Figure 3.

Morphological characters of the labium, maxillary, and mandibular stylets of the Potamocoridae. (a) The labium of Potamocoris nieseri according to von Doesburg [18]. (b) Shapes of the first (I) and second (II) segments of the labium of Potamocoris nieseri are presented as presumable shapes deduced presently by Brożek. (c) Magnification of the IV segment (black dots inside the segment point out the presence of mandibles). The drawings of mandibles (Rmd and Lmd) showing putative shapes of the mandibular file (a precise description based on the original drawing by von Doesburg [18] was impossible). (d) The shape of the right and left maxillae (Rmx and Lmx) of Potamocoris sp. shown on the basis of a drawing taken from Cobben [19]. The right apex (ax) is wider than the left one; the right apex is slightly curved while the left one is straight and narrow. The inner system of spines on the maxillae edges from the reduced and hidden rupturing device (brdex and brvin). On the right maxilla seven short spines are present on the internal ventral side (brvin). On the dorsal side the spines are strongly reduced (brdex). On the left maxilla, internally, one tuft of short spines (brvin) can be observed. I: first segment, II: second segment, III: third segment, IV: fourth segment, ax: apex of maxillae, cd: dorsal condyle (the articulation between the second and third segments on the dorsal surface), gr: labial groove, tp: triangular plate of the second segment, Lr: labrum, Rmd: right maxilla, Lmx: left maxilla, Rmd: right mandible, Lmd: left mandible.