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Eulithomyrmex
''Eulithomyrmex'' is an extinct genus of ant in the formicid subfamily Agroecomyrmecinae. The genus contains two described species, ''Eulithomyrmex rugosus'' and ''Eulithomyrmex striatus''. ''Eulithomyrmex'' is known from a group of Late Eocene fossils which were found in North America.
== History and classification ==
When described the genus ''Eulithomyrmex'' was known from over forty separate fossils preserved as impressions in fine shales of the Florissant formation in Colorado.〔 The formation is composed of successive lake deposits which have preserved a diverse assemblage of insects. The insects and plants suggest a climate similar to modern Southeastern North America, with a number of taxa represented that are now found in the subtropics to tropics and confined to the old world. When ''Eulithomyrmex'' was described, the Florissant formation was considered to be Miocene in age, based on the flora and fauna preserved.〔 Successive research and fossil descriptions moved the age older and by 1985 the formation had been reassigned to an Oligocene age. Further refinement of the formation's age using radiometric dating of sanidine crystals has resulted in an age of 34 million years old. This places the formation in the Eocene Priabonian stage.
At the time of description the holotype and three paratypes of ''E. rugosus'' plus the holotype and single paratype of ''E. striatus'' were deposited in the Museum of Comparative Zoology paleontology collections at Harvard University. One additional paratype specimen, number 17,019a, was part of the collections of the University of Colorado. The fossils were first studied by paleoentomologist Frank M. Carpenter of the Museum of Comparative Zoology. His 1930 type description of the new species was published in the ''Bulletin of the Museum of Comparative Zoology''. Carpenter described the genus under the name ''Lithomyrmex'', with the two species respectively as ''Lithomyrmex rugosus'' and ''Lithomyrmex striatus''. Carpenter designated ''L. rugosus'' ad the type species for the genus.〔 At the time of Carpenters description, the generic name ''Lithomyrmex'' had already been used in 1929 for a modern ant species ''Lithomyrmex glauerti''. As a result, Carpenter moved the two species to the new genus ''Eulithomyrmex''.
When described Carpenter noted the similarity between ''Eulithomyrmex'' and the genus ''Agroecomyrmex'' known from Baltic amber fossils and described in 1910 and placed both into the tribe Agroecomyrmecini. A third genus was added to the group in 1968 with the description of the living genus ''Tatuidris'' found in Central and South America. Placement of the group has changed several times, with the genera being placed in the Myrmicinae tribe Agroecomyrmecini from 1930 until 2003.〔 The placement of the tribe was Challenged in 2003 by Barry Bolton who suggested a closer relation ship between the group and the "poneromorph" subfamilies. In addition to the suggested relationship, Bolton moved the tribe from Myrmicinae to a new subfamily, Agroecomyrmecinae.〔
抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』
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