Phylogeny of cynipid genera and biological characteristics. Bulletin of the AMNH ; v. 42, article 7.
Supplemental Materials
Date
1920
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Publisher
New York : Published by order of the Trustees, American Museum of Natural History
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DOI
Abstract
"The following are my conclusions which apply to true gall-wasps: 1. The closed radial cell of the wing is more primitive than the open cell; closed-cell genera or genera containing any species with the closed cell must be derived from closed-cell genera. 2. The arcuate first abscissa of the radius is more primitive than the angulate vein showing a projection into the radial cell; the character of this vein is of generic importance and the extent of development toward the angulate vein indicates, in general, the extent of evolution of the genus. 3. The size of the dorsal plate of the second abdominal segment is of generic significance; the smaller plate is more primitive; but this character among some Cynipini does not always show as great specialization as other characters in a genus, indicating diverse lines of evolution within the Cynipini. 4. The primitive Cynipidae were polyphagous; the restriction of Diastrophus mainly to Potentilla and Rubus, and the almost complete restriction of the Rhoditini to Rosa and of the Cynipini to Quercus show great specialization which occurred along three distinct lines of evolution. 5. The form of the gall is an indicator of the specific nature of the insect and also of the generic relations of the insect; the degree of complexity of the gall-structure is likewise an expression of the generic position of the insect, the simplest galls being produced by the most primitive gall-wasps, and the more complex galls by more specialized wasps. The primitive cynipids were plant-tissue inhabiting, not gall-making insects. 6. The primitive Cynipidae were bisexual species with normal, sexual reproduction. By the gradual disappearance of the male and the gradual increase of parthenogenetic reproduction, species have become agamic at several times along distinct lines of evolution within the history of the gall-wasps. 7. Alternation of generations is a development of seasonal dimorphism, a gradual evolution incited by the differences in the nature of existence in different parts of the host plant at different seasons of the year, and achieved after a struggle for the fixation of the new generation. Agamy is not the primitive method of reproduction; it is of great advantage to the winter generation of dimorphic cynipids, and may have originated because of this. 8. The highly specialized phenomena characteristic of the gall-wasps (gall production, agamic reproduction, and heterogeny) are of doubtful advantage, with the apparent consequences of the loss of vitality, exposure to the force of many enemies, and the ultimate extinction of the insects. 9. Aulacidea and Phanacis are in every respect the most primitive of the Cynipidae. 10. Timaspis is almost as primitive. 11. Aylax is primitive, but shows some specialization. 12. Diastrophus is derived from the Aulacidea-Aylax group. 13. Gonaspis is a specialized development of Diastrophus. 14. Rhodites, derived directly from from Aulacidea, is highly specialized. 15. Neuroterus is the most primitive of the Cynipini, and in that genus are to be discovered the incipient stages of some of the peculiar phenomena of the Cynipidae. 16. Disholcaspis, highly specialized in most respects, shows somewhat direct relationships to more primitive groups"--P. 399-401.
Description
p. 357a-c, 358-402, [1] leaf of plates : ill. ; 24 cm.
Includes bibliographical references (p. 402).
Includes bibliographical references (p. 402).
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