Observations on some planktonic dinophysoid dinoflagellates (Dinophysales, Dinophyta) from the Mexican Pacific, including the description of a new species, Dinofurcula pseudoultima sp. nov., and taxonomic and distribution notes about the genera Latifascia and Triposolenia.

[摘要] Dinoflagellates are an important component of marine phytoplankton in terms of diversity, biomass, and ecological role as primary and secondary producers. Dinophysoids are thecate dinoflagellates with solitary cells divided in two halves, sagittal suture, reduced epitheca, and prominent cingular and sulcal lists. During the analyses of phytoplankton samples from the tropical Mexican Pacific, specimens of rare and little-known dinophysoid species were found, including a new species, Dinofurcula pseudoultima sp. nov., as well as Dinofurcula ventralis, Latifascia inaequale, Triposolenia bicornis, Triposolenia depressa and Triposolenia longicornis that were studied using basically light microscopy, and scanning electron microscopy for one species. All species are heterotrophic forms, with food vacuoles and no chloroplasts. The new species Dinofurcula pseudoultima is a small cell with a characteristic domed epitheca, an epithecal crest and a triangular dorsoposterior process, differing in cell shape and size from the closely related species Dinofurcula ultima. Dinofurcula ventralis in our samples was almost identical in shape and size to the original description. Detailed observations of Latifascia inaequalis showed important plates that characterize this species, particularly H1 (first hypothecal plate); the left sulcal list does not belong entirely to the left half, as originally described. Triposolenia longicornis had a shape and size very similar to the original description and, surprisingly, it was found in one coastal station. Dinofurcula ventralis and Triposolenia longicornis are illustrated since these are their original findings, and together with Latifascia inaequalis they represent new records in the Mexican Pacific. Triposolenia bicornis and Triposolenia depressa are firstly illustrated for the Mexican Pacific. New taxonomic combinations are proposed within the genus Latifascia.

[学科分类] 生物科学（综合）

[关键词] dinoflagellates;dinophysoids;morphology;new records;new species;Mexican central Pacific;phytoplankton