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

Figure 27

Shapes of the labial segments of the Naucoridae. Naucorinae, (a)–(e) Naucoris maculatus, (f) Namtokocoris siamensis. (a) Lateral view on the labium, the II segment has the shape of a narrow strap, the III segment is tubular, the IV segment is conical, the stylet groove is closed in these segments, (b) dorsal view (D) of the labium, the first segment (I) with the open stylet groove (gr), in the second segment the triangular plate is visible, laterally, the intersegmental sclerit (si) can be observed, (c) the shape of the segments in the dorsal view (D), the second segment is divided into the triangular plate (tr) and the convex plate (cp), intercalary sclerites are slightly visible, the articulation between the second and third segments (cd), (d) dorsal view (D), the second segment is divided into the triangular plate (tp) and the concave plate, detailed view, (e) the intercalary sclerites are slightly visible, and (f) dorsal view of the labium, the III and IV segment are visible, the intercalary sclerites (is) are almost reduced. Lr: labrum, stb: stylet bundle.