2 PROCEEDING OF THE NATIONAL MUSEUM vol. 124 



to get to its prey; these contrast markedly with the broad but thin, 

 sickle-shaped mandibles without subapical tooth of Mesa that are 

 adapted for tunneling through soil. Likewise, the legs of Hylomesa 

 are much less spinose than in Mesa, a reflection of the different kind 

 of substrate through which the latter has to tunnel to reach its prey. 



The presence of transverse ridges anteriorly on the pronotal disk 

 and the disk of the first abdominal tergum also serve to distinguish 

 both sexes of most species of Hylomesa from Mesa; these modifica- 

 tions serve no apparent functional purpose. Other distinguishing 

 characters of Hylomesa are: the lack of a closely striate pygidial 

 area in the female, the shorter male antennae, the lack of an apical 

 notch on the last abdominal tergum of the male, and the carinate 

 hind coxa of the male. 



Mesa, with its numerous species, has a relatively broad distribu- 

 tion in the Ethiopian and Oriental Regions, occasionally penetrating 

 the southern Palaearctic Region. Hylomesa has a much more re- 

 stricted distribution; its few species occur in Gabun, Uganda, Ceylon, 

 India, Assam, Malaysia, Borneo, Java, Sumbawa, and the Philippines. 

 The few detailed label data suggest that Hylomesa is restricted to 

 tropical forested areas at moderate altitudes, whereas Mesa is pri- 

 marily a genus of open lands, both tropical and temperate. 



Twenty-five years ago I set aside the National Museum specimens 

 as a genus discrete from any Myzininae treated in my earlier pub- 

 lication on the genera of this subfamily (Krombein, 1937). I delayed 

 erecting a new genus, however, because of uncertainty as to the 

 status of Poecilotiphia Cameron and also because of the desirability 

 of studying the primary types of all of the taxa referable to this 

 supposed new genus. 



Poecilotiphia was based on the Indian species albomaculata Cam- 

 eron, known originally only from a male. Cameron's generic and 

 specific descriptions did not agree well with any species in my sup- 

 posed new genus. His descriptive work, however, is so notoriously 

 poor that uncertainty still existed particularly because of some of 

 Turner's remarks. The latter author (1908b, p. 131) suggested that 

 Methocha rugosa Cameron and Myzine dimidiaticornis Bingham, both 

 based on males, were allied closely to Poecilotiphia. Later, Turner 

 (1909, p. 480) sank Poecilotiphia as a synonym of Myzine Latreille, 

 but he associated female apimacula Cameron as the opposite sex of 

 albomaculata. He stated further that apimacula differed from most 

 Plesia in the feebly sculptured last abdominal tergum, agreeing in 

 this detail with the peculiar female, Myzine tricolor Smith, which 

 I assigned to my supposed new genus. 



I was able to resolve the application of names satisfactorily when 

 I studied types in the collections of the British Museum and Oxford 



