Light micrographs showing selected morphological character states for characters 14 to 42.

<p>A. Ventral view of segment 1 in <i>Mixtophyes abyssalis</i>, showing an undifferentiated sternal plate (character 16, state 0), and lateral projections at the anterior segment margin (white arrows) (character 14, state 1). B. Ventral view of segment 1 in <i>Paracentrophyes anurus</i>, showing a partly differentiated sternal plate (partial fissure marked with black arrows) (character 16, state 1), and lateral projections at the anterior segment margin (white arrows) (character 14, state 1). C. Ventral view of segment 1 in <i>Pycnophyes greenlandicus</i>, showing fully differentiated midsternal (ms) and episternal (ep) plates (character 16, state 2). Note also the lateral projections at the anterior segment margin (white arrows) (character 14, state 1). D. Ventral view of segments 2 and 3 in <i>Echinoderes astridae</i>, showing segment 2 forming a completely closed ring (character 19, state 0). E. Ventral view of segments 2 and 3 in <i>Meristoderes macracanthus</i>, showing partly differentiated lateral fissures (black/white arrows) on segment 2, but no midsternal fissure (character 19, state 1). F-G. Ventral view of segments 2 and 3 in <i>Fissuroderes sorenseni</i> (F) and <i>Polacanthoderes martinezi</i> (G), showing completely developed lateral and midsternal fissures (black/white arrows) on segment 2, and hence fully differentiated sternal plates (character 19, state 3). H. Ventral view of segments 10 and 11 in <i>Wollunquaderes majkenae</i>, showing midterminal (mts), lateral terminal (lts) and lateral terminal accessory spines (ltas) (character 38, state 1 and character 41, state 1). I. Ventral view of segments 10 and 11 in <i>Paracentrophyes quadridentatus</i>, showing its minute midterminal process (mtp) (character 41, state 0 and character 42, state 1).