Key for identifying South American species of Heilus Kuschel, 1955

1 Pronotum and elytral interstriae with granules approximately uniform in size, or elytra with more robust and protuberant tubercles in interstriae 2, 3, and 5.......................................................................... 2

- Pronotum and elytral interstriae without protuberant granules or tubercles; only obsolete and indistinct granules on the sides of the pronotum, at the base, on the humeri, and the posterior callosity of the elytra (Fig. 10).................................................................................................... H. faldermanni (Boheman, 1836)

2 Elytra with robust tubercles in interstriae 2, 3, and 5 (Fig. 8)........................... H. freyreissi (Boheman, 1836)

- Elytra without robust tubercles in interstriae 2, 3, and 5, only granules of lesser degrees of development................ 3

3 Posterior femur not exceeding abdominal ventrite 3, or rarely reaching at most abdominal ventrite 4; elytra with macula occupying the posterior slope of the elytra................................................................... 4

- Posterior femur exceeding abdominal ventrite 3; elytra with or without macula in different positions................... 5

4 Elytra with protuberant, umbilicate granules, each with an extremely short (sometimes indistinct) scale (Fig. 17)..................................................................................... H. bistigma (Hustache, 1938)

- Elytra with non-protuberant and non-umbilicate granules, each one with a short and distinct scale at the apex (Fig. 7)................................................................................ H. rufescens (Boheman, 1836)

5 Elytra with granules present throughout length of interstria 1................................................... 6

- Elytra without granules throughout length of interstria 1 or with small, obsolete, and sparse granules from the median region to the apex............................................................................................ 7

6 Pronotum with subparallel sides, 1.5 times wider than long; without macula on the elytra (Fig. 14)................................................................................................. H. inornatus (Kirsch, 1874)

- Pronotum more strongly rounded on the sides, 1.3 times wider than long; with dense yellow scales forming a transverse band at the base of elytra and another one in the posterior third interrupted at the striae (Fig. 15)..... H. iniquus (Kirsch, 1874)

7 Elytra without granules throughout length of interstria 1, rarely with traces of tiny granules in the apical third; with elytral macula............................................................................................. 8

- Elytra with small and obsolete granules, starting from midlength of interstria 1 to the apex, or only a few tiny granules near the apex; with or without macula on the elytra................................................................. 9

8 Pronotum and elytra with more protuberant and denser granules; elytra with small, elongate macula, occupying the median third of interstria 4, sometimes with thickening of white scales, forming small spots scattered over the elytra; sometimes with elytra with tufts of black scales in front of some dorsal granules (Fig. 4)................ H. inaequalis (Boheman, 1836)

- Pronotum and elytra with smaller, sparse granules; elytra with larger, rounded macula, usually occupying interstriae 3 to 6 or 7, entirely outlined by a narrow band of whitish scales (Fig. 9)............................. H. myops (Boheman, 1836)

9 Elytra without distinct transverse or longitudinal macula, with a tuft of black scales in front of each granule, especially on those located on interstriae 2 to 5 (Fig. 12).......................................... H. fasciculatus (Boheman, 1843)

- Elytra with macula of different formats................................................................... 10

10 Elytra with a large lateral band of continuous or interrupted setae extending from the humeri until after the middle....... 11

- Elytra with a transverse band of setae after the middle, or with small velvet black macula in interstria 4 in the middle of the elytra, or small dense of black scales forming small macula scattered over the elytra............................... 12

11 Discontinuous lateral macula extending to the apex of the elytra (Figs. 16)............... H. admixtus (Hustache, 1938)

- Lateral macula not extending to the apex of the elytra, and with a small velvet black internal macula located on interstria 4 (Fig. 5)........................................................................... H. pupillatus (Olivier, 1790)

12 Without maculae in the middle of elytra, only with a transverse band of reddish brown to yellowish setae in the posterior half of elytra (Fig. 11)............................................................. H. ochrifer (Boheman, 1843)

- Irregular maculae in the middle of elytra.................................................................. 13

13 Elytra with dense black scales forming small maculae scattered over the elytra, and a velvety black macula in the middle of interstria 4 (Fig. 13)........................................................... H. asperulus (Erichson, 1847)

- Elytra with a whitish or yellowish transverse macula, wider in the middle and with irregular contour, usually covering interstriae 3 to 8, sometimes reduced; without dense black scales (Fig. 6).................... H. tuberculosus (Perty, 1832)