The cypridinid copulatory limb and a new genus Kornickeria (Ostracoda: Myodocopida) with four new species of bioluminescent ostracods from the Caribbean

Abstract

Kornickeria , a new genus of myodocopid ostracod (Cypridinidae) in the Caribbean Sea, is described in terms of morphology and species-specific bioluminescent display patterns. Four new species are described: Kornickeria louisi , the type species for the genus, K. coufali, K. marleyi and K. hastingsi , which includes two subspecies: K. hastingsi hastingsi and K. hastingsi carriebowae . Vargula bullae is reassigned to Kornickeria with a supplementary description. Of the new species, the first three are known only from Jamaica and the last from Jamaica, Belize and Roatan. All are found primarily among shallow coral reef habitats where the males produce vertical trains of luminescent secretions as species-specific courtship patterns. Kornickeria is defined by several derived morphological characters, but species differ more in luminescent displays than morphology. Displays are restricted to upward and downward variations of vertical displays and consist of a shortening phase of a few bright pulses and a longer trill phase of dimmer, fairly closely and evenly spaced pulses. Train lengths are relatively short compared to those of many other Caribbean signalling species. Both the described (5) and undescribed (c. 12) species of Kornickeria known thus far are confined to the Caribbean Sea, but the genus is distributed more widely within the Caribbean than the other signalling cypridinid clades. Kornickeria species have been found in all Caribbean sampling localities except Panama where they are apparently replaced by their sister clade, the Z-Group. The slight non-clinal geographic variation (as well as the behavioural variation of one population) exhibited in the most shallow-dwelling species, K. hastingsi , may reflect (1) the presence of morphologically and behaviourally cryptic species, (2) unexpected and unexplained dispersal abilities and/or (3) current but incomplete speciation processes. The paired male copulatory organs are an eighth pair of ostracod limbs, which bear many useful systematic characters. A general plan, which we here produce as a model, applies to the limb throughout the family Cypridinidae. Homologies within the Cypridinidae were found for many copulatory characters, particularly the setae, ornamentation, lobe shapes and internal sclerites. Articulation of internal sclerites marks separation of the limb into two articles. Three lobes extend from the limb: two (inner and central) from the basal article and one (outer) from the distal article.