James G. Morin
The cover graphic indicates the evolutionary relationships among the luminescent and non-luminescent species within the well-known cypridinid ostracods including the Japanese species Vargula hilgendorfii, formerly known as Cypridina hilgendorfii, from which the components of this luminescent system were identified, including the cypridinid luciferin shown in the upper left. Because all luminescent members of the clade use the same basic components, to avoid confusion, it is most parsimonious to use the term ‘cypridinid’ rather than generic designations. Based on the phylogeny it can be inferred that luminescence first evolved as a predator deterrent and secondarily, but only in the Caribbean, as courtship signals. Only about half the species in the family are luminescent. Of the luminescent species, all probably use their light to deter predators while about half (the Caribbean species) also use their light in sexual reproduction. The family includes three recently described new luminescent genera and at least four undescribed luminescent genera (and probably several more). Several species (A-F) are shown on the right including: A: Kornickeria n. sp.; B. H-Group (new undescribed genus) n. sp.; C. Photeros morini; D. ‘Vargula’hilgendorfii (note: this species belongs in a new undescribed genus separate from both Vargula and Cypridina); E. Cypridina dentata and F. Skogsbergia lerneri (a non-luminescent species). See cited references 11–13 and references therein for details.