Family common name: common sawflies
Genus: Pseudodineura Konow, 1885
The Tenthredinidae are the most species-rich family and are found throughout the world, in all continents but Antarctica. They are known as the “common sawflies.” They can generally be recognized by a cylindrical body and long, segmented antennae. Otherwise, they come in a variety of colors, sizes, and forms (Goulet 1992).
Nematinae is the second-largest subfamily of Tenthredinidae, with over 1250 species (Prous et al. 2014). They are most diverse in northern Eurasia and North America; only a few species occur in the Southern Hemisphere. Nematinae sawflies have a variety of feeding habits including external leaf feeding, leaf mining, and gall forming, and feed on a variety of hosts (Smith 2003b).
The Nematinae have been subject to numerous revisions in recent years. As of 2021, there are no comprehensive keys to many of the North American species of Nematinae (Prous et al. 2014). Because of changing taxonomy and extreme variability in morphology, identifying genera and species in the Nematinae may be more challenging than in other subfamilies of Tenthredindae. For this reason, knowing the host or behaviors of a specimen can be extremely helpful for identification within this subfamily.
Pseudodineura is a rare genus of small sawflies, about 4–5 mm in length found in northern ranges. Most species are black with red or yellow striping on the legs (Smith 1976b).
There are 10 described species worldwide. Five species occur in North America (Taeger et al. 2018).
A key to North American species is included in Smith 1976b.
Pseudodineura may be confused with other genera in the subfamily Nematinae—especially those with fore wing vein 2r-rs present and vein 2m-cu meeting cell 2Rs—but can be distinguished from most genera by the incomplete hind wing vein 2A (some species of Pristiphora also have this vein incomplete, but can be distinguished by their indistinct notauli). Pseudodineura can be distinguished from the closely related genus Kerita by the fine pits on the postocular region of the head (Goulet 1992) and by the position of the ocelli (Ross 1937).
Pseudodinerua enslini and P. mentiens in Europe are minor pests to landscaping plants. The plants are generally not severely damaged, but the leaf mines can make the plants unsightly as ornamentals and floral production can be reduced (Liston et al. 2019b).
Pseudodineura feeds on species of Hepatica (liverleaf) and Ranunculus (buttercup) (Goulet 1992).
Larvae are leaf miners (Smith 1976b). When disturbed, Pseudodineurini larvae secrete the compound citral, which repels ants. Presumably this is a beneficial defense strategy when they leave the mine to overwinter or pupate in the soil (Boevé et al. 2009).
North America: Pseudodineura has three ranges in North America. Three species occur in the northeastern United States and Canada west to Alberta, and one, P. lehosa, in the Pacific Northwest and British Columbia (Smith 1976b). One species, P. kasatochi, is only known from Alaska (Smith et al. 2010a). Pseudodineura fuscula may be introduced from Europe (Smith 1976b).
Map data from: GBIF.org (29 October 2019) GBIF Occurrence Download Pseudodineura
Details about data used for maps can be found here.