Mouthparts Morphology And Antennal Sensilla Of Panorpidae And Bittacidae(Mecoptera)

Mouthparts are closely associated with feeding behavior and can provide valuable characters for phylogenetic analyses of insects.Antennae are important sensory organ of insects and play an important role in founding food,mate and spawning place.The surface of mouthparts and antennae are furnished with numerous sensilla.The comparative morphology of mouthparts and antennae can provide important theoretical basis for the behavior,taxonomy and phylogenetic analyses of Mecoptera.Here,we investigated the mouthparts of Panorpa liui Hua,1997,Neopanorpa longiprocessa Hua & Chou,1997,Cerapanorpa dubia(Chou & Wang,1981),Dicerapanorpa magna(Chou,1981)and Furcatopanorpa longihypovalva(Hua & Cai,2009)of Panorpidae,Bittacus puripennis Cai & Hua,2006,Terrobittacus rostratus Du & Hua,2017 and Bicaubittacus appendiculatus(Esben-Petersen,1927)of Bittacidae,and investigated antennal sensilla of B.planus Cheng,1949,B.cirratus Tjeder,1956,B.puripennis Cai & Hua,2006,B.sinicus Issiki,1931,T.implicatus(Huang & Hua,2006),Bi.appendiculatus(Esben-Petersen,1927)and Bi.burmanus(Tjeder,1973)of Bittacidae by scanning electron microscopy.The mouthparts of all these species are of the typical mandibulate type,consisting of a labrum-epipharynx,paired mandibles and maxillae,labium and hypopharynx.The labrum of Panorpidae is a triangular lobe distal to the elongate clypeus.The labrum of Bittacidae is prolongation.The epipharynx of Bittacidae is glabrous,but the epipharynx of Panorpidae is usually furnished with abundant microtrichia,which are absent in N.longiprocessa.The mandibles are blade-shaped,with two distal teeth of various shape and length.The mandibles of Bittacidae possess a small conical projection on the inner side.The maxillae are well developed,each consisting of a cardo,a stipes,an inner lacinia,an outer galea and a five-segmented maxillary palp.The labium is formed by an elongated submentum,an inverted vase-shaped mentum,a prementum and a pair of two-segmented labial palps.The hypopharynx of Bittacidae is slightness,with a little number of microtrichia on the surface.The hypopharynx of Panorpidae is tongue-like,with numerous microtrichia ventrally,except for N.longiprocessa glabrous centrally on the ventral surface.The mouthparts of Panorpidae and Bittacidae have six types of sensilla: sensilla basiconica;sensilla chaetica;sensilla palmata and trichodea;sensilla campaniformia and hair plates.The morphology,distribution and number of sensilla vary among different species.Sensillae on antennae are similar in the three genera of Bittacidae.The antennae of Bittacidae bear sensilla basiconica,sensilla chaetica,sensilla coeloconica,sensilla trichodea,anomalous sensilla trichodea,sensilla campaniformia and hair plates.The distribution and number of sensilla vary in different species.Two different types of antennae are found in Bittacus,the seventh flagellomere of the long hair antennae is situated long sensilla trichodea.In ventral side,the sensilla chaetica is vertical with the axis of antennae.The number of the sensilla coeloconica is quite different among the three genera,Bittacus has the most sensilla coeloconica,Terrobittacus is the second,and Bicaubittacus is the least.Based on the comparative study of the mouthparts between Panorpidae and Bittacidae,and the antennal sensilla of Bittacidae,we think the diversities of the mouthparts and antennal sensilla in Mecoptera can provide characters for taxonomy.Based on the morphology of sensilla,we can infer their function,which can help us to analyze behaviours of insects.