H. woodruffi is one of two Eocene Okanagan Highlands mooneye species, and one of five fish identified in the Klondike Mountain Formation.

[1] The highlands likely had a mesic upper microthermal to lower mesothermal climate, in which winter temperatures rarely dropped low enough for snow, and which were seasonably equitable.

Potassium-argon radiometric dating of samples taken near the Tom Thumb mine in 1966 resulted in a tentative 55 million years old age.

[2] The Kishenehn Formation conservat lagerstätte[3] in Northwestern Montana has been dated to approximately 46.02 million years old[4] based on potassium-argon of the Coal Creek member.

[5] The earliest find, which were later identified as H. woodruffi, were specimens collected by Canada's first vertebrate paleontologist Lawrence Lambe in 1906 from Horsefly.

One set of fish was collected from the Toroda Creek Graben northwest of Republic by R. C. Pearson, and tentatively identified by paleoichthyologist David Dunkle as members of several genera including the Aphredoderid Tricophanes.

During the summers of 1976 and 1977 the University of Alberta also conducted field collecting in both the Toroda Creek and Republic areas, yielding a number of fossil fish material, including a single hiodontid.

[7] The Okanagan highland hiodontid fossils were studied in detail by paleoichthyologist Mark Wilson, of the University of Alberta, with a monograph overview of the British Columbian Eocene fish fauna and redescription of H. rosei being published in 1977,[9] followed by a smaller paper in 1978 containing the H. woodruffi description.

The etymology of the species name woodruffi was chosen in recognition of the Woodruff family for the collection and donation of the specimens studied.

The holotype fish was suggested to be either an adult female or immature large male, based on the lack of expanded anal rays.