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George O. Poinar

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George O. Poinar

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The Evolutionary History of Nematodes

As revealed in stone, amber and mummies

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George O. Poinar Jr.

Nematodes are one of the most abundant groups of invertebrates on the face of the earth. Their numbers are estimated to range from 1000 per cm2 in the sand-covered hydrogen sulphide ‘black zone’ beneath the ocean floors to 1.2 billion in a single hectare of soil. Estimates for their species diversity range from 100 000 to 10 million. The past history of nematodes is a mystery, since very few fossils have been discovered. This book establishes a solid base in palaeonematology with descriptions of 66 new fossil species and accounts of all previous fossil and subfossil nematodes from sedimentary deposits, coprolites, amber and mummies. It shows how nematode fossils can be used to establish lineages at various locations and time periods in the earth’s history and when nematodes entered into symbiotic and parasitic associations with plants and animals.
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George O. Poinar

Abstract

Poinar Jr, G. O.: A fossil palm bruchid, Caryobruchus dominicanus sp. n. (Pachymerini: Bruchidae) in Dominican amber. Ent. scand. 30: 219-224. Copenhagen, Denmark. July 1999. ISSN 0013-8711. The first fossil palm bruchid, Caryobruchus dominicanus sp. n. (Coleoptera; Bruchidae) is described from Dominican Republic amber. This species is closely related to extant Central American-West Indian members of the genus, all of which develop in the seeds of palms. Aside from providing indirect evidence of fan palms, especially those of the genus Sabal, in the original Dominican amber forest, the present find shows that seed predation by Caryobruchus spp. was established in the West Indies some 15-45 million years ago.

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George O. Poinar

Abstract

An ant bug of the subfamily Holoptilinae (Reduviidae: Hemiptera), Praecoris dominicana gen. n., sp. n., is described in amber from the Dominican Republic. Based on the functional morphology of extant forms, the behavior of the fossil bug as an ant predator is discussed. This find clearly establishes the Holoptilinae in the New World during the Tertiary and gives credence to the single New World extant specimen reported from Guyana. It is likely that the prey of the fossil specimen was the arboreal ant, Dolichoderus dibolia. Both the bug and its ant prey are now extinct and no descendents occur in the Greater Antilles today.

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George O. Poinar

A new species of fossil mermithid, Cretacimermis aphidophilus sp. n. (Nematoda: Mermithidae), is described from the primitive extinct aphid, Caulinus burmitis (Hemiptera: Burmitaphididae), in mid-Cretaceous Myanmar amber. Aphid parasitism by mermithid nematodes is rare today with only two known cases involving root-feeding aphids. Based on the habits of the parasitised extant aphid hosts, it is likely that the fossil aphid was also a root parasite and encountered the infective stage mermithid in the soil. Such fossils provide rare glimpses of nematode-host associations from the distant past and provide minimum dates for the appearance of specific mermithid clades.