Studies on the Genus Scenedesmus Meyen (Chlorphyceae, Cholorococcales) from South India, with Special Reference to the Cell Wall Ultrastructure

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In December 1975 the authors collected about 25 plankton samples mainly in and around Madras and Mysore, India. 150 Scenedesmus strains were isolated and studied with the light and electron microscope and if possible compared with natural populations of the ponds from which isolates were received. Several taxa were new records for India.

The cell wall ultrastructure was studied for the first time for Scenedesmus costato-granulatus SKUJA, S. armatus var. bicaudatus (GUGL.) CHOD., S. armatus var. spinosus FRITSCH et RICH, S. armatus var. microspinosus (HORTOB.) HEGEW. et HIND., S. armatus var. exaculeatus CHOD., S. opoliensis var. mononensis CHOD., S. opoliensis var. alatus DEDUS., S. opoliensis var. brevicaudatus HORTOB., S. brasiliensis BOHL., S. pannonicus var. caudato-granulatus HORTOB. and S. subspicatus var. longicauda (G.M. SMITH) CHOD.

The Indian strains of S. armatus CHOD. var. armatus differ from all other known isolates in the lack of armed warts and may be a local race. Scenedesmus fuscus (SHIH. et KRAUSS) HEGEW. and S. abundans (KIRCHN.) CHOD. show an extreme variability under the light and electron microscope and alternatively produce different cell wall structures. Both taxa are closely related to S. nanus CHOD. Contrary to the type strain of S. fuscus (SHIH. et KRAUSS) HEGEW., which produces only single cells, the Indian strain produces spineless as well as spined coenobia. Other species which produce different coenobia types and different EM structures are S. komarekii HEGEW. and S. spinosus CHOD. Another species with similar variability is the newly described taxon S. multiformis HEGEW. et HIND.

New combinations are S. armatus var. microspinosus (HORTOB.) HEGEW. et HIND. (S. spinosus var. microspinosus HORTOB.), S. armatus var. longispina (CHOD.) HEGEW. et HIND. (S. longispina CHOD.), S. komarekii var. hirsutus (HIND.) HEGEW. et HIND. (S. hirsutus HIND.) and S. brasiliensis var. serrato-perforatus (PATEL et GEORGE) HEGEW. et HIND. (S. serrato-perforatus PATEL et GEORGE), and the following names were reintroduced: S. armatus var. spinosus FRITSCH et RICH for S. armatus var. brevicaudatus (PÉTERFI) HEGEW. and S. arthrodesmiformis SCHRÖD. for S. pulloideus HEGEW.

9 of 22 strains studied showed high temperature resistance (38 °C), these were all strains of S. obliquus (TURP.) KÜTZ. and S. pectinatus MEYEN and one strain of S. opoliensis var. brevicaudatus HORTOB.

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