Navicula Key
Key to the Common Navicula Species
| 1a. |
Valves with conspicuous, wide striae, less than 10/10um,
not punctate, valve length generally less than 30um |
N. capitata |
| 1b. | Valve
appearing otherwise | 2 |
| 2a. | Valve elliptical, with
or without capitate ends | 3
|
| 2b. |
Valve linear to lanceolate | 8
|
| 3a. | Valves larger,
with subcapitate to capitate ends, inter-striae spaces wider than
striae | 4 |
| 3b. | Valve
length less than 15um | 6 |
| 4a. | Striae strongly radial
(sometimes difficult to see) | N.
atomus |
| 4b. | Striae parallel to weakly
radial | 5 |
| 5a. | Central area present,
may only consist of a shortened stria | N.
submuralis |
| 5b. | Central area absent |
N. subminuscula
|
| 6a. | Central area
with single stigma | N.
decusis |
| 6b. | Central area with stigma |
7 |
| 7a. |
Central area large, distinctly trans-apically widened |
N. elginensis |
| 7b. | Central
area small, irregular | N.
exigua |
| 8a. |
Striae weakly radial to almost parallel |
9 |
| 8b. | Striae clearly
radial | 10 |
| 9a. | Striae 17-20/10um , central
area with noticeable outline | N. salincola
|
| 9b. |
Striae 13-16/10um, central area with weak outline |
N. incertata |
| 10a. | Striae continuously radial
to the valve ends | N.
schroeterii |
| 10b. | VStriae radial,
tending to parallel or convergent at the valve ends |
11 |
| 11a. |
Central area distinctly rectangular |
N. veneta |
| 11b. | Central
area formed otherwise | 12 |
| 12a. | Proximal raphe ends clearly
deflected to one side, so that the central nodule is clearly enlarged
on that side | 13 |
| 12b. | Central
nodule symmetrical | 15 |
| 13a. | Valve ends blunt and
rounded, rarely pointed | N. erifugia
|
| 13b. |
Valve ends more or less drawn, often sub-capitate |
14 |
| 14a. |
Striae 7-10/10um | N.
viridula |
| 14b. | Striae 13-22/10um |
N.
gregaria |
| 15a. |
Valves distinctly linear | N.
angusta |
| 15b. | Valve lanceolate to linear-lanceolate |
16 |
| 16a. |
Valve ends drawn, more or less capitate, distinctly
punctate, lineolae large | N.
rhyncocephala |
| 16b. | Valve otherwise |
17 |
| 17a. |
Central area small and irregular, ends sharp rounded |
18 |
| 17b. | Central
area large | 19 |
| 18a. | Valve width 5-7um, narrow
lanceolate | N. cryptonella
|
| 18b. |
Valve width 7.5-12um | N.
menisculus |
| 19a. |
Striae 14-18/10um , width 5-7um, ends elongated to
sub-capitate | N.
cryptocephala |
| 19b. | Striae 10-14/10um,
width 9-12um, ends more rounded | N.
lanceolata |
Created by
Jason Sonneman 23/09/98
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