## 4 Discussion  
In the present study, _T. nigroantennatus_sp. nov. was identified as separate from the _T. arundicolens_ complex by either morphology or molecular analysis. This species (Figure 5A) is uniformly yellow, with antennae black, except for the antennal segments I-II, and the very base of segment III, which are pale. Three to six secondary rhinaria of antennal segment III are arranged rather near base of the segment. The body length is 1.4-1.9 mm. _T. arundicolens_ (Figure 5B) is characterized by a lack of dorsal abdominal markings, the black cauda and variegated antennae with 5-10 elliptical secondary rhinaria, distributed on the proximal quarter of the III antennal segment. The body length is 1.8-2.8 mm. The third similar species introduced to Europe and occupying the same trophic niche, i.e., the underside of mature leaves of different bamboos species is _T. arundinariae_ (Figure 5C). However, winged females of this species are whitish, pale yellow or greyish-yellow, with longitudinal dark stripes on the thorax, paired black elongate spots on abdominal tergite 1-7, variegated antennae with 5-10 elliptical secondary rhinaria, and a pale cauda. The body length is 1.7-2.6 mm. It can, therefore, be assumed that the _Takcallis_ forms with black antennae discovered in the United Kingdom [16, 43, 44] belong to the newly described species _T. nigroantennatus_sp. nov., and are not a color variant of _T. arundicolens_. This is also supported by the same host plant--both _T. nigroantennatus_sp. nov. and 'black antenna form' from the United Kingdom were collected from _Fargesia_ bamboo. At the same time, no other species belonging to the genus _Takcallis_ have so far been reported from _Fargesia_ spp. Thus, the discovery of a new species may be related to the recent introduction of frost-resistant varieties of bamboo (i.e., _Fargesia_ spp. ), frequently found in European garden centers. Until now, the species has probably been confused with _T. arundicolens_ or overlooked, and its distribution is wider, as evidenced by the finding of winged adult females and immutures of this species on _Fargesia nitida x murielae_ in the Meise Botanic Garden in Belgium. Relatively obscure insects that are moved in commerce can become better known in areas where they are non-native. This has happened in the case of _Cinara curripes_ Path or _Appendiseta robiniae_ [PERSON]. Their bionomics are better known in Europe [45, 46] than in North America. As all species of the genus _Takcallis_ (Figure 6A-D) introduced to Europe are treated as pests, knowledge of their biology and distribution as well as correct identification is needed, especially due to the unique ornamental and aesthetic values of bamboo. Chemical control is still the most important measure to combat populations of aphids. However, it currently is replaced by the plant-pest-biological control agent  
DNA barcoding provides a significant tool to aid in the determination of species boundaries and the discovery of new taxa, evolutionary biology, and conservation. Although sequence variation in traditional DNA barcodes is sometimes insufficient for species-level discrimination in many large clades, the advances in computational and sequencing technology are changing the concept of DNA barcodes, from just a few loci to large, genome-scale sequences from organelles [47]. In particular, with the development of the next-generation sequencing (NGS) technologies, increasing numbers of insect complete mitogenomes (mitochondrial DNA sequence, mtDNA) have been extensively used in species identification for insects [48]. Therefore, in the integrative taxonomy, the use of mtDNA is also promoted as an effective tool in a broad taxonomic toolkit. Conceptualization, K.W. and N.S.-G.; methodology and investigation, K.W. and N.S.-G.; project supervision and administration, resources and funding acquisition, K.W. ; writing, original draft preparation, review and editing, K.W. and N.S.-G. All authors have read and agreed to the published version of the manuscript.