There is only one known species within this genus. The species is found in both Britain and Ireland.
The Halidamia can be identified by the following characteristics. The antennal pedicel is longer than it is wide and the first flagellomere is longer than the second flagellomere. The apical four segments are shortened such that combined they are subequal in length to the pedicel and first flagellomere combined. There is no post-genal carina. The prepectus is absent. In the forewing, the vein stub 2A+3A curves up at the apex. The hindwing lacks cell M. On the legs the tarsal claws have a basal lobe and an inner tooth similar in length to the outer tooth.
The larvae feed on cleavers and hedge bedstraw.
Halidamia affinis (Fallén, 1807)
Benson, R.B., 1952. Handbooks for the Identification of British Insects. Hymenoptera, Symphyta, Vol 6, Section 2(a-c), Royal Entomological Society, London
Liston A, Knight G, Sheppard D, Broad G, Livermore L (2014) Checklist of British and Irish Hymenoptera - Sawflies, ‘Symphyta’. Biodiversity Data Journal 2: e1168. https://doi.org/10.3897/BDJ.2.e1168
Smith, D. R. 1969: Nearctic Sawflies. I. Blennocampinae: Adults and larvae (Hymenoptera: Tenthredinidae). - Technical Bulletin, U.S. Department of Agriculture, Washington 1397: 1-176