Lagonis

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Taxonomy

Family: Tenthredinidae
Family common name: common sawflies
Subfamily: Blennocampinae
Tribe: Phymatocerini
Genus: Lagonis Ross, 1937
Subgenera: none

Background

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).

Sawflies in the subfamily Blennocampinae have a diverse set of life histories and habits. Many species are restricted to subtropical and tropical regions, but the genus is still fairly species-rich in North America. Blennocampinae includes many sawflies that feed on ornamental and forestry crops. This subfamily can be recognized by wing venation and bidentate mandibles (Smith 1969d).

Lagonis is monotypic in North America. Lagonis nevadensis is about 8 mm in length and mostly black with white abdominal striping. The species has slightly different coloring along a latitudinal gradient of its range: thorax mostly red in the south and entirely black in the north (Smith 1969d).

Diversity

There are three described extant species worldwide. One species occurs in North America (Taeger et al. 2010).

Diagnostic characteristics

Subfamily characters

• angle of intersection of fore wing veins Cu1 and 1m-cu between 120°–150° (Goulet 1992)
• fore wing veins M and 1m-cu parallel (Smith 1969d)
• fore wing veins 2A and 3A incomplete (Smith 1969d)

Genus characters

• clypeus slightly emarginated (Smith 1969d)
• third antennal segment about as long as, or slightly longer than fourth (Goulet 1992)
• prepectus absent (Smith 1969d)
• fore wing veins 2A and 3A curved upward and almost connecting to 1A (Smith 1969d)
• hind wing cell M present (Smith 1969d)
• large pits present on mesoscutllum and mesepisternum (Goulet 1992)
• pulvilli on the first and second tarsomeres well developed (Goulet 1992)
• tarsal claw basal lobe absent (Goulet 1992)
• tarsal claw with short inner tooth (Smith 1969d)

May be confused with

Lagonis can be confused with similar species in the subfamily Blennocampinae. It can be distinguished from most other genera by the large pits on the mesoscutellum and mesepisternum and the upwardly curved apex to veins 2A and 3A of fore wing (Smith 1969d, Goulet 1992).

Exotic pest species of concern

none

Host associations

Lagonis nevadensis feeds on species of Sambucus (elderberry) (Goulet 1992).

Life history

unknown

Distribution

World: This genus is known from North America, Russia, and Japan (Sundukov 2017, Taeger et al. 2018).

North America: Lagonis nevadensis occurs west of the Rocky Mountains, from southern California north to British Columbia and as far as Wyoming and Alberta in the eastern part of the range (Smith 1969d).

Map data from: GBIF.org (29 October 2019) GBIF Occurrence Download Lagonis

Details about data used for maps can be found here.