Diplolepis rydbergiana

The type fly and gall of this species are in the National Museum. The writer collected galls at the type locality. Las Vegas Hot Springs. N. M., in October, 1921, and cut out living flies January 2. Galls sent east for rearing gave flies December 31, January 4, 20, February 1 and 6, the flies coining out in largest numbers on last date. From galls collected at Shoemaker on October 23, 1922, flies emerged and were alive on February 16, 1923. Galls were collected at Wagon Mound also. They are saddled on the midrib on the under side of the leaf. The type fly measures 2.8 mm. The series of reared specimens ranges from 2.5-3.8 mm. Average of 88 specimens, 3.16 mm.

Cynips mellea variety rydbergiana
agamic form

Dryophanta rydbergiana
Diplolepis rydbergiana
Cynips mellea var D Kinsey

GALL. — Finally naked, flesh-colored to light brown, with little solid material; rounded or flattened basally, occurring singly on the leaves of Quercus undulata varieties (Q. fendleri, Q. rydbergiana , etc.).

RANGE. — New Mexico: Las Vegas Hot Springs (acc. Cockerell 1903; also acc. Weld 1926). Wagon Mound and Shoemaker (acc. Weld 1926). Figure 51.

Probably confined to a southern Rocky Mountain area in southern Colorado and New Mexico, probably not extending south of the Sandia Mountains in New Mexico.

This is the southern Rocky Mountain variety of mellea. It occurs on at least two and probably several of the other oaks which are hardly more than varieties of Q. undulata.

Weld found mature galls in October and obtained emerging adults on December 31 (1921), January 4 and 20, and February 1 and 6 (in 1922, from galls collected in the fall of 1921), most of the emergence occurring at the later dates. From galls collected in the fall of 1922, Weld secured adults on February 16, 1923. Cockerell cut the type female (dead or alive?) out of a gall on March 21.

Cockerell and later workers have placed this insect in our present genus (known to them as Dryophanta or Diplolepis), but with the remark that “it does not exactly agree with any described American genus.” Cockerell added that “In Mayr’s table, given by Cresson, it runs to Biorhiza , but it does not belong there. The gall is like that of Amphibolips.”

The mesonotum is more shining in rydbergiana than in any other variety of mellea, and this and the nearly simple tarsal claw provide the superficial resemblance to Biorhiza. The gall, as I understand our cynipid genera, does not have the slightest resemblance to an Amphibolips gall. A direct com- parison of rydbergiana with other varieties of mellea, especially with unica and anceps which are its geographically closest relatives, gives convincing proof of the relationships of all these insects. The gall of rydbergiana is quite indistinguishable from the galls of anceps and compta. While recognizing the extreme position of mellea in the subgenus, I have given my reasons, under the subgeneric description, for keeping this species in Acraspis.

We owe the recognition of this insect to Weld’s collection of a good series from the type locality. Rydbergiana would otherwise have to pass in this paper as an unrecognizable name, for the type is a broken and immature specimen that as recently as the summer of 1926 did not convince me of its relations. Thru Mr. Weld’s courtesy I have been able to study some of his material and have reached my present conclusions. Altho Cockerell described this insect with 12-segmented antennae, better material shows the 14 segments common to the other varieties of the species.