The Heptamelidae were previously considered to be within the Tenthredinidae. However, following genetic analysis, the Heptamelidae were found to be a sister group to the Tenthredinidae and were elevated to family level. Having previously been considered as part of the Selandrinii tribe, the Heptamelidae share characteristics with this group. The Heptamelus genus has antennae with 7 or 8 segments and in the forewing veins M and Cu-a are interstitial. The width of the stigma is as wide as the width of vein 2r.
Globally there are 44 species in six genera. Heptamelus is the largest genus with 38 species. In Britain and Ireland the genus is represented by two species.
The larvae bore into ferns working from the tip of a stem downwards.
Family Heptamelidae Benson, 1938
Genus Heptamelus Haliday, 1855
Heptamelus dahlbomi (Thomson, 1870)
Heptamelus ochroleucus (Stephens, 1835)
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
Malm, T.; Nyman, T. 2015: Phylogeny of the symphytan grade of Hymenoptera: new pieces into the old jigsaw(fly) puzzle. - Cladistics, London u. a. 31: 1-17.