Deliberations on the External Morphology and Modification of the Labial Segments in the Nepomorpha (Heteroptera: Insecta) with Notes on the Phylogenetic Characteristics
Shapes of the labial segments of the Notonectidae. Anisopinae. (a)-(b) Anisops camaroonensis, (c)-(d) Buenoa uhleri. (a) Dorsal view of the labium, the shape of the second segment—the planar triangular plate (tp) and the slightly convex plate (cp), the third segment is tubular, the fourth segment is conical, the articulation between the second and third segments (cd), the intersegmental sclerit (si) is visible on the membrane of the first segment, the stylet groove (gr) in the III and IV segments is closed, (b) lateral view of the segments, the first segment and the base of the second segment each have an open a stylet groove (gr), (c) dorsal view of the labium, the first segment (I), the second (II) segment is invisible (covered by the labrum), the III segment is tubular, the IV segment is conical, the stylet groove is closed in these segments, and (d) ventral view (V) of the labium, on the distal edge of the first segment (I) and proximal edge of the fourth (IV) segment there are midventral condyles (cv), the apical plate can be observed, the second segment on the ventral side is evidently modified—the convex sack (sa) can be observed. Lr: labrum, stb: stylet bundle.