Prorocentrum micans

P. micans is one of the most common and diversified species in the genus Prorocentrum. It is a planktonic species commonly found in neritic and estuarine waters, but it is also found in oceanic environments; it is cosmopolitan in cold temperate to tropical waters. This species is also known to tolerate very high salinity: populations have been reported from hypersaline salt lagoons (>90o/oo) in the Caribbean islands (Steidinger & Tangen 1996). Cells are active swimmers (Dodge 1982; Steidinger & Tangen 1996). This species forms extensive red tides in many parts of the world (Fukuyo et al. 1990; 1999).

P. micans is commonly found in marine waters all over the world (Dodge 1975).

P. micans is a photosynthetic species with two golden-brown chloroplasts situated peripherally. A large kidney-shaped nucleus is situated posteriorly. Two anterior vacuoles are usually present (Dodge 1975; 1982; Toriumi 1980; Fukuyo et al. 1990).

Holotype: Prorocentrum micans Ehrenberg, 1834: 307
Type Locality: North Sea: near Kiel, Berlin, Germany

P. micans reproduces asexually by binary fission.

P. micans varies considerably in shape and size and may be confused with closely related species; e.g. P. gracile, P. scutellum and P. caribbaeum. P. gracile has a very strong winged apical spine, is not as broad, and has a length:width ratio usually larger than 2; P. scutellum is in the same size range as P. micans, but bears a shorter and broader apical spine (Dodge 1975; 1982). P. caribbaeum is also in the same size range, but is heart-shaped and broadest around the anterior end, whereas P. micans is more tear-drop shaped and broadest around the middle (Dodge 1985; Faust 1993a). P. gracile and P. micans share two distinct features: a.) similar trichocyst pore pattern (Steidinger & Williams 1970; Steidinger & Tangen 1996); and b.) similar arrangement of apical spine: the spines lie adjacent to the periflagellar area (Toriumi 1980). Trichocyst pore number is highly variable in this species (Dodge 1985): 83 pores per valve were illustrated for one P. micans specimen (Dodge 1965), 101 pores per valve for another specimen (Dodge 1985), and 139 pores per valve in yet another specimen (Sournia 1986). Trichocyst pore morphology of this species resembles that of P. caribbaeum; however, the latter species has a much greater number of pores per valve: 145-203 (Faust 1993a).

P. micans is an armoured, marine, planktonic, bloom-forming dinoflagellate. This is a cosmopolitan species in cold temperate to tropical waters.

Cercaria sp. Michaelis, 1830
Prorocentrum schilleri Böhm in Schiller, 1933
Prorocentrum levantinoides Bursa, 1959
Prorocentrum pacificum Wood, 1963

P. micans is a bivalvate species often observed in valve view. Cells of this species are highly variable in shape and size (Figs. 1-5) (see Bursa 1959; Dodge 1975). Cells are tear-drop to heart shaped, rounded anteriorly, pointed posteriorly, and broadest around the middle (Figs. 1, 2, 4-6). This species is strongly flattened with a well-developed winged apical spine (10 µm long) on the left valve (Figs. 1, 3). Cells are medium-sized (35-70 µm long, 20-50 µm wide) with a length:width ratio usually less than two. The cell surface is rugose, covered with shallow minute depressions (Figs. 1,2). Numerous tubular trichocyst pores are also present in short rows arranged radially (Figs. 1, 5, 6). Intercalary band is smooth and wide (Figs. 1, 4-6)(Wood 1954; Toriumi 1980; Dodge 1975; 1982; 1985; Fukuyo et al. 1990; Steidinger & Tangen 1996; Faust et al. 1999). The periflagellar area is a relatively small, shallow, broad triangular depression situated apically on the right valve off-center (Fig. 3). Two periflagellar pores are present: one large flagellar pore and one smaller auxiliary pore (Fig. 3). Adjacent to the flagellar pore is a small, slightly curved periflagellar plate (Fig. 3). The large pointed apical spine lies adjacent to the periflagellar area, directly opposite the periflagellar plate (Fig. 3)(Taylor 1980; Toriumi 1980).

Although P. micans is capable of forming extensive blooms, it is usually considered harmless (see Taylor & Seliger 1979; Anderson et al. 1985; Graneli et al. 1990). It may excrete substances that inhibit diatom growth, but apparently these substances do not enter the food chain or affect organisms at higher trophic levels (Uchida 1977). There are only a few reports of P. micans having caused problems: shellfish kills in Portugal (Pinto & Silva 1956) and South Africa (Horstman 1981).

needs confirmation. Early reports on P. micans being a paralytic shellfish poison (PSP) producer (Pinto & Silva 1956) are unconfirmed, and recent incidents involving shellfish mortality have been attributed to oxygen depletion (Lassus & Berthome 1988).