Saturday, 27 February 2016

Prolyda dimidia and Prolyda elegantula: Two new species of Xyelyid Sawflies from the Middle Jurassic of Inner Mongolia.

Sawflies, Symphyta, are thought to be the oldest group of Hymenopterans, with a fossil record dating back to the Triassic, and the oldest group of Sawflies are considered to be the Xyeloids. The Xyeloids are considered to be paraphyletic (i.e. not everything descended from the last common ancestor of all Xyeloids is classifies as a Xyeloid), and can be split into two groups, the Xyelids, from which all other Sawflies are thought to be derived, and the Xyphidrids, which are thought to have been ancestral to the Wood Wasps, and thence all other Wasps, Ants and Bees, though the relationships between early members of these groups is unclear, and it is likely that this classification system will be replaced with something quite different in the future.

In a paper published in the journal ZooKeys on 26 February 2016, Chen Wang and Chungkun Shih of the College of Life Sciences at Capital Normal University, Alexandr Rasnitsyn of the PaleontologicalInstitute of the Russian Academy of Sciences and the Invertebrate Palaeontology Department at the Natural History Museum, and Mei Wang, also of the College of Life Sciences at Capital Normal University, describe two new species of Xyelyid Sawfly from the Middle Jurassic Jiulongshan Formation of Inner Mongolia. Both new species are placed in the genus Prolyda, which was erected by Alexandr Rasnitsyn in 1968 to describe Sawflies from the Jurassic of Kazakhstan.

The first new species is named Prolyda dimidia, meaning 'half', in reference to the pterostigma cell on the forewing, which has a darker posterior half. The species is described from a single specimen preserved in ventral viewon a slab from which the counterpart is not known. The specimen is about 11.4 mm in length, with a large, circular head.

Prolyda dimidia, photograph of only known specimen. Wang et al. (2016).

The second new species is named Prolyda elegantula, meaning 'graceful'. This species is also described from a single known specimen, again preserved on a slab with the counterpart missing. This specimen is 12 mm in length, with a massive and wide head.

Prolyda elegantula, photograph of only known specimen. Wang et al. (2016).

See also... Sawflies from the Middle Jurassic of Inner Mongolia.                                            The Xyelydidae are an extinct group of Sawflies, Pamphilioidea, known from the Middle Jurassic to Early Cretaceous of Eurasia. They are possibly ancestral to other members of the group, though their relationships are poorly understood, though since Sawflies... early Woodwasp from the Early Cretaceous of Brazil.                                   The Hymenoptera are one of the largest groups of insects, comprising Sawflies, Wasps, Ants and Bees. The earliest members of the group were Sawflies, which appeared around the beginning of the Late Triassic. Sawflies have caterpillar-like larvae...
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