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10-15mm in size. Short round thorax with elongated abdomen. No hairs on metapleuron. The abdominal dorsum is completely black , with black humeri. There is also a pile on the first three abdominal segments. It is visible as an evenly grayish species with yellow pile and yellow bristles. Adults of S. obscuriventrus have a hump on the back of their head (gibbosity) which almost reaches the antennal base. The antennae should be uniformly coloured with an orange brown style. On the prothorax, bristles are only on the pronotum. The legs are three quarters black, with a yellow end to the femora and brownish basally and apically black claws. The wings have brownish veins, and in the males a silvery white tinge to the auxillary cell. All posterior wing cells are open, and the anal wing cell is either closed or very narrow. The male genitalia and female ovipositor are both orange brown in colour with a variable number of bristles present. (Adisoemarto, 1967)

This species is very similar to Stenopogon rufibarbis Bromley but the male genitalia is slightly different. Stenopogon rufibarbis is found from British Columbia to Arizona, and probably does not occur in Alberta.