Taxonomy And Phylogenetic Analysis Of Bittacidae(Insecta: Mecoptera)

Bittacidae, a cosmopolitan family in Mecoptera, are important ecological indicators. Ingeneral, they frequent moist temperate forests with dense vegetation.Their larvae bear a pair ofcompound eyes and a median ocellus on the head, a unique character in Holometabola,implying that they occupy an important positon in the phylogeny of Insecta and a significantlinkage between the Hemimetabola and Holometabola. However, the systematics of Bittacidaehas been in chaos to date, and the taxonomic and phylogenitic researches of the familyurgently need to investigate comprehensively.The phylogenetic relationship of15genera and51species of Bittacidae was cladisticallyanalyzed using NONA and TNT for the first time, with maximum parsimony based on44external morphological characters of adults, including one character on habitus, sevencharacters on head, one character on thorax, four characters on legs,18characters on wingsand13characters in male genitalia, with Microchorista Byers,1974and NannochoristaTillyard1917in Nannochoristidae as outgroups. The taxonomy of the world Bittacidae wascomprehensively revised based on the results of the phylogenitic analyses.The phylogenetic analysis shows that the genera Bicaubittacus Tan&Hua,2009,Harpobittacus Gerstaecker,1885, Kalobittacus Esben-Petersen,1914, NeobittacusEsben-Petersen,1914, Pazius Navás,1913, and Terrobittacus Tan&Hua,2009are allmonophyletic groups. However, the genus Bittacus is reconfirmed to be a complicated gradeand is paraphyletic with the genera except Anabittacus and Eremobittacus. Bittacus needs tobe split further as a repository containing many “non-outstanding” species in Bittacidae. Thegenus Nannobittacus Esben-Petersen,1927is paraphyletic with Issikiella Byers,1972. Fourgenera, Kalobittacus+(Pazius+(Nannobittacus+Issikiella), form a clade. AnabittacusKimmins,1929is positioned in Bittacidae as the most basal lineage showing moreplesiomorphies. Eremobittacus Byers,1997is placed in the genera except for Anabittacus asthe most basal lineage. Austrobittacus Riek,1954, Edriobittacus Byers,1974, andHylobittacus Byer,1979are difficult to differentiate from each other. Orobittacus Villegas&Byers,1981is a sister group of Bittacus ussuriensis Plutenko,1985.Based on the results of the phylogenetic analysis, a new genus Longibittacus gen. nov. was erected with Bittacus alexanderi Byers,1999from Mexico as its type species.Correspondingly, four new combinations, Longibittacus alexanderi (Byers,1999) comb. nov.,L. banksi (Esben-Petersen,1915) comb. nov., L. mexicanus (Klug,1838) comb. nov. and L.sylvaticus (Byers,1996) comb. nov. were transferred from the genus Bittacus.Although the genus Neobittacus Esben-Petersen,1914was synonymized with Bittacus,the results of the phylogenetic analyses show that Neobittacus is evidently a monophyleticgroup with high branch support values. Therefore the generic status of Neobittacus isrecovered. It is suggested that the genera Nannobittacus and Issikiella need to merge into onegenus with subgenera or species groups, because they are very similar in appearence withslightly different venation, and the two genera form a paraphyletic group based on thephylogenetic analysis. The position of the genus Orobittacus in the phylogenetic tree isconfusing, which may result from the reason that the characters contain many autapmorphies,which were treated as non-informative characters by the phylogenetic softwares, and it isdifficult to seperate the genus by using non-outstanding characters. To solve this problem,more suitable characters are needed.The taxonomy of the worldwide fauna of the Bittacidae was dealt with based on theresults of phylogenetic analyses in combination with the world Bittacidae specimensexamined. Some confusing genera were revised. Sixty-nine species in twenty genera wererecorded and illustrated. Keys to genera and species were provided. Five new species (four ofwhich have been published) of Bittacus are described from China, i.e. Bittacus diaoluoshanusChen&Hua,2011; Bittacus longantennatus Chen et al.,2013; Bittacus jiulianshanus Chen etal.,2013, Bittacus setigerus Chen et al.,2013, and Bittacus liupanshuicus sp. nov. Two newdistributional records, Bittacus monastyrskiyi Bicha,2007rec. nov. and Bittacus ussuriensisPlutenko,1985rec. nov. are discovered from China for the first time.