48 PROCEEDINGS OF THE NATIONAL MUSEUM vol. us 



Family characteristics: These polyphagous beetles range in size 

 from 5 to 20 mm. in length, but most specimens are between 8 and 12 

 mm. Their body surface has a soft appearance, and the moderate 

 vestiture of recumbent setae covers the somewhat shining body surface. 

 The color is fuscus to testaceous, or bicolorous with head and/or 

 pronotum reddish orange, more rarely, dark or piceus or metallic 

 colored. The head is not strongly constricted behind the eyes. The 

 antenna are filiform. The pronotum is broadest anteriorly or at 

 middle, without lateral margins. The procoxal cavities are open 

 behind and the tarsal formula is 5-5-4, with at least the penultimate 

 segment dilated and tomentose ventrally; claws simple, or with a 

 basal tooth. 



Key to the Species of Big Bend Oedemeridae ^ 



1. Antennal base situated within deep emarglnation of eyes; mandibles entire 



(Calopodinae) Sparedrus depressus (Champion) 



Antennal base situated in front of eyes which are emarginate (Oedemeri- 

 nae) 2 



2. Both mandibles entire 5 



Both mandibles bifid at apices 3 



3. Second antennal segment short, one-third or less length of third segment; 



head and elytra piceus, pronotum reddish orange. 



Eumecomera obscura (LeConte) 

 Second antennal segment long, one-half or more length of third segment . . 4 



4. Second antennal segment nearly as long as third; body slender; eyes nearly 



entire; pronotum with nearly parallel sides; uniformly dark, metallic in color. 



Vasaces elongatus Arnett 



Second antennal segment approximately one-half length of third; eyes 



reniform; pronotum much broader anteriorly than at base; color fuscus. 



Oxycopis howdeni Arnett 



5. Vestiture very coarse and dense, obscuring punctation. 



Oxacis pallida LeConte 

 Vestiture coarse to fine, but not obscuring punctation 6 



6. Head, thorax, and elytra fuscus or reddish brown 7 



Thorax orange red with or without darker markings 9 



7. Each elytron marked with two orange striae (to distinguish fi'om 0. bernadettea, 



not yet reported from Big Bend Region, pronotum without anterior lateral 



mirror spots) Oxacis barbara Arnett 



Elytra without orange striae 8 



8. Head and pronotum piceus brown with testaceus markings; elytra with sutural 



area pale; elongate narrow species; pubescence fine. 



Oxacis angustata Champion 

 Color uniformly reddish brown; elytra rarely stained with piceus. 



Oxacis subfusca Horn 



3 For full descriptions and illustrations of these species and others that might 

 occur in the area, see bibliography. This key includes only the known species in 

 the Big Bend Region and is so designed that, should additional species be found 

 in the region, they will not be mistaken for the included species. 



