189 Ditylum brightwellii 布氏雙尾藻 Phylum: Heterokontophyta 门：不等鞭毛門 Class: Mediophyceae 纲：中型硅藻綱 Order: Lithodesmiales 目：石絲藻目 Family: Lithodesmiaceae 科：石絲藻科 Morphology Cells are generally in a triangular prism shape, with a triangular valve and a roughly rectangular girdle view. The heights are generally remarkably larger than width. There is a circlet of short spines on valves edge and a long robust hollow spine with flat end in center of the valve. Cells are solitary or form short chains connected by the large hollow spine extending from the valve center. The frustules are relatively thin. Numerous small granular chloroplasts are present in the cells. 形態 細胞一般呈三棱柱形狀，殼面通常為三角形，殼環面觀大致為矩形。一般高度明顯 大於寬度。殼面邊緣有一列小短刺, 殼面中央生一中空粗壯大刺，末端平截。細胞 單個生存或者通過殼面中央的中空大刺相連形成短鏈。細胞壁較薄。色素體數量較 多，為小顆粒狀。 Ecology and distribution Ditylum brightwellii is a species with a broad temperature range which is widely distributed from cold zone to tropical waters. 生態與分佈 布氏雙尾藻是廣溫性物種，廣泛的分佈於寒帶到熱帶。
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