Prorocentrum elegans Faust, 1993a
Species Overview:
Prorocentrum elegans is an armoured, marine, benthic dinoflagellate species. This species is associated with floating detritus and sediment in tropical embayments of the Caribbean Sea.
Taxonomic Description:
Prorocentrum elegans is a bivalvate species often observed in valve view. Cells are small and ovate (15-20 µm long and 10-14 µm wide) with straight sides and a flattened (Fig. 1) or oblique anterior end (Fig. 2). Valve surface is smooth with large pores (0.12 µm average diameter) and small pores (0.6 µm average diameter) (Figs. 1-3). The pores are uniformly round with smooth margins. The large pores, approximately 22 per valve, are arranged in a pattern characteristic of this species (Figs. 1,2). The small pores are unevenly distributed (Fig. 2) and situated in an array at the periphery of the valves along the intercalary band (Figs. 1,4). The valve center is devoid of pores (Figs. 1,2,5). The intercalary band is transversely striated (Fig. 4) (Faust, 1993a).
The periflagellar area is large relative to the cell size (Faust, 1990b). It is located apically on the right valve, in a large, broad, shallow, triangular depression composed of seven apical platelets (Fig. 3). Included is an inclined, protuberant periflagellar plate (2.0 X 0.6 µm in size) located adjacent to the auxiliary pore (Figs. 1,3). Two unequal periflagellar pores are present: a large flagellar pore and a much smaller auxiliary pore (Fig. 3). The left apical margin is flattened (Fig. 1) or oblique (Fig. 2).
Morphology and Structure:
Prorocentrum elegans is a photosynthetic species containing golden-brown chloroplast(s). No pyrenoid observed. The nucleus is situated anteriorly (Faust, 1993a).
Reproduction:
Prorocentrum elegans reproduces asexually by binary fission.
Species Comparison:
P. elegans has a valve pore pattern and cell shape similar to P. formosum (Faust, 1993b); however, P. elegans cells are smaller with a less complex periflagellar architecture. These two species share a number of morphological characteristics: a.) straight sides; b.) a flattened oblique anterior end; c.) a smooth thecal surface with two pore types, situated in similarly arranged arrays: P. formosum has 42-55 large pores per valve, while P. elegans bears 20-22 large pores per valve; and d.) a smooth transversely striate intercalary band with broad evenly spaced bands (Faust, 1993a, 1933b).
The anterior end of the left valve in P. elegans flattened, and can be angled (Fig. 2) (Faust, 1993a). A flat anterior end was illustrated for P. ovum (Schiller, 1918, Dodge, 1975), and an angled anterior end for P. cassubicum (Dodge, 1975) and P. formosum (Faust, 1993b). The shape and size of P. elegans, however, distinguishes this species from the round P. ovum (diameter 13 µm), the almost round P. nanum (8-10 µm long and 6.5-12 µm wide) (Schiller, 1918), and the much larger species P. cassubicum (Dodge, 1975) and P. formosum (Faust, 1993b).
The valve pore pattern of P. elegans differs from all other Prorocentrum species: P. triestum (Dodge, 1985) and P. venetum (Tolomio and Cavolo, 1985a) possess arrays of pores that radiate perpendicularly from the posterior margins on both valves; P. ovum has irregularly scattered trichocyst pores (10-14 per valve); and P. nanum has only a few trichocyst pores (1-4 per valve) (Schiller, 1918, Dodge, 1975).