Species Definition And Potential Distribution Of The Protogyne And Deutogynes Of Epitimerus Sabinae S.L. (Acari: Eriophyidae)

Eriophyoid mites are abundant and widely distributed phytophagous mites,the type is various,and more than 4400 species have been described.Eriophyoid mites are highly host specific compared to other species in the Acari,more than 80% of eriophyoid mites have been reported only on one host plant.Compared with other mites,the Eriophyoid mites are with the special morphology: the tiny body,the average body length is about 200μm;special morphological structure,body shape is fusiform or vermiform,only with two pairs of legs.Setae in the body of eriophyoid mites are simple and the characters for taxonomy are not so many.In addition,Eriophyoid mites also have polymorphic phenomenons:protogynes and deutogynes.The morphological characteristics of some species differ greatly between the protogynes and deutogynes,reaching the level of genus,which affects the accuracy of the identification of eriophyoid mites based on morphological characteristics.Epitrimerus sabinae s.l.was a unique species found only on Juniperus chinensis L.,they can damage the axillary buds,leaves,forming blister and other parts,affects the photosynthesis of plant leaves,leading to poor growth of Juniperus chinensis L.and yellow leaves.Previous studies have shown that there are two types of eriophyoid mites,namely protogynes and deutogynes.In this study,morphological and molecular identification of eriophyoid mites from 26 populations in China were conducted,and three species were found.One was Epitrimerus sabinae,and the other two were Leipothrix juniperensis sp.nov.Xue & Yin,2020,composed of protogynes and deutogynes forms.The main findings are as follows:(1)A total of 1136 Epitimerus sabinae s.l.individuals from 26 populations were compared in morphological characteristics.It was found that Epitimerus sabinae s.l.had three morphologic types according to the body size and the structure of dorsal pedipalp genual seta,which were LNS: large size,normal palp seta d.MBS: medium size,bifurcated palp seta d.SBS: small in size,bifurcated palp seta d.Four lines of evidence including DNA-based species delimitation,phylogenetics,haplotype network,mitochondrial genome architecture,indicated that the MBS and SBS groups were very distinct from LNS.Results based on genetic distance and topological structures such as GMYC,ABGD,BIN,b PTP,and BPP all support that MBS and SBS are considered as a species,while LNS is considered as a separate species.COI-based haplotype analysis found that there was only one haplotype between MBS and SBS,and that haplotypes of LNS were not shared with haplotypes of either MBS or SBS,suggesting that there was no gene exchange between the two sympatric species.The comparison of mitochondrial genomes showed that there were significant differences in gene sequence,codon and total length between LNS,MBS and SBS.(2)Molecular results showed that there were significant differences among the three morphologic species,and we further conducted more subtle morphological comparisons.The morphological classification characteristics of the Epitimerus sabinae s.l.were measured,and 32 morphological measurement data were used for principal component analysis.The principal component analysis results showed that PCA1 distinguished LNS from MBS and SBS,while MBS and SBS were not distinguished by PCA1 or PCA2.Combine molecular evidence with morphological identification evidence,we suggest that the MBS and SBS morphotypes are properly placed in the genus Leipothrix,so we named a new species,Leipothrix juniperensis sp.nov.Xue & Yin,2020.The MBS form is the protogynes form of the new species,while the SBS form is the deutogynes form.The protogynes and deutogynes forms of the new species are described in characters.(3)Max Ent and Arc Map were used to estimate the potential distribution of Epitimerus sabinae and Leipothrix juniperensis sp.nov.Xue & Yin,2020.From Epitimerus sabinae and Leipothrix juniperensis sp.nov.Xue & Yin,2020 the potential distribution in China found that the potential distribution in central and southern parts of China,a total of two species live in the form of three Eriophyoid mites,and in the north of China region(especially in northeast China)only live Epitrimerus sabinae this one species.The distribution of LNS,MBS and SBS in 19 of the 26 populations was homogeneous,while only LNS existed in the other 7 populations,which might be related to the adaptation of the two species to climate conditions.Moreover,we also defined the criteria of Eriophyoid mites in protogynes and deutogynes.Expanding the approaches used to link protogynes and deutogynes of eriophyoid mites,this study provides a way to accelerate the delineation of species boundaries in this important group of plant pests.In future analyses,we should study more synpatric samples or samples from different host groups that cause the same damage to the same host plants,in order to reveal the true extent of species having protogyne and deutogyne forms.