56 MISC. PUBLICATION 5 0, U. S. DEPT. OF AGRICULTURE 



eluded among those placed in Malaraeus Jordan, the\ believe the 

 genus Trichopsylla should displace Malaraeus. 



Furthermore, the characters used to separate Malaraeus from 

 Megabothris can hardly be regarded as of generic importance. In 

 the key given by Jordan (43, p. 79) Megabothris is separated from 

 Malaraeus and closely related genera by the size of the stigma of 

 tergum VIII. Although this stigma is much enlarged in the type 

 species of Megabothris, M. walkeri (Rothschild), it is not so en- 

 larged in some of the others, and hardly makes a good distinguish- 

 ing character. Hence Megabothris, as well as Malaraeus, should fall 

 into the synonymy of Trichopsylla. 



The genus Monopsyllus Kolenati requires consideration in connec- 

 tion with the synonymy of Megabothris. To this genus, which has 

 as its type species Pulex sciurorum Schrank, 1803, Jordan (Jp3, p. 78), 

 in 1933, referred a number of Xearctic species. The species are 

 not regarded by the authors as congeneric with the Palaearctic type 

 of the genus, hence the genus MonopsyUus Kolenati is believed not 

 to occur in North America. The species listed by Jordan in it from 

 the Nearctic Region are here given under Trichopsylla. In 1936 

 Ioff (33, pp. 96-98) divided Monopsyllus into three groups of species, 

 including in the third group the American species which had been 

 referred to it and one other fro? a Siberia. To this group he gave 

 the name Amonopsyllus hut did not designate a type species, and 

 further stated that he did not desire to introduce any change in 

 nomenclature. The species Ioff included in his Amonopsyllus are so 

 very closely related to those in Megabothris that if Amonopsyllus 

 had a valid nomenclatorial standing there would be some justifica- 

 tion in regarding it as a synonym of Trichopsylla Kolenati. 



The Subgenus TRICHOPSYLLA Kolenati 



This subgenus has the same synonyms as given for the genus 

 Trichopsylla Kolenati. It is here regarded as a subgenus for the 

 first time. 



Eyes well pigmented, frequently reduced. Bristles on segment II of male 

 antenna short, never reaching to more than slightly beyond middle of club. 

 Stigmata of abdominal segment VIII sometimes much enlarged. In male, 

 sternal plate VIII either much reduced and without setae or long, narrow, and 

 with 1 or 2 apical bristles and a membranous flap on each side; sternal plate 

 IX with vertical process apically rounded on posterior side and sometimes 

 dilated apically. In female, stylet with or without lateral bristles; head of 

 receptaculum seminis much longer than broad and sometimes longer than 

 tail. 



Type species. — Same as for the genus Trichopsylla. 



The type subgenus of Trichopsylla is hard to differentiate from 

 Pleochaetis on any one character because there is a tendency for the 

 characters of the two subgenera to overlap. It appears, however, 

 that these two subgenera represent natural groups. 



The subgenus Trichopsylla, as here recognized, could be further 

 divided into two groups or subgenera on the basis of the male 

 terminal ia. In one group, including penicilliger Grube, would be 

 placed those species in which the eighth sternal plate of the male 

 is long and narrow and bears apically on each side one or two bris- 

 tles and a membranous flap. In the other group, including such 



