Diastrophus tumefactus Kinsey, 1920

Feeds on: Induces galls on Tridophyllum norvegicum (L.) Greene (= Potentillamonspeliensis var. norvegica)

Distribution: Canada: Ontario, Québec

Diastrophus tumefactus

Potentilla monspeliensis var norvegica

Gall similar to niger [small oval blisters on internodes] but on Potentilla monspeliensis var norvegica from Quebec.

[Photo caption (no photo)]
On Potentilla monspeliensis var norvegica. Types were cut out of galls collected 40 years previously in Quebec.

Diastrophus tumefactus
Rough cinquefoil gall wasp

Host: Norwegian cinquefoil (Potentilla norvegica var. monspeliensis).

Gall location: On the stem.

Description: Nodular swellings that are multiple-chambered or agglomerate, with many cells in close vicinity. Up to 3 centimeters in length and 2 centimeters in diameter. When several galls are confluent, they may form clusters up to 7 centimeters in length. Shape is apparently quite variable, from subspherical to entirely amorphous. Generally smooth or bark-like and with minute, blunt spines.

Range: Thus far, this gall has only been reported from Ontario and Quebec.

This gall is poorly known. It was described by Alfred C. Kinsey from adults dissected from galls collected 40 years prior, and the gall has been rarely reported since. The gall was described from only the Norwegian cinquefoil variety monspeliensis, but it is unknown of they occur on other varieties.

Diastrophus tumefactus, new species

Galls.--Nodular swellings of the stem. Polythalamous or agglomerate, ie many separate cells nearly together in a single stem. Each swelling averages about 15 mm long by 10 mm in diameter, but several swellings will fuse to make one gall 7 cm, more or less, in length; it is covered with the smooth bark of the stem, but has scattered, very minute, blunt spines. The larval cells within are distributed irregularly through the pith which proliferates somewhat about the chamber, but this cell is not separable, nor is it formed of a distinct layer. On the stems of Potentilla monspelienesis var norvegica.

Range: Quebec, Ontario