CHLOROPHYLL C PIGMENT PATTERNS IN 18 SPECIES (51 STRAINS) OF THE GENUS PSEUDO-NITZSCHIA (BACILLARIOPHYCEAE)

The pigment composition of 18 species (51 strains) of the pennate diatom Pseudo-nitzschia was examined using HPLC. The carotenoid composition was typical for diatoms, with fucoxanthin (the major xanthophyll), diadinoxanthin, diatoxanthin, and beta,beta-carotene. However, a diverse array of chl c pigments was observed in the studied strains. All Pseudo-nitzschia strains contained chl a and chl c(2), traces of Mg-2,4-divinyl phaeoporphyrin a(5) mono-methyl ester (MgDVP), and traces of a chl c(2) like pigment originally found in the haptophyte Pavlova gyrans. The distribution of chl c(1) and chl c(3) was variable among species (present in seven and 14 species, respectively). Based on chl c distribution, three major pigment types were defined: type 1 (chl c(1) + c(2), four species: P. australis, P. brasiliana, P. multiseries, and P. seriata), type 2 (chl c(1) + c(2) + c(3), three species: P. fraudulenta, P. multistriata, and P. pungens), and type 3 (chl c(2) + c(3), 11 species: P. arenysensis, P. calliantha, P. cuspidata, P. decipiens, P. delicatissima, P. galaxiae, P. mannii, P. pseudodelicatissima, P. subcurvata, P. cf. subpacifica, and a novel Pseudo-nitzschia species). Type 1 and 2 species also shared the absence of a particular morphological character, the central nodule in the raphe, with the only exception of P. fraudulenta. The implications of such pigment diversity in chemotaxonomy, HAB monitoring, ecology, and phylogeny of Pseudonitzschia species are discussed.