Basso D., Rodondi G. and Bressan G. 2011. A re-description of Lithothamnion crispatum and the status of Lithothamnion superpositum (Rhodophyta, Corallinales). Phycologia 50: 144-155. DOI: ...10.2216/10-20.1
After re-examination of the original Hauck's collection, a buried, empty multiporate tetrasporangial conceptacle was detected in the lectotype material of Lithothamnion crispatum. The morphology and anatomy of the type material were compared to freshly collected representative plants from the Mediterranean. In L. crispatum, the five to seven rosette cells surrounding each pore of the tetra/bisporangial conceptacle roof are larger than the normal epithallial cells and undergo degeneration. As a consequence of the disintegration of the outermost cells in filaments surrounding the pore canals, the tetra/bisporangial conceptacle roofs appear pitted with depressions, each one hosting a pore and the surrounding rosette cells. A previous revision of the type material of Lithothamnion superpositum from South Africa showed this same tetra/bisporangial conceptacle roof structure and development, and corresponding vegetative and reproductive characters. These taxa are thus conspecific; therefore, L. superpositum is a younger heterotypic synonym of L. crispatum, the latter having nomenclatural priority. While the type specimen lacked gametangial plants, these are described for representative freshly collected material and found to be dioecious.
Issue Title: Theme Marine Biodiversity: Patterns and Processes, Assessment,Threats, Management and Conservation The practical assessment of the biogenic structural complexity poses some problems in ...non-symmetrical or three-dimensional macroalgae. This study represents the first attempt to measure quantitatively the phenology and the plasticity of Cystoseira barbata (Stackhouse) C. Agardh in the Mediterranean Sea. This canopy-forming brown alga is characterised by a ramified monopodial cauloid and a dendroid frond. To analyse the morphological-spatial changes in time and the plasticity of C. barbata an experiment was conducted in a protected sea area of the Northern Adriatic Sea on thalli taken from a natural population and a transplanted one, re-located in deeper water. The three-dimensional complexity of thalli and the frond architecture were analysed by means of quantitative structural (total area, perimeter) and spatial (intercepting area, volume and interstitial area) attributes. A preliminary assessment of the primary production of the basiphyite-epiphyte system was investigated by a volumetric analysis. The thalli showed a seasonal pattern characterised by a marked phenological variation of the fronds, both in size and in shape. The seasonal trend was comparable in the both populations studied, with fronds largest in spring-summer, whereas the fall of phylloids and branchelets occurs in autumn-winter. Also the abundance of algal epibionts on the host varied seasonably and depended mainly on the life-form of Cystoseira fronds, where complex fronds encouraged more abundant associated epibionts. The morphological variability of different individuals was also investigated using some bio-structural indices. These indices were proposed as useful for a more detailed description of the phenology of C. barbata and for a better evaluation of the potential micro-spatial and structural habitat available inside the fronds. The proposed protocol and the quantitative descriptors analysed may be employed in physiological or ecological studies, being useful for a standardisable classification of a habitat's complexity. The analysed spatial and structural attributes, as well as the definition of the complexity of C. barbata, enable the evaluation of the area available for the attachment and shelter of epibionts together with the number and type of potential habitats.PUBLICATION ABSTRACT
PDF
