22, 6 Rohwer: New Malayan Wasps 597 



Diodontus bakeri Rohwer. 



A female from Iligan, Mindanao, has been examined and 

 returned to the sender, C. F. Baker. 

 Diodontus ajax Rohwer. 



A female from Singapore forwarded by C. F. Baker is smaller 

 than the type (length 9.5 millimeters), has the black of the 

 thorax more extensive, and has the petiole rufous. 



The following five species, known only from the male run 

 to D ajax Rohwer in my key,"- None of them agree with any 

 o± the females examined and until the antigeny of this group 

 is better understood they would best be given separate names. 

 They may be separated as follows: 



1. Posterior face of propodeum smooth, without sculpture; scutum yellow, 



with a single black spot D . sandakanensis sp. nov. 



Posterior face of propodeum coarsely sculptured; scutum with at least 

 three black spots 2 



2. Flagellar joints cylindrical, not rounded out beneath. 



D. filicornis sp. 



Flagellar joints 5 to 12 rounded out beneath 



S. First recurrent received in second cubital cell; scutum with three 1 



e black 



D. davanns sp. nor. 



, recurrent received in first cubital cell; scutum with three black 



4. Third and fourth antennal joints subequal; petiole unicolorous. 



D. ajaxellus sp. nor. 

 Third joint distinctly longer than fourth; apex of petiole black. 



Diodontus sandakanensis sp. nov. 



Evidently closely allied to Diodontus inter stitialis (Cameron). 

 It differs from the description of Psen lutescens Turner, which 

 is said to be a synonym, in having the first recurrent received 

 near apex of first cubital cell and in having the base of petiole 

 yellow. 



Male. — Length, 5.5 millimeters. Clypeus convex, the apical 

 margin with two small median teeth; face shining, with close 

 setigerous punctures; the transverse ridge below antennae 

 rounded laterally and joining antennal fossae; frons smooth; 

 ocelli in a low triangle ; postocellar line much shorter than ocel- 

 locular line; antennae slender, third joint longer than fourth, 

 joints 5 to 12 slightly rounded out beneath; thorax smooth; 

 suture in front of scutellum finely foveolate; propodeal inci- 

 sure broadly triangular in outline, with ten slightly oblique 



1 Philip. Journ. Sci. 18 (1921) 310. 



