Figure 12.

Shapes of the labial segments of the Belostomatidae. (a)–(d) Hydrocyrius colombiae. (a) Dorsal view (D) of the labium, all segments are visible, the articulation of the dorsal condyle (cd) between the II and III segments on the dorsal side, the intercalary sclerites (is) and the stylet groove are visible, (b) the shape of the first segment (I) dorsal view of the triangular shape with the distal margin that is curved inside, the stylet groove is opened, the shape of the proximal part of the second stylet groove is opened, the intersegmental membrane is visible, (c) ventral view (V), the first segment with the midventral condyle, the second segment is elongated, (d) the shape of the third segment (III), ventral view (V), the midventral condyle (cv) on the distal edge of the third segment is visible, the intersegmental membranes are distinctly visible. Bu: buccula of posterior plate. Lr: labrum, Mxp: maxillary plate, Pp: posterior plate of the cranium, stb: stylet bundle.