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

Figure 23

Shapes of the labial segments of the Naucoridae. Limnocorinae, (a)–(g) Limnocoris lutzi, (a)-(b) Dorsal and lateral view (D-L) of the labium, the shape of the first segment (I) with the open stylet groove (gr), the second segment dorsally divided into the triangular plate (tp) and the strong convex plate (cp), the wing plate laterally extended (wd), the intercalary sclerites are distinctly visible, the articulation of condyles and the intersegmental membrane are visible, (c) the dorsal surface of the second segment in detailed, (d) the conical shape of the fourth segment, the tubular shape of the third segment (II) and the conical shape of the IV segment, the stylet groove is opened, (e) the connection between the second and third segments on the ventral side (V), (f) the shape of the third segment and its connection with the fourth segment, the midventral condyle is probably situated on the fourth segment, and (g) the shape of the IV segment and the apical plate from the ventral side (V). bu: buccula, Lr: labrum, Pp: posterior plate of the cranium, stb: stylet bundle.