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

Figure 18

Shapes of the labial segments of the Gelastocoridae. (a)–(e) Nerthra macrothorax. (a) Dorsal view (D) of the labium, all segments are visible, the dorsal condyle (cd) between the II and III segments on the dorsal side, intercalary sclerites, (b) slightly triangular shape of the first segment (I), intersegmental membrane (mb), dorsal view, (c) the shape of the first (I) segment with a notch (no), the cuplike second (II) segment, lateral view, no midventral condyle (cv) on the distal edge of the third segment, the shape of the apical plate (ap), (d) the intersegmental membranes connecting the I, II and III segments, the second segment is retracted into the first one, and (e) ventral view, a connection between the first (I) and second (II) segments, no midventral condyle (cv) on the distal edge of the first segment, Lr: labrum, Mxp: maxillary plate, Pp: posterior plate of the cranium.