Marine Species Identification Portal : Alexandrium pseudogonyaulax

Alexandrium pseudogonyaulax (Biecheler) Horiguchi ex Yuki and Fukuyo, 1992

Species Overview:

Alexandrium pseudogonyaulax is an armoured, marine, planktonic dinoflagellate. It is a toxic species found in coastal regions and brackish environments.

Taxonomical Description:

Cells of A. pseudogonyaulax are medium to large, irregularly pentagonal-shaped with moderate dorsoventral flattening. Cells are wider than long; the epitheca is slightly shorter than the hypotheca (Figs. 1,2). The first apical plate (1') is characteristically displaced with a large ventral pore on the anterior margin (Figs. 3,4). The thecal plates are smooth and thin with scattered minute pores. Cells range in size between 34-60 µm in length and 39-69 µm in width (Balech, 1995, Montresor et al., 1993, Steidinger and Tangen, 1996).

Thecal Plate Description:

The plate formula for A. pseudogonyaulax is: Po, 4', 6'', 6c, 10s, 5''', 2''''. The apical pore plate (Po) is oval shaped, contains a large comma-shaped foramen and a number of irregular pores, and is positioned longitudinally on the apex (Figs. 3,4,9). The distintive 1' plate does not come in contact with the Po; it is roughly pentagonal and wider anteriorly (Figs. 3,4,9). The sloped anterior margin bears a large ventral pore that is wider than long (Figs. 3,4). The ventral pore does not penetrate the 4' plate (Figs. 3,4) (Balech, 1995, Montresor et al., 1993, Yuki and Fukuyo, 1992).

The short, convex epitheca is dome-shaped (Figs. 1,2). The hypotheca is slightly longer with an obliquely concave antapex (Figs. 1,2). The shallow cingulum is displaced in a descending fashion less than one time its width (Figs. 1,8). The sulcus lacks lateral lists. It slightly penetrates the epitheca obliquely on the right (Balech, 1995).

Morphology and Structure:

A. pseudogonyaulax is a photosynthetic species with central radiating yellow-brown chloroplasts. The transversely elongated nucleus is large and curved, and centrally located (Balech, 1995, Montresor, 1995).

Reproduction:

A. pseudogonyaulax reproduces asexually by binary fission. This species also has a sexual cycle with isogamous mating types. The smaller rounder gametes (Fig. 5) fuse (one gamete engulfs the other), produce a planozygote which then encysts into a characteristic resting cyst (Figs. 6,7) (Montresor et al., 1993, Montresor, 1995).

Ecology:

A. pseudogonyaulax is a coastal and brackish water dinoflagellate species. Blooms of this species are commonly reported in the Strait of Georgia, British Columbia (North Pacific Ocean) (Taylor and Haigh, 1993).

This species produces a characteristic and unusual resting cyst: a non-smooth cyst. The cysts are round and dark, and are often covered with a mucilaginous layer (Fig. 6). They contain a reddish-orange accumulation body. Size ranges from 40 to 55 µm in diameter. The cyst wall consists of two layers: a smooth inner layer and a paratabular outer layer (Fig. 7). The cyst paratabulation equals the tabulation of a vegetative cell. This is the only reported species in the genus Alexandrium to produce a non-smooth cyst (Montresor et al., 1993, Nichetto et al., 1995).

Species Comparisons:

A. pseudogonyaulax closely resembles two other Alexandrium species: A. hiranoi and A. satoanum. Common features include general shape and size, and lack of contact of the first apical plate, 1', with the Po. Distinguishing features lie in the cell outline, the ventral pore, the 1' plate, cyst morphology and habitat: a) A. hiranoi has a round shape, A. pseudogonyaulax is wider than long, A. satoanum is also wider than long with the general outline resembling a top: the epitheca and hypotheca have straighter sides; b) the ventral pore of A. hiranoi is circular and invades the 4' plate, in A. pseudogonyaulax the ventral pore is semi-circular and does not invade the 4', and in A. satoanum, no ventral pore is present (has a.a.p. and p.a.p); c) the 1' plate in A. hiranoi is slender and rectangular, whereas in A. pseudogonyaulax the 1' is almost pentagonal; d) the cyst of A. hiranoi is smooth, while the cyst of A. pseudogonaulax is paratabulate with thick sutures; and e) A. hiranoi is found in rockpools, A. pseudogonyaulax is found in coastal brackish habitats (Kita and Fukuyo, 1988, Montresor et al., 1993, Steidinger and Tangen, 1996).

This species roughly resembles A. tamarense; however, the latter species is not as round, and has a broader APC (Taylor et al., 1995).

Ecology:

A. pseudogonyaulax is a coastal and brackish water dinoflagellate species. Blooms of this species are commonly reported in the Strait of Georgia, British Columbia (North Pacific Ocean) (Taylor and Haigh, 1993).

This species produces a characteristic and unusual resting cyst: a non-smooth cyst. The cysts are round and dark, and are often covered with a mucilaginous layer (Fig. 6). They contain a reddish-orange accumulation body. Size ranges from 40 to 55 µm in diameter. The cyst wall consists of two layers: a smooth inner layer and a paratabular outer layer (Fig. 7). The cyst paratabulation equals the tabulation of a vegetative cell. This is the only reported species in the genus Alexandrium to produce a non-smooth cyst (Montresor et al., 1993, Nichetto et al., 1995).

Toxicity:

A. pseudogonyaulax produces a unique phycotoxin called goniodomin A (GA) that has an antifungal effect (Murakami et al., 1988). The toxin GA targets the liver and thymus (Terao et al., 1989, Terao et al., 1990).

Habitat and Locality:

A. pseudogonyaulax is a coastal species which has been reported from several localities in Europe: France along the Mediterranean coast (Biecheler, 1952), Italy in the Gulf of Trieste, North Adriatic Sea (Honsell et al., 1992, Montresor et al., 1993, Nichetto et al., 1995), Portugal and Norwegian fjords (Balech, 1995). In the Pacific Ocean this species is a common bloom former in the Gulf of Georgia in British Columbia (Taylor and Haigh, 1993), and populations have been observed in coastal waters of Japan (Inoue, in Kita and Fukuyo, 1988).

Balech, E. 1995. The Genus Alexandrium Halim (Dinoflagellata), Sherkin Island Marine Station, Ireland. 151 pp.

Biecheler, B. 1952. Recherches sur les Peridiniens. Bulletin Biologie de France et Belgium (Supplement) 36: 1-149.

Honsell, G., L. Boni, M. Cabrini and M. Pompei 1992. Toxic or potentially toxic dinoflagellates from the Northern Adriatic Sea. Sci. Total Environ. (Suppl.): 107-114.

Horiguchi, T. 1983. Life History and Taxonomy of Benthic Dinoflagellates (Pyrrhophyta). Ph.D. thesis, University of Tsukuba, Japan, 141 pp.

Kita, T. and Y. Fukuyo 1988. Description of the gonyaulacoid dinoflagellate Alexandrium hiranoi sp. nov. inhabiting tidepools on Japanese Pacific coast. Bull. Plank. Soc. Jpn. 35: 1-7.

Montresor, M., A. Zingone and D. Marino 1993. The paratabulate resting cyst of Alexandrium pseudogonyaulax (Dinophyceae). In: Smayda, T. and Y. Shimizu (eds), Toxic Phytoplankton Blooms in the Sea, Elsevier, Amsterdam: 159-164.

Montresor, M. 1995. The life history of Alexandrium pseudogonyaulax (Gonyaulacales, Dinphyceae). Phycologia 34: 444-448.

Murakami, M., K. Makabe, K. Yamaguchi, S. Konosu and M.R. Walchli 1988. Goniodomin A, a novel polyether macrolide from the dinoflagellate Goniodoma pseudogoniaulax. Tetrahed. Lett. 29: 1149-1152.

Nichetto, P., G. Honsell and G. Bressan 1995. First survey of dinoflagellate cysts in the Gulf of Trieste (Northern Adriatic Sea). In: Lassus, P., G. Arzul, E. Erard, P. Gentien and C. Marcaillou (eds), Harmful Marine Algal Blooms, Lavoisier Pub., Paris: 205-211.

Steidinger, K.A. and K. Tangen 1996. Dinoflagellates. In: C.R. Tomas (ed), Identifying Marine Diatoms and Dinoflagellates, Academic Press, New York: 387-598.

Taylor, F.J.R. and R. Haigh 1993. The ecology of fish-killing blooms of the chloromonad flagellate Heterosigma in the Strait of Georgia and adjacent waters. In: Smayda, T.J. and Y. Shimizu (eds), Toxic Phytoplankton Blooms in the Sea, Elsevier, Amsterdam: 705-710.

Taylor, F.J.R., Y. Fukuyo and J. Larsen 1995. Taxonomy of harmful dinoflagellates. In: G.M. Hallegraeff, D.M. Anderson and A.D. Cembella (eds), Manual on Harmful Marine Microalgae, IOC Manuals and Guides No. 33. UNESCO, France: 283-317.

Terao, K., E. Ito, M. Murakami and K. Yamaguchi 1989. Histopathological studies on experimental marine toxin poisoning-III. Morphological changes in the liver and thymus of male ICR mice induced by goniodomin A, isolated from the dinoflagellate Goniodoma pseudogoniaulax. Toxicon 27: 269-271.

Terao, K., E. Ito, T. Yasumoto and K. Yamaguchi 1990. Enterotoxic, hepatotoxic and immunotoxic effects of dinoflagellate toxins on mice. In: Graneli, E., B. Sundstrom, L. Edler and D.M. Anderson (eds), Toxic Marine Phytoplankton, Elsevier, Amsterdam: 418-423.

Yuki, K. and Y. Fukuyo 1992. Alexandrium satoanum sp. nov. (Dinophyceae) from Matoya Bay, Central Japan. J. Phycol. 28: 395-399.

No distribution map was available at OBIS the last time we checked. Retry now.

Alexandrium pseudogonyaulax