PLANKTONIC DIATOMS FROM THE GULF OF CALIFORNIA AND COASTS OFF BAJA CALIFORNIA: THE GENERA RHIZOSOLENIA, PROBOSCIA, PSEUDOSOLENIA, AND FORMER RHIZOSOLENIA SPECIES

Abstract

Net plankton samples from the Gulf of California and coasts off Baja California were analyzed for species of Rhizosolenia, Proboscia and Pseudosolenia, as well as other species of “Rhizosolenia” which do not belong to the genus. Twenty taxa were found: 18 species, one variety and one form. These are briefly described and illustrated by light and electron (both scanning and transmission) microscopy. A new taxonomie combination, Proboscia indica (H. Peragallo) Hernández-Becerril, is proposed. New morphological observations include a large pore open to the outside at the tip of the proboscis and the absence of spinulae. Details of a structure analogous to the contiguous area of typical Rhizosolenia species are given for “Rhizosolenia” pungens; this structure develops as part of the valvocopula rather than the valve. Four new records for the Gulf of California are reported: Rhizosolenia clevei var. communis, Rhizosolenia debyana, “Rhizosolenia” crassispina, and “Rhizosolenia” pungens. The most widely distributed species was Proboscia alata. Possible previous misidentifications in the study area are discussed.