394 PROCEEDINGS OF THE NATIONAL MUSEUM vol. 117 



Australia. Many of the Neotropical species are conspicuously 

 patterned in bold reds and yellows. Only P. ellipticum, among the 

 Nearctic forms, approaches them in this respect. 



Key to North American Species of Platydema 



1. Frons with two well-developed horns (males) or small tubercles (fe- 



males) 2 



Frons with neither horns nor tubercles 5 



2. Dorsal surface dull, lustreless; horns and tubercles thick and blunt. 



erythroceruni Laporte and BruU^ 



Dorsal surface shining blue or black; horns slender and pointed, tubercles 



sharply pointed 3 



3. Dorsal surface blue cyanescens Laporte and Brull6 



Dorsal surface black 4 



4. Eyes separated ventrally by at least three times the longer axis of one eye 



(pi. 7, fig. 66) ; body narrowly oval teleops, new species 



Eyes separated ventrally by less than 2.5 times the longer axis of one eye; 

 body broadly oval excavatum (Say) 



5. Dorsal surface entirely dull and lustreless 6 



Dorsal surface glossy to strongly shining 10 



6. Dorsal surface bicolored; black with oblique red band on each elytron. 



ellipticum (Fabricius) 

 Dorsal surface unicolorous, dark brown or black 7 



7. Antennae unicolorous from base to apex 9 



Antennae with at least basal 3 segments distinctly lighter in color 



than remaining segments 8 



8. Entire antennal club dark; average size smaller (3.6-5.4 mm. in length). 



flavipes (Fabricius) 



Apical antennal segment entirely lighter than remaining segments; average 



size larger (4.6-7.8 mm. in length) nigratum (Motschoulsky) 



9. Pronotum indistinctly punctured; average size larger (5.5-7.8 mm. in 



length) ; known only from Arizona and New Mexico. 



wandae, new species 



Pronotum distinctly punctured, especially laterally; average size smaller 



(3.5-5.8 mm. in length) ; widespread and common in eastern North America. 



riificome (Sturm) 



10. Each elytron with 8 complete discal striae plus at least a trace of a short 



basal one which more or less parallels scutellum 11 



Each elytron with 8 complete discal striae; short basal one completely 

 absent 18 



11. Prosternal process horizontal, its apex acute and prominent;frons with more 



or less distinct longitudinal impression between eyes; eyes viewed from 

 beneath separated by a distance not exceeding 1.5 times the longer axis 



of one eye 12 



Prosternal process convex between coxae, its apex deflected (sometimes 

 feebly prominent in laevipes) ; frons evenly convex or flat between eyes; 

 eyes viewed from beneath separated by a distance nearly twice the longer 

 axis of one eye (except inquilinum) 15 



12. Pronotum roughly trapezoidal in shape (pi. 6, fig. 52), sides nearly straight, 



rapidly converging toward apex; apical angles right angled and promi- 

 nent 13 



