1. Elytral striae raised, distinctly carinate, carinae nearly continuous (Fig. 17A, C)................... 2

— Elytral striae convex or nearly flat, not distinctly carinate, carinae reduced to short segments, or very short, serving only as setal bases (Fig. 12A, 16E)........................................................... 3

2(1). Posterolateral mesotibia with 4-5 spines on lateral margin, spinal bases widely separated (Fig. 17D); metatibial surface with small, mostly oblique transverse ridges or carinae (Fig.17F); size small, length 2.60 to 3.20 mm; body form short, stout, lateral margins of elytra slightly rounded medially (Fig. 17A)......................................................................................... G. inducta Horn

— Posterolateral metatibia with 6 or more spines on lateral margin, spinal bases close together (Fig. 18D); metatibial surface with coarse, dense armature composed of tubercles and ridges(Fig. 18F); size large, length 3.30 to 4.30 mm; body form comparatively more elongate, lateral margins of elytra not rounded medially (Fig. 18A)............................................ G. canadensis Brown

3(1). Metasternal groove present, distinct (Fig. 15D); southern Utah, Wyomng........................................................................................................................................................ G. sabulosa , n. sp.

— Metasternal groove not visible or only slightly so (Fig. 13D); Arizona, southern California, South America............................................................................................................................ 4

4(1). Elytral striae flat, or nearly so, strial carinae reduced to setal bases (Fig. 12C); Arizona, southern California, South America......................................................................................................... 5

— Elytral striae raised, strial carina composed of widely separated carinal segments (Fig.16E); El Paso Co., Texas............................................................................................. G. warneri , n. sp .

5(4). Posterior metatrochanteral margin serrate, with large tooth near metafemur (Fig. 14H); posterior metafemoral margin with tooth (Fig. 14H); South America........... G. fritzi Martinez et al.

— Posterior metatrochanteral margin not serrate, without large tooth; posterior metafemoral margin without tooth; not known from South America....................................................................... 6

6(5). Outer margin of metatibia with pronounced, continuous, wide shelf-like projection extended about 1/2 width of metatibia (Fig. 12F); mesotibia with 4 or 5 spines on external margin (Fig. 12D); spines on posterosuperior metatrochanteral surface widely separated; Kelso Dunes, San Bernardino Co., California........................................................................ G. arenata Gordon

— Outer margin of metatibia with posteromedian projection not shelf-like, usually not extended more than 1/3 width of metatibia (Fig. 13G); mesotibia with 6 or more spines on external margin; spines on posterosuperior metrochanteral surface narrowly spaced (Fig. 13H); Arizona............................................................................................................... G. zvirgzdinsi Warner