apex : 6 µm
Rapport L/l : 15
courbure : 30° - slightly curved
Extrémités arrondies (avec pore ?)
présence de cristaux mobiles
Pyrénoïdes axiales
surface striée, env. 13/14 stries/10µm
absence de bande d'élongation
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Coesel
Closterium rostratum Ralfs Plate 18: 1-3
Cells (very) slightly curved with a broad fusiform midregion and narrow, colourless, beak-like
ends. Ventral side of the midregion usually more convex than the dorsal side. Beak-like cell ends
shorter than the midregion and usually curved along their overall length, slightly widened at
the apex. Apices truncately rounded. Cell wall without girdle bands, brownish (rarely colourless),
finely striate (8-15 str/10 μm), at the poles indistinctly punctate. Cell length (240-) 300-500
(-550) μm, breadth (17-) 20-30 (-37) μm, L/Br (8.5-) 12-18 (-20). Zygospores in frontal view rectangular
with concave sides and broadly truncate-concave angles extending with a tooth or short
spine into the gametangial cells.
Occurrence: mesotrophic, scattered in moorland pools and fen hollows. Zygospores known from
a few sites (e.g., Korenburgerveen).
John
Closterium rostratum
Cells 20-30 µm wide,300-500 µm long,dorsal margin gently curved throughout length, inner margin sxollen in mi-region, narrowing to distinctive, subparrallel cell end ; apices 3.5-5 µm wide, slightly inflated, sub-truncate to rounded ; girdle bands absent ; chloroplasts with 3-5 longitudianl ridges and 4 or 5 axile pyrenoids, occupy only broad region ; walls coulourless to brown, striated (8-15 striae in 10 µm), orften striae difficult to detect ; terminal vacuoles at base of rostrate ends, with 5-15 moving crystals.
Probably cosmopolitan, acidophile (pH 4-7,2) ; mostly associated with acid habitats, usually with Sphagnum, also in circum-neutral ponds with abundance of submerged macrophytes.
