148 
Psyche 
[June 
III. Micronecta and Hesperocorixa 
Two previous papers (Parsons 1970, 1974) have described the 
ways in which the pterothorax of Hesperocorixa differs from that 
of the typical Hydrocorisae. Micronecta shares these characteristics 
to a greater extent than does Diaprepocoris. 
The mesothoracic epimeron of Micronecta and Hesperocorixa 
is considerably different from that of Diaprepocoris and the typical 
Hydrocorisae. It possesses no lateral epimeral ridge, and its lateral 
lobe (Fig. 14B, LL), which is greatly widened, curves strongly 
dorsolaterally rather than projecting laterally and only slightly 
dorsally (compare Figs. 14A and 14B). In both corixids the edge 
of the lobe (Figs. 16 and 17, LL) extends dorsal to the level of the 
metathoracic spiracle (S III) and reaches nearly to the level of the 
mesothoracic scolopophorous organ (SO II). The costal margin 
of the forewing (Fig. 14B, FW), which rests on the edge of the 
lateral lobe, lies farther dorsally on the body than in Diaprepocoris. 
Thus on the mesothorax the ventral part of the subalar air space 
is bounded by the lateral lobe (LL) rather than by the forewing. 
NH son 2PH EMIE PR PNHI 3PH T1 
Fig. 18. D. zealandiae; internal view of pterothorax and anterior abdomen, cut 
parasagittally lateral to mesocoxa. Cross-hatched cut edge of mesothoracic pleural 
ridge (PL II) indicates base of pleural apophysis (removed). Metacoxa and soft 
tissues removed; part of metacoxal membrane (MM) cut away to show sclerotized 
strip (SS) and inner wall of metathoracic epimeral lobe (EML). First abdominal 
spiracular trachea (S 1) emerges from spiracle lying in thoracico-abdominal mem- 
brane lateral to sclerotized strip. 
