Journal of the Marine Biological Association of India

Volume 14 Issue 1

Reproduction in the calcareous green algae of coral reefs

Lewellya Hillis-Colinvaux
Abstract

Reproduction in Halimeda is often summarised in text books as ' sexual'; for Penicillus the existence of any sexual stage has been questioned. In this paper I present information on physiological and morphological aspects of sexual stages in the two genera, based on material from the International Indian Ocean Expedition [IIOE] and my Laboratory cultures.

 

Although Halimedae with the so-called 'gametangia' appear in culture relatively frequently, the life cycle is not completed. The many new plants in my cultures, and possibly those in the field, arise vegetatively in several ways. The commonest method, the development of new plants at the end of certain rhizoids, occurs in Halimeda, Penicillus, Rhipocephalus, and Udotea. New plants may also develop at cut surfaces, and by fragmentation.

 

The distributional pattern of some species has been extended considerably, based on the large amount of Halimeda material from the 1963-65IIOE which filled the existing void. Sixteen species are now known for the Indian Ocean, two macrophysa and velasquezifor the

first time. Halimeda micronesica is known from many sites throughout the Indian Ocean rather than from the Seychelles only -.H. copiosa is new; and H. remschii reinstated. Particularly exciting is the extension for H. cuneata, the only distinctly subtropical species in the genus. It had seemed to be restricted to the southern hemisphere, but during the IIOE was collected in the northern subtropics too. The vertical distribution of certain species is extended also.

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Date : 30-06-1972