Figure 2.

Characters of the labial segments of the Mesovelia (Gerromorpha). (a) Shapes of segments: first (I) is ring shaped, well visible from the dorsal side, the second (II) is similar to the first but slightly shorter, and the third (III) is tubular and very long. (b) The fourth segment is tubular, ventral view. (c) The shape of the ventral apical plate (lobe shaped). (d) Shapes of the intercalary sclerites (three large sclerites are visible: dorsal right (is (dr), left (is (dl), and ventral left (is (vl)). (e) The complete view of the labial segment of Mesovelia mulsanti (drawing from Andersen [17]).