Systematics,Historical Biogeography And Population Genetics Of Parnara Butterflies

The butterfly genus Parnara(Hesperiidae: Baorini),ground color brown or dark brown,inhabits in tropical and subtropical zones,currently consists of 10 species and several subspecies and distributes in Africa,Asia and Australia.The larvae feed exclusively on Poaceae,of which some are major pests of economic crops(e.g.,rice,wild rice stems and sugarcane).Because of the simplicity and resemblance of wing markings and male genitalia,and sympatric distribution among species,as well as intra-specific individuals variation,morphology-based classification is really confused,resulting in an erroneous identification.The species boundaries of some species are controversial,intra-specific relationship and phylogeographic pattern are uncertain.All above hinder precise identification and effective control of the pests.The aim of this study is to understand the systematics and evolutionary pattern of Parnara based on the ultrastructure of antennal sensilla,phylogenetic analyses,species delimitation,and population genetics.Firstly,ultrastructure of antennal sensilla of five Parnara species was scanned to determine whether the antennal sensilla can be treated as diagnostic characters and provide phylogenetic signals.Secondly,the Maxumum Likelihood and Bayesian trees were reconstructed based on eight genes and 101 specimens representing all 10 recognized species to determine the systematic relationships,biogeographical history and diversification dynamic of this genus,providing a reliable classification and elucidating the evolutionary pattern.Thirdly,the restriction site-associated DNA(RAD)sequencing and population genetics analytical methods were employed to preliminarily discover the diversity of P.bada complex based on 101 specimens.The main results are as follows:(1).Six types of sensilla were found on the antennae of all five Parnara species,namely,sensilla squamiformia(SQ),sensilla trichodea(ST),sensilla chaetica(SCh),sensilla coeloconica(SCo),sensilla auriicillica(SAu)and B?HM bristles(BB),of which SQ,ST and BB have only one type in five species,and no significant difference are present.Both SCh and SCo have two subtypes,while SAu has three subtypes,which different subtypes are present across different species.Two subtypes of SAu,SAu I and SAu III,were found in P.guttata,of which the later is unique to this species.All types and subtypes of sensilla,except SAu III,were observed in P.batta,which are the most abundant in five species.For P.ganga,only SCo with two subtypes were observed,which are the least in five species.For P.bada and P.apostata,the subtype and shape of sensilla are very similar,but the difference in the length of some types or subtypes were found between these two species.As mentioned above,the ultrastructure of antennal sensilla could identify and classify the most Parnara species,suggesting that the antennal sensilla can be treat as diagnostic characters and provide phylogenetic signals.The similarity in types and distribution patterns of sensilla reflect their close relationship.(2).Base on the results of phylogenetic analyses and three species dimilations,the status of the taxon P.naso poutieri is revised as a distinct species,Parnara poutieri(Boisduval,1833)stat.rev.,the subspecies P.guttata mangala(Moore,1866)syn.nov.is synonymized with P.guttata guttata(Bremer & Grey,1853).The monophyly of Parnara is strongly supported,with the following relationships: P.amalia +((P.monasi +(P.poutieri + P.naso))+((P.kawazoei + P.bada complex)+(P.ganga +(P.ogasawarensis +(P.guttata + P.batta))))).Divergence time and ancestral range estimates indicate that the common ancestor of Parnara originated either in Africa or Australia in the mid Miocene-early Pliocene.Transoceanic long-distance dispersal(LDD)is therefore the most parsimonious hypothesis to explain the extant global distribution of Parnara.More recent dispersal events and range expansion have played an important role in the diversification of this genus,particularly in Asia.Relatively stable geotectonic plates and the cool paleoclimate present at the time when most extant lineages appeared during the early Pliocene-late Pleistocene might have been the factors responsible for the relatively constant low dynamic rate of diversification within the group.(3).The results from population structure,PCA,NJ tree and SNAPP-BFD* based on RAD sequence data from 101 specimens show that P.bada complex include at least three species,P.bada,P.apostata and P.mysteria sp.nov.,neither so-called two species in morphological study nor a distinct Molecular Operational Taxonomic Unit(MOTU)discriminated by three species delimitation methods in charpter three,which are suggestive of the existence of cryptic species diversity.The species diversity within P.bada complex were underestimation,resulting in cryptric speciation.Such cryptric speciation event can be explained by habitat heterogeneity(ecological differentiation)in sympatry as potential drivers,thereby causing high genetic diversity in evolutionary history.(4).According to multiple evidence,the genus Parnara now comprises 12 species: P.amalia(Semper,1879),P.monasi(Trimen,1889),P.naso(Fabricius,1798),P.poutieri(Boisduval,1833)stat.rev.,P.guttata(Bremer & Grey,1853),P.batta Evans,1949,P.ganga Evans,1937,P.ogasawarensis Matsumura,1906,P.kawazoei Chiba & Eliot,1991,P.bada(Moore,1878),P.apostata(Snellen,1886),P.mysteria sp.nov.