Elateriformia (Coleoptera)


J. F. Lawrence, A. M. Hastings, M. J. Dallwitz, T. A. Paine and E. J. Zurcher


J. F. Lawrence — taxonomy

A. M. Hastings — illustrations

M. J. Dallwitz, T. A. Paine and E. J. Zurcher — computing


This publication is an extract from the CD-ROM ‘Beetles of the World’ (Lawrence et al. 1999), which can be obtained from CSIRO Publishing (http://publish.csiro.au).

Introduction to ‘Beetles of the World’

This package is generated from a DELTA database (Dallwitz 1980; Dallwitz, Paine, and Zurcher 1993). It comprises an interactive identification and information retrieval system using the program Intkey (Dallwitz, Paine, and Zurcher 2000), descriptions, illustrations, references, and other subsidiary material. It allows the user to obtain (1) identifications of adult beetles from any part of the world to family or subfamily level, and occasionally to tribe or genus, with the assistance of extensive character notes and hundreds of character images; (2) information on synonymy, classification, distribution and biology plus a set of bibliographic references for each included taxon; (3) diagnostic or full descriptions of any taxon; (4) lists of taxa having particular attributes or character states (e.g. 8-segmented antennae); and (5) images of selected species representing each taxon (more than 2500 based on habitus drawings, video captures and photos of living beetles or museum specimens). In addition, the product contains an interactive glossary of major regions of the beetle body (Beetle Browser), a full glossary of terms and a general bibliography of works on the order Coleoptera.

The Order Coleoptera

Coleoptera is the largest and most diverse group of living organisms, with about 350,000 named species and estimates of a similar number still to be discovered. The number of beetle species exceeds that of vascular plants or fungi and is 90 times greater than the number of mammals. The oldest beetle fossils are known from the Lower Permian (about 280 million years ago) of Eurasia, and true beetles were a dominant part of the Mesozoic insect fauna. Today they occupy virtually every terrestrial and freshwater habitat and are enormously diverse both in size and structure. The largest beetles (two Cerambycidae or longicorns from Fiji and the Amazon) attain a length of 200 mm, which is almost 800 times that of certain minute species of Ptiliidae, which may be smaller than some Protozoa.

The importance of studying beetles is often measured by the economic cost of the damage some species inflict on materials such as agricultural crops, pasture plants, stored products or timber resources, or the economic benefit of others used in controlling various pests or noxious plants. In recent years, however, it has become more and more obvious that beetles, like any other large group of animals or plants, represent a major portion of the earth’s biodiversity — our natural heritage which is under threat from human activity. As the largest and most diverse group of living organisms, Coleoptera may be viewed as an appropriate yardstick for measuring human impact on natural ecosystems. This interactive system will assist in placing unknown beetles, whether they be agricultural pests, quarantine interceptions or potential environmental indicators. Additionally, the several thousand images of beetles from all over the world, including many rare and unusual forms, will give the user some idea of the enormous diversity exhibited by a single group of organisms. Personally, I would add a another compelling reason for studying beetles: it is fun!

The Nature of the Database

This database consists of a set of 945 taxa (family, subfamily, tribe, genus or rarely an unusual species), each of which is coded for 324 characters with from 1 to 14 character states (usually 2 or 3) plus six additional text characters, which include a short statement on geographic distribution, notes on general biology (habitat, feeding habits etc.), alternate group name(s) (synonymy), and a list of references pertaining to that taxon. Because many of the larger families were broken up into several separately-coded taxa (up to 64 of them in Chrysomelidae), an additional set of family-level taxa were coded by using the ‘Output Summary’ option in INTKEY (combining the matrices for individual components). These taxa, in combination with those families which have not been subdivided, are used for family-level interrogation (by using the toolbar button ‘Restrict taxa to families’) but this family-level subset is not as useful for identification. Notes on phylogenetic relationships and classification were meant to be included for all family-level taxa; because of time constraints, however, only a portion of these have been completed. Hopefully, a more complete and updated set of comments will be included in the next release.

The Character Set

Because this interactive tool and database has been developed to meet the needs of a variety of users, the characters used range from those easily observable with minimal magnification (e.g. relative lengths and widths of major body segments, number of antennomeres) to those requiring complete dissection and high magnification. In general, characters of the second group have been given lower ‘reliabilities’ and thus do not usually appear at the top of the lists which are automatically produced during the course of an identification. The character ‘ommatidium (type)’ would almost never be used in an identification, since it requires special preservation and preparation; it is included in the matrix because of its importance in phylogenetic studies. Aedeagal characters, on the other hand, require clearing and dissection but may be very useful in separating externally similar taxa belonging to very different groups (e.g. Leiodidae versus Phalacridae).

Many of the characters used here have clear-cut states, while other are a bit ‘fuzzy’. Several of the latter group are three-state ‘ordered’ characters, with state 2 being intermediate between 1 and 3. Examples are ‘body: strongly flattened, slightly flattened to moderately convex, strongly convex’ or ‘procoxal cavity: strongly transverse, slightly transverse, circular or longer than wide’. When in doubt, two states can be selected instead of one.

Several characters require a measurement or the ratio of two measurements to be placed in a box. At first glance this looks like a character to avoid; however the variation in size and body type in Coleoptera makes such characters quite useful in eliminating many taxa from consideration. Since a range of measurements or ratios can be used (e.g. 2–5 mm, 1.6–1.9), the figures do not have to be exact, and the Windows Calculator can be accessed to assist with calculations.

Sources of Data

Except in a very few groups where material was rare or unavailable for study, character states were coded from both dried (pinned or pointed) specimens and those which have been macerated and cleared with potassium hydroxide (and occasionally bleached) and then completely dissected to reveal details of mouthparts, hindwings, male genitalia and internal cuticular apodemes. Comparisons were also made with published figures and descriptions. In a very few instances, specimens were not available for dissection and character states were obtained from external examination alone, making it necessary to code some characters as ‘unknown’. The ovipositor and female internal tract were not studied and no characters have been based on these structures.