Studies on some Indian members of the Rhodymeniales

Kalimuthu, S (2000) Studies on some Indian members of the Rhodymeniales. ["eprint_fieldopt_thesis_type_phd" not defined] thesis, Bharathidasan University, Tiruchirappalli.

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Abstract

The order Rhodymeniales is a 'rell-defined group when compared with some of the other orders of the class, Rhodophyceae. This order consists of rather naturally distinctive groups (Kylin, 1956; Sparling, 1957). Rhodymeniales currently includes three families viz. Champiaceae, Lomentariaceae and Rho1dymeniaceae (Silva et al., 1996) . Schmitz (1889) introduced the order Rhodymeninae with six families : Sphaerococcaceae, Rhodymeniaceae, Delesseriaceae, Bonnemaisoniaceae, Rhodomelaceae and Ceramiaceae. Later the Delesseriaceae, Rhodomelaceae and Ceramiaceae were transferred to ceraliales by Oltmanns (1904). Sjoestedt (1926) erected a new order Sphaerococcales for he Sphaerococcaceae and Kylin (1928) placed Bonnemaisoniaceae in Nemalionales. The order Rhodymeniales is ,haracterised by the procarp bearing one or two auxiliary-cell branches composed of 0 cells (except for Epymenia obtusa which bears three-celled ones), which are initiated directly from the supporting cell before fertilisation. However, these cell branches become distinctive generally only after fertilisation. The algal thallus is flattened or slightly flattened, cylindrical or hollow, and shows multiaxial growth with meristems located at the apex or margin. Tetrasporangia occur either terminally or intercalarily in the cortical layer and are divided cruciately or tetrahedrally (except Coeloseira which bears polysporangia). Spermalangia originate from superficial cortical cells. Cystocarps are surrounded by a perica)p with ostiole. The life cycle is generally of triphasic haplodiplontic type i.e. Polysiphonia-type.

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