本文描述位於臺灣東北部南澳闊葉林保留區內之神祕湖的矽藻，為系列報告之最後
一個部份。本文主要係以掃描電子顯微鏡下觀察到的微細形態構造為鑑定依據，共描述在
湖積物表層出現之17 種，分屬於2 目4 科4 屬。其中有9 種為臺灣的新紀錄種，即Navicula
cryptotenella, Navicula ingrata, Navicula subfasciata, Pinnularia borealis var. rectangularis,Pinnularia interrupta, Pinnularia maior, Sellaphora laevissima, S. vitabunda, and Nitzschia perminuta 等。綜合各項資料，顯示此湖有豐富的矽藻資源，在總共發現之76 種矽藻中，有33 種 (約43%) 為臺灣新紀錄種。此外，此湖之矽藻群落種歧異度和種豐富度都比一般水庫高，推測這些現象與此湖為未受污染之貧養湖有關。

This is the last part of study about the diatom flora found in the Mystery Lake, a slightly acidic lake situated within a
hardwood nature preserve in northeastern Taiwan. In this article, we reported 17 species, belonging to 4 genera, 4 families, and 2
orders, based on scanning electron microscopic observations. The species described here, 9 are newly recorded in Taiwan. They are:
Navicula cryptotenella, Navicula ingrata, Navicula subfasciata, Pinnularia borealis var. rectangularis, Pinnularia interrupta,
Pinnularia maior, Sellaphora laevissima, S. vitabunda, and Nitzschia perminuta. In total, we found 76 diatom species in the surface
sediments of this lake. Among them, 33 (43%) are newly recorded to Taiwan. The present study indicates that this lake is
characterized by high species diversity and high species richness, which are related to the oligotrophic and non-polluted
environmental conditions.