Deliberations on the External Morphology and Modification of the Labial Segments in the Nepomorpha (Heteroptera: Insecta) with Notes on the Phylogenetic Characteristics

Figure 22

Shapes of the labial segments of the Naucoridae. Laccocorinae, (a)–(d) Laccocoris hoogstraali, (e)-(f) Heleocoris humeralis. (a)–(c) Dorsal and lateral views (D-L) of the labium, the shape of the first segment (I) and intersegmental sclerites (si), the tubular shape of the third segment (II) and the conical shape of the IV segment, (d) the intercalary sclerites (is) are slightly visible (reduced), (e) dorsal surface of the second segment (II) is divided into the triangular plate (tp) and the convex plate (cp), the intercalary sclerites (is) are slightly visible (reduced), and (f) the shape of the segment on the dorsal side (D), dorsal view of the first segment with the open stylet groove (gr), the second segment is divided into the triangular plate (tp) and the concave plate (cp), the articulation of the dorsal condyle is distinctly visible, the stylet groove is closed in the II, III, and IV segments. Lr: labrum.