Cytotaxonomy and molecular phylogeny of the genus Cerapanorpa Gao, Ma & Hua, 2016 (Mecoptera: Panorpidae)

A new species of the genus Cerapanorpa (Mecoptera, Panorpidae) from the eastern Bashan Mountains

BACKGROUND

Cerapanorpa Gao, Ma & Hua, 2016, an endemic genus of Panorpidae in central China's mountain regions, currently comprises 21 described species. Recently, the short-horned scorpionfly C.brevicornis (Hua & Li, 2007) was confirmed to contain two valid species by phylogeographic and morphological data. Individuals from the highlands of the eastern Bashan Mountains were suggested as a good species, separated from the original short-horned C.brevicornis.

NEW INFORMATION

Cerapanorpaalpina sp. nov. was described from the alpine zone of the eastern Bashan Mountains in central China. The new species differs from its congeners by the following combination of characters: male bearing an extra-short anal horn on posterior margin of tergum VI; paramere elongate, extending beyond the median tooth of gonostylus and curved laterally at basal half; female medigynium slightly constricted medially without dorsal basal plate. The species number of Cerapanorpa is raised to 22.

Two new species of Cerapanorpa (Mecoptera, Panorpidae) from the Qinling and Minshan mountains

Two new species of Cerapanorpa Gao, Ma & Hua, 2016 are described from the Qinling and Minshan mountains, respectively. Cerapanorpa qinlingensis sp. nov. can be readily distinguished from its congeners by the elongate hypovalves and the extremely developed basal process of gonostylus in male genitalia. Cerapanorpa minshana sp. nov. is characterized by its bifurcated parameres and a cluster of long black bristles on the inner apex of the gonocoxite. The number of species of Cerapanorpa is raised to 21. An updated key to species of Cerapanorpa is presented.

The highly rearranged karyotype of the hangingfly Bittacus sinicus (Mecoptera, Bittacidae): the lowest chromosome number in the order

Cytogenetic features of the hangingfly Bittacus sinicus Issiki, 1931 were investigated for the first time using C-banding and DAPI (4',6-diamidino-2-phenylindole) staining. The karyotype analyses show that the male B. sinicus possesses the lowest chromosome number (2n = 15) ever observed in Mecoptera, and an almost symmetric karyotype with MCA (Mean Centromeric Asymmetry) of 12.55 and CVCL (Coefficient of Variation of Chromosome Length) of 19.78. The chromosomes are either metacentric or submetacentric with their sizes decreasing gradually. Both the C-banding and DAPI+ patterns detect intermediate heterochromatin on the pachytene bivalents of B. sinicus, definitely different from the heterochromatic segment at one bivalent terminal of other bittacids studied previously. The male meiosis of B. sinicus is chiasmate with two chiasmata in metacentric bivalents and one in the submetacentric bivalent. The sex determination mechanism is X0(♂), which is likely plesiomorphic in Bittacidae. Two alternative scenarios of karyotype origin and evolution in Bittacus Latreille, 1805 are discussed.

Molecular phylogeny of the scorpionflies Panorpidae (Insecta: Mecoptera) and chromosomal evolution

Panorpidae is the most species-rich family in Mecoptera with ca. 470 species in the Northern Hemisphere. However, the intergeneric phylogenetic relationships of Panorpidae remain unsatisfactorily resolved to date. Here, we used molecular and cytogenetic approaches to determine the phylogenetic relationships of Panorpidae in the evolutionary scenario of chromosomes, and estimated their divergence times using fossil-calibrated Bayesian analysis. In total, 89 species representing all seven genera of Panorpidae were used to reconstruct the phylogenetic trees using maximum parsimony, maximum likelihood and Bayesian inference based on the nuclear 28S rRNA and mitochondrial cox1 and cox2 genes. The results reveal that Panorpidae is a well-supported monophyletic group that can be categorized into two major clades. Major Clade I comprises Neopanorpa and Leptopanorpa, and Major Clade II consists of all the other genera (Cerapanorpa, Dicerapanorpa, Furcatopanorpa, Panorpa and Sinopanorpa). Neopanorpa and Cerapanorpa are regarded as paraphyletic groups for the first time. BEAST analysis indicates that Panorpidae originated in the Lower Cretaceous approximately 122.5 Ma (96.8-149.3 Ma), and that most diversification occurred from the Selandian (59.8 Ma) to the Middle Pleistocene (0.6 Ma) in the Cenozoic. Cytogenetic data plotted on the cladogram show that the lineage differentiation of Panorpidae is closely related to the chromosomal evolution, especially the reduction of chromosome number. Our study suggests that a taxonomic revision of Panorpidae is urgently needed at the generic level.