Andricus atrimentus (sexgen)

Diplolepis atrimenta

Striped Volcano Gall Wasp (bisexual generation)

Cynipidae

Feron

Quercus berberidifolia

California

Quercus cornelius-mulleri

Quercus douglasii

Quercus dumosa

Quercus garryana

Oregon

Washington

British Columbia

Quercus john-tuckeri

Quercus lobata

Nevada

Unisexual generation of Andricus atrimentus (Hymenoptera: Cynipidae)

Cynipid Galls of the Pacific Slope

New Pacific Coast Cynipidae (Hymenoptera)

Feron atrimentum (sexgen)

Andricus atrimentus, new species

Galls (Pl. XXIV, Figs. 15, 16) - Small, inflated capsules in the leaf-blade. Monothalamous. Spherical, 3-5, mm. in diameter, about smooth, leaf-green when fresh, soon paling, finally drying yellow-brown. Walls thin, a thin-walled larval cell about 1.5 mm in diameter is connected with the outside by a tangle of dense, not not definitely branched fibers. In the leaf-tissue, projecting about equally on either side, usually near the edge of very young leaves of Quercus douglasii.

Range - California: Three Rivers, Redding.

These galls develop early on the unfolding leaves, looking like small air-bubbles blown in the tissue. The galls were always very new and fresh when gathered, but were also practically mature. The development of this generation of the species must be a matter of only a month or two; the other generation is unknown. The adults were maturing, had not emerged, but did emerge at some date later than the dates of collecting the galls: March 23 at Three Rivers, and April 2 at Redding. Of 23 adults, 13 were females. This species resembles Andricus palustris form palustris (Osten Sacken) of the black oaks of the eastern part of the United States, and it might prove desirable to consider the two as varieties of one species. Morphologically the two are very similar, even in many minute details of venation, thoracic sculpture, abdominal and antennal characters; in atrimentus the parapsides are more convergent at the scutellum, the scutellum is less elongate, less rugose, with the foveal groove smoother and less distinctly bifoveate than in palustris. In the male of atrimentus the abdomen is not as small as in palustris. Atrimentus occurs on a white oak in one distinct faunal area; palustris on black oaks in a very different faunal area. It is exceedingly significant that the galls of the two species show similarity of structure, for as has been repeatedly shown the gall is an expression of the physiological nature of the insect. Physiologically then the two species are related,just as they are morphologically, but physiologically they differ even more markedly than morphologically. For though the galls are similar hollow bladders in the leaf, the Pacific Coast species does not have the thick and succulent walls of palustris; while the attached larval cell of atrimentus is distinctly unlike the remarkable, loose cell of palustris.Both forms are bisexual generations, developing very quickly in early spring on the unfolding leaves. The other generation of palustris, namely Andricus palustris form compressus (Gillette), is a wingless, agamic species forming a small, hollow, egg-shaped, separable gall on theleaves in late summer, the gall dropping to the ground in autumn, the insect emerging very early in the spring. It is not unlikely that atrimentus has a similar history, but it will be important that some one determine exactly what differences exist in the life-histories of the two-insects.

Diplolepis atrimenta

This species was described from imperfect specimens from galls on Q. douglasii from Three Rivers and Redding, Calif. The writer has collected the galls on two other California oaks also: on Q. douglasii at Three Rivers, Kaweah, Bagby, Placerville, Oroville, Red Bluff, Shasta, Ukiah, Lakeport (flies emerging May 12), Cloverdale, Calistoga, St. Helena, Mt. Diablo, Stanford University (flies emerged May 1-8), Los Gates, Paraiso Springs, Bradley, Jolon, Paso Robles (flies emerged April 25), Santa Margarita, and Lebec; on Q, lobata at Los Gatos, Stanford University, Lake- port, and Red Bluff; on Q. dumosa at Paso Robles, Jolon (flies emerged April 25) and Paraiso Springs. The galls are sometimes attached to the staminate flower axis as well as to leaves. 

Miss Egbert reared adults of this species in April, 1917, and included a description in her manuscript thesis presented at Stanford University in May, 1917. 

Field notes on gall-inhabiting cynipid wasps with descriptions of new species

Dros atrimentum

Quercus douglasii, dumosa, garryana, lobata
Leaf galls, integral
Fig 98. Black cell, 3 mm long, supported by fine fibers inside a tissue paper thin membrane. On under side before the new leaves are full-grown. Adults out in late April.

Fig 98. Q. douglasii, dumosa, lobata. On under side of leaf. Outer wall thin as tissue paper. Within is a black cell supported by fine fibers. Fresh galls are found in mid-April when the new leaves are 1/2 to 5/4 inch long. Miss Egbert reared adults in April (Stanford). Adults emerged Apr. 25 (Paso Robles). Andricus brunneus Full. was erroneously associated with this gall. 

Andricus atrimentus (bisexual generation)

Gall:
By mid-March the integral leal galls of the bisexual generation usually reach full size and the outer white layer develops its pink-tinted tissue paper texture. The blue-black larval cell is connected to the outer layer by numerous blue-black filaments which become white distally.

Host:
Quercus douglasii
*similar galls noted on Quercus dumosa [berberidifolia?] and Quercus turbinella californica [john-tuckeri], but not confirmed by reared insects. 

Andricus atrimentus (bisexual generation)
[Page 107]

Bisexual generation galls are bulbous and hollow, with a thin, felty and web-like, transparent skin. 

Host:
Quercus douglasii

Plant Galls of the Western United States