The 4th edition of this catalogue contains information on the cultivation and composition characteristics of 50 microalgae. Each entry includes relevant links to Atlantic Area stakeholders known to have a relevant connection with each of the species listed, be it in the form of culture collections, research expertise, technology developers, or biomass producers. We invite the readers to visit and/or join the EnhanceMicroAlgae Stakeholder database: an easily accessible, visual and open access database that brings together all the European Atlantic Area players working in the microalgae sector.This publication is part of the deliverables of the Interreg-funded international project EnhanceMicroAlgae. The authors gratefully acknowledge the European Regional Development Fund (ERDF) Interreg Atlantic Area programme which funded the EnhanceMicroAlgae project: EAPA_338/2016, "High added-value industrial opportunities for microalgae in the Atlantic Area"