Dictyotales


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Dictyotales

 

an order of brown algae (Phaeophyceae) comprising more than 100 species. They live in warm seas; in the USSR they live in the Black Sea and the Sea of Japan. There are four known genera. The thallus is eight to 25 cm high, dichotomously divided into two flat branches (Dictyota) or fan-shaped branches (Padina). It consists of one or several layers of large cells and a single-layer cortex of small cells: it grows from the apex. Reproduction is both sexual and asexual. The gametophytes and sporophytes have identical structure. The sexual process is oogamy. One immobile ovum grows in each oogonium. The male cells (antherozoids) have one flagellum and are formed in multilocular antheridia. The sporophytes usually produce tetraspores; meiosis occurs during this process. Often the sporangia, which do not produce spores, fall off and grow into new plants; sometimes the sporangia begin to grow on the mother plant. If the Dictyotales have tetraspores and single-flagellum antherozoids, they are sometimes placed in a separate class of brown algae—Aplanosporophy ceae.

References in periodicals archive ?
Howe C1 HETEROKONTOPHYTA Clase Phaeophyceae Orden Dictyotales Dictyotaceae 41.
In general, the reef habitat was characterized with a wide coverage of fleshy algae (mainly brown algae that belongs to the Order Dictyotales and the green algae Caulerpa racemosa ((Forsskal) J.
Herbivorous ampithoids from the genera Ampithoe and Peramphithoe often cause blade loss on brown algae from the orders Dictyotales and Laminariales (e.
Dictyotales, Sphacelariales, and algal turfs, which occurred abundantly at the site.
In the Mediterranean there is a zone dominated by other species of Cystoseira, members of the order Dictyotales (another order of phaeophytes) and by Halopteris scoparia (a phaeophyte of the order Sphacelariales).
diesingiana are all from the order Dictyotales, which is well known to contain a diverse range of biologically active secondary metabolites (Hay and Fenical 1988).
Species from the Order Dictyotales are the most abundant on both islands, but the sea floor of Robinson Crusoe differs from that of Easter Island in that it is made up of rocky reefs with high abundances of sessile invertebrates (e.
Nuclear content estimates suggest a synapomorphy between Dictyota and six other genera of the Dictyotales (Phaeophyceae).
W DIVISION OCHROPHYTA Class Phaeophyceae Order Dictyotales Family Dictyotaceae Dictyota dichotoma (Hudson) Lamouroux E&W Diciyoia sp.
Agardh Tropical 2138 Caluerpa sertularioides (Gmelin) Howe Tropical 2139 Familia Codiaceae Codium magnum Dawson Templado 2140 Codium pincturatum Pedoche & Silva Endemico 2141 Codium simulans Setchell & Gardner Endemico 2142 Familia Bryopsidaceae Bryopsis pennatula Lamouroux Cosmopolita 2143 Derbesia marina (Lyngbye) Solier Templado 2144 Familia Udotaceae Halimeda discoidea Decaisne 2145 DIVISION PHAEOPHYTA CLASE PHAEOPPHYCIDAE ORDEN SPHACELARIALES Familia Sphacelariaceae Sphacelaria californica (Suvers) Setchell & Gardner Templado 2146 Sphacelaria rigidula Kutzing Tropical 2147 ORDEN DICTYOTALES Familia Diclyotaceae Dictyota crenulata J.
and three other genera of Dictyotales (see references in Hay et al.