158 PROCEEDIXGS OF THE NATIONAL MUSEUM vol.86 



Phy talus vexatus Horn { = cavifrons Linell) has been removed by 

 Chapin to the genus Chlaenohia, which differs from Phyllophaga 

 (and Phytalus) in that the tarsal soles are usually very densely pilose 

 in the male and the hind thoracic angles usually constricted rather 

 abruptly at the base ; the genus Chlaenohia also has a distinct facies, 

 enabling one familiar with the group to recognize specimens on sight. 

 Some of the true Listrochelus (e. g., scoparim) also have densely 

 pilose soles in the male sex, and later studies may show that Chlaeno- 

 bia may be better placed as a subgenus. 



Phytalus is no longer tenable as a genus because some of the species 

 exhibit characters that absolutely grade into those of Phyllophaga 

 and leave no single character or group of characters distinguishing 

 the two. Although it can no longer be used in a generic sense, the 

 name Phytalus is of use subgenerically as applied to a group of 

 species having narrowly cleft claws in at least the male sex. 



In probably no other group of American scarab beetles is there 

 such a variety of opinion as to the validity of genera and of their 

 names as in that of the phyllophagans. In 1920 Arrow, of the Brit- 

 ish Museum, stated that Phytalus, Brahmina, and Holotnchia were 

 not separable from Phyllophaga (^Lachnosterna), and with this I 

 heartily agree,^ as I have found by experience that the use of the 

 claws alone for generic characters is in most instances unsatisfactory 

 because the claws may be very different in species that in every other 

 character are obviously of the same genus. 



In Phyllophaga, as at present recognized, there are several good 

 groups, which, if segregated as different genera, however, would 

 separate species greatly alike in most characters and apparently of 

 the same lineage. Such a separation would, in most instances, be 

 on the basis of the male characters alone, certainly undesirable cri- 

 teria for generic definitions. Among such characters are the de- 

 formed middle claws, fixed hind tibial spurs, and narrowly cleft 

 tarsal claws; the first two are nonvariable, but the last varies greatly 

 in degree in the sexes. Another group could be defined if the very 

 long basal claw dilation, giving the appearance of a third tooth, 

 were used; in the single species concerned, P. heteronycha Bates, 

 the tarsal claws of the fore and midlegs are 3-toothed, while those of 

 the hind pair, like those of Phytalus, are narrowly cleft. Such a 

 segregation is unadvisable, however, as all degrees in length of the 

 tooth formed by the basal dilation can be found in various species. 

 Furthermore, in my opinion it would serve no useful purpose to 

 form a special genus for those species in which the usual three seg- 

 ments of the antennal club are increased to four or five, as other 

 characters are the same as in the species with the normal number of 

 segments in the club. 



» See Revista Ent., voL 7, fa«c. 2-3, pp. 818-322, 1937. 



