Molecular Phylogenetics and Light Microscopy Reveal “True” and “False” Calacarines and Novel Genital Structures in Gall Mites (Acariformes, Eriophyoidea)

Gall mites (Eriophyoidea) are cosmopolitan microscopic phytoparasites that often transmit viruses and induce gallogenesis. The tribe Calacarini is diagnosed by a set of plesiomorphic and homoplastic traits, including elimination of setae sc shared with other lineages of Eriophyoidea. We reviewed data on the generic diversity of calacarines, revised the concept of the type genus Calacarus Keifer 1940, and proposed three zones (MZ, SMZ, LZ) in the prodorsal shields of calacarines to simplify descriptions of their shield patterns. We describe three new calacarine species (Calacarus baviensisn. sp., C. burchelliaen. sp., and Viginticus searsiaen. sp.) from indigenous dicotyledonous trees from South Africa and Vietnam and report on new findings of Paracalacarus podocarpi Keifer in Brazil, Jiangsuacarus sp. in the USA, and Calacarus pusillus Pye in Latvia and Russia. The latter represents the new most northern locality of Calacarini. Reinvestigating the type species of Jaranasia Chandrapatya &amp: Boczek 2000 revealed that absence of setae l&rsquo:&rsquo: II is the only character separating it from Jiangsuacarus Xue 2009. We proposed two new combinations: Jiangsuacarus sesleriae (Skoracka 2004) n. comb. (transferred from Jaranasia) and Procalacarus mussaendae (Keifer 1977) n. comb. (transferred from Calacarus). Partial sequences of Cox1 and 28S genes were obtained for six calacarines, some of them originating from old ethanol material kept at room temperature. Molecular phylogenetics revealed a stable cluster of &ldquo:true&rdquo: calacarine sequences comprising Calacarus, Jaranasia, Latitudo, and Viginticus and a polyphyletic group of erroneous sequences assigned to Calacarini in GenBank. All investigated females of calacarines have a pair of genital tubules associated with the vestibulum and hypothesized to participate in fertilization. This finding may contribute to resolving the question on how the fusion of gametes happens in gall mites.