Gomphonema olivaceum (Hornemann) Brebisson, 1838

Levkov, Zlatko & Williams, David M., 2011, Fifteen new diatom (Bacillariophyta) species from Lake Ohrid, Macedonia, Phytotaxa 30, pp. 1-41 : 32-33

Key for identification of members of the Gomphonema olivaceum complex and related taxa from Lake Ohrid

1. Valves broader than 12 µm, marginal lamina present (visible in girdle view) ........................................................... 2

-. Valves narrower than 12 µm, marginal lamina absent ................................................................................................ 3

2. Central area panduriform, striae 7.5–9 in 10 µm ................... Gomphoneis ohridana Levkov (in Levkov et al. 2007)

-. Central area round, striae 9–12 in 10 µm ...................................................................................................................... ........................................................... Gomphoneis prespanenis Levkov, Metzeltin & Krstic (in Levkov et al. 2007)

3. Four stigmoids present in central area ...................... Gomphonema perolivaceoides Levkov (in Levkov et al. 2007)

-. Stigmoids absent in central area ................................................................................................................................. 4

4. Valves linear, narrower than 7 µm, length/breadth ration 5–7 ................................ Gomphonema linearoides Levkov

-. Valves always broader than 7 µm ............................................................................................................................... 5

5. Valves shorter than 25 µm, length/bread ratio around 2 ................................................................................................ ....................................................................... Gomphonema subolivaceum Levkov & Nakov (in Levkov et al. 2007)

-. Valves always longer than 25 µm, length/bread ratio higher than 4 ........................................................................... 6

6. Valves with truncate head pole, maximal width at head pole ........................................................................................ ............................................................ Gomphonema fonticolum (Hustedt) Levkov & Krstic (in Levkov et al. 2007)

-. Valves with broadly rounded head pole, maximal width near mid–valve .................................................................. 7

7. Valves wider than 9 µm ............................................................................. Gomphonema perolivaceolacuum Levkov

-. Valves narrower than 9 µm ................................................................................. Gomphonema densistriatum Levkov