Neogene Cupuladriidae of tropical America. II: taxonomy of recentDiscoporellafrom opposite sides of the Isthmus of Panama

Abstract

We used up to 30 morphological characters to discriminate and describe species of the genusDiscoporellabased on complete colony specimens collected from both coasts of the Isthmus of Panama. The characters included zooidal characters and colony-level characters such as colony size and basal granule density. Species were classified by a series of multivariate cluster and linear discriminant analyses until the majority of specimens were assigned to their putative species with high confidence. In the first phase of the analyses, the colonies were grouped by ocean (Caribbean versus eastern Pacific), discriminated predominantly by colony size and basal granule density, characters that might reflect ecophenotypic responses to different conditions in primary productivity and predation between the two oceans. Further analyses of these two groups separately resulted in the discrimination of seven species. Five new species from the Caribbean (D. scutella, D. peltifera, D. bocasdeltoroensis, D. terminataandD. triangula), and two from the eastern Pacific (D. marcusorumandD. cookae). Of these,D. cookaehad been identified previously asD. umbellata, a species once considered cosmopolitan, with a range spanning the Caribbean and eastern Pacific coasts of America. With the exception of one genetically defined clade represented by only two specimens, the correspondence of classification between groups discriminated morphometrically by separate step-wise multivariate analyses and those detected by a previous genetic analysis, ranged from 91% to 100%. In analyses of all specimens combined or separated by ocean, but using the total number of characters, 20% to 30% of the specimens could not be distinguished morphometrically from extremely similar sympatric species or cognate (“geminate”) species from the opposite ocean. Diversity was higher in the Caribbean compared to the eastern Pacific, which reflects a similar pattern recently described for the genusCupuladriafrom the same region.