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

Figure 10

Shapes of the labial segments of the Belostomatidae. (a)–(f) Belostoma flumineum. (a) Dorsal view (D) of the labium, all segments are visible, the articulation of the dorsal condyle (cd) between the II and III segments on the dorsal side, (b) the shape of the first segment (I), the stylet groove is opened, the shape of the proximal part of the second segment, the stylet groove is opened, (c) the elongated second segment, ventral view (V), (d) the shape of the first segment (I) in the lateral view (L), the stylet groove is opened, the intersegmental membrane is visible, (e) the midventral condyle (cv) on the distal edge of the first segment, ventral view (V), the intersegmental membrane is distinctly visible, (f) the connection between the third and fourth segments on the ventral side, the midventral condyle (cv) on the third segment is clearly visible. Bu: buccula of the posterior plate, gl: orifice of the maxillary gland, Lr: labrum, Mxp: maxillary plate, Pp: posterior plate of the cranium, stb: stylet bundle.