Recent Divergence of <i>Neolitsea</i>-associated <i>Pseudasphondylia</i> Gall Midges (Diptera: Cecidomyiidae) with Description of a New Species from Taiwan.

Taiwanese <i>Pseudasphondylia</i> species inducing spherical leaf galls on six <i>Neolitsea</i> hosts, viz, <i>N. acuminatissima</i>, <i>N. daibuensis</i>, <i>N. konishii</i>, <i>N. parvigemma</i>, <i>N. sericea</i> and <i>N.</i> <i>variabillima</i>, was regarded as a species allied to Japanese <i>P. neolitseae</i> Yukawa due to similarity of gall structure and host. The Taiwanese species is morphologically different from <i>P. neolitseae</i> in adult palpus segmental number, shapes of pupal antennal horn, pupal prothoracic spiracle, and larval sternal spatula, resulting in its description as a new species to science, <i>Pseudasphondylia</i> <i>hooki</i> sp. n. The species delimitation (Assemble Species by Automatic Partitioning method) supported that <i>P.</i> <i>hooki</i> sp. n. is distinct from <i>P. neolitseae</i>. The sistership of <i>P. hooki</i> sp. n. and <i>P. neolitseae</i> was also supported in the Maximum likelihood tree based on the 1^st codon of <i>COI</i> region. The speciation event of them is assumed to be geographical isolation because the divergence corresponded to the separation of Taiwan and Japan in the Pleistocene. The patterns of ecological features (host species) on the phylogeny revealed that galling on <i>N. sericea</i> is primitive of <i>Neolitsea-</i>associated <i>Pseudasphondylia</i> lineage. Accordingly, the divergence pathway from north to south in Taiwan is suggested by the distributions of primitive (<i>N</i>. <i>sericea</i>) and most derived hosts (<i>N. daibuensis</i>).