ART. 28 CHALCID FLIES NORTH OF MEXICO BALDUF 55 



20. DECATOMA FLAMMINNEIVENTRIS Girault 



Plate 2, Figure 18 ; Plate 3, Figures 27-29 ; Plate 4, Figures 37, 41 



Decatoma flamminneiventris Girault, Proc. U. S. Nat. Mus., vol. 58, p. 208, 

 1920. 



This is one of the outstanding species of the genus, differing from 

 all other mostly j^ellow species in having in most specimens a sub- 

 quadrate submarginal band, the wings clothed with very minute 

 spines on the surfaces and margins, and in the absence of the pat- 

 tern of large hairs usually found on the basal third of the front 

 wings; definitely larger than any other mostly yellow species, 

 except disholcaspidis Balduf. 



Female. — Length 3.7 mm., fairly robust, colors chiefly black and 

 yellow; head and antennae honey yellow, mandibles brown, ocellar 

 region and occiput narrowly, black, apex of scape and base of pedicel 

 light brown, eyes brown; prothorax colored like the head, with a 

 broad dorsal longitudinal band of black widening behind and merg- 

 ing reddish brown into the surrounding yellow; rest of thorax and 

 propodeum more brownish yellow, dorsal band of pronotum con- 

 tinuing to end of propodeal groove, spreading laterad on front por- 

 tion of propodeum, scutellar black area oval covering all but lower 

 sides, and prescutal band only half as broad with edges almost 

 straight, scapulae and axillae without black, sterna of thorax black 

 between coxae; legs honey yellow, tibiae and tarsi slightly darker, 

 except hind tibiae yellow-brown; submarginal band of wing deep 

 brown at base, fading toward apex, subquadrate (one-half 

 longer than broad on the specimens from New Mexico and as broad 

 as long on the Colorado specimens), proximal edge concave, apical 

 margin convex and reaching beyond apex of stigma but not to end 

 of stigmal vein, extending less than a third across the wing, second- 

 ary band wanting; abdomen light brown, ochreous. 



Head slightly more than a half longer than wide, face moderately 

 convex, vertex but feebly so, malar groove definite, reaching to base 

 of mandibles, cheeks entirely smooth, polished and bare, rest of head 

 uniformly rather coarsely umbilicate punctate, but ocellar area also 

 finely punctured and moderately hairy, antennae slightly more hairy ; 

 scape (not including bulb) a little longer than pedicel plus Fl, 

 pedicel slightly longer than Fl, latter a third longer than F2, F2 to F4 

 subequal in length, one-fifth longer than thick, and almost equal in 

 diameter; prothorax only slightly narrower than head and meso- 

 thorax, nota moderately hairy and umbilicately punctate, mesopl'eura 

 rather coarsely aciculate and finely punctate, a row of 15 to 17 

 setae on submarginal vein, surface of apical two-thirds finely and 

 irregularly undate and rather sparingly vested with minute taper- 

 ing hairs that are easily overlooked, margin also bearing such hairs. 



