A Key to the More Frequently Occurring Freshwater Algae - Freshwater Algae: Identification, Enumeration and Use as Bioindicators - page 150

disc-like cushion. Cells frequently have long
bristles sheathed at their bases. There is a
single parietal plate-like chloroplast with one
or two pyrenoids. Widespread as an epiphyte
on aquatic macrophytes and other surfaces.
Chlorophyta. Plate III.

16 (14) (a) Filaments enclosed in soft watery
mucilage which has no definite shape
..................................... 17

(b) Filaments with a firm mucilage sur-
round having a definite shape. Often forming
macroscopic attached masses. Chaetophora

13 (9) (a) Some cells along the filament bear hairs
orsetae.............................. 14

Chaetophora filaments are frequently
attached to stones or submerged aquatic
plants. Filaments can be quite long (10+
cm). Branching more common towards fila-
ment apex. End cells of filament/branch with
a pointed shape or in the form of a long
multicellular hair. The erect system is well
developed but the prostrate one is not. Fairly
widespread distribution at the edges of shal-
low flowing or still waters attached to a sub-
strate such as aquatic plants. Chlorophyta.
Plate III.

(b) Nohairsorsetaepresent............ 18

14 (13) (a) Hairs or setae having a bulbous base
..................................... 15

(b) No bulbous base present with the hairs
orsetae.............................. 16

15 (14) (a) Filaments growing horizontally or pros-
trate, epiphytic. Branching irregular or may
be absent. Some cells with one to several
hairs...................... Aphanochaete

17 (16) (a) Main filament axis composed of a sin-
gle row of larger cells from which arise
tufts of branches composed of much smaller
cells, the whole enclosed in soft mucilage
........................... Draparnaldia

Aphanochaete is a prostrate creeping epi-
phyte. Cells longer than wide (sometimes
slightly swollen in the centre) often bearing
one or more long bristles which are swollen
atthebase.Chloroplastsaredisc-shapedwith
one or more pyrenoids. Widespread distribu-
tion, often reported in nutrient-rich waters on
submerged macrophytes and larger filamen-
tous green algae. Chlorophyta. Plate III.

Draparnaldia has erect filaments, embedded
in soft mucilage, attached to the substratum
by means of rhizoids. Main filament cells
barrel-shaped (40-100 μm wide) containing
a net-like or complete band-shaped parietal
chloroplast with several pyrenoids. Branches
arise in whorls from main axis. Branch cells
smaller with single chloroplast and up to
three pyrenoids. Branches have either a blunt
terminal cell or form a multicellular hair.
Widelydistributed,ofteninphosphorus-poor
waters. Chlorophyta. Plate III.

(b) Filaments not prostrate, branched, with
cells somewhat wider at the top than the base.
Many cells have one or more characteris-
tic colourless chaetae (a terminal hair with a
swollen base) arising from the top of the cell.
............................ Bulbochaete

Bulbochaete is a member of the Oedogo-
niales. It has branched filaments and is easily
identified by the hairs which have distinctly
swollen bases. Chloroplast parietal and net-
like with several pyrenoids. Widespread dis-
tribution, growing attached to submerged
macrophytes or stones. Wide pH and nutrient
range. Chlorophyta. Plate III.

(b) Filament main axis cells not markedly
different to branches (except end cells of
branches which are thinner and hair-like).
Branches not usually born in distinct whorls
.......................... Stigeoclonium

Filaments of Stigeoclonium are usually
attached by means of basal cells to a