ABT. 28 REVISION OF DISONYCHA NORTH OF MEXICO BLAKE 43 



17. DISONYCHA DISCOIDEA (Fabricius) 

 Plate 5, Figure 23 



Oalleruca disooidea Fabricius, Entoraologia systematica, vol. 1, pt. 2, p. 25, 



1792 (North America; type lost?). 

 Chrysotnela discoidca Fabricus, Systema Eleutheratorum, vol. 1, p. 445, 1801. 

 Haltica discoidca Illiger, Mag. fiir Insekt., vol. 6, p. 143, 1807. 

 Disonyha discoidca Melsheimer, Catalogue, p. 122, 1853. — Crotch, Proc. Acad. 



Nat. Sci. Philadelphia, vol. 25, p. 64, 1873.— Horn, Trans. Amer. Ent. Soc, 



vol. 16, p. 20S, 1SS9. 

 Disonycha nigridorsis Sturm, Catalogue; in Gemmiuger and Harold, Catalogue 



coleopterorum, p. 3497, 1876 (as synonym). (Amer. bor.) 



Description. — Large (7 mm), broadly oblong oval, feebly shining; 

 pale with large cliscoidal black spot, somewhat variable in size, but 

 never attaining margin of elytra; tibiae with a darker outer streak, 

 tarsi black; in variety ahhreviata a dark sutural and a median vitta 

 instead of discoidal spot. Head with interocular space over half 

 W'idth of head; carina broadly rounded, a little produced; frontal 

 tubercles merely indicated; surface smooth and shining, nearly im- 

 punctate, with a single large fovea on each side near eye; entirely 

 pale. Antennae short, robust, dark, the basal joints and sometimes 

 the apical ones paler; third joint a little shorter than fourth or fifth, 

 which are subequal. Prothorax about twice as wide as long, some- 

 what convex, without depressions, narrowed slightly anteriorly with 

 feebly arcuate sides; surface finely alutaceous and finely punctate, 

 entirely pale. Scutellum pale or dark. Elytra broadl}^ oblong oval, 

 somewhat convex; humeri not prominent, with only faint trace of 

 intrahumeral sulcus ; surface alutaceous, moderately closely and dis- 

 tinctly punctate; discoidal spot variable in size, always more than 

 half the elytra, never covering margin, usually tapering to apex but 

 not quite reaching it. Body beneath finely pubescent, entirely pale, 

 tibiae with a darker outer edge, tarsi darlc. Length, 6.5 to 7.8 mm ; 

 width, 3.8 to 4.5 mm. 



Type locality. — North America. 



Distribution.— MurylviVid (Plummers Island, Great Falls, Marshall 

 Hall); District of Columbia; Virginia (Nelson County); South 

 Carolina (Charleston) ; Georgia (Atlanta) ; Kentucky (Louisville) ; 

 Tennessee (Knoxville, Blount County) ; Alabama (Langdale, Cham- 

 bers County, Sheffield) ; Louisiana (Baton Rouge) ; Texas (Dallas, 

 Colorado County) ; Arkansas (Prairie County) ; Kansas (Douglas 

 County). 



Food plant. — Passi-flora lutea Linnaeus (H. S. Barber). 



Rernarks.—This is the only species of Duonycha in the United 

 States with a black discoidal spot, evidently formed by the coales- 

 cence of vittae, a common phenomenon in some other genera of Chry- 



