Planctonema
| Planctonema | |
|---|---|
Scientific classification 
| |
| Clade: | Viridiplantae |
| Division: | Chlorophyta |
| Class: | Trebouxiophyceae |
| Order: | Chlorellales |
| Family: | Oocystaceae |
| Genus: | Planctonema Schmidle |
| Type species | |
| Planctonema lauterbornii Schmidle[1]
| |
| Species | |
Planctonema is a genus of green algae in the class Trebouxiophyceae.[2] It is found in freshwater habitats as plankton,[1] and is found worldwide. It is dominant in lakes during the summer and autumn months.[3]
The classification of Planctonema has varied historically. It was originally described by Wilhelm Schmidle as a heterokont, and has also been placed in the family Ulotrichaceae. Molecular phylogenetic evidence has shown that Planctonema is closely related to members of the family Oocystaceae,[3] and AlgaeBase places Planctonema in Oocystaceae.[1] However, it lacks the cell wall ultrastructure characteristic of the family.[3]
Description
[edit]Planctonema consists of short, uniseriate filaments surrounded in a common mucilaginous sheath. Individual cells. Individual cells are spaced apart equidistantly, or end-to-end in separate pairs; the space between cells is filled with mucilage. Cells are cylindrical, with a parietal, plate-like chloroplast without pyrenoids or starch. The nucleus is located in the median constriction of the chloroplast. At the ends of the cell poles are vacuoles containing conspicuous oil globules.[1]
Vegetative reproduction occurs by the fragmentation of filaments. Sexual reproduction is unknown.[1]
Similar genera include Psephonema (formerly considered to be synonymous with Planctonema), and Planctonemopsis, described in 2017. Psephonema has shorter cells than Planctonema (with a length–width ratio of 1.5–2, while Planctonemopsis has chloroplasts with pyrenoids).[3]
References
[edit]- ^ a b c d e Guiry, M.D.; Guiry, G.M. "Planctonema". AlgaeBase. University of Galway. Retrieved 2025-02-05.
- ^ See the NCBI webpage on Planctonema. Data extracted from the "NCBI taxonomy resources". National Center for Biotechnology Information. Retrieved 2007-03-19.
- ^ a b c d Liu, Xudong; Zhu, Huan; Liu, Benwen; Liu, Guoxiang; Hu, Zhengyu (2017). "Classification of Planctonema-like algae, including a new genus Planctonemopsis gen. nov., a new species Planctonema gelatinosum sp. nov. and a reinstated genus Psephonema (Trebouxiophyceae, Chlorophyta)". Journal of Phycology. 53 (4): 869–879. Bibcode:2017JPcgy..53..869L. doi:10.1111/jpy.12551. PMID 28542872.
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