424 PROCEEDINGS OF THE NATIONAL MUSEUM vol. in 



Key to the known species of Melanaethus 



1. Terminal lobe of peritreme triangular posteriorly, separated from lateral 



margin of evaporatorium by much more than transverse diameter of the 



lobe (fig. 97) 2 



Terminal lobe of peritreme semicircular or subquadrate posteriorly, 

 separated from lateral margin of evaporatorim by less than transverse 

 diameter of the lobe (fig. 96) 5 



2. Anterior convexity of propleuron with numerous coarse punctures. 



cavicollis (Blatchley) (p. 428) 

 Anterior convexity of propleuron impunctate 3 



3. Dorsum of head and sides of anterior pronotal lobe impunctate. 



cubensis (Barber and Bruner) (p. 432) 



Dorsum of head and sides of anterior pronotal lobe with several to many 



coarse punctures 4 



4. Posterior pronotal lobe and scutellar disc with many crowded, coarse, foveate 



punctures aereus, new species (p. 425) 



Posterior pronotal lobe and scutellar disc with many small, widely separated 

 punctures externus, new species (p. 433) 



5. Dorsum of head with a fine marginal carina extending from eye to apex . . 7 

 Dorsum of head without a fine marginal carina or with a partial one immedi- 

 ately anteiior to eye 6 



6. Pronotum with transverse impression and intercallar area distinctly but 



obtusely impressed; labium surpassing base of sternite III. 



anthracinus (Uhler) (p. 426) 



Pronotum convex, transverse impression and intercallar area not depressed; 



labium not surpassing middle coxae .... spinolae (Signoret) (p. 449) 



7. Costal edge thick, calloused, strongly but narrowly convex dorsally; jugum 



with three coarse (rarely more), widely separated setigerous punctures 



submarginally planifrons, new species (p. 443) 



Costa flat, thin, neither calloused nor convex dorsally; jugum with not more 

 than one setigerous puncture submarginally 8 



8. Head dorsally impunctate or with few patches of minute punctures. 



pensylvanicus (Signoret) (p. 441) 

 Head dorsally distinctly punctate or rugopunctate over most of surface . . 9 



9. Pronotal disc, especially transverse impression, with numerous punctures 



of which many are as coarse as those on sides; scutellum usually distinctly 



punctured to base 11 



Pronotal disc, especially transverse impression and posterior lobe, polished, 

 with few minute punctures much finer than those on sides; scutellar puncta- 

 tion becoming obsolete basally 10 



10. Costa straight and subparallel on basal half, neither explanate nor recurved 



near base uhleri (Signoret) (p. 453) 



Costa gently convex, diverging on basal half, explanate and gently recurved 

 near base subpunctatus (Blatchley) (p. 451) 



11. Pronotum with punctures of transverse impression and posterior lobe (and 



usually also one-half of scutellum) of two sizes, coarse and fine ones 



intermixed 12 



Pronotum with punctures of transverse impression and posterior lobe of one 

 size or those of latter becoming finer posteriorly, often with fine longi- 

 tudinal rugae between the punctures 15 



