Key to Nearctic (north of Mexico) species of Elacatis

1. Pronotal disc flat to slightly concave; elytra unicolorous red-brown, without lighter color or contrastingly lighter setal pattern (Fig. 2)....................................................................... E. immaculatus (Champion)

- Pronotal disc variously convex; elytra not unicolorous, with contrasting light and dark areas.......................... 2

2. Head and pronotal punctation relatively shallow and sparse, with distinct spaces around punctures (up to about the diameter of a single puncture); elytra (Fig. 1) dark with 3 well-delimited, lighter areas: several irregular spots at base, transverse band near midlength, widest at suture, not reaching lateral margin, and isolated round subapical spot; legs yellow, distinctly contrasting dark dorsal body color................................................................. .. E. fasciatus (Bland)

- Head and pronotal punctation deep and dense, spaces (if any) among punctures less than diameter of single puncture; elytra dark with lighter areas, more diffuse, not as described above; legs darker, similar in color to dark dorsal body color........ 3 notal punctation rugose, borders of punctures confluent, forming contiguous, longitudinal meshes; elytra with extensive lightcolored areas (Fig. 3), in approximate X-shape in most specimens, shoulders yellow.......... .. E. senecionis (Champion) - Antennae longer, reaching posterior margin of pronotum or beyond; pronotum less convex, somewhat flattened at midline; pronotal punctation less rugose, borders of punctures not forming longitudinal meshes; elytral color not as described above......................................................................................................4

3. Antennae very short, reaching only to near midlength of pronotum (Fig. 3); pronotum distinctly convex, even at midline; pro-

4. Head, pronotum, and in some specimens, also elytra, with slight to distinct aeneous or bronzy metallic luster; elytra dark (Figs 4–5) with variously developed light “zig-zag” markings (in some specimens (e.g. Fig. 6), elytra with greater area of lighter than darker color), but not consisting at least in part of isolated circular spots; antennae of both sexes relatively short, extending only to near posterior margin of pronotum (Figs 4–5); associated with conifers in western North America............................................................................................. .. E. umbrosus (LeConte)

- Head, pronotum and elytra without metallic reflection; elytra dark, with light markings consisting in part of at least several isolated circular spots, especially on posterior half of elytra; antennae sexually dimorphic, relatively short in female (no paired pits on mentum), extending to near posterior margin of pronotum; antennae longer in males (paired pits on mentum), extending beyond hind margin of pronotum; not known to be associated with conifers....................................... 5

5. Lateral pronotal carina of most specimens with 3 tubercles (hind angle, widest point, and one in between) (Figs 11–14); lateral pronotal margins evenly arcuate, anterior margin width subequal to posterior margin width; male tegmen relatively elongate (Figs 32–33)......................................................................................... 6

- Lateral pronotal carinae (Figs 7–10) relatively smooth, tubercles at hind angles and in some specimens, slight suggestion of tubercle at maximum width; lateral pronotal margins only slightly arcuate, anterior margin width greater than posterior margin width; male tegmen relatively short, wide (Fig. 31)............................................ E. longicornis Horn

6. Tegmen with relatively long, narrow basal piece (length of apicale <1.5 x length basale); length of basale subequal to width (Fig. 32); distribution (Fig. 38): southern Great Plains (CO, KS, NE, MT)....................... E. larsoni, new species

- Tegmen with relatively short, wide basal piece (length of apicale> 1.5 x length basale); length of basale distinctly greater than width (Fig. 33); distribution (Fig. 39): southeastern Arizona and Mountains and Basins region of Texas ................................................................................................... E. stephani, new species