Evolutionary history of the complex polymorphic dobsonfly genus Neoneuromus (Megaloptera: Corydalidae)

Abstract

The dobsonfly genus Neoneuromus van der Weele is endemic to the Oriental region. Species possess highly variable body and wing colouration and markings, not only among species but also among conspecific individuals of certain species. This stark polymorphism hinders accurate species identification, and obscures an undocumented species diversity as well as our understanding of the evolutionary history of this genus. We used multiple methods of molecular identification combined with morphological evidence to delimitate species, circumscribing a total of 13 species in Neoneuromus. Five new species are herein described: Neoneuromus indistinctus Liu, Hayashi & Yang, sp.n., Neoneuromus maculatus Liu, Hayashi & Yang, sp.n., Neoneuromus niger Liu, Hayashi & Yang, sp.n., Neoneuromus similis Liu, Hayashi & Yang, sp.n. and Neoneuromus vanderweelei Liu, Hayashi & Yang, sp.n. The dated phylogeny with reconstructed ancestral areas indicates an initial divergence of Neoneuromus during the mid‐Eocene. A broad area including northeastern India and northern Indochina could be a centre for early divergence of the genus, while complex dispersal and vicariance events dating from the late Eocene to the Pliocene probably shaped the present diversity and distribution of the genus. Our ancestral character state reconstruction suggests that the pale and dark colour forms among different species, or conspecifics, could evolve rapidly and that changes in colouration could be driven by species‐specific mate recognition.

Phylogeography of the Oriental dobsonfly, Neoneuromus ignobilis Navás, suggests Pleistocene allopatric isolation and glacial dispersal shaping its wide distribution

“…Our ancestral area reconstruction consistently recovered the ancestral range of N. ignobilis as inferred by Yang et al (2018), which is also supported by the higher genetic diversity of the SV, YN and SG groups compared with the CC and EC groups (Table 2). The phenomenon of higher genetic diversity in ancestral areas (Hewitt, 1996) is possibly caused by the accumulation of genetic variation over a longer evolutionary history (Chiang & Schaal, 1999;Huang et al, 2001).…”

“…The larvae of Notophthiracarus ignobilis are predatory benthic macroinvertebrates in relatively large streams with clean running water. This species is one of the few widespread megalopteran species endemic to the Oriental region, distributed from southern Vietnam and southern Laos through southern China to the northern edge (i.e., the Qinling mountain range) of central China, primarily occurring in mountainous regions with low or mid-elevation (200-1900 m) (Yang et al, 2018). Considering that broad distributions are rare in Megaloptera, the phylogeographic history of N. ignobilis and the mechanisms that formed its current widespread range are of considerable interest.…”

“…A previous study estimated the timeline of the interspecific divergence within Neoneuromus showed that N. ignobilis diverged from its sister species during the middle Miocene (15.04 Ma, 95% high posterior density [HPD]: 6.00-26.37 Ma) (Yang et al, 2018). The ancestral area reconstruction based on the S-DEC model in Yang et al (2018) demonstrated that ancestral N. ignobilis ranged over a broad region comprising central and southwestern China as well as northern and southeastern Indochina.…”

“…A previous study estimated the timeline of the interspecific divergence within Neoneuromus showed that N. ignobilis diverged from its sister species during the middle Miocene (15.04 Ma, 95% high posterior density [HPD]: 6.00-26.37 Ma) (Yang et al, 2018). The ancestral area reconstruction based on the S-DEC model in Yang et al (2018) demonstrated that ancestral N. ignobilis ranged over a broad region comprising central and southwestern China as well as northern and southeastern Indochina. The topography and climate change of the mountainous areas in southwestern China were greatly affected by the uplift of the Qinghai-Tibet Plateau, a dramatic tectonic event produced by collision of the Indian and Eurasian plates (Zhang et al, 2000).…”