Desmidiales

Micrasterias is one of the desmids, flattened green algae in which the organism has a central constriction which gives the organism the appearance of being two cells joined together. Differential interference contrast.

Micrasterias radiosa (RALFS,1848).  M. sol (EHRENBERG ex KÅ°TZING,1849) is a junior synonym. Phase contrast.

 Docidium undulatum BAIL.  The cells are 15-25 times longer than wide with truncated ends. The sides are repeatedly flatly undulated. The central cut is little formed. On both sides around the cut runs a ring with tiny, broadly rounded nipples. Dimension: Length 200 – 250 µm, width 12 – 17 µm Ecology: Acidophilic alga, in acidic fens together with Micrasterias jenneri, Micrasterias truncata und Euastrum armatum. Occurrence: Ubiquitous 

Docidium undulatum BAIL.  The cells are 15-25 times longer than wide with truncated ends. The sides are repeatedly flatly undulated. The central cut is little formed. On both sides around the cut runs a ring with tiny, broadly rounded nipples. Dimension: Length 200 – 250 µm, width 12 – 17 µm Ecology: Acidophilic alga, in acidic fens together with Micrasterias jenneri, Micrasterias truncata und Euastrum armatum. Occurrence: Ubiquitous 

Euastrum attenuatum WOLLE var. splendens (F.E.FRITSCH & RICH.) GRÖNBLAD The cells are almost two times longer than wide. The cell halves have three lobes, the lateral lobes are broad and shallowly undulated at the ends. The vertex lobes are widened at the ends and are surrounded with a collar of warts. In the center of each cell half and on both sides of them there are broad swellings. The central cuts open outwards in an acute-angle. .  Dimension: Length 57 – 60 µm, width 33 – 35 µm  Ecology: In shallow, moderate acidic waters of fens and bogs. Occurrence: South America (Anden up to altitude of 3000 m toTierra del Fuego), Africa (Natal, Sudan), firstly recorded for Europe! 

Euastrum attenuatum WOLLE var. splendens (F.E.FRITSCH & RICH.) GRÖNBLAD The cells are almost two times longer than wide. The cell halves have three lobes, the lateral lobes are broad and shallowly undulated at the ends. The vertex lobes are widened at the ends and are surrounded with a collar of warts. In the center of each cell half and on both sides of them there are broad swellings. The central cuts open outwards in an acute-angle. .  Dimension: Length 57 – 60 µm, width 33 – 35 µm  Ecology: In shallow, moderate acidic waters of fens and bogs. Occurrence: South America (Anden up to altitude of 3000 m toTierra del Fuego), Africa (Natal, Sudan), firstly recorded for Europe! 

Euastrum crameri RACIB. The cells are appr. 1.5 times longer than wide and trapezoidal in shape. The cell sides are formed by flat depressions from two distinct waves.The  vertex lobes are clearly separated, strongly broadened towards the ends. They have a central cut with a spine each on the sides. The central cut of the cell is narrow, the cellwall is covered with warts and denticles.  Dimension: Length 60 – 65 µm, width 45 – 50 µm  Ecology: Sporadic in medium acidic waters of fens and moorlands Occurrence: Rather rare, most of the reported finds are in northern areas and higher altitudes. 

 Euastrum crameri RACIB. The cells are appr. 1.5 times longer than wide and trapezoidal in shape. The cell sides are formed by flat depressions from two distinct waves.The vertex lobes are clearly separated, strongly broadened towards the ends. They have a central cut with a spine each on the sides. The central cut of the cell is narrow, the cellwall is covered with warts and denticles.  Dimension: Length 60 – 65 µm, width 45 – 50 µm  Ecology: Sporadic in medium acidic waters of fens and moorlands Occurrence: Rather rare, most of the reported finds are in northern areas and higher altitudes.

Euastrum crassum (BREB.) KÜTZ. The cells are almost two times longer than wide and rounded rectangular in shape. The lateral lobes are broad and rounded off flat concave. The vertex lobes are short and strongly broadened towards the flat recessed ends. They are separated form the lateral lobes only by shallow cuts. The central cuts aren’t broadened towards the periphery. At the base of the cell halves there are three swellings with a big pore at their center.  Dimension: Length 150 – 200 µm, width 75 – 90 µm  Ecology: Acidophilic alga (pH 4 – 6.5), common in shallow sphagnum ponds. Occurrence: Probably ubiquitous 

Euastrum crassum (BREB.) KÜTZ. The cells are almost two times longer than wide and rounded rectangular in shape. The lateral lobes are broad and rounded off flat concave. The vertex lobes are short and strongly broadened towards the flat recessed ends. They are separated form the lateral lobes only by shallow cuts. The central cuts aren’t broadened towards the periphery. At the base of the cell halves there are three swellings with a big pore at their center.  Dimension: Length 150 – 200 µm, width 75 – 90 µm  Ecology: Acidophilic alga (pH 4 – 6.5), common in shallow sphagnum ponds. Occurrence: Probably ubiquitous 

Euastrum germanicum (SCHMIDLE) WILLI KRIEG. he cells are only a little longer then wide. The cell halves constist of five broadly rounded lobes. The vertex lobes which are outward somewhat widened are separated from the lobes by extended, inside rounded recessings. Each center of the cell halves showes a hemispheric bump. The cellwall is covered with parallel rows of spines. The central cuts are slender and broadly opened towards the periphery.  Dimension: Length 50 – 60 µm, width 40 – 50 µm  Ecology: Especially in medium acidic to weakly alcaline waters of ponds and alluvial areas (Danube meadows) Occurrence: Mainly in Europe, but probably ubiquitous 

Euastrum germanicum (SCHMIDLE) WILLI KRIEG. The cells are only a little longer then wide. The cell halves constist of five broadly rounded lobes. The vertex lobes which are outward somewhat widened are separated from the lobes by extended, inside rounded recessings. Each center of the cell halves showes a hemispheric bump. The cellwall is covered with parallel rows of spines. The central cuts are slender and broadly opened towards the periphery.  Dimension: Length 50 – 60 µm, width 40 – 50 µm  Ecology: Especially in medium acidic to weakly alcaline waters of ponds and alluvial areas (Danube meadows) Occurrence: Mainly in Europe, but probably ubiquitous 

Euastrum intermedium CLEVE The celles are almost two times longer than wide. The cell sides are loboid broadly rounded. The vertex lobes are protruding clearly, broadened on the ends and with a cut in the middle. In the center of the cell halves there are pairs of bumps which are covered with small warts. The central cuts are far opened towards the periphery.    Dimension: Length 70 – 80 µm, width 35 – 45 µm Ecology: Acidophilic alga, rather rare in shallow waters between sphagnum. Occurrence: Ubiquitous, prefers boreal areas (mountains), rather rare in Central Europe. 

Euastrum intermedium CLEVE The celles are almost two times longer than wide. The cell sides are loboid broadly rounded. The vertex lobes are protruding clearly, broadened on the ends and with a cut in the middle. In the center of the cell halves there are pairs of bumps which are covered with small warts. The central cuts are far opened towards the periphery.    Dimension: Length 70 – 80 µm, width 35 – 45 µm Ecology: Acidophilic alga, rather rare in shallow waters between sphagnum. Occurrence: Ubiquitous, prefers boreal areas (mountains), rather rare in Central Europe. 

Micrasterias furcata RALFS The cells are about as long as wide and have a circular shape. The cell halves consist of three lobes. The lateral lobes are clearly separated. At the ends of the lateral lobes there are two outwards standing projections. Between the projections there is a concave area. The central cut is deep and peripherally strongly widened. Dimension: Length 150 - 180 µm, width 150 – 160 µm  Ecology: In acidic to moderate acidic fens and bogs. Occurrence: Ubiquitous, rather rare in Central Europe.

Micrasterias furcata RALFS The cells are about as long as wide and have a circular shape. The cell halves consist of three lobes. The lateral lobes are clearly separated. At the ends of the lateral lobes there are two outwards standing projections. Between the projections there is a concave area. The central cut is deep and peripherally strongly widened. Dimension: Length 150 - 180 µm, width 150 – 160 µm  Ecology: In acidic to moderate acidic fens and bogs. Occurrence: Ubiquitous, rather rare in Central Europe. 

Micrasterias jenneri RALFS The cells are appr. 1.5 times longer than wide, rounded off rectangular in shape. The cells have five lobes, the lateral lobes are broadened towards the periphery and emaginated in the center, the cuts between them are closed and short. The lateral lobes aren’t spread apart, they are strongly widened peripherally and rounded with shallow emarginations in the center. The central cut is deep, closed, and not peripherally widened. Dimension: Length 150 - 180 µm, width 100 – 130 µm Ecology: Acidophilic alga, lives in sphagnum ponds together with other algae which prefer upland moor waters. Occurrence: Probably ubiquitous, mainly in colder zones. 

Micrasterias jenneri RALFS The cells are appr. 1.5 times longer than wide, rounded off rectangular in shape. The cells have five lobes, the lateral lobes are broadened towards the periphery and emaginated in the center, the cuts between them are closed and short. The lateral lobes aren’t spread apart, they are strongly widened peripherally and rounded with shallow emarginations in the center. The central cut is deep, closed, and not peripherally widened. Dimension: Length 150 - 180 µm, width 100 – 130 µm Ecology: Acidophilic alga, lives in sphagnum ponds together with other algae which prefer upland moor waters. Occurrence: Probably ubiquitous, mainly in colder zones. 

Staurastrum polonicum RACIB. The cells are up to 1.4 times longer than wide. The cell halves are rounded off sexangular in shape with bulged out sides and broadly truncated vertex. Around the basis of the cell halves there is a ring of tiny spherical calottes. The central cuts are far opened towards the periphery. The vertex view is circular with 8 to 9 shallow waves. Another ring of such bulges leads around the vertex center. The cell wall is closely covered by tiny warts.    Dimension: Length 60 – 65 µm, width 45 – 50 µm Ecology: In little acidic fens and siltation zones. Occurrence: Ubiquitous 

Staurastrum polonicum RACIB The cells are up to 1.4 times longer than wide. The cell halves are rounded off sexangular in shape with bulged out sides and broadly truncated vertex. Staurastrum polonicum RACIB. Around the basis of the cell halves there is a ring of tiny spherical calottes. The central cuts are far opened towards the periphery. The vertex view is circular with 8 to 9 shallow waves. Another ring of such bulges leads around the vertex center. The cell wall is closely covered by tiny warts.    Dimension: Length 60 – 65 µm, width 45 – 50 µm Ecology: In little acidic fens and siltation zones. Occurrence: Ubiquitous 

Staurastrum teliferum RALFS. Length 35 - 45 µm, width 25 - 35 µm. Species very adaptive. Widely spread in moderate acidic waters of the alps up to altitudes of 2800 m.