Raphidophycidae Cavalier-Smith in Cavalier-Smith & Chao 2013
Vacuolariales Shameel 2001
The raphidophytes, previously known as chloromonads,[4][5] are a small but widespread group of single-celled eukaryoticalgae, found in both marine and freshwater environments.[6][7] They are taxonomically known as class Raphidophyceae and order Chattonellales.
Characteristics
All raphidophytes are unicellular, with large cells (50 to 100 μm), but no cell walls. Raphidophytes possess a pair of flagella, organised such that both originate from the same invagination (or gullet). One flagellum points forwards, and is covered in hair-like mastigonemes, while the other points backwards across the cell surface, lying within a ventral groove. Raphidophytes contain numerous ellipsoidchloroplasts, which contain chlorophylls a, c1 and c2. They also make use of accessory pigments including β-carotene and diadinoxanthin. Unlike other heterokontophytes, raphidophytes do not possess the photoreceptive organelle (or eyespot) typical of this group.
In terms of ecology, raphidophytes occur as photosyntheticautotrophs across a range of aquatic systems. Freshwater species are more common in acidic waters, such as pools in bogs. Marine species often produce large blooms in summer, particularly in coastal waters. Off the Japanese coast, the resulting red tides often cause disruption to fish farms, although raphidophytes are not usually responsible for toxic blooms.
Several genera have been proposed as raphidophytes but their position remains uncertain. The genus OltmannsiaSchiller 1925 was tentatively placed in the order Chattonellales by Jahn Throndsen in 1993,[12]:30[13]:511 but it is not included in later studies. Similarly, the genus SwirenkoiamonasSkvortzov 1968 was described as a member of the Chloromonadales,[14] was later regarded as a euglenid in 1991,[15]:428 and is not mentioned by subsequent studies.[7] The genus Olisthodiscus was originally proposed as a raphidophyte,[12]:30 but it currently composes a separate class, Olisthodiscophyceae.[16]
12Yamaguchi, Haruyo; Nakayama, Takeshi; Murakami, Akio; Inouye, Isao (2010). "Phylogeny and taxonomy of the Raphidophyceae (Heterokontophyta) and Chlorinimonas sublosa gen. et sp. nov., a new marine sand-dwelling raphidophyte". Journal of Plant Research. 123 (3): 333–342. doi:10.1007/s10265-009-0281-1. ISSN0918-9440.
↑Herbert Graffius, J. (1966). "Additions to Our Knowledge of Michigan Pyrrhophyta and Chloromonadophyta". Transactions of the American Microscopical Society. 85 (2): 260–270. doi:10.2307/3224637. JSTOR3224637.
↑Demir‐Hilton, Elif; Hutchins, David A.; Czymmek, Kirk J.; Coyne, Kathryn J. (2012). "Description of Viridilobus marinus (gen. et sp. nov.), a new raphidophyte from Delaware's inland bays". Journal of Phycology. 48 (5): 1220–1231. doi:10.1111/j.1529-8817.2012.01212.x. ISSN0022-3646.
12Throndsen, Jahn (1993). "The Planktonic Marine Flagellates". In Tomas, Carmelo R. (ed.). Marine Phytoplankton: A Guide to Naked Flagellates and Coccolithophorids. San Diego: Academic Press. pp.7–145. ISBN0-12-693010-4.
↑Hallegraeff, G. M.; Hara, Y. (2004). "Taxonomy of harmful marine raphidophytes". In Hallegraeff, G.M.; Anderson, D.M.; Cembella, A.D. (eds.). Manual on Harmful Marine Microalgae. Monographs on Oceanographic Methodology. Vol.11 (2nded.). Paris: UNESCO Publishing. pp.511–522. ISBN92-3-103948-2.
