Diatom of the Month – May 2017: Navicula lanceolata
by Martyn Kelly*, in collaboration with Luca Marazzi Navicula lanceolata (Agardh) Ehrenberg 1838 is a symmetrical biraphid diatom with lanceolate valve margins, broad in the central valve and slightly rostrate, rounded ends (Fig. 1, #1); the central area is an irregular oval (Fig. 1, #2), and striae are radiate, except at the ends where they become convergent (Fig. 1, #3). This species has two chloroplasts, one along each side of the girdle (Fig. 2) and is highly motile. Fig. 1 . Navicula lanceolata (Source: http://westerndiatoms.colorado.edu/taxa/species/Navicula_lanceolata ) . Fig. 2 . Navicula lanceolata in fresh samples with brown chloroplasts (Source: http://craticula.ncl.ac.uk/EADiatomKey/html/taxon13521390.html ; Image Copyright: E.J. Cox ). This is one of the most widely-distributed and frequently-encountered diatoms in both Europe and North America and is particularly abundant in winter and early spring; like a few other motile diatoms, it can...