Key to the Subfamilies of North and Central American Ichneumonidae

By David Wahl

•         Downloadable PDF file of Section 1 of the key is available here

NOTE: The PDF file 'Subfamily_key_1_2015.04.10' has systematic figure numbering errors. If you have previously downloaded it, discard and instead use 'Subfamily key 1_2015.08.17'

•         Downloadable PDF file of Section 2 of the key is available here

•         Downloadable PDF file of Section 3 of the key is available here

•         Downloadable PDF file of Section 4 of the key is available here

NOTE: The PDF file 'Subfamily key_4_2015.04.10' has systematic figure numbering errors. If you have previously downloaded it, discard and instead use ''Subfamily key 4_2016.07.01'

•         Downloadable PDF file of Section 5 of the key is available here

•         Downloadable PDF file of the figures for Section 1 is available here

•         Downloadable PDF file of the figures for Section 2 is available here

•         Downloadable PDF file of the figures for Section 3 is available here

•         Downloadable PDF file of the figures for Section 4 is available here

•         Downloadable PDF file of the figures for Section 5 is available here

The modern era of English-language ichneumonid subfamily keys dates, in my opinion, to the Smith & Shenefelt (1955) treatment of the Wisconsin fauna. As noted by the authors, the choice of characters was based in part on 'an unpublished artificial key by Dr. H.K. Townes (1943) to the ichneumonid genera of the northeastern part of the United States'. The Smith & Shenefelt key reflected the recent activities of Townes in breaking up the traditional five subfamilies (Townes, 1944-1945; Townes & Townes, 1952). Looking at it from 60 years later, it appears in practice to be unworkable due to its rambling nature, heavy reliance upon measurements, and use of subfamilies instead of more meaningful tribes*. Perkins (1959) provided a key to the British ichneumonid subfamilies. He was an excellent ichneumonid worker; his key is concise and well-illustrated, with a much better selection of characters. The dominant keys of the future, however, were those of Townes, starting with his 1961 key to the subfamilies of the Indo-Australian region (Townes, Townes & Gupta, 1961). This was followed by regional keys to the eastern Palearctic (Townes, Momoi & Townes, 1965) and Neotropic (Townes & Townes, 1966). These efforts culminated in his key to World subfamilies (1969). Wahl's key to World subfamilies (1993) is essentially an updated version of the 1969 Townes key, with updated taxonomy and embedded illustrations (the 1969 key, as with Townes' earlier keys, was unillustrated). Subsequent subfamily keys have been regional (Gauld, 1984 & 1991).

Two considerations have informed the GIN key. I'm not in favor of worldwide keys to subfamilies. A worldwide key must ignore regional specialties to a certain degree, otherwise the resulting product will be so complex as to be unworkable. Hence, the key is for only North and Central America. Secondly, the key is not interactive. I've tried various programs and have not been impressed:

-- Some have problems with version compatibilities.

-- To the best of my knowledge, they do not allow printouts of the text portions.

-- The embedded illustrations pop up one at a time, and do not allow side-by-side comparisons of character states.

Keys are heuristic devices that allow one to discriminate various taxa. After a certain point, the key and relevant characters should be internalized so that the text need be only occasionally consulted, and it seems to me that long interactive keys work against this. Printed text is not available to place on one side of the microscope and so the user is confined to the computer screen, slowly grinding through pop-up illustrations while juggling specimens. The process seems designed to keep the user dependent upon the interactive key, or at least to make the weaning period very long indeed. The approach taken here is to separate text and figures, making them available as downloadable PDF files from the GIN site. The text files are to be printed out, while the figures (arranged in plates of six) are meant to be viewed on a laptop or tablet. As the user gains familiarity with the key, reliance upon illustrations should lessen and the text is used as an aide to memory.

Several closing comments:

- Unlike various versions of the key that I have used in the various North American Hymenoptera identification courses since 1986, this one treats all the subfamilies in North and Central America.

- A number of subfamilies are morphologically diverse (such as the Cryptinae and Orthocentrinae) and need to run out in several places. Accounting for every variant would lead to an unworkable final product (long and reduced to taking taxa off one at a time), and so personal elements of taste and prejudice come in to play.

- The GIN key's structure is basically that of Townes (1969). In my experience this seems to be the most robust framework and allows beginnners to readily grasp subfamily characters.

- User reviews and comments are greatly desired!

Images for plates were taken with an EntoVision micro-imaging system. This system consists of a Leica M16 zoom lens attached to a JVC KY-75U 3-CCD digital video camera that feeds image data to a desktop computer. The program Archimed 5.3.1 is then used to merge an image series (representing typically 15-30 focal planes) into a single in-focus image. Lighting was provided by an EntoVision dome light.

My sincere thanks to Andy Bennett and Katja Seltmann for painstakingly reviewing the text and figures.

* Many subfamilies were subsumed as tribes within inclusive subfamilies: examples are Ophioninae (containing today's modern Anomaloninae, Campopleginae, Cremastinae, Ophioninae s.s., and Tersilochinae) and Pimplinae (containing today's Labeninae, Pimplinae, Poemeniinae, Rhyssinae, and Xoridinae).

References

Gauld, I.D. 1984. An introduction to the Ichneumonidae of Australia. British Museum (Natural History): London. 413 pp.

Gauld, I.D. 1991. The Ichneumonidae of Costa Rica, 1. Memoirs of the American Entomological Institute 47: 1-589.

Perkins, J.F. 1959. Hymenoptera. Ichneumonoidea. Ichneumonidae, key to subfamilies and Ichneumoninae 1. Handbooks for the Identification of British Insects 7 (2ai): 1-116.

Smith, L.K. & R.D. Shenefelt. 1955. A guide to the subfamilies and tribes of the family Ichneumonidae (Hymenoptera) known to occur in Wisconsin. Wisconsin Academy of Sciences, Arts and Letters 44: 165-219.

Townes, H. 1944-1945. A catalogue and reclassification of the Nearctic Ichneumonidae. Memoirs of the American Entomological Society 11(1-2): 1-925.

Townes, H. & M. Townes. 1951. Ichneumonidae. In: Hymenoptera of America north of Mexico, synoptic catalog. (Muesebeck, C.F.W, K.V. Krombein & H. Townes (eds.). United States Department of Agriculture. Agricultural Monograph 2: 1-1420.

Townes, H. 1969. The genera of Ichneumonidae, part 1. Memoirs of the American Entomological Institute 11: 1- 300.

Townes, H., S. Momoi & M. Townes. 1965. A catalogue and reclassification of the Eastern Palearctic Ichneumonidae. Memoirs of the American Entomological Institute 5: 1-661.

Townes, H. & Townes, M. 1966. A catalogue and reclassification of the Neotropic Ichneumonidae. Memoirs of the American Entomological Institute, 8: 1-367.

Townes, H., M. Townes & V.K. Gupta. 1961. A catalogue and reclassification of the Indo-Australian Ichneumonidae. Memoirs of the American Entomological Institute 1: 1-522.

Wahl, D.B. 1993. Family Ichneumonoidea. In H. Goulet & J.T. Huber (eds.), Identification manual to families of Hymenoptera (Insecta) of the world. Agriculture Canada, Ottawa. 668 pp.