Synonyms and other taxonomic changes
genus needs revision mainly because of high morphological similarity between adults of various species and possible hybridization/intergradation of individuals once deemed as separate species(1)
Explanation of Names
Coptotomus Say 1834
Greek copto 'cut, strike' + tomos 'part'
~10 spp. in our area; 5 in the east, perhaps a few additional undescribed species in the west (1)
generally elongate-oval in shape, with the surface of the elytra variously maculate (patterned)
eyes notched at antennal bases
labial and maxillary palps notched apically on the last (outermost) segment (separates from all othe genera in the subamily)
Can be easily separated from other dytiscid larvae as they have elongated lateral abdominal gills.
Species identification of adults relies on examination of technical features such as colouration/patterning, characters on the underside (e.g. metasternal wing width), and genitalia.
transcontinental, Canada to n. Mexico(2)
Deeper sections of permanent ponds with emergent vegetation, lakes and slowly flowing streams(2)
Hilsenhoff W.L. (1980) Coptotomus (Coleoptera: Dytiscidae) in eastern North America with descriptions of two new species. Trans. Amer. Entomol. Soc. 105(4): 461-471.