Macremphytus

Taxonomy

Family: Tenthredinidae
Family common name: common sawflies
Subfamily: Allantinae
Tribe: Allantini
Genus: Macremphytus MacGillivray, 1908
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 Allantinae subfamily are mostly black and shining, sometimes with other colors. They have agricultural importance as some species are pests on cultivated and ornamental plants (Smith 1979a). They can be distinguished from other subfamilies by wing venation (Smith 2003a).

Macremphytus are medium-sized, about 8–12 mm in length, and generally black and reddish-brown. The genus is associated with dogwood trees (Smith 1979a).

Diversity

There are six described extant species worldwide. Five occur in North America (Taeger et al. 2010).

A Nearctic key to species is included in Smith 1979a.

Diagnostic characteristics

Subfamily characters

Genus characters​

May be confused with

Macremphytus can be confused with similar species in the subfamily Allantinae or tribe Allantini. It can be distinguished from most other genera by the asymmetrical mandibles, deep circular clypeus emargination, flattened antennal segments, and the presence of cell M in the hind wing (Smith 1979a).

Exotic pest species of concern

none

Host associations

In North America, Macremphytus feeds on Cornus (dogwood) trees, including C. alternifolia (pagoda dogwood), C. racemosa (gray dogwood), Cornus alba (tatarian dogwood), and C. sericea (redosier dogwood) (Smith 1979a, Klingeman et al. 2007, O’Brien 2015).

Life history

Female Macremphytus lay eggs near the mid vein of the leaf. Larvae feed externally on foliage and then overwinter as prepupae in decayed wood or wooden structures. All known species are univoltine (Smith 1979a).

Macremphytus tarsatus is a pest of dogwood that has been observed feeding gregariously, resulting in skeletonizing and complete defoliation of trees. Because dogwood is deciduous, and because defoliation occurs most often late in the season, an infestation of M. tarsatus is usually not fatal to the tree. Macremphytus tarsatus is univoltine (O’Brien 2015).

Distribution

World: This genus is mostly known from North America, with one species, M. crassicornis, in East and Southeast Asia (Smith 1979a, Taeger et al. 2010).

North America: Macremphytus occurs in northern United States and southern Canada. Macremphytus lovetti is restricted to west of the Rocky Mountains, in Alberta, British Columbia, Oregon, Idaho, and Montana, while the other species are widespread east of the Rocky Mountains as far south as northern Georgia (Smith 1979a). Macremphytus albitegularis is more southern in distribution and has been collected once from Dallas, Texas and once from Mexico, specific locality unknown (Koch 1988b, Smith 2003a).

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

Details about data used for maps can be found here.

Macremphytus tarsatus female lateral habitus; photo by J. Orr, WSDA

Macremphytus tarsatus female lateral habitus; photo by J. Orr, WSDA

Macremphytus tarsatus female dorsal habitus; photo by J. Orr, WSDA

Macremphytus tarsatus female dorsal habitus; photo by J. Orr, WSDA

Macremphytus tarsatus female face; photo by Q. Baine, WSDA

Macremphytus tarsatus female face; photo by Q. Baine, WSDA

Macremphytus lovetti male lateral habitus; photo by J. Orr, WSDA

Macremphytus lovetti male lateral habitus; photo by J. Orr, WSDA

Macremphytus lovetti male dorsal habitus; photo by J. Orr, WSDA

Macremphytus lovetti male dorsal habitus; photo by J. Orr, WSDA

Macremphytus lovetti male face; photo by Q. Baine, WSDA

Macremphytus lovetti male face; photo by Q. Baine, WSDA

Macremphytus lovetti wings; photo by P. Jones, WSDA

Macremphytus lovetti wings; photo by P. Jones, WSDA