Sunday, 22 July 2012

New Ommatid Beetles from the Mesozoic of China.

The Ommatidae are generally considered to be one of the most primitive groups of Beetles, possibly close to the origin of the group. There are six known extant species in two genera, restricted to arid subtropical regions of Australia and South America. A number of fossil species have also been described, from Mesozoic sites across Eurasia; since Beetles are known to have been in existence by the late Carboniferous, if the Ommatidae are close to the origin of the group, then the fossil record of the earliest members is apparently missing.

The extant Ommatid Beetle, Omma rutherfordi, from the Twin Creeks Community Conservation Reserve in Western Australia. Farhan Bokhari.

In a paper published in the journal BMC Evolutionary Biology on 9 July 2012, a team of scientists led by Jingjing Tan of the Key Laboratory of Zoological Systematics and Evolution at the Institute of Zoology of the Chinese Academy of Sciences, and the College of Life Sciences at Capital Normal University describe four new species of Ommatid Beetles from the Mesozoic of China.

The first new species described is placed in the genus Pareuryomma, which already contains one species (Pareuryomma tylodes) from the Early Cretaceous Jehol Biota of northeast China. This is Pareuryomma ancistrodonta, where ancistrodonta means 'curved tooth', in reference to the shape of the mandible. This comes from the Middle Jurassic Jiulongshan Formation at Daohugou Village in Inner Mongolia.

Pareuryomma ancistrodonta, a new Ommatid Beetle from the Middle Jurassic of Inner Mongolia. Tan et al. (2012).

The second new species described is also placed in the genus Pareuryomma. This is Pareuryomma cardiobasis, where cardiobasis means 'heart-shaped' a reference to a marking on the Beetle's thorax. Pareuryomma cardiobasis comes from the Early Cretaceous Yixian Formation at Chaomidian Village in Liaoning Province, the same locality as Pareuryomma tylodes.

Pareuryomma cardiobasis, a new Ommatid Beetle from the Early Cretaceous of Liaoning Province. Tan et al. (2012).

The third new species is placed in the genus Omma; this species is still extant, with four known species in Australia, as well as eleven previously described species from the Late Triassic to Early Cretaceous of England, Kyrgyzstan, Mongolia, Kazakhstan, Germany and Russia. This new species is named as Omma delicata, where delicata means 'delicate' a reference to the small size of the fossil. It comes from the Middle Jurassic Jiulongshan Formation of Daohugou Village in Inner Mongolia.

Omma delicataa new Ommatid Beetle from the Middle Jurassic of Inner Mongolia. Tan et al. (2012).

The final new species described is placed in the genus Tetraphalerus, a genus that includes two extant species from South America and 23 previously described fossil species from the Mesozoic of Eurasia. It is named Tetraphalerus decorosus, where decorosus means 'well-preserved'. It also comes from the Middle Jurassic Jiulongshan Formation of Daohugou Village in Inner Mongolia.

Tetraphalerus decorosusa new Ommatid Beetle from the Middle Jurassic of Inner Mongolia. Tan et al. (2012).


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