Question: Write on the topic of classification of coleoptera.
The Coleoptera have been probably more assiduously studied by systematic naturalists than any other order of insects. The number of described species can now hardly be less than 100,000, but there is little agreement as to the main principles of a natural classification. About eighty-five families are generally recognized; the difficulty that confronts the zoologists is the arrangement of these families in "superfamilies" or "sub-orders." Such obvious features as the number of segments in the foot and the shape of the feeler were used by the early entomologists for distinguishing the great groups of beetles. The arrangement dependent on the number of tarsal segments--the order being divided into tribes "Pentamera," "Tetramera," "Heteromera" and "Trimera"--was suggested by E. L. Geoffroy in 1762, adopted by P. A. Latreille, and used largely through the 19th century. W. S. Macleay's classification, which rested principally on the characters of the larvae, is almost forgotten nowadays, but it is certain that in any systematic arrangement which claims to be natural the early stages in the life-history must receive due attention. In recent years classifications in part agreeing with the older schemes but largely original, in accord with researches on the comparative anatomy of the insects, have been put forward. Among the more conservative of these may be mentioned that of D. Sharp, who divides the order into six great series of families: "Lamellicornia" ; "Adephaga" ; "Polymorpha" ; "Heteromera" ; "Phytophaga," and "Rhynchophora." L. Ganglbauer divides the whole order into two sub-orders only, the "Caraboidea" and the "Cantharidoidea," since the larvae of "Caraboidea" have five-segmented, two-clawed legs, while those of all other beetles have legs with four segments and a single claw. A. Lameere has suggested three sub-orders, the "Cantharidiformia," the "Staphyliniformia," and the "Carabidiformia." Lameere's classification is founded on the number of abdominal sterna, the nervuration of the wings, the number of malpighian tubules and other structural characters. Preferable to Lameere's system, because founded on a wider range of adult characters and taking the larval stages into account, is that of H. J. Kolbe, who recognizes three sub-orders: the "Adephaga"; the "Heterophaga," including the "Staphylinoidea," the "Actinorhabda," the "Heterorhabda," and the "Anchistopoda" ; the "Rhynchophora."
Students of the Coleoptera have failed to agree not only on a system of classification, but on the relative specialization of some of the groups which they all recognize as natural. Lameere, for example, considers some of his "Cantharidiformia" as the most primitive Coleoptera. J. L. Leconte and G. H. Horn placed the "Rhynchophora" in a group distinct from all other beetles, on account of their supposed primitive nature. Kolbe, on the other hand, insists that the weevils are the most modified of all beetles, being highly specialized as regards their adult structure, and developing from legless maggots exceedingly different from the adult; he regards the Adephaga, with their active armored larvae with two foot-claws, as the most primitive group of beetles, and there can be little doubt that the likeness between larvae and adult may safely be accepted as a primitive character among insects. In the Coleoptera we have to do with an ancient yet dominant order, in which there is hardly a family that does not show specialization in some point of structure or life-history. Hence it is impossible to form a satisfactory linear series.
In the classification adopted in this article, the attempt has been made to combine the best points in old and recent schemes, and to avoid the inconvenience of a large heterogeneous group including the vast majority of the families.
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