New records and combinations of Lyrella (Bacillariophyceae: Lyrellales) from a protected coastal lagoon of the northwestern Mexican Pacific

To determine the diversity of species and subspecific taxa of diatoms of the genus Lyrella found in subtidal sediments of Laguna Guerrero Negro (LGN), BCS-BC (Mexico), samples from 4 seasons were analyzed. Twenty-one species and sub-specific taxa of Lyrella are here recorded within a floristic list of 232 identified epipelic diatom taxa. Seven Lyrella taxa are new records for the Mexican coasts and 12 for the northwestern Mexican region. Additionally, we are proposing 6 transfers of taxa into Lyrella that remained hitherto in the genus Navicula. Morphometric and meristic data, and an iconographic reference are provided. Environmental conditions in the lagoon favor the diversity and abundance of Lyrella species and sub-specific taxa. Thus, LGN is proposed as a diversity hotspot for this genus. Lack of floristic studies on benthic diatoms in much of the Mexican coasts precludes insight of their ecology and distribution. However, continuous floristic surveys should eventually allow precise definition of their biogeographic affinities.