Recent approaches to the taxonomy of the Gracilariaceae (Gracilariales, Rhodophyta) and the Gracilaria verrucosa problem

Abstract

Recognition of species in the Gracilariaceae, often notoriously difficult, is being aided by a combination of classical and modern techniques . We review some recent findings and present new results that may lead to redefinition of Gracilaria verrucosa, the type species of its genus . Plastid DNA restriction profiles (patterns of banding obtained by electrophoresis of DNA after restriction endonuclease digestion) from eleven strains ascribed to G. verrucosa indicated that the concept of this species in northern Europe includes possibly three taxa, one of which is known now to be a species of Gracilariopsis . In contrast, restriction profiles from Argentinian and Japanese strains were closely similar to the predominant pattern for European G . verrucosa . Profiles of several other strains, from the western Atlantic and eastern Pacific, were dissimilar to the European group and to each other . A chromosome number of n = 24 was determined for a representative of the predominant European group, and preliminary results of hybridization trials suggest that these strains, and others with approximately the same plastid DNA restriction pattern, are interfertile .

Chemical structure and quality of agars from Gracilaria

“…The recently added order of Gracilariales constitutes one of the largest in the phylum, accounting for 42 families, 170 genera and over 1120 species (Fredericq & Hommersand, 1989;Woelkerling, 1990;Gargiulo et al, 1992). In this order, the genus Gracilaria includes many species with taxonomic problems arising from the incomplete knowledge of their reproductive features, a high degree of morphological variability and the complexity of the cell wall chemistry (McCandless, 1978;Gabrielson & Garbary, 1986;Goff& Coleman, 1988;Bird & Rice, 1990;Bird et al,1992). The nomenclature in this review follows Bird and Kain (1995).…”

Morphological variations of Gracilaria chilensis Bird, McLachlan et Oliveira, 1986 (Rhodophyta, Gracilariales) in the southeast Pacific

“…Candia (1988) and Möller & Westermeier (1988) reported Gracilaria chilensis in southern Chile without mentioning the presence of nutritive filaments, as is observed in the present work. This may be related to the variability of the character (Papenfuss 1967, Yamamoto 1978, Bird & McLachlan 1984, Oliveira 1984, Bird & Rice 1990. Searles et al (1974) TABLA IV.…”

Macroalgal Distribution Patterns and Ecological Performances in a Tidal Coastal Lagoon, with Emphasis on the Non-indigenous Codium Fragile ssp. Tomentosoides

“…fragile, and include ( tikvahiae (Bird & Rice 1990, McLachlan 1979. In this thesis the two morphologies were treated as independent species and their old taxonomic nomenclature used (Humm 1979) because of significant differences in abundance patterns within Hog Island Bay.…”

“…2 The terete Gracilaria form is referred to as G. verrucosa (Humm 1979, Schneider & Searles 1991) and the flat as G. foliifera, although they may be conspecific and potentially should be referred to as G. tikvahiea (Bird & Rice 1990, McLachlan 1979. 3 Potentially with a minor component of U. rotunda and Monostroma sp.…”