Birka

Taxonomy

Family: Tenthredinidae
Family common name: common sawflies
Subfamily: Selandriinae
Tribe: Aneugmenini
Genus: Birka Malaise, 1944
Subgenera: Birka, Lineobirka

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 Selandriinae subfamily are relatively small and slender. The range of Selandriinae is worldwide; it occurs on all continents except Antarctica (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.). It is the most common and diverse group of tenthredinids in tropical regions, particularly in Central America, South America, and Southeast Asia (Smith 1969eSmith 1969e:
Smith DR. 1969e. Nearctic Sawflies. II. Selandriinae: Adults (Hymenoptera: Tenthredinidae). Technical Bulletin, U.S. Department of Agriculture 1398: 1-48.). Selandriinae contains the only known sawflies that feed on non-vascular plants, specifically ferns (Smith et al. 2013Smith et al. 2013:
Smith DR, Janzen DH and Hallwachs W. 2013. Food plants and life histories of sawflies of the families Argidae and Tenthredinidae (Hymenoptera) in Costa Rica, a supplement. Journal of Hymenoptera Research 35: 17-31. https://doi.org/10.3897/JHR.35.5496). The subfamily can be distinguished from other subfamilies by wing venationvenation:
the network of veins on a wing
(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.).

Birka is monotypicmonotypic:
describes having only one representative; ex. a genus that includes only one species
in North America. Birka nordica is small and stout, about 6 mm in length, and mostly black with some white on the thoraxthorax:
the second and middle segment of the body, between the head and abdomen
. This species is northern in distribution (Smith 1969eSmith 1969e:
Smith DR. 1969e. Nearctic Sawflies. II. Selandriinae: Adults (Hymenoptera: Tenthredinidae). Technical Bulletin, U.S. Department of Agriculture 1398: 1-48.).

Diversity

There are 17 described extantextant:
in existence; opposite of extinct
species worldwide. One species occurs 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.).

Diagnostic characteristics

Subfamily characters

• fore wing fore wing:
  the anterior wing of each pair of wings; usually the largest wing of the pair
  vein Rs+M curved near intersection with veinvein:
  a tube-like, often darkened, structure on the wings
  Sc+R (Smith 1969eSmith 1969e:
  Smith DR. 1969e. Nearctic Sawflies. II. Selandriinae: Adults (Hymenoptera: Tenthredinidae). Technical Bulletin, U.S. Department of Agriculture 1398: 1-48.)
• fore wing fore wing:
  the anterior wing of each pair of wings; usually the largest wing of the pair
  vein M meeting Sc+R basalbasal:
  towards the base; closest to the body
  to intersection of Rs+M and Sc+R (Smith 1969eSmith 1969e:
  Smith DR. 1969e. Nearctic Sawflies. II. Selandriinae: Adults (Hymenoptera: Tenthredinidae). Technical Bulletin, U.S. Department of Agriculture 1398: 1-48.)
• fore wing fore wing:
  the anterior wing of each pair of wings; usually the largest wing of the pair
  veins M and m-cu about parallel (Smith 1969eSmith 1969e:
  Smith DR. 1969e. Nearctic Sawflies. II. Selandriinae: Adults (Hymenoptera: Tenthredinidae). Technical Bulletin, U.S. Department of Agriculture 1398: 1-48.)
• fore wing fore wing:
  the anterior wing of each pair of wings; usually the largest wing of the pair
  vein 2r-m present (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.)

Genus characters​

• clypeus clypeus:
  sclerotized area on the front of the head located between the antennal insertions and labrum
  margin straight (Smith 1969eSmith 1969e:
  Smith DR. 1969e. Nearctic Sawflies. II. Selandriinae: Adults (Hymenoptera: Tenthredinidae). Technical Bulletin, U.S. Department of Agriculture 1398: 1-48.)
• malar space malar space:
  the minimum distance between the base of the mandible and the ventral margin of the compound eye
  length about twice the diameter of front ocellusocellus:
  a simple bead-like eye, often on the dorsum of the head in groups of 1-3
  (Smith 1969eSmith 1969e:
  Smith DR. 1969e. Nearctic Sawflies. II. Selandriinae: Adults (Hymenoptera: Tenthredinidae). Technical Bulletin, U.S. Department of Agriculture 1398: 1-48.)
• occipital ridge absent (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.)
• antennae short (Smith 1969eSmith 1969e:
  Smith DR. 1969e. Nearctic Sawflies. II. Selandriinae: Adults (Hymenoptera: Tenthredinidae). Technical Bulletin, U.S. Department of Agriculture 1398: 1-48.)
• pedicel pedicel:
  the second antennal segment, between the scape and flagellum
  as wide as long (Smith 1969eSmith 1969e:
  Smith DR. 1969e. Nearctic Sawflies. II. Selandriinae: Adults (Hymenoptera: Tenthredinidae). Technical Bulletin, U.S. Department of Agriculture 1398: 1-48.)
• fore wing fore wing:
  the anterior wing of each pair of wings; usually the largest wing of the pair
  anal crossveinanal crossvein:
  a crossvein that goes through the center of the basal anal cell
  absent (Smith 1969eSmith 1969e:
  Smith DR. 1969e. Nearctic Sawflies. II. Selandriinae: Adults (Hymenoptera: Tenthredinidae). Technical Bulletin, U.S. Department of Agriculture 1398: 1-48.)
• hind wing hind wing:
  the posterior wing of each pair of wings
  anal cellanal cell:
  cell A of either the fore wing or hind wing
  petiole present (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.)
• tarsal claw tarsal claw:
  sharpened appendage emerging from the apex of the tarsus
  with small inner tooth (Smith 1969eSmith 1969e:
  Smith DR. 1969e. Nearctic Sawflies. II. Selandriinae: Adults (Hymenoptera: Tenthredinidae). Technical Bulletin, U.S. Department of Agriculture 1398: 1-48.)

May be confused with

Birka can be confused with similar species in the subfamily Selandriinae or tribe Aneugmenini. It can be distinguished from most other genera by the absence of a fore wingfore wing:
the anterior wing of each pair of wings; usually the largest wing of the pair
anal crossveinanal crossvein:
a crossvein that goes through the center of the basal anal cell
, from closely related Aneugmenus by the lack of an occipitalocciput:
the posterior surface of the head
ridge, and from Nesoselandria by the malar spacemalar space:
the minimum distance between the base of the mandible and the ventral margin of the compound eye
length (Smith 1969eSmith 1969e:
Smith DR. 1969e. Nearctic Sawflies. II. Selandriinae: Adults (Hymenoptera: Tenthredinidae). Technical Bulletin, U.S. Department of Agriculture 1398: 1-48.).

Exotic pest species of concern

none

Host associations

No hosts are known for North American Birka. Some species in Europe feed on grasses and sedges (Smith 1969eSmith 1969e:
Smith DR. 1969e. Nearctic Sawflies. II. Selandriinae: Adults (Hymenoptera: Tenthredinidae). Technical Bulletin, U.S. Department of Agriculture 1398: 1-48.). Uniquely for Selandriinae, some species feed on dicots: B. carinifrons in Japan on Lysimachia spp. (loosestrife), B. cinereipes in Finland on Myosotis spp. (forget-me-not), and B. annulitarsis in Czech Republic on Pulmonaria angustifolia (blue lungwort) (Macek 2013Macek 2013:
Macek J. 2013. Descriptions of larvae of Birka annulitarsis and B. cinereipes (Hymenoptera: Symphyta: Tenthredinidae). Acta Entomologica Musei Nationalis Pragae 53(2): 815-819., Shinohara and Ibuki 2017Shinohara and Ibuki 2017:
Shinohara A and Ibuki S. 2017. Host plants and larvae of two dicot-feeding Selandriine sawflies (Hymenoptera, Tenthredinidae) from Japan. Bulletin of the National Museum of Natural Science 43(2): 87-91.).

Life history

unknown

Distribution

World: This genus is known from North America, Europe, and Japan (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: Birka nordica occurs in Alaska, Yukon Territory, British Columbia, Alberta, and Manitoba (Smith 1969eSmith 1969e:
Smith DR. 1969e. Nearctic Sawflies. II. Selandriinae: Adults (Hymenoptera: Tenthredinidae). Technical Bulletin, U.S. Department of Agriculture 1398: 1-48.).

Map data from: GBIF.org (29 October 2019) GBIF Occurrence Download Birka and the Smithsonian National Museum of Natural History Entomology Collection (USNM)

Details about data used for maps can be found here.