Prorocentrum hoffmannianum Faust, 1990b
Species Overview:
Prorocentrum hoffmannianum 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:
Prorocentum hoffmannianum is a bivalvate species often observed in valve view. Cells are ovoid, broadest in mid-region, tapering slightly apically (Figs. 1,2). Cells are 45-55 µm long and 40-45 µm wide. Both valves are slightly concave in the center. The intercalary band is smooth and appears as a flared ridge around the cell (Figs. 1,2). Observed under LM, the marginal areolae can give the appearance of a striated intercalary band (Figs. 8,9) (Faust, 1990b).
The valve surface is deeply areolate; areolae are dense, large, and round to oblong (Figs. 1-3). Small round to ovoid pores are found within deep areolae; these pores have smooth margins, are 1.0-1.5 µm in diameter, and many bear trichocyst pores (Fig. 3). There are approximately 650-700 areolae on each valve (Figs. 5-7) (Faust, 1990b).
The periflagellar area is a wide triangle situated apically on the right valve. It houses eight periflagellar platelets and two periflagellar pores: a flagellar pore and auxiliary pore (equal in size); accessory pores are also present. The flagellar pore is surrounded by a small flared periflagellar collar (Fig. 4). Both left and right valves are apically excavated (Figs. 1,2,4). The left valve exhibits a flared and flattened curved apical collar that borders the periflagellar area (Fig. 2) (Faust, 1990b).
Morphology and Structure:
Prorocentrum hoffmannianum is a photosynthetic species containing golden-brown chloroplasts and a centrally located pyrenoid. A large nucleus is situated posteriorly (Figs. 8,9) (Faust, 1990b).
Reproduction:
Prorocentrum hoffmannianum reproduces asexually by binary fission.
Species Comparison:
Prorocentrum hoffmannianum is similar in shape to P. lima, but larger and broader with dense areolae. P. hoffmannianum is often misidentified as P. concavum, but can be distinguished by its ovoid shape and presence of areolae in the center of the valve (Fukuyo, 1981, Faust, 1990b, Faust, 1991).
The architecture of the periflagellar area of P. hoffmannianum is similar to P. lima, P. concavum (Fukuyo, 1981) and P. playfairi (Croome and Tyler, 1987); however, P. hoffmannianum has a more complex platelet configuration (Faust, 1990b). P. reticulatum (Faust, 1997), P. sabulosum (Faust, 1994), P. belizeanum (Faust, 1993a) and P. hoffmannianum (Faust, 1990b) share a distinct feature in the periflagellar area: three small accessory pores adjacent to a periflagellar pore (Faust, 1997).
Both P. hoffmannianum and P. belizeanum have a prominent flared curved apical collar on the left valve bordering the periflagellar area, although the apical collar of the latter species is rounder and more prominent, whereas that of the former is flatter (Faust, 1993a).
Remarks:
In Carlson, 1984, P. concavum identified on Plate 5, figs. n-s, is P. hoffmannianum based on thecal surface morphology, periflagellar area and intercalary band characteristics. In addition, the illustration of P. concavum (Fig. 17) by Steidinger, 1983 is neither P. concavum nor P. hoffmannianum, but is an unidentified species (Faust, 1990b).