Lower Eocene aphids (Insecta) from Denmark
1970; Volume: 20; Linguagem: Inglês
ISSN
2245-7070
Autores Tópico(s)Insect-Plant Interactions and Control
ResumoFew aphids have been found as fossils in the Danish Eocene diatomaceous earth at the Limfjord in North-Jutland until now. There may be climatic reasons for their small number. From the knowledge of the fossil fauna of other insect groups in the Danish diatomaceous earth it has been deduced that the climate was tropical or nearly tropical in Denmark during Lower Eocene (Henriksen 1922). The number of aphid species in the tropical regions of the present day is rather small. Most species occur in the temperate zone of the northern hemisphere today. Aphids, as a rule, are adapted to climates with considerable seasonal variations'by having alternation between several parthenogenetic female-generations in the summer and an autumnal generation of males and females producing fertilised eggs, which survive the winter. Consequently it could not be expected that a rich diversity of aphid species be found among the fossil insects of the diatomaceous earth. Add to this the small size and the fragile constitution of aphids, and their infrequency will seem quite comprehensible. Previously three finds have been recorded (Heie 1967, pp. 197-200), viz. two specimens belonging in species within the genus Siphonophoroides Buckton (described from Oligocene deposits in North America), 5. breineri Heie (M-l) and S. magnalata Heie (M-3), and one unidentifiable aphid (M-2), all of them alate. Later on further six alate specimens, all of them occurring in cement stone (lime concretions), have been discovered in the collection of fossils in diato
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