No. 2368. AMERICAN SUBTERRANEAN GALLS ON OAK— WELD. 219 



20. CALLIRHYTIS ENIGMA, new species. 



Plate 33, figs. 19, 20. 



Female. — Almost bare and almost black, the legs and antennae 

 reddish-brown. Head broader than high, as broad as thorax, cheeks 

 a trifle longer than half the eye, finely pebbled above and punctate 

 pubescent on face which has a broad median elevation from base of 

 antennae to the impressed clypeus, mandibles 2-toothed, palpi 5-and 

 3-segmented, antennae 15-segmented, arising below middle of eyes, 

 first longest and stoutest, third one and one-half times fourth, the 

 rest becoming gradually shorter and stouter, the last at least one 

 and one-half times as long as preceding (which is as broad as long) 

 and as stout. Mesoscutum not high-arched, polished, beautifully 

 coriaceous with scattered punctures bearing scarcely visible hairs. 

 Parapsidal grooves distinct, percurrent, broader behind, deep with 

 transverse ridges in bottom, median groove extending forward 

 nearly half-way, anterior and lateral lines very faint impressions. 

 Scutellum rugose behind with a median smoothish area on disk, 

 the rugose pits are distinctly bordered behind and separated by a 

 septum as broad as a parapside in which there is often a trace of a 

 median groove; with impressed hairy areas at sides. Propodeum 

 with two outwardly bent ridges inclosing a smooth area slightly 

 narrower above, in which are two faint longitudinal lines, spiracular 

 areas hairy, spiracles nearly round, petiole very rugose. Mesopleura 

 longitudinally striate below. Legs punctate pubescent, hind coxae 

 with bare ridge behind, tarsal claws simple, divergent. Wings 

 with pale yellow distinct veins, second cross-vein heaviest and not 

 angled, areolet present, surface pubescent, margin distinctly ciliate 

 only on hind margin of hind wing. Abdomen slightly compressed, 

 longer than high, smooth and shining, posterior edge of second and 

 exposed parts of others microscopically punctate, second with 

 widely separated, small, narrow pubescent patches at base. Ventral 

 spine mostly concealed, not twice as long as wide. Ovipositor when 

 dissected out one and one-third times as long as antenna. Using 

 width of head as a base, the length of mesonotum ratio is 1.2; antenna, 

 2.4-2.5; ovipositor, 3.3; wings, 3.65. 4 



Range in length of 76 pinned specimens, 3.0-4.1 mm. Average, 

 3.7 mm. Mode, 3.9 mm. 



This species is closely related to saltatus which Ashmead in 1881 

 made the type of the new genus Trisolenia separated from Andricus, 

 which he understood to have simple claws by the sharply defined 



* These ratios are from the type material from Q. rubra from Winnetka, Illinois. Paratype flies from 

 Florida from Q. catesbaei and Q. myrti/olia agree with these in sculpture but have length of antenna ratio 

 2.0; ovipositor, 2.6; and wing, 3.1. 



