VITTATE CHRYSOMELID BEETLES DISONYCHA — BLAKE 13 



and apex, sometimes along base of each segment, femora reddish 

 brown with the tibiae and tarsi darker brown. Length 6.5 to 8 mm.; 

 width 3.5 to 4 mm. 



Type: In Naturhistoriska Riksmuseet, Stockholm, from Buenos 

 Aires, Argentina. 



Other localities: Argentina: Afiatuya, Santiago del Estero, 

 Monros; Isla Martin Garcia, Bneiios Aires, M. Viana; Concordia, 

 Entre RIos, M. A. Cazier; Corrientes, N. Kisliuk; Flores, Buenos 

 Aires; Formosa, A. Martinez; Pampas; Quinta; Reconquista, H. L. 

 Parker; Rio Santiago, Buenos Au-es, Monros; San Isidro, Buenos Aires, 

 Monros; San Pedro de Calalao, Trancas, Tucum^n, Moiir6s; Santiago 

 del Estero, Monros; Tucumdn, G. F. Moznette; Paysandii, P. A. 

 Berry. Paraguay: Asuncion, A. Martinez. Chile: Germain. 



Remarks: This species belongs to that gi'oup of Disonycha having 

 elytral costae that feeds on Polygonaceae. There are three other 

 closely related species from South America and one {D. recticollis) 

 from Central America as well as several from the United States. In 

 aU, the head markings are very much the same, the elytra have a 

 tendency to have a costa or costae more pronounced in the female, 

 and the aedeagi resemble each other markedly. In an article by 

 Frers (Physis, vol. 4, pp. 565-567, 1919) the biology of D. bicarinata 

 is given and the food plant is reported as Muhlenbeckia sagittijolia 

 Meisner (Polygonaceae) . 



Disonycha immaculataf new species 



FiGUBE 7 



About 7 mm. in length, elongate oblong, somewhat shining, although 

 finely alutaceous and finely and rather densely punctate; pale yeUow 

 brown; dark band across the occiput behind the eyes, dark outer 

 joints of the antennae; dark scutellum and slightly darkened sutural 

 edges ; elytra with a trace of a submarginal vitta, median vitta narrow ; 

 the body beneath with the breast and abdomen except at apex dark, 

 legs pale, with the tarsi dark. 



Head with interocular space more than half width of head, smooth 

 over occiput except for the circle of punctures about fovea near eye, 

 frontal tubercles visibly marked, space between antennal sockets 

 broad, not much produced, lower front rather short, with a small 

 dark labrum; a dark band across occiput behind the eyes. Antennae 

 long, dark except the thi-ee basal joints that are pale-edged. Pro- 

 thorax scarcely twice as broad as long, v/ith curved sides, not very 

 convex, a slight depression on each side at base and over the scutellum ; 

 surface faintly shining, finely alutaceous and finel}^ punctate. Scutel- 

 lum dark. Elytra pale with the sutural edges slightly darkened and 

 a similar slight trace of submarginal vitta not extending to the apex, 



