Dros sessile

Quercus arizonica, oblongifolia
Leaf galls
Detachable
Fig 107 and 172.

Diplolepis sessilis, new species

Host. — Quercus arizonica.

Gall (figs. 7 and 35). — Cylindrical with a deep broad cup at apex, dark red, attached on under side of leaf in the fall, falling with the leaf. Usually only one or two on a leaf. The galls measure up to 5 mm. high and 5 mm. in diameter at upper end. The lower end with a sharp flaring rim is sessile on the leaf surface, the upper half dilated, not so smooth, brownish, often inrolled at top, giving the gall somewhat the appearance of a sea anemone. The basal half of the gall is occupied by a centrally placed conical cavity, above which and immediately below the floor of the cup is an excentrically placed larval cell which is cut transversely, if at all, when the gall is split lengthwise.

Andricus sessilus [sic]
Cup-gall wasp
[Page 186]

Hosts Quercus arizonica, oblongifolia

Galls look like cups sitting on top of broad stalks that usually have flared bases at the point of attachment, which can be lacking in some specimens.

The taxonomic position of the Dros species north of Mexico is discussed, concluding than at least two species belong to the genus Dros: D. sessile (Weld, 1927) and D. viscidum (Weld, 1944).

transferred to Andricus: sessilum (Weld), comb. nov.