Samples of attached diatoms were taken from the flat upper surfaces of submerged stones in the Rio Negro, a tributary of the Amazon River, at Ponta da Praia (Km 18), opposite the Tropical Hotel, Manaus, Amazonas, Brazil, on August 8,1986.
The samples were examined with a light microscope and each taxon was photographed, illustrated and measured for identification.19 taxa from 12 genera are recorded, distributed as follows; one species of genus Actinella (
A. brasiliensis GRUN. ), one species of genus
Anomoeoneis (
A. exilis (K
ÜTZ. ) Cleve f.
lanceolata A. MAYER, ) two species of genus
Cymbella (
C. amphicephala NAEG. and
C. ventricosa K
ÜTZ. ), five taxa of genus
Eunotia (E. diodon E
HR., E.
lunaris (E
HR. ) GRUN.,
E. valida HUST,.
E. fallax A. CLEVE var.
gracilima KRASSKE and
E. pectinalis (Dillw. ? K
ÜTZ. ) Rabenh. var.
minor (K
ÜTZ. ) RABENH.), one species of
Cyclotella (
Cyclotella sp. ), one species of
Fragilaria (
F. constricta E
HR. ), two taxa of
Frustulia(
F. rhomboides (RABENH). D
E TONI f. saxonica and f. undulata HUST. ), (RABENH), one species of
Gomphonema (
G. subclavatum E
HR. ?), two species of
Pinnularia (
P. subcapitata GREG. and P.
hemiptera RABENH. ), one species of
Navicula (
N. cryptotenella LANGE-BERTAL ? ), one species of
Nitzschia (
N. palea (K
ÜTZ. ) W. SMITH), and one species of
Synedra (
S. rumpens K
ÜTZ. var.
scotica GRUNT. ?).
Eunotia was the best represented genus in number of taxa identified, while
Actinella, Cyclotella, Synedra, Fragillaria, Nitzschia, Anomoeoneis and Gomphonema were the least represented of all.
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