common in marsh areas and forest ponds both in lowlands and in alpine regions, considerably more frequent than the type variety of species Micrasterias thomasiana. 

Micrasterias thomasiana Archer var. notata (Nordst.) Gruenblad  Length: 200 - 240 microns, width: 170 - 210 microns.   Common in marsh areas and forest ponds both in lowlands and in alpine regions, considerably more frequent than the type variety of species Micrasterias thomasiana. 

Staurastrum senarium (EHR.) RALFS.  Length 26 - 30 µm, width 30 - 33 µm.  Widely spread in sphagnum ponds both in lowlands and in alpine areas.

Staurastrum senarium (EHR.) RALFS   Length: 26 – 30 µm, width: 30 – 33 µm.   Widely spread in sphagnum ponds both in lowlands and in alpine areas. 

Collected from Cumloden Swamp on August 28, 2002.