The pencil urchins (order Cidaroida) were represented in our study by Eucidaris tribuloides, collected on the Atlantic coast of Panama; the order Diadematoida by Diadema antillarum, also from the Atlantic coast of Panama.
As the figure indicates, bindin is present not only in the Echinoida and the Arbaeioida (from which it was previously known), but also in the sand dollars (Clypeasteroida) and the heart urchins (Spatangoida), as well as the phylogenetically much more distant Diadematoida and Cidaroida.
In two other large orders, Echinoida and Diadematoida, respectively, 69% of 65 species and 54% of 48 species were sampled.
Part 2, Echinothurioida, Diadematoida and Stirodonta (1, Calycina).
Orden Cidaroida Claus, 1880 Familia Cidariidae Gray, 1825 Genero Eucidaris Pomel, 1883 Eucidaris thouarsii (valenciennes, 1846) Orden Diadematoida
Duncan, 1889 Familia Diadematidae Gray, 1855 Genero Diadema Gray, 1825 Diadema mexicanum (A.
The presence of a posterior process and posterodorsal arms makes the larva of Aspidodiadema jacobyi much more similar to larvae of irregular urchins in the order Spatangoidea than to other families of the order Diadematoida, to which the family i s normally assigned.
Emlet (1988a) has argued on the basis of larval form that the Micropygidae, which have also been raised to ordinal status by Jensen (1981), should also be included as a family in the Diadematoida.
By assuming that the 2-arm larval form with widely spread arms is synapomorphic, Emlet (1988a) argues parsimoniously that the Aspidodiademidae must be a sister group to the Diadematoida, having branched off the major clade of regular euechinoids earlier than the diadematids or micropygids.
The order Diadematoida is currently composed of three families: Diadematidae, Lissodiadematidae, and Aspidodiadematidae (Smith, 1984).