The marine planktonic diatom Rhizosolenia robusta (Bacillariophyta): morphological studies support its transfer to a new genus, Calyptrella gen. nov.

The marine planktonic diatom Rhizosolenia robusta Norman is widely distributed in tropical and subtropical areas and occurs occasionally in more temperate ones. Traditionally it has been considered a species of the genus Rhizosolenia, but its taxonomic status has not been reviewed. The present study is based on light and electron microscopy of net plankton samples front several tropical and Subtropical locations. including Pacific and Atlantic coasts of Mexico and the Indian Ocean. Features unique for this species include Undulated and ribbed valves, the Structure Of the valve wall, the morphology of the process at the apex of each valve, the location and shape of the labiate structure, and the arrangement of the girdle hands. These features Support transfer to a new genus Calyptrella gen. nov. its Calyptrella robusta (Norman) Hernández-Becerril et Meave. Morphological variability includes Shape Of file cell and length of the external tube. The term 'calyptra' is reintroduced for it structure analogous to the process of Rhizosolenia sensu stricto. The morphology of the complex labiate structure-external tube is discussed, and the term 'conflatuportula' (United rimoportula) is proposed for this Structure. Further studies are necessary to decide whether Rhizosolenia firma Karsten belonggs to the new genus

Toxic and harmful marine phytoplankton and microalgae (HABs) in Mexican Coasts

Harmful Algal Blooms (HABs) are becoming an increasing problem to human health and environment (including effects on natural and cultured resources, tourism and ecosystems) all over the world. In Mexico a number of human fatalities and important economic losses have occurred in the last 30 years because of these events. There are about 70 species of planktonic and non-planktonic microalgae considered harmful in Mexican coasts. The most important toxin-producing species are the dinoflagellates Gymnodinium catenatuni and Pyrodinium bahamense var. compressum, in the Mexican Pacific, and Karenia brevis in the Gulf of Mexico, and consequently the poisonings documented in Mexico are Paralytic Shellfish Poisoning (PSP) and Neurotoxic Shellfish Poisoning (NSP). Although there is evidence that Amnesic Shellfish Poisoning (ASP), Diarrhetic Shellfish Poisoning (DSP) and Ciguatera Fish Poisoning (CFP) also occur in Mexico, these problems are reported less frequently. The type of phytoplankton and epiphytic microalgae, their toxins and harmful effects as well as current methodology used to study these phenomena are presented in this paper. As an experienced group of workers, we include descriptions of monitoring and mitigation programs, our proposals for collaborative projects and perspectives on future research