Description
Cells obovate-lanceolate , obovate or almost spherical, flatten ed dorsoventrally with a furrow on the ventral surface, caudus short; rod-shaped trichocysts around cell periphery or concent rated at the 2 ends of the cell; flagella usually the same length as the cell , but the trailing flagellum may reach twice that length ; many chloroplasts in a single layer in the cell periphery ; frequently among aquatic plants in acidic bogs or pools . See Hovasse (1945). shaped trichocysts often grouped at ends of cell; grown on defined medium at pH 5.5-5.8 (Heywood , 1980) ; division stages observed during the dark period in labo ratory cultures (Heywood, 1980) ; during unfavorable conditions may be present as cysts (Gronberg et al ., 1988) ; frequently collected , usually from acidic bogs , pools, and lakes; diurnal movement occurs in natural populations (Gronberg et al., 1988), cells being near the surface in early hours of daylight; 3 other species have been recognized (Fott , 1968) : G intermedium , G. tatum (Fig . 2) and G. ovatum GenusHeterosigma Hada , 1968 Cell shape variable, from approximately spherical to ovoid , somewhat compressed dorsoventrally; flagella arise from separate pits in a furrow running from near the apex along the ventral side; both flagella approximate ly the same length as the cell; the beat of the anterior flagellum causes cell to rotate helically while swimming ; discoid chlorop lasts , 10-30 per cell , in peripheral layer , yellowish-brown to brown in color; mucocysts present. See Fukuyo et al. {1990) ; Hara and Chihara (1987); Ve sk and Moestrup {1987). 1-Jm ; only species of the genus ; was maintained in some culture collections as 0/isthodiscus luteus ; other synonyms: Heterosigma inlandica , Chattonella inlandica , Chattonella luteus . A GenusMerotricha Mereschkowsky, 1879 Cells appear elliptical in front view; anterior end of cell enlarged into a distinctive convex structure containing a group of trichocysts; flagella inserted laterally below this region; bright green discoid chloroplasts occur in cell periphery except for the cell anterior where the trichocysts occur . 18-25 1-Jm ; only species of the genus; trailing flagellum overlooked in original description but subsequently described by Skuja (1934) as M . capitata , which is almost certainly synonymous with M . bacillata (Fott , 1968) ; no accounts of laboratory culture, biochemistry, or ultrastructure ; from acidic bogs and ponds (Skuja, 1934; Graffius, 1966) . as Fig. 1; distinctive anterior region contains battery of trichocysts. x1 000. Fig . 8. Vacuo/aria virescens , side view ; organelles as Fig . 1; periphera l cytoplasm contains small , spherical mucocysts between the chlorop lasts . x1000. RAPHIDOMONADIDA
Type species
Merotricha bacillata Mereschowsky , 1879 (Fig. 7). Cell 40-50 x
Figures
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Raw text
Cells obovate-lanceolate , obovate or almost
spherical, flatten ed dorsoventrally with a
furrow on the ventral surface, caudus short;
rod-shaped trichocysts around cell periphery
or concent rated at the 2 ends of the cell;
flagella usually the same length as the cell , but
the trailing flagellum may reach twice that
length ; many chloroplasts in a single layer in
the cell periphery ; frequently among aquatic
plants in acidic bogs or pools . See Hovasse
(1945).
shaped trichocysts often grouped at ends of
cell; grown on defined medium at pH 5.5-5.8
(Heywood , 1980) ; division stages observed
during the dark period in labo ratory cultures
(Heywood, 1980) ; during unfavorable
conditions may be present as cysts (Gronberg
et al ., 1988) ; frequently collected , usually
from acidic bogs , pools, and lakes; diurnal
movement occurs in natural populations
(Gronberg et al., 1988), cells being near the
surface in early hours of daylight; 3 other
species have been recognized (Fott , 1968) : G
intermedium , G. tatum (Fig . 2) and G. ovatum
GenusHeterosigma Hada , 1968
Cell shape variable, from approximately
spherical to ovoid , somewhat compressed
dorsoventrally; flagella arise from separate
pits in a furrow running from near the apex
along the ventral side; both flagella
approximate ly the same length as the cell; the
beat of the anterior flagellum causes cell to
rotate helically while swimming ; discoid
chlorop lasts , 10-30 per cell , in peripheral
layer , yellowish-brown to brown in color;
mucocysts present. See Fukuyo et al. {1990) ;
Hara and Chihara (1987); Ve sk and Moestrup
{1987).
1-Jm ; only species of the genus ; was maintained
in some culture collections as 0/isthodiscus
luteus ; other synonyms: Heterosigma
inlandica , Chattonella inlandica , Chattonella
luteus .
A
GenusMerotricha Mereschkowsky, 1879
Cells appear elliptical in front view; anterior
end of cell enlarged into a distinctive convex
structure containing a group of trichocysts;
flagella inserted laterally below this region;
bright green discoid chloroplasts occur in cell
periphery except for the cell anterior where
the trichocysts occur .
18-25 1-Jm ; only species of the genus; trailing
flagellum overlooked in original description
but subsequently described by Skuja (1934)
as M . capitata , which is almost certainly
synonymous with M . bacillata (Fott , 1968) ;
no accounts of laboratory culture,
biochemistry, or ultrastructure ; from acidic
bogs and ponds (Skuja, 1934; Graffius,
1966) .
as Fig. 1; distinctive anterior region contains
battery of trichocysts. x1 000. Fig . 8. Vacuo/aria
virescens , side view ; organelles as Fig . 1;
periphera l cytoplasm contains small , spherical
mucocysts between the chlorop lasts . x1000.
RAPHIDOMONADIDA