Phylogenetic tree of all currently available <i>coi</i> gene sequences of morphotyped trombiculid mites (n = 52 new; n = 25 from GenBank).

<p>This study provided 52 new <i>coi</i> gene sequences (marked by *, approx. 640 bp length) from Lao PDR (n = 47), Thailand (n = 4), Cambodia (n = 1), and included all available <i>coi</i> sequences from NCBI (n = 25). The phylogenetic tree constructed from these <i>coi</i> gene sequences demonstrated distinct grouping of assigned morphotypes at the genus levels. Although evidence of both genetic and morphological plasticity was found and sample sizes for each species were small, there was preliminary evidence of sub-structuring of chigger populations below the species level. Different branch colors indicate morphological classification of Trombiculidae [<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0193163#pone.0193163.ref025" target="_blank">25</a>]; blue = <i>Walchia</i>, purple = <i>Neotrombicula</i>, green = <i>Ascoschoengastia</i>, yellow = <i>Schoutedenichia</i>, orange = <i>Schoengastia</i>, pink = <i>Blankaartia</i>, red = <i>Leptotrombidium</i>. Black branch represents sequences of house dust mites (out group). This indicated that DNA extracted from specimens used for autofluorescence analysis was of sufficient quality for downstream PCR amplification.