Schusteria marina sp. nov. is a newly discovered intertidal mite species found on the Lesser Antillean Islands of Martinique and Grenada. It represents the first record of the genus Schusteria within the Caribbean area. Schusteria marina sp. nov. is very similar to the type species, S. littorea from Brazil, but can be distinguished by its smaller body size, a median sternal dark sclerotized small ridge on epimeron I and a few other less pronounced differences. Both species are closely related and form a Western Atlantic Schusteria clade, which is characterized by the possession of a pair of faint anterior epimeral ridges. Schusteria marina sp. nov. occurs on different littoral substrates, e.g. mangrove roots, anthropogenic concrete structures, but seems to be associated with an intertidal red alga belonging to the genus Bostrychia Montagne, 1842 growing on these substrates. http://zoobank.org/urn:lsid:zoobank.org:pub:C246533E-D108-4F2C-8577-545C059D46CE.