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

Figure 25

Shapes of the labial segments of the Naucoridae: Naucorinae. (a)-(b) Ilyocoris cimicoides, (c)–(g) Pelocoris femoratus. (a) Dorsal view (V) of the labium, the first segment (I) with the open stylet groove (gr), the second segment is divided into the triangular plate (tr) and the convex plate (cp), intercalary sclerites (is) are distinctly visible, the stylet groove (gr) is closed in the II, III and IV segments, the articulation between the second and third segments (cd), (b) ventral view of the shape of the segments (V), the midventral condyle is situated on the proximal edge of the fourth segment, the apical plate viewed from the ventral side (V), the intersegmental sclerit (si) can be observed, (c) the shape of the segments in the dorsal view (D), intercalary sclerites are visible, the conical shape of the IV segment, the elements of the first segment (lateral and ventral sides), (d) dorsal and lateral views (D-L), the second segment is divided into the triangular plate (tp) and the convex plate, the articulation of condyles and the intersegmental membrane with two intersegmental sclerites (si) are visible, on the ventral side of the first segment the midventral condyle (cv) is present, (e) intersegmental sclerites (si) magnified, (f) the intercalary sclerites are distinctly visible, the membrane (ms) is slightly visible, and (g) the shape of the segments, ventral view (V), the midventral condyle is situated on the proximal edge of the fourth segment, ventral view of the apical plate (V). Lr: labrum, Pp: posterior plate of the cranium.