218 



On DITROPIDUS AND ALLIED GENERA 

 (COLEOPTERA, CH RYSO M E LI DAE). 



By Arthur M. Lea, F.E.S. 



[Contribution from the South Australian Museum.] 



[Read September 9, 1920.] 



The Australian Chrysomelidae of the subfamily Crypto- 

 cephalides may be regarded as belonging to two sections: — 



1. Cryptocephalides verae. The species of this section 

 ■have the scutellum large and usually sloping upwards to its 

 end, and the antennae more or less filiform. 



2. Monachides. The species of this section have a small 

 scutellum, never sloping upwards, and the antennae have a 

 five or six-jointed club. The main genus is Ditropidus, and 

 the ones I am acquainted with may be thus tabulated : — 



A. Antennal club composed of five joints. 



a. Intercoxal process of prosternum longer than 



wide ... ... ... ... ... ... Praso'notus 



aa. Intercoxal process transverse. 



b. Joints of the club rather wide and short Ditropidus 0) 

 hh. Joints longer and lax ... ... ... Elaphodes 



A A. Antennal club composed of six joints. 



B. Eyes close together Coenohius 



BB. Ej^es distant. 

 C. Scutellar lobe of pronotum entire ... ... Polyachus 



CC. Scutellar lobe notched Euditropidus 



DiTROPIDUS. 



The species of this genus are occasionally extremely 

 abundant on wattles (Acacia, spp.), but they occur on many 

 other kinds of trees and shrubs. They are short, thick-set 

 insects, the male occasionally with very powerful jaws; the 

 female has a large, deep, and more or less circular apical 

 fovea on the abdomen, but the males of a few species also 

 have the abdomen foveate, althoug^h the fovea on such 

 specimens is much shallower, smaller than on the females, 

 and is not margined with hairs, as it frequently is in the 

 females ; in fact on the males of most species there may be 

 seen sn vague depression on the apical segment, if this is 

 viewed from several directions; the eyes of the male are 

 usually larger and closer together than those of the female, 

 their distance apart is frequently a useful specific character, 

 but it needs; to be considered with the sex; the front 



(1) D. antennarius has exceptional antennae in the male. 



