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

Figure 24

Shapes of the labial segments of the Naucoridae. Cryphocricinae, (a)-(b) Cryphocricos hungerfordi, (c)–(e) Ambrysus occidentalis. (a) Lateral view (L) of the labium, the first segment (I) is invisible, the part of the second segment is visible, the tubular third and the conical fourth segments are visible, (b) intercalary sclerites (is) are distinctly visible, the stylet groove (gr) is closed, (c) dorsal and lateral view (D-L), in the first segment viewed from the dorsal side the stylet groove (gr) is opened, the second segment is divided into the triangular plate (tp) and the convex plate (cp), the intercalary sclerites are not distinctly visible (reduced), the articulation of condyles and the intersegmental membrane with the intersegmental sclerit (si) are visible, on the ventral side of the first segment the midventral condyle (cv) is present, (d) the shape of the segment in the dorso-lateral view (D-L), the stylet groove is closed in the III and IV segments, the midventral condyle on the first segment is visible, and (e) the shape of the segments, ventral view (V),the midventral condyle situated on the proximal edge of the fourth segment, the apical plate viewed from the ventral side (V). bu: buccula, Lr: labrum, Pp: posterior plate of the cranium.