Craterocercus

Taxonomy

Family: Tenthredinidae
Family common name: common sawflies
Subfamily: Nematinae
Tribe: Nematini
Genus: Craterocercus Rohwer, 1911
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).

Nematinae is the second-largest subfamily of Tenthredinidae, with over 1,250 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.

Craterocercus are about 6–9 mm in length and mostly black with white, yellow, or red markings and clear wings (Smith 1969a).

Diversity

There are six described species worldwide, all of which occur only in North America (Taeger et al. 2018).

Two incomplete keys to species are included in Smith 1969a and Smith 2003b.

Diagnostic characteristics

Subfamily characters​

Genus characters

May be confused with

Craterocercus can be distinguished from other genera of Nematinae that have fore wing vein 2A+3A curved upwards and vein 2r-rs present by the semi-circular emargination of the clypeus, the short inner tooth of the tarsal claw, and the stocky antennae (Smith 1969a, Goulet 1992).

Exotic pest species of concern

none

Host associations

Craterocercus feeds on Quercus (oak) species (Smith 1969a).

Life history

Craterocercus are external feeders of leaves (Nyman et al. 2006a).

Distribution

World: The genus is known only from North America (Taeger et al. 2018).

North America: Craterocercus occurs in the eastern United States as far west as Texas, the west coast in California and Oregon, and in Baja California and northern Sonora, Mexico (Smith 1969a, Smith 2003b).

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

Details about data used for maps can be found here.

Craterocerus obtusus female lateral habitus; photo by J. Orr, WSDA

Craterocerus obtusus female lateral habitus; photo by J. Orr, WSDA

Craterocercus obtusus female dorsal habitus; photo by J. Orr, WSDA

Craterocercus obtusus female dorsal habitus; photo by J. Orr, WSDA

Craterocercus obtusus female face; photo by Q. Baine, WSDA

Craterocercus obtusus female face; photo by Q. Baine, WSDA

Craterocerus obtusus male lateral habitus; photo by J. Orr, WSDA

Craterocerus obtusus male lateral habitus; photo by J. Orr, WSDA

Craterocercus obtusus male dorsal habitus; photo by J. Orr, WSDA

Craterocercus obtusus male dorsal habitus; photo by J. Orr, WSDA

Craterocercus obtusus male face; photo by Q. Baine, WSDA

Craterocercus obtusus male face; photo by Q. Baine, WSDA

Craterocerus obtusus wings; photo by J. Orr, WSDA

Craterocerus obtusus wings; photo by J. Orr, WSDA