Cynips (plumbea) euconus, new species
agamic form

GALL.-Unique, a warped cone (quite like a “chocolate bud”) in shape. The base strictly circular, flat or somewhat concave, up to 11.0 mm., averaging near 9.0 mm. in diameter, centrally bearing a very short ridge or single point of tissue by which the gall is attached to the leaf; the conical body of the gall rising directly from the circular base, rising less abruptly basally, prolonged into a long, sharply-pointed tip which is often a bit bent or twisted; the whole gall up to 11.5 mm., averaging under 9.0 mm. in height; in color a peculiar chocolate tan with a more or less abundant bluish gray scurf. Figure 115.

HOST.-Quercus sacame [arizonica]

RANGE.-Durango: Patos, 15 W, 8000' (types). Known only from this one locality in more southern Durango. Figure 102.

LIFE HISTORY..—Adults: February 10. March 10.

This species is unique in the complex in having sharply conical galls with circular, flattened bases. This gall represents a mutation from the spherical or hemispherical galls of the com plex which is, in its way, as striking as the short-winged insect mutants which we have found so interesting in Cynips. The gall would never lead one to place the species in the plumbea complex, but the insect is strikingly close to C. plumbea and C. subfusca, the relatives immediately to the north, differing from them only in being more yellow brown in color with darker markings on the thoracic lines and on the sides of the mesothorax.

In our collections, euconus was found at only a single locality, Patos, in more southern Durango, but it was fairly common there. On the same trees, in the same locality, we found C. (plumbea) glabrescens. The significant thing is the close identity of euconus with the more northern insects of the com plex, and its more remote relation to glabrescens which occurs in the same locality with euconus. Euconus and glabrescens appear to have been independent mutants from the more northern stock of the complex; but the two species represent such diverse developments that they are apparently (probably physiologically) incapable of interbreeding. Thus they maintain their specific identity even though they occur on the same oaks in the same locality.