Introduction to Glossary of Positional and Morphological Terms

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Those taxonomists who publish in English like to think that they write in English, though most non-specialists probably would beg to disagree. As in most scientific disciplines, taxonomists use many highly specialized terms - jargon - in their descriptions and keys to characterize and differentiate taxa. Terms used to describe structure, morphological terms, are a form of shorthand:  to the specialist they embody extensive implicit information such as the type, location, function, and homology of structural features. The purpose of such terms is to facilitate communication. Many terms such as tibia, thorax, sternum, antenna, etc. are so widely used throughout entomology that they are understood by many non-entomologists as well as entomologists, taxonomist or not. Such terms do facilitate communication. However, every taxonomic group, regardless of hierarchal level, has its own set of much more specialized terms that often are used uniquely within the group or even sometimes with a meaning different than in other groups. Such terms do not facilitate communication except among the relatively very few taxonomists specializing in the particular group; rather, to the rest of us they make reading and understanding a key or description intimidating and at least difficult if not next to impossible. This is probably one of the reasons why non-specialists often do not even try to identify specimens using previously published keys and descriptions.

The purpose of this glossary is to assist non-chalcidologists in interpreting chalcid descriptive literature, including that presented over this web site, by defining and illustrating those terms that have been used in taxonomic and morphological studies of chalcid wasps. The glossary has also enabled us to hyperlink many of the more specialized morphological terms used in the key and in other chalcid documents on this site to the glossary definition and illustrations.

The glossary and illustrations began as an adaptation of the chapter on morphology and terminology in Gibson (1997), but was expanded to include specialized terms used in other chapters of the same publication as well as other chalcid publications. It now includes about 605 terms or their synonyms that have been used in modern chalcid literature to describe external structure. Included are very general terms, including the more commonly used terms to describe position or shape, as well as highly specialized structural terms that are used uniquely within the superfamily or even within one chalcid family. Where relevant we have indicated terms that are used in different families for what likely are homologous or at least analogous structures, as well as the few instances in which the same term is used for different structures in different families. Because there are no 'rules' of morphological nomenclature as there are for zoological nomenclature, there is no objective method to determine which term to define as 'accepted' and which to include as a synonym. We have tried to use common usage as the determining factor but also admit to some degree of personal preference. We have not attempted to harmonize usage of terms that include 'line', 'groove', 'furrow', 'suture', or 'sulcus' with their strict morphological meaning and users should interpret these as being more or less interchangeable within chalcid literature. Not currently included in the glossary are terms for internal structure, sculpture and setation, or terms in languages other than English. Almost all structural terms are illustrated by at least one line drawing and/or scanning electron photomicrograph. We thank John LaSalle, John Pinto, Jean-Yves Rasplus, and Jim Woolley for permission to use figures from their publications in order to illustrate certain terms. Although certainly not exhaustive, the glossary and illustrations should be sufficient to enable individuals to interpret the vast majority of chalcid descriptive literature and, with hope, this web site. For a comprehensive glossary of terms used in entomology users are referred to Nichols (1989).

Individuals who would like a hard copy of the terms and definitions, without illustrations, can download several different types of files and outputs to their computer by using the download button near the top of this page. go to top

Method of Citation

Gibson, G.A.P., Read, J.D. and Fairchild, R. 1998.
Chalcid wasps (Chalcidoidea):  illustrated glossary of positional and morphological terms.

Use of Frames

Frames have been used to present the glossary so the user can see the definition and its illustration on the same screen. To find a morphological term, first select its first letter in the top frame. A list of available choices for that letter will appear in the left frame. By clicking on the pertinent term, its definition appears in the same frame, along with all other terms beginning with the same letter. To see an illustration of that term, click on the link at the end of the definition, indicated either by [drawing] or [photo].

Each illustration has links to the terms it illustrates, chosen by clicking on the term shown in blue. The corresponding definition will appear in the left frame.

You may also resize the two lower frames by positioning the mouse cursor over the separation bar and dragging it sideways. This is really useful if you are running at a monitor setting greater than the basic 640x480 pixels, and want to see the definitions text in an easier-to-read format. If you are running at 640x480, and some of the lower frames are cut off at the bottom, try turning off some of the tool bars at the top of the screen to increase the size of the main window (under 'Options' and 'Show ...' in Netscape).go to top


Gibson, G.A.P. 1997.
Chapter 2. Morphology and Terminology. Pages 16-44 in Gibson, G.A.P., J.T. Huber, and J.B. Woolley (eds). Annotated Keys to the Genera of Nearctic Chalcidoidea (Hymenoptera). National Research Council of Canada Research Press, Ottawa, Canada. 794 pp.
Nichols, S.W. 1989.
The Torre-Bueno Glossary of Entomology. Revised Edition of A Glossary of Entomology by J.R. de la Torre-Bueno including Supplement A by George S. Tulloch. New York Entomological Society, New York, USA. xiii + 840 pp.

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Webpage last updated on 09-Oct-2007