Taxonus

Taxonomy

Family: Tenthredinidae
Family common name: common sawflies
Subfamily: Allantinae
Tribe: Allantini
Genus: Taxonus Hartig, 1837
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 antennaeantenna:
the sensory organ emerging from the front of the head, usually between the compound eyes and above the clypeus; includes the flagellum, scape and pedicel
. Otherwise, they come in a variety of colors, sizes, and forms (Goulet 1992Goulet 1992:
Goulet H. 1992. The genera and subgenera of the sawflies of Canada and Alaska: Hymenoptera. Symphyta. The insects and arachnids of Canada. Part 20. Agriculture Canada Publication.).

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 1979aSmith 1979a:
Smith DR. 1979a. Nearctic sawflies. IV. Allantinae: Adults and larvae (Hymenoptera: Tenthredinidae). Technical Bulletin, U.S. Department of Agriculture 1595: 1-172.). They can be distinguished from other subfamilies by wing venationvenation:
the network of veins on a wing
(Smith 2003aSmith 2003a:
Smith DR. 2003a. A Synopsis of the sawflies (Hymenoptera: Symphyta) of America south of the United States: Tenthredinidae (Allantinae). Journal of Hymenoptera Research 12 (1): 148-192.).

Taxonus are medium-sized, about 5–10 mm in length, and generally black and orange in color. The genus is species-rich worldwide. (Smith 1979aSmith 1979a:
Smith DR. 1979a. Nearctic sawflies. IV. Allantinae: Adults and larvae (Hymenoptera: Tenthredinidae). Technical Bulletin, U.S. Department of Agriculture 1595: 1-172.).

Diversity

There are 62 described extantextant:
in existence; opposite of extinct
species worldwide. Nine occur in North America (Taeger et al. 2010Taeger et al. 2010:
Taeger A, Blank SM, and Liston AD. 2010. World Catalog of Symphyta (Hymenoptera). Zootaxa 2580: 1-1064.).

A NearcticNearctic:
describing the region of the Northern Hemisphere that includes North America south through northern Mexico
key to species is included in Smith 1979aSmith 1979a:
Smith DR. 1979a. Nearctic sawflies. IV. Allantinae: Adults and larvae (Hymenoptera: Tenthredinidae). Technical Bulletin, U.S. Department of Agriculture 1595: 1-172..

Diagnostic characteristics

Subfamily characters

• fore wing fore wing:
  the anterior wing of each pair of wings; usually the largest wing of the pair
  vein M and 1m-cu parallel (Smith 1979aSmith 1979a:
  Smith DR. 1979a. Nearctic sawflies. IV. Allantinae: Adults and larvae (Hymenoptera: Tenthredinidae). Technical Bulletin, U.S. Department of Agriculture 1595: 1-172.)
• fore wing fore wing:
  the anterior wing of each pair of wings; usually the largest wing of the pair
  vein 2A+3A complete, connected to 1A by crossveincrossvein:
  short section of wing vein that connects two larger veins
  (Smith 1979aSmith 1979a:
  Smith DR. 1979a. Nearctic sawflies. IV. Allantinae: Adults and larvae (Hymenoptera: Tenthredinidae). Technical Bulletin, U.S. Department of Agriculture 1595: 1-172.)
• anal crossvein anal crossvein:
  a crossvein that goes through the center of the basal anal cell
  angled (Smith and Schiefer 1997Smith and Schiefer 1997:
  Smith DR and Schiefer TL. 1997. A new genus and species of Allantinae (Hymenoptera: Tenthredinidae) from southeastern United States. Proceedings of the Entomological Society of Washington 99 (3): 472-476.)

Genus characters​

• mandibles asymmetrical: left with one or more inner teeth, right simple (Smith 1979aSmith 1979a:
  Smith DR. 1979a. Nearctic sawflies. IV. Allantinae: Adults and larvae (Hymenoptera: Tenthredinidae). Technical Bulletin, U.S. Department of Agriculture 1595: 1-172.)
• clypeus clypeus:
  sclerotized area on the front of the head located between the antennal insertions and labrum
  deeply notched, circularly emarginated (Smith 1979aSmith 1979a:
  Smith DR. 1979a. Nearctic sawflies. IV. Allantinae: Adults and larvae (Hymenoptera: Tenthredinidae). Technical Bulletin, U.S. Department of Agriculture 1595: 1-172.)
• genal ridge extending beyond top of compound eye, complete behind ocelliocellus:
  a simple bead-like eye, often on the dorsum of the head in groups of 1-3
  (Smith 1979aSmith 1979a:
  Smith DR. 1979a. Nearctic sawflies. IV. Allantinae: Adults and larvae (Hymenoptera: Tenthredinidae). Technical Bulletin, U.S. Department of Agriculture 1595: 1-172.)
• second antennal segment longer than wide (Smith 1979aSmith 1979a:
  Smith DR. 1979a. Nearctic sawflies. IV. Allantinae: Adults and larvae (Hymenoptera: Tenthredinidae). Technical Bulletin, U.S. Department of Agriculture 1595: 1-172.)
• fore wing fore wing:
  the anterior wing of each pair of wings; usually the largest wing of the pair
  vein 2r present (Smith 1979aSmith 1979a:
  Smith DR. 1979a. Nearctic sawflies. IV. Allantinae: Adults and larvae (Hymenoptera: Tenthredinidae). Technical Bulletin, U.S. Department of Agriculture 1595: 1-172.)
• fore wing fore wing:
  the anterior wing of each pair of wings; usually the largest wing of the pair
  vein M intersecting Sc+R at the intersection of Sc+R and Rs+M (Smith 1979aSmith 1979a:
  Smith DR. 1979a. Nearctic sawflies. IV. Allantinae: Adults and larvae (Hymenoptera: Tenthredinidae). Technical Bulletin, U.S. Department of Agriculture 1595: 1-172.)
• hind wing hind wing:
  the posterior wing of each pair of wings
  cellcell:
  1. a membranous area of the wing between veins, 2. a small cavity or closed space
  M present (Smith 1979aSmith 1979a:
  Smith DR. 1979a. Nearctic sawflies. IV. Allantinae: Adults and larvae (Hymenoptera: Tenthredinidae). Technical Bulletin, U.S. Department of Agriculture 1595: 1-172.)
• male hind winghind wing:
  the posterior wing of each pair of wings
  with peripheral veinvein:
  a tube-like, often darkened, structure on the wings
  present (Smith 1979aSmith 1979a:
  Smith DR. 1979a. Nearctic sawflies. IV. Allantinae: Adults and larvae (Hymenoptera: Tenthredinidae). Technical Bulletin, U.S. Department of Agriculture 1595: 1-172.)
• tarsal claw tarsal claw:
  sharpened appendage emerging from the apex of the tarsus
  bifidbifid:
  divided or forked into two branches or parts
  with basalbasal:
  towards the base; closest to the body
  lobe (Smith 1979aSmith 1979a:
  Smith DR. 1979a. Nearctic sawflies. IV. Allantinae: Adults and larvae (Hymenoptera: Tenthredinidae). Technical Bulletin, U.S. Department of Agriculture 1595: 1-172.)

May be confused with

Taxonus 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 clypeusclypeus:
sclerotized area on the front of the head located between the antennal insertions and labrum
emargination, presence of cellcell:
1. a membranous area of the wing between veins, 2. a small cavity or closed space
M in the hind winghind wing:
the posterior wing of each pair of wings
, and male peripheral veinvein:
a tube-like, often darkened, structure on the wings
I hind winghind wing:
the posterior wing of each pair of wings
(Smith 1979aSmith 1979a:
Smith DR. 1979a. Nearctic sawflies. IV. Allantinae: Adults and larvae (Hymenoptera: Tenthredinidae). Technical Bulletin, U.S. Department of Agriculture 1595: 1-172.).

Exotic pest species of concern

none

Host associations

In North America, Taxonus feeds on species of Fragaria (strawberry) and Rubus (blackberry, raspberry) (Smith 1979aSmith 1979a:
Smith DR. 1979a. Nearctic sawflies. IV. Allantinae: Adults and larvae (Hymenoptera: Tenthredinidae). Technical Bulletin, U.S. Department of Agriculture 1595: 1-172.).

Life history

Specific biology for Taxonus species is unknown. LarvaeLarva:
the immature stage of holometabolous insects
feed singly on the underside of the leaf. At maturity prepupae burrow into the soil beneath the host to pupate. Taxonus pallicoxus and T. pallidicornis are bivoltinebivoltine:
describing a life cycle with two generations per calendar year
(Smith 1979aSmith 1979a:
Smith DR. 1979a. Nearctic sawflies. IV. Allantinae: Adults and larvae (Hymenoptera: Tenthredinidae). Technical Bulletin, U.S. Department of Agriculture 1595: 1-172.).

Distribution

World: This genus is known from North America, Europe, and throughout Asia (Smith 1979aSmith 1979a:
Smith DR. 1979a. Nearctic sawflies. IV. Allantinae: Adults and larvae (Hymenoptera: Tenthredinidae). Technical Bulletin, U.S. Department of Agriculture 1595: 1-172., Taeger et al. 2010Taeger et al. 2010:
Taeger A, Blank SM, and Liston AD. 2010. World Catalog of Symphyta (Hymenoptera). Zootaxa 2580: 1-1064.).

North America: Taxonus occurs mainly east of the Mississippi River, south to Texas and Florida. There are a few collections of T. pallicoxus in Alberta and British Columbia (Smith 1979aSmith 1979a:
Smith DR. 1979a. Nearctic sawflies. IV. Allantinae: Adults and larvae (Hymenoptera: Tenthredinidae). Technical Bulletin, U.S. Department of Agriculture 1595: 1-172.).

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

Details about data used for maps can be found here.