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Name derivation:
Greek melon meaning melon-like and seira meaning chain.
Classification:
Melosira C. Agardh 1824; 57 of 740 species descriptions are currently accepted taxonomically (Guiry and Guiry 2013). Order Melosirales; Family Melosiraceae Synonyms in this key: Aulacoseira, Ellerbeckia
Morphology:
Cyclindrical cells with length greater than width. The valves can be either flat or convex. Convex forms can have a small ring of teeth along with a gelatinous cushions in the center of the valve face that help individual cells form chains. Melosira appears circular in valve view. There is annular constriction (sulcus) at the girdles of half-cells. Girdles Trichomes with a wide range of size. Can have a small gap between adjacent cells in trichome. The protoplasts contain countles numbers of discoid chromatophores. These chromatophores can be so dense that they obscure any markings on the cell wall. Can form resting spores.
Similar genera:
Aulacoseira Thwaites 1848 is a synonym. Ellerbeckia R.M. Crawford 1988 is proposed at a new genus removing some species from Melosira, but in this key is treated as a synonym.
Habitat:
Plankton, freshwater and marine depending on species. Northern cold water regions, Baltic Sea and in the Oslofjord in Norway. Temperate regions including New England USA.
References:
Agardh, C.A. 1824. Systema Algarum. pp. [i]-xxxvii, [1]-312. Lundae [Lund]: Literis Berlingianis [Berling]. Crawford, R.M. 1988. A reconsideration of Melosira arenaria and M. teres resulting in a proposed new genus Ellerbeckia. In: Algae and the Aquatic Environment. (Round, F.E. Eds), pp. 413-433. Bristol: Biopress. Guiry. M.D. and G.M. Guiry 2013. AlgaeBase. World-wide electronic publication, National University of Ireland, Galway. http://www.algaebase.org; searched on 21 Dec 2013. Hasle, G. et al. Identifying Marine Phytoplankton. Academic Press. (1997).