Aprosthema

Taxonomy

Family: Argidae
Family common name: argid sawflies
Subfamily: Sterictiphorinae
Genus: Aprosthema Konow, 1899
Subgenera: none

Background

Argidae are found in all non-polar regions of the world (Smith and Middlekauff 1987, Smith 1992). They are external foliage feeders with a wide range of host plants. Additionally, the family exhibits some uncommon behaviors like the excretion of defensive compounds and subsocial habits (Smith 1992).

Aprosthema are rarely collected, and most species worldwide are described from a few or from a single specimen. They are recognized by characteristic 3-segmented antennae, which in males are distinctly forked (Smith 1971c, Vikberg 2004).

Diversity

There are 57 described species restricted to the Northern Hemisphere. Species richness is relatively low in North America, with only two known species (Taeger et al. 2010).

A key to North American species of Aprosthema is included in Smith 1971c.

Diagnostic characteristics

May be confused with

The family Argidae can be distinguished by the single-segmented flagellum of the antenna. The genus Aprosthema can be distinguished from other genera in the family by the lack of preapical spurs on the tibiae, simple tarsal claws, and a lack of vein Sc in the fore wing. Males are distinguished from related genera Arge and Atomacera by the conspicuous forked antennae (Smith 1992).

Exotic pest species of concern

none

Host associations

Larvae are external leaf feeders, and in North America feed on species of Fabaceae, including Acmispon grandifloras (chaparral bird’s-foot trefoil), Hosackia sp., and Lotus sp. (Smith 1992). Other leguminous hosts such as Vicia cracca (bird vetch) and Lathyrus vernus (spring vetchling) are recorded for European species of Aprosthema (Vikberg 2004).

Life history

Little is known about the biology of Aprosthema. In other genera of Argidae, the female oviposits along the margin of the leaf. After hatching, the larvae are external feeders on the foliage of plants (Smith 1989). Unlike other Argidae, larvae of the genera of the subfamily Sterictiphorinae are not known to live or pupate in aggregations (Smith 1992).

Distribution

World: This genus ranges throughout Europe, east into China and Russia, and in North America (Taeger et al. 2010).

North America: Aprosthema is a western genus, with both North American species occurring in the Pacific Northwest (Washington, Oregon, California). Aprosthema brunniventre also occurs farther south into Nevada and Baja California Norte (Smith 1971c, Smith 1992, Taeger et al. 2010).

Map data from: GBIF.org (26 June 2019) GBIF Occurrence Download Aprosthema

Details about data used for maps can be found here.

Aprosthema sp. female lateral habitus; photo by J. Orr, WSDA

Aprosthema sp. female lateral habitus; photo by J. Orr, WSDA

Aprosthema sp. female dorsal habitus; photo by J. Orr, WSDA

Aprosthema sp. female dorsal habitus; photo by J. Orr, WSDA

Aprosthema sp. male lateral habitus; photo by J. Orr, WSDA

Aprosthema sp. male lateral habitus; photo by J. Orr, WSDA

Aprosthema sp. male dorsal habitus; photo by J. Orr, WSDA

Aprosthema sp. male dorsal habitus; photo by J. Orr, WSDA

Aprosthema sp. fore wing; photo by J. Orr, WSDA

Aprosthema sp. fore wing; photo by J. Orr, WSDA

Aprosthema sp. female dorsal view of head and partial thorax; photo by J. Orr, WSDA

Aprosthema sp. female dorsal view of head and partial thorax; photo by J. Orr, WSDA