Reclassification of Gall Midges (Diptera: Cecidomyiidae: Cecidomyiini) from Amaranthaceae, with Description of Ten New Species Based on an Integrative Taxonomic Study †

SIMPLE SUMMARY: Plants of the family Amarantaceae are hosts to hundreds of gall-midge taxa (Diptera: Cecidomyiidae), one of which is the genus Halodiplosis, which has been known so far from 99 species, almost all of which are from Central Asia. Immature stages have never been described in this genus nor have molecular data been used in its classification. In preparation for the description of 10 new species from Israel, we conducted a thorough review of the taxonomic literature on Halodiplosis (almost all of which is in Russian) and found that this genus should be divided into several genera based on morphological and life-history attributes. As a result, we reinstated the genus Asiodiplosis for most of the species in this group, all of which develop in complex bud galls. This leaves only 14 species in Halodiplosis, which live in galls induced by other gall-midges or develop in plant tissues without causing distinct galls. Here we describe nine Asiodiplosis species and one Halodiplosis species from Israel based on morphological and molecular data, including the first description of larvae and pupae for these genera. This work demonstrates the value of combining morphological, molecular, and life-history data to resolve the systematics of taxonomically difficult groups. ABSTRACT: The genus Halodiplosis includes 99 species restricted to host-plants of the Amaranthaceae, virtually all of which are from Central Asia. The discovery of numerous undescribed species putatively belonging to this genus in Israel instigated an exhaustive review of the original descriptions of all known species in this genus. This study revealed that the generic concept of Halodiplosis and some of the genera synonymized under it should be redefined based on morphological and life-history attributes, such that Halodiplosis is limited to only 13 species developing in plant tissues without obvious gall formation or as inquilines in galls of other cecidomyiids. Revised status were proposed for Asiodiplosis, Onodiplosis, and Desertomyia, all species of which are gall inducers. A detailed morphological study of the Israeli species combined with data on their life history and an analysis of mitochondrial COI and 16S gene sequences revealed nine gall-inducing species belonging to Asiodiplosis and one inquilinous species belonging to Halodiplosis. All ten species (Asiodiplosis admirabilis n.sp., A. bimoda n.sp., A. delicatula n.sp., A. largifica n.sp., A. mohicana n.sp., A. mucronata n.sp., A. paradoxa n.sp., A. pillosaeconspicua n.sp., A. stellata n.sp., and Halodiplosis fugax n.sp.) are described here as new to science, including the first descriptions of larvae and pupae for these genera.