Diplolepis variabilis (Bassett)

Diplolepis variabilis was first described from galls collected in North Dakota (Bassett 1890). Beutenmüller (1907) and Kinsey (1922) reported galls from Washington to Texas. In Canada, D. variabilis is found only west of the Rocky Mountains and is very common on tall R. woodsii from Kelowna to Osoyoos, British Columbia. Galls of D. variabilis are found on the leaves of the upper branches and are usually larger and denser than galls of D. ignota.

Galls are single-chambered and spherical and are found on the abaxial surface of leaflets. However, most galls coalesce to make clusters irregularly rounded and globular to ovate (Fig. 30). Single-chambered galls are about 8 mm in diameter, whereas coalesced galls are often 2 cm in diameter. They have a smooth surface and internally are pith-like with the consistency of packed sawdust. The chambers are located at the centre, deep within the galls (Fig. 31). Galls are green when immature but turn tan to brown when mature. They are often so dense that branches droop with the combined weight of the galls. They remain on the host plants over winter. Galls are initiated in late summer.

Inhabitants were reared from a large population of galls collected in the fall near Oliver, British Columbia. Of recovered insects (Fig. 44K), 7.7% were inducers, 23.2% were Periclistus, and 69.3% were parasitoids. The most abundant parasitoids were Aprostocetus at 47.5% and Eurytoma at 17%.

Diplolepis variabilis (Bassett, 1890)

Nomenclature: Rhodites variabilis Bassett, 1890 | Rhodites globuloides Beutenmüller, 1907

Feeds on: Induces galls on Rosa woodsii Lindl.

Distribution: United States: Colorado, Itado, Texas, Utah, Washington, Wyoming;Canada: British Columbia

Diplolepis variabilis (Bass.).

Rosa sp.
A leaf gall. Irregularly rounded, 6–20 mm. in diameter, russet, smooth. S. Utah.

Rhodites variabilis n.sp.

Irregularly rounded, sometimes ovate or reniforni, and varying so much in form and size as to make a description difficult. They are from one-quarter to three-quarters of an inch in diameter in the more regular forms, but the reniform specimens often exceed an inch in diameter. Polythalamous, but evidently so through the perfect coalescence of two or more galls. The surface, like that of a russet apple and the color, nearly the same. Some, gathered perhaps before they were fully matured, are of a darker color, and are shrunken. These last may possibly prove to be a distinct species, but the insects offer no essential points of difference.

The development of these galls is as variable as their form. Some appear to grow on the ends of the small branches, others are attached to the leaf stems, while others are developed from an abortive leaflet, while still others grow on the surface of fully developed leaves. Internally, they ai-e of a rather solid, pith-like substance,
and the larvae have no free larval cell.

Diplolepis variabilis

GALL. — Irregularly ovate, smooth, solid, leaf gall. Polythalamous, each gall with usually three or four larval cells. Very irregular in shape, globular, to ovate, elliptical, or massive, all edges rounded; aver- aging 10. by 20. mm., observed to 25. mm. in diameter; smoothed, naked of bloom or scurf, light to rich brown (in mature galls). Internally solid, compact, soft, like compacted sawdust; the larval cells large, 2.0- 3.5 mm. in diameter, more round than usual, with a distinct but thin and inseparable lining. On roses, attached to leaves, or replacing leaf- lets, or replacing the whole leaf and attached directly to stems.

RANGE. — From Texas and Wyoming to Washington. A very closely related species, Diplolepis ignota (O. S.), extends over the eastern half of the United States. I have not seen the insects of this species which have been recorded from Texas (according to Beutenmuller) , Wyoming, or Washington, altho I have seen the galls of the Washington material. Undoubtedly these regions as well as others in the western part of the United States have varieties distinct from any yet described. What data have been over-looked by the approximate taxonomy which fails to distinguish the several varieties concerned! Important information as to the age of the species and factors in the origin of species are mentioned in connection with variety lutescens. Diplolepis ignota (Osten Sacken) with its varieties occur- ring thruout the eastern part of the United States is so closely related to variabilis that there cannot be found differences in the insects which one could presume are of more than varietal rank. With a single change in regard to the sculpture of the mesopleuras, the general description of this species will apply to all varieties of ignota. On the other hand, the galls of ignota varieties are covered with a white scurf which the galls of all varieties of variabilis lack, and all of the white- galled varieties occur in the eastern half and all of the brown-galled varieties in the western half of the United States. This indicates closer affinities within each group than between the groups. One must choose between considering the groups as species and over-emphasizing their distinctness; and consi ering it a single species involved and attempting to express the groupings of the varieties by a system of quadrinomials, which is objectionable. If we will keep in mind the close relations of the two it may prove most convenient to use two specific names. Of 1622 insects which I have bred, 784, or over 48 per cent, are males. I have a relatively small amount of material of ignota, and I had previously believed that the high percentage of males obtained there was abnormal. But it would appear as if these species have a more nearly equal sex ratio than some others of the genus. As with other rose cynipids I have bred, the males appear to emerge earlier than the females, accounting for instance for the 57 per cent males collected at Provo, and the 43 per cent collected at Holly. The insects emerge early in the spring, in late April in the Rocky Mountain country, probably earlier or later in regions of earlier or later seasons. I have recounted the life history of ignota (Bull. Amer. Mus. Nat. Hist., XLII, p. 331), and that species in Massachusetts does not have an alternation of generations. The field data for variabilis do not disagree, and it is prob- able that an alternation does not occur for any variety of either group.

[Kinsey goes on to describe several varieties; see paper for details]

Rhodites variabilis Bass.

Gall (Plate XLVI, Figs. 5-9). --Monothalamous. Variable in size and shape. Spherical, irregularly rounded, somewhat ovate or reniform, though coalescence of two or more galls. Russet brown sometime tinged with red. Internally they are pith-like with a large larval cell in the center. In the larger galls where two are more are confluent there are several larval cells. The galls occur usually in a cluster of from two to ten on the small terminal twigs, or are attached to the leaf stems while others grow on fully developed leaves of a wild rose (Rosa sp.).