Prorocentrum arenarium

Prorocentrum arenarium is a benthic and epiphytic species. Cells are motile, propelled by two flagella, or are attached to sand or coral rubble. This species can be a significant component of benthic Prorocentrum assemblages in colored sand patches in the Caribbean (1200-6000 cells/g sand) (Faust 1994).
The presence of a peduncle-like structure may indicate mixotrophic feeding within the sand (Faust 1994).

Prorocentrum arenarium is associated with coral rubble and colored sand in tropical embayments of the Caribbean Sea and the SW Indian Ocean (Faust 1994; Ten-Hage et al. 2000).

Prorocentrum arenarium is a photosynthetic species with a prominent central pyrenoid and a posterior nucleus (Fig. 6). A small (2-3 µm), narrow, tubular, peduncle-like structure in the periflagellar area has been observed in this species. This structure originates and emerges from the flagellar pore (Faust 1994).

Holotype: Prorocentrum arenarium Faust, 1994: figs. 14, 15
Type Locality: Caribbean Sea: Carrie Bow Cay, Belize, Central America

Prorocentrum arenarium reproduces asexually by binary fission.

Only a few round to nearly round Prorocentrum species are known: P. arenarium (Faust, 1994) is smaller than P. emarginatum (cell diameter 35-40 µm) (Faust 1990b), but larger than P. ruetzlerianum (cell diameter 28-35 µm) (Faust 1990b) and P. compressum (cell diameter 36 µm) (Matzenauer 1933; Böhm 1936; Schiller 1937; Tafall 1942; Dodge 1975).
The valve poroids of P. arenarium are distinct from similarly known benthic Prorocentrum species: P. lima has approximately 58-86 round pores per valve and 55-72 marginal pores with a diameter of 0.3-0.7 µm (Faust 1991); P. maculosum has about 85-90 valve poroids and 65-75 marginal poroids with a diameter of 0.6 µm (Faust 1993b).
The architecture of the periflagellar area of P. arenarium, with no ornamentation (Faust 1994), is similar to that of P. concavum, P. ruetzlerianum (Faust 1990b), P. foraminosum (Faust 1993b), and P. tropicalis (Faust 1997).
P. arenarium has a smooth intercalary band. This feature is also characteristic of other benthic Prorocentrum species: P. lima (Faust 1991), P. hoffmannianum (Faust 1990), and P. foraminosum (Faust 1993b).
The peduncle-like organelle in P. arenarium is similar in structure to the peduncle observed in P. norrisianum (Faust 1997).

Prorocentrum arenarium is an armoured, marine, sand-dwelling, benthic dinoflagellate species. This toxic species is associated with coral rubble and colored sand in tropical embayments of the Caribbean Sea.

Prorocentrum arenarium is a bivalvate species often observed in valve view. Cells are round to slightly oval in valve view (Figs. 1,2,6); cell size ranges between 30 to 32 µm in diameter. Both valves are concave in the center. The thecal surface is smooth (Figs. 1-3) with distinct randomly distributed valve poroids (65-73 per valve). The valve centers are devoid of pores. The poroids vary from kidney-shaped to oblong (Figs. 1-5), with an average size of 0.62 µm long and 0.36 µm wide. Spacing between poroids is 2-3 µm. Valve margins exhibit evenly spaced marginal poroids, 50-57 per valve, and are similar in size to valve poroids (Figs. 1-5). These poroids are useful diagnostic features of this species and are easily viewed under the light microscope. The intercalary band is smooth and wide (Figs. 2, 3) (Faust 1994).
The periflagellar area, which lacks ornamentation, is a broad triangle on the right valve at the anterior end of the cell (Figs. 1, 3, 5). The anterior region of the right valve is excavated; the left valve margin is flattened (Fig. 2). The flagellar and auxiliary pores are unequal in size (Fig. 5). The longitudinal flagellum is short (average length of 11 µm) (Fig. 1)(Faust 1994).

This is a known diarrhetic shellfish poison (DSP) toxin-producing species, producing okadaic acid (OA) (Ten-Hage et al. 2000).