204 Skeletonema 骨條藻 Phylum: Heterokontophyta 门：不等鞭毛門 Class: Mediophyceae 纲：中型硅藻綱 Order: Thalassiosirales 目：海鏈藻目 Family: Skeletonemataceae 科：骨条藻科 Morphology Cells are generally spherical, lenticular, or short cylindrical in shape, with relatively thin frustules. Diameters range from 5 to 38 μm. Valves are circular, flat or slightly convex. A circle of long, thin, tube-like fultoportula arise from valve margin, parallel with pervalvar axis. Adjacent cells are united by fultoportula and form chains with different length. There are 13 Skeletonema species in total, which are difficult to identify with light microscopic observation only. The differentiation of different species is mainly based on number of chloroplasts, length of chains and ultrastructure of frustules analyzed by electron microscopy. One to two chloroplasts are present in cells generally and some species possess up to 10 chloroplasts. Ecology and distribution Skeletonema species are one of most important and dominant diatom groups in coastal waters globally and form blooms frequently. Skeletonema species have caused more than 50 blooms in Hong Kong coastal waters since 1985. 形態 細胞一般呈球形、透鏡形或短圓柱形，細胞壁比較薄，直徑5到38微米。殼面呈 圓形，平或者輕微凸起，殼面邊緣生成一圈與貫殼軸平行的細長的管狀支持突。相 鄰細胞之間支持突連接形成長短不同的鏈狀群體。今生骨條藻目前有13 個物種， 光學顯微鏡下極難分辨。不同物種的鑒定主要依據電子顯微鏡觀測細胞壁超顯微 結構差異。一般具1到2個色素體，也有的物種多達10個色素體。
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