RESPIRATORY SIGNIFICANCE OF THE THORACIC AND 
ABDOMINAL MORPHOLOGY OF THREE CORIXIDAE, 
DIA PREPOCORIS, MICRONECTA, AND HESPEROCORIXA 
(HEMIPTERA: HETEROPTERA: HYDROCORISAE)* 
By Margaret C. Parsons 
Department of Zoology, University of Toronto 
Toronto, Ontario M5S 1A1, Canada 
A. Introduction 
The Corixidae are an extremely successful and abundant family 
of Hydrocorisae (aquatic Heteroptera). The more than 500 living 
species of corixids were grouped by Hungerford (1948) into six 
subfamilies; more recently Popov (1971) has recognized only three 
subfamilies, the Diaprepocorinae, Micronectinae, and Corixinae. 
The Corixinae, which include four of Hungerford’s subfamilies, 
have been extensively investigated; they consist of approximately 
30 genera, occur throughout the world, and range up to 16 mm. 
in length. Morphological and physiological studies are almost 
totally lacking, however, for representatives of the other two sub- 
families. The Micronectinae are nearly worldwide in distribution 
but members of their three genera are very small (1. 5-6.0 mm.) and 
difficult to dissect. The Diaprepocorinae consist of a single rare 
genus, Diaprepocoris, which occurs only in Australia, Tasmania, 
and New Zealand. 
The mode of respiration in the Corixinae has been studied by 
many workers, including Hagemann (1910), Ege (1918), Popham 
(1960) and Parsons (1970). Like most Hvdrocorisae, the Corixinae 
use “air-bubble” respiration and depend upon atmospheric air, 
which they carry in air stores on their bodies. The parts of the air 
stores which are exposed to the water can extract dissolved oxygen 
from the water by acting as “physical gills” (Thorpe 1950). The 
stored air is not a true plastron ( sensu Thorpe 1950) because it is of 
considerable volume and must be periodically renewed at the 
surface of the water. 
The air-bubble mode of respiration is reflected in the gross 
morphology of Hesperocorixa (Corixinae; Parsons 1970, 1974). 
In the present study the respiratory morphology of this corixid is 
* Manuscript received by the editor June 15, 1976. 
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