Taxonomic Review and Phylogeny of Marine Long-Legged Flies (Diptera :Dolichopodidae) in Peninsular Thailand

Abstract

A taxonomic review of marine long-legged flies (Dolichopodidae) in peninsular Thailand was investigated. The flies were randomly sampled and collected from rocky shores, sandy beaches and mangroves in eight provinces (namely Pattani, Songkhla, Nakhon Si Thammarat, Surat Thani, Chumphon, Satun, Krabi, and including Phang Nga) along the Thai seacoasts from November 2014 until May 2015. Four fly collection methods such as Malaise trap, yellow pan trap, sweep net and hand collecting method were used. In addition, external morphology features and Next Generation Sequencing techniques, NGS barcodes were employed in order to identify species. Totally, 60 species belonging to 19 genera, 7 subfamilies and one unplaced genus (genus incertae sedis) of marine long-legged flies were recognized from Thai seacoasts. All of these, consisting of 22 species from both sides of Peninsular Thailand, 23 species from the Andaman Sea, and 15 species from the Gulf of Thailand. Seventeen new species have been described from this study: Asyndetus sp.1, Cymatopus mayakunae sp. nov., Diaphorus sp.1, Hercostomus propermeieri sp. nov., Ngirhaphium chutamasae sp. nov., N. meieri sp. nov., Ornamenta siamese sp. nov., gen. nov., Paraclius sp.1, Phoomyia talumpuk sp. nov., Thinophilus boonrotpongi sp. nov., T. langkawensis sp. nov., T. minutus sp. nov., T. parvulus sp. nov., T. parmatoides sp. nov., T. spinatus sp. nov., T. spinatoides sp. nov. and including T. variabilis sp. nov. Furthermore, traditional identification and molecular phylogenetic analysis confirmed the monophyly of marine long-legged flies with reference to Ngirhaphium Evenhuis and Grootaert and Hercostomus Loew. The results clearly showed that the recent Ngirhaphium Evenhuis and Grootaert was divided into five major clades consisting of N. caeruleum, N. chutamasae sp. nov., N. meieri sp. nov., N. murphyi, and N. sivasothii, and the genus Hercostomus Loew was also separated into five distinct clades, namely, H. lanceolatus, H. plumatus, H. obtusus, H. brevicornis and H. brevidigitalis. Moreover, the results of haplotype network analysis and distribution pattern of mangrove Hercostomus lanceolatus Zhang, Yang and Grootaert from Thailand and Singapore population clearly indicated that haplotype pattern of Surat Thani assemblage was the parental population or the origin of H. lanceolatus in this region. Geographical distances and human anthropogenic threats were suggested to play an important role on genetic variation of marine long-legged flies.