(Figs. 79–86, 87)

Hydnobius strigilatus Horn, 1880: 281; Hatch 1957: 24.

Hydnobius femoratus Hatch, 1936: 36; Hatch 1957: 25, new synonymy.

Type material. Lectotype of H. strigilatus here designated to ensure the name’s proper and consistent application, male, in MCZC, Horn collection; bearing white label “Nev”; red label “ LectoTYPE / 3010”; white handwritten label “ Hydnobius / strigilatus / Horn”; red label “MCZ TYPE / 3199” and our red lectotype label; seen and dissected. Paralectotypes: one labeled "Nev" in Horn collection, MCZC; and one labeled "Vanc" in LeConte collection, MCZC. Type locality: Nevada [probably in vicinity of Lake Tahoe, Reno, or Carson City, Douglas County, Nevada].

Hydnobius femoratus, holotype, male, USNM; bearing white label “ Seattle, Wash. / V-28 1929 / M.H. Hatch ”; red handwritten label “TYPE / [male symbol] / Hydnobius / femoratus / M.H. Hatch 1929 ”; seen and dissected. Paratypes; three from Seattle, Washington, in OSUC, seen. Type locality: Seattle, Washington.

Additional material examined. We examined 293 specimens (See Appendix).

Diagnosis. Body reddish brown, shining; antennomeres 7–10 darker, apical antennomere pale. Small species, length of pronotum + elytra = 2.0–2.3 mm (males), 2.0–2.1 mm (females). Head finely punctate with microsculpture of irregular lines. Pronotum broad, widest before base, sides rounded, basal angles obtuse; ratio length:width = 1:1.7; minutely punctate, some punctures joined by microsculpture of straight, fine lines. Elytra short, ratio length:width = 1:0.8; with 9 punctate striae; stria 1 impressed in apical one-half, striae 6 and 7 do not reach apex; intervals with a single row of fine punctures and transversely striolate; uneven intervals with scattered larger punctures. Antennal club (Fig. 79) moderately slender, ratio club width:length = 1:3.2; width ratio of antennomeres 7:8:9 = 1.2:1:1.4. Mandibles (Fig. 80) stout, a thin plate forming inner apical margins. Labrum entire. Male profemur (Fig. 81) with small tooth at middle of posterior margin, unarmed in female; mesofemur (Fig. 82) unarmed in both sexes; male metafemur (Fig. 83) with small denticles on posterior margin, unarmed in female. Protibia of both sexes evenly widened from base to apex; male mesotibia (Fig. 82) strongly angulate at basal one-third, broad at apex; female mesotibia slender, unmodified; metatibia of both sexes slender, unmodified; all tibiae of both sexes spinose on outer margins. Male. Aedeagus (Fig. 84) with median lobe elongate, broad, tapering to narrow, elongate apex. Parameres inserted near middle of median lobe, broad and flat throughout, with a small notch laterally near base, setose apically.

Female. Coxites (Fig. 86) short, broad, with narrow apices; apices concave, setose, with no visible styli. Sternite 8 (Fig. 85) protuberant apically; anterior apophysis narrow, parallel-sided.

Distribution. The species occurs in forested coastal northwestern North America and east to the the Rocky Mountains of Colorado and Arizona (Fig. 87). We have seen specimens from Canada: the province of British Columbia; USA: the states of Arizona, California, Colorado, Montana, Nevada, Oregon, and Washington.

Field notes and habitats. Adults have been collected most frequently in mixed forests in flight intercept traps with smaller numbers in evening flight and in litter. The more southerly California records are from seasonal oak forests.

Seasonality. Adults have been collected mostly in the spring and summer months of March to August, with two in December. The greatest numbers are from April (20), May (35), June (176), and July (29).