Molecular Phylogeny Of Panorpidae (Mecoptera) And Species Delimitation In Panorpa Centralis Species

Scorpionfly is one of essential ecological indicating insects. However, the generic taxon in the family of Panorpidae is disordered so far. The dominant genera Panorpa was recognized as a paraphyletic group with Neopanorpa which has restricted the classification and determination of this insect and more importantly, the phylogenetic relationships among Mecoptera was still not clear and in dispute. Hence, the redivide and revisal of the genus in Panorpidae cries for solution.Three genes, mitochondrial COI (approximately 620 bp), COII (approximately 632 bp) and nuclear 28S rDNA (approximately 454 bp) gene fragments were amplified and sequenced from 15 species of Panorpidae and one species in Bittacidae. Besides, Cyt b (432 bp) gene fragment in P. obtusa from six geographic distributions was also sequenced. We also analyzed nucleotide composition of these sequences. With Bittacus sinensis as outgroup and combining the six Panorpa and two Panorpodes scorpionflies gene fragments sequences that downloaded from the GeneBank, phylogenetic reconstructions in Panorpidae and P. centralis group were then analyzed using through maximum-parsimony (MP), maximum-likelihood (ML) and Bayesian methods, respectively. The phylogenetic relationship among Panorpidae, conspecific variation and species delimitation based on morphology and molecular data in scorpionflies were discussed. These conclusions obtained through analyses were as follow:The three gene fragments had a relative high A-T content of 66.3% for the COI fragment, 70.8% for the COII fragment, 72.1% for the Cyt b fragment and 65.0% for the 28S rDNA gene fragment. This A-T content was comparable to the mitochondrial gene fragments of other insects. Low G contents were also observed from the analyses (14.9% in COI, 14.7% in COII,18.6% in Cyt b and 16.0% in 28S rDNA).The paraphyly of Panorpa Linneaus and monophyly of Neopanorpa Weele are well supported both in the analyses of single and combined gene sequences. P. liui, P. longiprocessa and P. decolorata, which may represent the primitive Panorpa species in China, were found in a subtle relationship with Neopanorpa. Moreover, the P. centralis group is evidently monophyletic, P. magna and its related species in P. diceras group almost definitely merit a generic status. From the topology of the single gene and combined gene analyses in combination with morphological characters, the heterogeneous Panorpidae should be further divided.Conspecific variation widely exists in P. centralis group. P. wangwushana separated from P. centralis group more early than P. emarginata, P. nanwutaia, P. dubia, P. byersi, P. obtusa. Supported from our molecular evidence, the scorpionflies collecting from Guamagou Forest Farm (Pengyang) and Fengtai Forest Farm (Longde) were suspected to be the same species. Likewise, species collecting from Xixia Forest Farm (Jingyuan) and Huangling (Shaanxi) were the same species. Combining with the morphological characters, the suspected P. obtusa in Sutai Forest Farm (Longde) was regarded as a new species. The scorpionflies molecular delimitation should not merely depend on the COI fragment only but consider the combination of multi-mtDNA gene fragments based on morphology.