Key to Rhopalomyia galls on North American goldenrods

1. Vegetative bud gall, fleshy or leafy, just above the ground or high above it................................................................ 2

- Galls on other plant parts .............................................................................................................................................. 7

2. Fleshy gall on shoot tip or at the base of the plant, surrounded by few leaves. Larval chambers embedded in the fleshy tissue................................................................................................................................................................... 3

-. Not fleshy; composed of many short leaves that form a rosette on apical or sometimes lateral shoot tips ................. 4

3. Smooth, bare gall on Solidago juncea either at the base of the plant, just above the ground, or on a growing shoot tip up to 60 cm above the ground; up to 4 cm in diameter (Figs. 58–61) .................................. R. hirtipes (Osten Sacken)

- Spongy, spherical gall tightly surrounded by leaves, on growing shoot-tips of Euthamia graminifolia . Up to 6 cm in

diameter (Figs. 78–81) ............................................................................................................................. R. lobata Felt 4. Galls found in spring (April–early June); cryptic......................................................................................................... 5

- Galls found in summer and fall (late July–early October); large and conspicuous...................................................... 6

5. Gall found very close to the ground on S. gigantea sprouts and therefore cryptic despite its large size; usually con- taining 3–20 larval chambers; composed of many short and narrow leaves surrounded by 5–10 much longer leaves (Fig. 74)................................................................................................................... R. capitata Felt, spring generation

- Gall found at least 20 cm above the ground on young S. altissima, S. rugosa, or S. canadensis plants; usually con- taining 1–3 larval chambers; composed of 5–10 short leaves surrounded by several longer leaves. Hardly distin- guishable from normal growing shoot tips (Figs. 70, 72)............................. R. solidaginis (Loew), spring generation

6. Gall on S. gigantea, containing 5–30 larval chambers situated among uniformly distributed short leaves (Fig. 75).... ............................................................................................................................. R. capitata Felt, summer generation

- Gall on S. altissima or S. rugosa, containing 3–10 larval chambers, each individually surrounded by a set of narrow leaves (Figs. 71, 73) .................................................................................... R. solidaginis (Loew), summer generation

7. Galls in rhizomes .......................................................................................................................................................... 8

- Galls in or on leaves, inflorescences or stems .............................................................................................................. 9

8. Tapered, bud-like, single-chambered galls in clusters on rhizomes of S. juncea .................................. R. bulbula Felt

- Cylindrical, multi-chambered galls in rhizomes of S. altissima ........................................................ R. thompsoni Felt

9. Galls inside flower heads (capitula)............................................................................................................................ 10

- Galls on leaves or stems. If associated with inflorescence, then gall not developing inside a capitulum but situated on or among capitula........................................................................................................................................................ 12

10. Galls smooth, on S. bicolor ...................................................................................................... R. guttata Dorchin n.sp.

- Galls densely covered by bristles, on other goldenrods.............................................................................................. 11

11. Cylindrical galls on S. altissima; slightly wider at base (Figs. 56–57)........................... R. anthophila (Osten Sacken)

- Bulb-shaped galls, tapered at tip, on S. altissima and S. fistulosa ................................................... R. racemicola Felt

12. Bulb-shaped, grayish galls with tapered apices, forming rosette-like aggregations on stems of S. fistulosa .... R. n. sp.

- Different galls on other goldenrod species ................................................................................................................. 13

13. Slender and elongate, green to purple galls with longitudinal stripes on Euthamia spp. .......................................... 14

- Conical, mostly green galls, sometimes with purple longitudinal stripes, on Solidago spp....................................... 15

14. Gall carried on long stalk on leaves, stems, or inflorescences (Figs. 84–85)................................... R. pedicellata Felt

- Gall sessile, without long stalk, on leaves, stems, or inflorescences (Figs. 82–83) ......................... R. fusiformae Felt

15. Hairy galls on S. rugosa and S. altissima (Figs. 62–65) ......................................................................... R. clarkei Felt

- Smooth galls on S. gigantea or S. juncea ................................................................................................................... 16

16. On leaves of S. juncea; sometimes with a tail-like extension on other side of leaf. May be found on leaves compos- ing rosette galls of Asphondylia monacha on this host (Figs. 68–69) ......................................... R. gina Dorchin n.sp.

- On leaves or rarely stems of S. gigantea; without extension on other side of leaf. May be found on leaves composing rosette galls of R. capitata and Dasineura folliculi on this host (Figs. 66–67) ................................ R. inquisitor Felt ?