Ostracods are a group of small crustaceans found abundantly across freshwater and marine habitats. Within the family Cypridinidae, males of many species found exclusively in the Caribbean evolved to produce magnificent bioluminescent courtship displays. During courtship displays, males swim helically in the water column and emit pulses of bioluminescence in a variety of species-specific patterns. The species-specific nature of these displays may have led to an increase in diversification rates, since clades from multiple groups that use bioluminescent signaling consistently have more species than non-displaying sister groups. Due to such high levels of diversity, putative new species are collected frequently by targeting unique display patterns. During a field expedition to Belize, we captured a previously undescribed species of cypridinid ostracod with a downward angled display that could not be easily matched to any previously described species, and was even difficult to place within a genus. Here, we present a species description for this population of ostracods. By identifying distinguishing morphological features using compound microscopy and confocal imaging, as well as transcriptome-based phylogenetic methods, we establish this group of ostracods as a new species in Cypridinidae within the genus Maristella.