Pseudo-nitzschia caciantha

P. caciantha is a chain-forming pennate diatom found in tropical waters. It is not a known domoic acid producer. P. caciantha has not been reported in a large monospecific bloom.

From Lundholm et al. 2003: Overlapping cells in colonies. Cells lanceolate with a tendency to being slightly asymmetrical in apical axis, 2.7-3.5 microns wide, 53-75 microns long. Raphe eccentric, divided in the middle by a central nodule. Fifteen to 19 fibulae in 10 microns, interstriae 28-31 in 10 microns. Striae perforated by one row of poroids, 3.5-5 poroids in 1 micron. Hymen of poroids usually divided into four to five sectors. Valve mantle structured as valve face, 1-2 poroids high. Valvocopula contains 33-38 striae in 10 microns; each stria is two poroids wide and 3-5 poroids high. Striae of the second copula two poroids wide and two poroids high.

Pseudo-nitzschia caciantha has thus far only been reported in tropical waters.

P. caciantha form the step-chains characteristic of the genus. Cells are long and thin and slightly asymmetrical in valve view. Each stria contains one row of nearly square poroids with hymen perforations in a hexagonal pattern.

Analysis of ITS and ML shows that P. caciantha is most closely related to P. subpacifica and P. calliantha (Lundholm et al. 2002).