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''Riedelia'' is a genus of alga known from the fossil record, comprising approximately eight species. Many of the species were originally described under the closely allied genus ''Hemiaulus''. Paleontologists Hans-Joachim Schrader and Juliane Fenner, working with fossil specimens obtained from Leg 38 of the Deep Sea Drilling Program in the Norwegian and Greenland Seas, decided that several previous descriptions of diatoms belonging to ''Hemiaulus'' were rightfully placed on ''Riedelia''. Schrader and Fenner note that while ''Hemiaulus'' diatoms have polygonal areolated valves, ''Riedelia'' valves are punctate with isolated punctae. Additionally, ''Riedelia'' typically have two spines, while ''Hemiaulus'' have only one. These characteristics were used to justify the placement of these species in ''Riedelia''.〔Schrader HJ, and J Fenner. 1976. (Norwegian Sea Cenozoic diatom biostratigraphy and taxonomy. ) ''Initial Reports of the Deep Sea Drilling Project'', 38: 997. 〕 ''Riedelia clavigera'' is known from fossils dating from the early Eocene to the middle Oligocene.〔 == Species == The valid species currently considered to belong to this genus are: *''R. alata'' (Greville) H.J.Schrader & J.Fenner *''R. altar'' (J.Brun) H.J.Schrader & J.Fenner *''R. clavigera'' (A.Schmidt) H.J.Schrader & J.Fenner *''R. longicornis'' (Greville) H.J.Schrader & J.Fenner *''R. lyriformis'' (Greville) H.J.Schrader & J.Fenner *''R. mirabilis'' Jousé *''R. sublevata'' J.Fenner *''R. tenuicornis'' (Greville) H.J.Schrader & J.Fenner 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Riedelia (alga)」の詳細全文を読む スポンサード リンク
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