Prorocentrum triestinum Schiller, 1918
Species Overview:
Prorocentrum triestinum is an armoured, marine, planktonic, bloom-forming dinoflagellate. This cosmopolitan species is found in neritic and oceanic waters world-wide.
Taxonomic Description:
Prorocentrum triestinum is a bivalvate species often observed in valve view. This species is highly variable in shape and size. Cells are small (18-22 µm in length and 6-11 µm in width), long and slender, and about twice as long as wide (Figs. 1-4,6-8). This species has a rounded anterior, a pointed posterior, and a prominent narrow winged apical spine (3-5 µm long) (Figs. 1-8). Thecal plates are delicate with a smooth surface; a few peripheral trichocyst pores with thickened rims are present (Figs.1-8) (Bursa, 1959, Dodge, 1965, Dodge, 1975, Dodge, 1982, Toriumi, 1980, Steidinger and Tangen, 1996).
The periflagellar area is a shallow depression located apically and off-center on the right valve with only one periflagellar pore: a flagellar pore (Figs. 1,5). The prominent thin winged apical spine is located adjacent to the flagellar pore on the left valve (Figs. 1-5). A second much smaller apical spine lies opposite (Fig. 5) (Bursa, 1959, Dodge, 1975, Loeblich et al., 1979b, Toriumi, 1980, Steidinger and Tangen, 1996).
Morphology and Structure:
P. triestinum is a photosynthetic species with a round nucleus situated posteriorly (Dodge, 1975, Toriumi, 1980). Yellow-green chloroplasts and a pusule are also present (Bursa, 1959).
Reproduction:
P. triestinum reproduces asexually by binary fission.
Species Comparison:
P. triestinum resembles a short, thin and narrow P. micans, but it is distinguished by its smaller size, smooth thecal plates, and scattered thick-rimmed trichocyst pores (Dodge, 1965, Dodge, 1975, Toriumi, 1980, Steidinger and Tangen, 1996).
P. triestinum has only one pore in the periflagellar area (Loeblich et al., 1979b). Only one other species in this genus has been observed to have this trait, the benthic species P. formosum (Faust, 1993b).