Planktonic diatoms from the Gulf of California and coasts off Baja California: Species of the genus Thalassiosira

Net phytoplankton samples from the Gulf of California and coasts of Baja California were analyzed, and observations are given on the species encountered of the diatom genus Thalassiosira. The material was studied by light and electron microscopy. Nineteen taxa (18 species and one variety) were identified, with two tentative identifications. Morphological details are provided for most of the species. Four species are new records for the Pacific Mexican waters (including the Gulf of California). This appears to be the first record of the species T. exigua, since its original description. Some species are fairly rare in tropical region