Prorocentrum maculosum

P. maculosum is a benthic species. Cells are motile or attach to detritus or sediment by mucous strands (Faust 1993b).

The name 'maculosum' originates from Latin and refers to 'speckled, spotted', which describes the thecal surface of this species (Faust 1993b).

Populations of P. maculosum are often associated with floating detritus in tropical coastal regions of the Caribbean Sea (Faust 1993b).

P. maculosum is a photosynthetic species containing golden-brown chloroplasts and a centrally located pyrenoid. A large posterior nucleus is situated adjacent to the pyrenoid (Fig. 5) (Faust 1993b).

Holotype: Prorocentrum maculosum Faust, 1993: figs. 1, 2
Type Locality: Caribbean Sea: Twin Cays, Belize, Central America

P. maculosum reproduces asexually by binary fission.

The use of scanning electron microscopy has revealed major differences in the micromorphology of benthic species within the genus Prorocentrum (Faust 1990a; Faust 1993b). Under LM P. maculosum may be confused with P. lima (Faust 1991) which has round valve pores and a smooth thecal surface. Dodge (1975), when revising the taxonomy of the genus Prorocentrum, described P. lima to be a morphologically variable species. However, the architecture of the flagellar pore area was not considered. P. maculosum and P. lima can be distinguished by a number of surface features. The thecal surface of P. maculosum is rugose, covered with large kidney-shaped poroids; a periflagellar collar surrounds both equally-sized flagellar and auxiliary pores (Faust 1993b). In P. lima the thecal surface is smooth with round pores; only the larger flagellar pore is surrounded by a curved periflagellar collar (Faust 1991). The valve margins of P. tropicalis form a distinct ridge that appears as a flange around the cell, similar to P. maculosum (Faust 1993b). The periflagellar architecture of P. maculosum is similar to P. hoffmannianum (Faust 1990b), P. compressum (Abe 1967; Dodge 1975), P. playfairi and P. foveolata (Croome & Tyler 1987).

P. maculosum is an armoured, marine, benthic dinoflagellate species. This toxic species is often associated with floating detritus in tropical coastal regions of the Caribbean Sea.

Exuviaella maculosum (Faust) McLachlan, Boalch and Jahn, 1997

P. maculosum is a bivalvate species often observed in valve view. Cells are 40-50 µm long and 30-40 µm wide, broadly ovate with the maximum width behind the middle region, and slightly tapered at the anterior end (Figs. 1, 2). The thecal surface is rugose with distinct scattered valve poroids (85-90 per valve) (Figs. 1-3). The poroids vary from kidney-shaped to circular or oblong (average diam.=6.0 µm), 2-4 µm apart (Fig. 3). Valve center is devoid of poroids (Figs. 1, 2, 6) (Faust 1993b). The valve margins form a distinct ridge which appears as a flange around the cell (Figs. 1,2). Marginal pores are equally spaced (65-75 per valve), and appear larger and more uniform than the valve poroids (Figs. 1, 2) (Faust 1993b). The periflagellar area is a broad triangle on the anterior end of the right valve (Figs. 1, 4) made up of 8 platelets and 2 pores (Fig. 4). A thin apical ridge (raised margin) on the left valve surrounds the periflagellar area (Figs. 2, 4). The flagellar and auxiliary pores are about equal in size, both surrounded by a curved and flared periflagellar collar (Fig. 4) (Faust 1993b).

This is a known toxic species that produces prorocentrolide B, a fast-acting toxin (Hu et al. 1996). A diarrhetic shellfish poison (DSP) toxin, okadaic acid (OA), has also been reported from one Caribbean clone previously identified as P. concavum (Dickey et al. 1990), but reassigned to P. maculosum (Faust 1996b; Zhou & Fritz 1996).