gallers on Sambucus

(For a dichotomous table for galls on Sambucus by Hans Roskam click here)

1a On parts above ground => 2

1b Roots with little, ± spindle-shaped swellings. S. nigra: Meloidogyne hapla

2a On flowers => 6

2b On stems, buds or leaves => 3

3a On leaves => 4

3b Buds swollen, unopened. S. nigra: ? gall midge

4a Leaf blade loosely rolled downwards or curled or distorted without rolling => 5

4b The margins usually of all leaflets of several terminal leaves narrowly rolled upwards. Leaf blades narrowed, often curled or furrowed and ± discoloured. S. canadensis, ebulus, nigra, racemosa: Epitrimerus trilobus

4c Deformation and discolouration of the leaves, inrolling of the leaf margin. Sambucus spp.: Callyntrotus trilobus

= Despite the confusing identity of the specific name, this is not a synonym of Epitrimerus trilobus, which often is cited as (the only) causer of leaf margin galls in elder. Whether both species co-occur in the same gall, perhaps the one as an inquiline of the other, is not clear

5a Large leaflets, complete leaves or also several leaves disfigured on the ± stunted shoot tip. Leaf blades strongly curved downwards, curled, locally deep green. Sambucus spp.: Philaenus spumarius

5b Leaf blade is strongly infected ± rolled downwards. S. ebulus, maderensis, nigra, racemosa: Aphis sambuci

6a Corolla globularly swollen, slightly leather-like; tube slightly elongated. Flowers unopened. Midge galls containing usually several non-jumping larvae => 7

6b Similar malformation. Filaments shortened and thickened. Ovaries ± irregularly swollen. Contain several yellow, jumping larvae. Sambucus spp.: Contarinia sambuci

7a Gall similar to previous one, often slightly smaller; corolla more irregular and less compactly closed. Containing usually only a single pale- to orange-yellow non-jumping larva. Sambucus spp.: Placochela nigripes

7b Similar malformation; containing several white larvae. S. ebulus, nigra:
Arnoldiola sambuci