There are thought to be around 46 species of Cladius globally. The majority are distributed in the holarctic regions with one or two species in the neotropics and Australia. Separation of the species in the Western Palaearctic is unclear. Seven species are present in Britain and Ireland falling into two subgenera.
The genus can be characterised within the Nematinae by the following features. The antennal scape and the pedicel combined are noticably shorter than the third segment. In males the basal flagellomeres may be modified with protruberances. In the forewing, the anal cell is widely divided into two cells, vein 2r-rs is absent from the marginal cell and vein 2m-cu normally runs into submarginal cell 2Rs. The tarsal claws have an inner tooth.
Larvae feed on the leaves of various trees and shrubs.
Cladius (Priophorus) brullei (Dahlbom, 1835)
Cladius (Priophorus) compressicornis (Fabricius, 1804)
Cladius (Priophorus) pectinicornis (Geoffroy, 1785)
Cladius (Priophorus) rufipes Serville, 1823
Cladius (Trichiocampus) grandis (Serville, 1823)
Cladius (Trichiocampus) pilicornis Curtis, 1833
Cladius (Trichiocampus) ulmi (Linnaeus, 1758)
Benson, R.B., 1952. Handbooks for the Identification of British Insects. Hymenoptera, Symphyta, Vol 6, Section 2(a-c), Royal Entomological Society, London
Chambers, V. H. 1977: Unusual host-plant of Cladius pectinicornis (L.) (Hym., Tenthredinidae). - The Entomologist's Monthly Magazine 112(1348-1351): 202
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
Prous, M., Liston, A., Kramp, K., Savina, H., Vårdal, H. and Taeger, A., 2019. The West Palaearctic genera of Nematinae (Hymenoptera, Tenthredinidae). ZooKeys, 875, p.63.
Smith, D. R. 1974: Sawflies of the tribe Cladiini in North America (Hymenoptera: Tenthredinidae: Nematinae). - Transactions of the American Entomological Society, Philadelphia 100: 1-28
Tsujita, M. 1952: Studies on the larvae of the Tenthredinidae (IV). Morphological studies on the rosaceous leaf-feeder sawfly, Cladius pectinicornis Geoffroy. - Mushi, Fukuoka 23(7): 57-60
Wei, M., 2001. Revision of Cladiini (Hymenoptera: Tenthredinomorpha: Nematidae) from China (I): Notes on Cladiini and Driocampus Zhang with revision of Cladius Illiger from Chin. Journal of Jishou University (Natural Science Edition), 22(3), pp.34-39.