Additional record of Tuponia Reuter (Heteroptera, Miridae, Phylinae) from Korea, with a new synonym and discussion on distribution

Abstract Background The genus Tuponia Reuter, 1875 belongs to the subfamily Phylinae and comprises 91 species worldwide. Before this study, only T.koreana Kim & Jung had been recorded from the Korean Peninsula. New information Two species of Tuponia Reuter, 1910 are recognised from the Korean Peninsula including the first record of T.mongolica Drapolyuk, 1980. T.koreana Kim & Jung, 2021 is proposed as a junior synonym of T.chinensis Zheng & Li, 1992. The species is identified, based on the dorsal habitus and male and female genitalic structures. A brief discussion of the distribution of Korean Tuponia species also is presented.


Introduction
The phyline plant bug genus Tuponia Reuter, 1875 comprises 91 species worldwide (Schuh 2002, Kim et al. 2021). This group is distributed in the Palaearctic, Oriental Asia and northern Afrotropical Region and a large number of species use diverse Tamarix plants as their breeding host (Kerzhner andJosifov 1999, Li andLiu 2016). In the United States, Tamarix has been recognised as an invasive species, producing negative effects on ecosystems. For example, they accelerate salinisation of the soil (Ladenburger et al. 2006 ), increase wildfire severity by replacing fire-resistant plants and deplete groundwater (Pattison et al. 2011, Drus et al. 2013. In Korea, Tamarix has been planted on a limited basis as an ornamental tree, with natural populations only observed in Ansan and Incheon, which are distributed throughout the western coast of the Peninsula (NIBR 2011, Lee et al. 2018). Since a natural population exists in Korea and the plants can survive in many environments, research on related insects is important to understand more about the Tamarix species and its effect on the local ecosystem.
After the genus Tuponia was first erected by Reuter (1875), taxonomic analysis for this genus was actively conducted. In East Asia, Drapolyuk revised the subgenera Chlorotuponia Wagner, 1964 and Tuponia in Russia and Mongolia with the addition of 18 new species (Drapolyuk 1980, Drapolyuk 1982 and Chinese Tuponia was recently revised by Li and Liu (2016) with movement of 16 species including three new species. Later, Konstantinov (2016) reassessed the validity of some Tuponia species and synonymised three endemic Chinese species, including two of the new species described by Li and Liu (2016). In Korea, Tuponia koreana Kim & Jung was recently described by Kim et al. (2021). Herein we discuss two species of Tuponia in Korea, including a new distributional record of T. mongolica Drapolyuk and suggest a new synonym of Tuponia koreana Kim & Jung syn. n. with T. chinensis Zheng & Li. Images of the dorsal habitus and genitalic structures of both sexes were presented for these two Korean Tuponia species.

Materials and methods
All examined specimens are deposited in the collection of Insect Biosystematics Laboratory, Research Institute for Agriculture and Life Science, Seoul National University, Korea (SNU) and National Institute of Biological Resources (NIBR), Incheon, Korea. External characteristics were observed under a Leica Z16 APO microscope and digital images were obtained with a Leica DMC 5400 camera. Genitalic structures were dissected and observed under a Leica DM 4000B microscope and images were taken using a digital camera combined with the microscope (Lumenera Infinity 3). All measurements (mean and range) are provided in millimetres, unless otherwise noted. Terminology used to describe the genitalic structures follows Menard et al. (2014), Li and Liu (2016) and Kim et al. (2021), with the following abbreviations: Male: HP: hypophysis; SG: secondary gonopore; SL: sensory lobe. Female: DP: dorsal labiate plate; IL: interramal lobe; IS: interramal sclerite; RM: ramus; SR: sclerotized ring; VP: ventral labiate plate.

Diagnosis
Tuponia can be recognised by the following characters: body elongate oval; dorsum somewhat shining, without distinct punctures and covered with pale, sericeous setae and dark setae; basic colouration greenish or yellowish-brown with brown, dark brown or reddish spots; membrane dark grey, vein pale green to brown; endosoma elongated, C-, S-or J-shaped; sometimes with sclerotised apical structures and membranous lobes; secondary gonopore usually developed between subapical part of sclerotised lobes; sclerotised ring elongated oval, interramal sclerite elongate and smooth. For detailed diagnostic characters and figures, see Drapolyuk (1980), Drapolyuk (1982), Li and Liu (2016) and Kim et al. (2021).

Subgenus Tuponia
The subgenus can be recognised by the following characters: body elongate oval (male) or suboval (female), comparatively moderate to large (2.1-4.1 mm, usually around 3.0 mm); dorsum somewhat shining, without distinct punctures and covered with pale, sericeous setae; apical 1/3 of clavus and median part of hemelytra usually with suberect, dark brown to reddish setae, forms transverse line; basic colouration pale green to yellowish-green, partly brownish or tinged with red; membrane dark grey, vein pale green to brown; endosoma C-, S-or J-shaped, usually with one or two sclerotised apical structures; endosomal membrane rather developed, situated along apical processes; secondary gonopore usually developed between the subapical part of sclerotised lobes; female sclerotised ring elongate oval, surrounded by wide and weakly sclerotised labiate plates; bursa copulatrix with a pair of distinct, round structures dorsally; posterior wall with elongated, distally round interramal sclerites and weakly sclerotised, rough interramal lobe.

Subgenus Chlorotuponia
This subgenus was established by Wagner (1964) and can be recognised by the following characters: body elongate oval (male) or suboval (female), comparatively small (1.7-2.5 mm, usually around 2.0 mm); dorsum somewhat shining, without distinct punctures and covered with long, pale hair and short, suberect brownish setae; basic colouration green to yellowish-green, usually concolorous; membrane dark grey, vein pale green to brown; endosoma C-, S-or J-shaped, usually with one or two sclerotised apical structures; endosomal membrane weakly developed, indistinct; secondary gonopore usually developed between the subapical part of sclerotised lobes; female sclerotised ring elongate oval, surrounded by wide and weakly sclerotised labiate plates; inner margin of bursa copulatrix with thin, arch-shaped sclerotised structure; posterior wall with elongated, distally round interramal sclerites and weakly sclerotised, interramal lobe with rough surface

Notes
We examined specimens of Tuponia chinensis in SNU and propose T. koreana Kim & Jung as a junior synonym of T. chinensis Zheng & Li. The diagnostic characteristics of T. koreana nearly match those of T. chinensis and the genitalia of the two nominal species are identical. Kim et al. (2021) separated T. koreana from T. chinensis by the following characters: i) metatarsal segment II distinctly shorter than segment III, ii) left paramere with one long process pointing down and iii) endosoma without visible secondary gonopore. However, as in Fig. 7, they only measured the length of each segment at the ventral side of the metatarsus and the actual length of segment II is not distinctly shorter than that of segment III. Additionally, in the structure of the left paramere, our specimen shows a straight lateral process (Fig. 4C). However, we could not find other structural differences and concluded that these were minor intraspecific variations. In addition, Kim et al. (2021) stated that a secondary gonopore of T. koreana is 'clearly invisible,' but it can be seen upon displacement of the two apical sclerites of the endosoma, as shown in Fig. 4E-H. When compared with the description of Zheng and Li (1992), the secondary gonopore of the Korean specimen looks conspecific in its subapical location and rugged margin.

Notes
This species can be confused with T. jaxartensis Drapolyuk and T. zhenyuanensis Li & Liu, from which it is easily distinguished by endosoma with laterally serrate and elongated apical sclerites, phallotheca with a fin-like protrusion at the inner margin and a structural difference of parameres.

Distributions of Korean Tamarix population and Tuponia
In this work, T. chinensis Zheng & Li and T. mongolica Drapolyuk were found at a coastal wetland near Incheon. This area provides an adequate environment for Tamarix and is adjacent to an international Airport, which may have been its source of introduction. According to a recent study, it is assumed that Ansan and Incheon populations of Tamarix were introduced about 40 years ago from China (Beijing) and from another unknown origin (Lee et al. 2018). Kim et al. (2021) also mentioned this hypothesis and suggested the need for subsequent research on the distributions of T. koreana and the closely allied species T. chinensis. Since these two species are regarded as conspecific, we can assume that T. chinensis was introduced along with the Tamarix. To support this, a comparison of the relationships of Tamarix in naturalised and intentional ornamental populations is crucial. In addition, considering the Tuponia diversity of China (Li and Liu 2016), further investigations may yield additional records for Korean Tuponia.