Inverse larval development in a Devonian edrioasteroid from Spain and the phylogeny of Agelacrinitinae

The first edrioasteroid to be discovered from the Iberian Peninsula is reported from the Emsian (late Lower Devonian) of the north Spanish coast. It belongs to the species Krama devonica (Bassler) but is unusual in being a mirror image form. This is interpreted as the product of situs inversus during larval development whereby the coeloms on the right side rather than the left side of the bilateral larva have given rise to the definitive adult structures. Thus the hydropore lies in its mirror image position vis-à-vis the anterior/posterior axis and this axis must be homologous with Lovén's symmetry plane in echinoids. The phylogenetic position of Krama is analysed cladistically and, by combining this with available stratigraphical information, the most parsimonious phylogenetic tree is produced for the subfamily Agelacrinitinae.