ICHNEUMON-FLIES — GELINAE : MESOSTENINI 413 



This subgenus is of Indo-Australian distribution. Tliere are only- 

 two described species, the genotype and Suval^a transversa Cameron 

 1912. 



4. Subgenus Listrognathus 



Figure 320,a 



Listrognathus Tschek, 1870, Verh. Zool.-Bot. Gesell Wien, vol. 20, p. 153. Type: 



Listrognatlnis cornutus Tschek; monobasic. 

 Mesostenoideus Ashmead, 1900, Proc. U.S. Nat. Mus., vol. 23, p. 45. Type: 



Mesostenus albomaculatus Cresson; original designation. 



Front wing 4.7 to 12.5 mm. long; clypeus sharply elevated medially, 

 pyramidal in profile; lower end of occipital carina curved sharply 

 toward hypostomal carina and usually more or less recurved, weak or 

 interrupted next to hj^jostomal carina, the hypostomal carina very 

 high; shoulders on upper edge of pronotum moderately strong, usually 

 obtuse; apical transverse carma of propodeum forming moderately 

 strong crests, weaker medially and sometimes interrupted medially; 

 thyridium wider than its distance from base of second tergite; upper 

 valve of ovipositor beyond nodus more or less flattened. 



This subgenus is Holarctic, Oriental, and Neotropic. There are 11 

 Nearctic species. Besides these we assign the following to the sub- 

 genus: Vagenatha armata Cameron 1905, Listrognathus eccopteromus 

 Uchida 1930, L. coreensis Uchida 1930, L. sauteri Ucliida 1932, L. 

 cornuta Tschek 1870, and Ichneumon moctator Thunberg 1822. 

 Some unnamed species and certainly some additional ones with 

 names belong here also, but they cannot be placed from literature, 

 and specimens are not available. 



Some of the Nearctic "species" seem to be identical or very closely 

 similar in structure, and in these cases it is not certain whether we 

 are dealing with species, subspecies, or sometimes varieties. For the 

 present we have recognized most of the reasonable segregates as 

 species. Discovery of more structural characters of taxonomic value, 

 or further collecting should show their relationships more clearly. 



Key to the Nearctic species of the subgenus Listrognathus 



1. Third tergite fulvous, ferruginous, or mostly ferruginous, without an apical 



white band 2 



Third tergite black, usually with an apical white band 5 



2. Thorax mostly or entirely fulvous or ferruginous 3 



Thorax mostly or entirely black 4 



3. Thorax with whitish markings on scutellum, upper margin of pronotum, 



propodeum, etc 6. rufa, new species 



Thorax without whitish markings, uniformly ferruginous. 



11. acheloma, new species 



