4 PROCEEDINGS OF THE NATIONAL MUSEUM vol. loi 



Myochrous is one of 23 genera that are grouped together under the 

 Myochroini and are chiefly cliaracterized by being covered by scales 

 or coarse hairs ; in addition, the prothorax has a distinct margin, and 

 the prosternum is lobed under the eyes. The two pairs of posterior 

 tibiae are not emarginate except in the genus Pachnephorus, which in 

 this regard unites the group with the Typophorini. 



Only eight of the genera occur in the Western Hemisphere, and of 

 these only three, Glyptoscelis LeConte, Myochrous Erichson, and 

 Colaspidea Laporte, are from North and Central America. Chalco- 

 sicya Blake is confined to the West Indies. Dictyneis Baly, composed 

 of a group of very odd wingless beetles with the elytra decorated with 

 warts and tubercles, is known only from Chile. Jansonius Baly is a 

 monotypic genus from Chile. Trichochalcea Baly and Cellomius 

 Lefevre are both monotypic genera from Brazil. The remainder of 

 the group of genera is chiefly from Asia and Africa. Pachnephorus 

 Redtenbacher is found also about the Mediterranean, and Colaspina 

 Weise is a monotypic genus from Provence. One Australian genus, 

 Neocles, Chapuis described as being the Myochrous of Australia. The 

 description of the thorax with two big tubercles on the projected 

 anterior margin together with a median sulcation sounds very much 

 like that of the unique species M. curculionoides Lefevre from 

 northern South America. 



In North America Myochrous comes nearest to Glyptoscelis and is 

 distinguished from it by having the front tibiae and thorax usually 

 toothed, the claws appendiculate, not bifid, and the elytra striately 

 punctate. 



Myochrous is composed of a fairly homogeneous lot of species. Yet 

 in this natural group there are variations that suggest its close rela- 

 tionships with the other genera. For instance, some species of 

 Pachnephorus occurring about the Mediterranean are not unlike some 

 species of the M. squamosus group, which occur in the more arid regions 

 of the United States. Like Pachnephorus^ M. squamosus is without 

 thoracic toothing and has broad, often bifid scales, but the shorter 

 first abdominal segment and the lack of emargination of the hind 

 tibiae place it definitely with Myochrous. 



DESCRIPTION OF THE GENUS 



From 3.5 to 9.5 mm. in length, usually stout, oblong, reddish brown, 

 piceous, or black beetles, frequently shining with a bronzy luster when 

 denuded of the usually dense and appressed grayish, pure white (in 

 M. sallei), pale brownish, or yellowish scales that cover the entire 

 upper surface, the lower surface less densely and more finely pubescent ; 

 beneath the scales the surface usually coarsely and the elytra striately 

 punctate. Prothorax for the most part 3-tootlied, antennae short. 



