A re-examination of Tetrasporopsis (Chrysophyceae) and the description of Dermatochrysis gen. nov. (Chrysophyceae): a monostromatic alga lacking cell walls

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Abstract
Studies on the generitype and Australian material of Tetrasporopsis (De Toni) Lemmermann are used to elucidate the concept of this genus. A specimen collected by A. Braun in 1846 is chosen as the lectotype for the type species, T. fuscescens (A. Braun ex Kützing) Lemmermann. Australian collections closely matched the type material and could be examined in more detail. Both the Australian and type specimens have cell walls, chloroplasts with girdle lamellae, chloroplast lamellae with three adpressed thylakoids, and mitochondria with tubular cristae. Contractile vacuoles were not observed in living Australian material. Centrioles were also present, but flagella and zoospores were not observed; no microtubules were preserved in the type material. A new genus, Dermatochrysis gen. nov., is proposed for colonial monostromatic algae belonging to the Chrysophyceae that lack cell walls and contain contractile vacuoles. Three species are transferred from Tetrasporopsis to Dermatochrysis: D. reticulata (Meyer) comb. nov., the type species; D. pseudofenestrata (Lund) comb. nov. and D. pelagica (R.E. Norris) comb. nov. The relationship of Dermatochrysis to Tetrasporopsis and other capsoid and coccoid genera is discussed.