• Amphora exigua: Gregory W. (1857)
• Amphora coffeaeformis var. exigua : (Gregory) Rabenhorst

Single-celled. The frustule is narrow and has a linear-elliptical shape. The valve surface is decorated with striae that become thicker along the margin of the cell. The raphe is positioned along the ventral margin of the valve. In the cytoplasm there are numerous chloroplasts.

Marine.

Distribution: as Amphora exigua (Gregory)
in Europe: Britain (Whitton et al. 1998), Romania (Caraus, 2002), Spain (Varela, 1982); Atlantic Islands: Canary Islands (Gil-Rodríguez et al. 2003, Anon, 2011); South America: Brazil (Eskinazi-Leça et al. 2010).

The algae of Romania., Studii si Cercetari, Universitatea Bacau, Biologie 7, Caraus I., 2002, 1-694

A coded list of freshwater algae of the British Isles., LOIS Publication number 222. Wallingford: Institute of Hydrology & NERC., Whitton B.A., John D.M., Johnson L.R., Boulton P.N.G., Kelly M.G. e Haworth, E.Y., 1998, 1-274

Bacillariophyceae. In: Catálogo de plantas e fungos do Brasil., Rio de Janeiro: Andrea Jakobsson Estúdio; Instituto de Pesquisas Jardim Botânico do Rio de Janeiro. Vol. 1. (Forzza, R.C. Eds), Eskinazi-Leça E., Gonçalves da Silva Cunha M. da G., Santiago M.F., Palmeira Borges G.C., Cabral de Lima J.M., Da Silva M.H., De Paula Lima J., Menezes, M., 2010, 262-309

Proctoctista. In: Lista de especies marinas de Canarias (algas, hongos, plantas y animales). (Moro, L., Martín, J.L., Garrido, M.J. & Izquierdo, I. Eds), Las Palmas: Consejería de Política Territorial y Medio Ambiente del Gobierno de Canarias., Gil-Rodríguez M.C., Haroun R., Ojeda Rodríguez A., Berecibar Zugasti E., Domínguez Santana P., Herrera Morán B., 2003, 5 - 30

Catálogo florístico de las diatomeas bentónicas de las costas de Galicia, Collectanea Botanica 13(2), Varela M., 1982, 987 - 996