Anomoneura taiwanica sp. nov. (Hemiptera, Psylloidea, Psyllidae, Psyllinae) is described based on samples from Taiwan that were previously misidentified as A. mori Schwarz, 1896. Morphological and genetic differences between the two species, as well as their distribution, are detailed and discussed. Comments on the pest status of Anomoneura spp. in East Asia are also provided.

Asia, DNA barcoding, mulberry, new species, Oriental region, psyllid, Sternorrhyncha, taxonomy

Psyllids (Hemiptera, Psylloidea) are small phytophagous insects, ranging from 1−10 mm. About 4,000 species are known worldwide (Burckhardt and Ouvrard 2012). Some species are important pests of crops and forest trees, damaging plants by direct feeding and vectoring plant diseases. Psyllids are generally host specific and related psyllid species often develop on related host taxa (Ouvrard et al. 2015).

Knowledge of the psyllid fauna of Taiwan was first developed by foreign researchers during the first half of the 20^th century (Kuwayama 1908, 1910, 1931; Enderlein 1914). More comprehensive taxonomic work was later carried out by C.T. Yang and others (Yang 1984; Fang and Yang 1986; Yang et al. 1986; Lauterer et al. 1988; Fang 1990; Yang et al. 2004, 2009, 2013; Liao et al. 2016; Liao and Yang 2018). In total, nearly 150 species from 46 genera with representatives of all eight currently recognized families of Psylloidea have been recorded in Taiwan.

Until now, Anomoneura Schwarz, 1896 was considered a monotypic genus of jumping plant-lice (Hemiptera, Sternorrhyncha, Psylloidea, Psyllidae, Psyllinae) and was only known from East Asia (Uhler 1896; Kwon 1983; Labina 2006; Li 2011; Liao and Yang 2018; Ouvrard 2019). The single species of the genus, Anomoneura mori Schwarz, 1896, is a serious pest of mulberry (Morus spp.; Moraceae) (Kuwayama 1971). The species causes damage to mulberry plants by excessive removal of phloem sap and soiling fruit by secreting a large amount of honeydew and thread-like wax masses. Very recently A. mori was reported from Taiwan (Liao and Yang 2018). We have recently come to the conclusion that the material from Morus australis from Taiwan was misidentified by Liao and Yang (2018) and is actually an undescribed Anomoneura species that is morphologically similar to A. mori. We formally describe the new species here.

Material for this study was examined from the following institutions: Korea National Arboretum, Pocheon, Korea (KNA); National Chung Hsing University, Taichung, Taiwan (NCHU); Naturhistorisches Museum, Basel, Switzerland (NHMB); National Institute of Biological Resources, Incheon, Korea (NIBR); National Museum of Natural Science, Taichung, Taiwan (NMNS); National Pingtung University of Science and Technology, Pingtung, Taiwan (NPUST); National Taiwan University, Taipei, Taiwan (NTU); Seoul National University, Seoul, Korea (SNU); Taiwan Agriculture Research Institute, Taichung, Taiwan (TARI); and Zoological Institute, Russian Academy of Sciences, St Petersburg, Russia (ZIN).

Morphological terminology follows mostly Ossiannilsson (1992), Hollis (2004), and Yang et al. (2009). For molecular diagnosis, the COI-tRNA^leu-COII fragment of mitochondrial DNA was used, as it is usually effective for comparison of closely related psyllid species (Cho et al. 2020). Protocols for DNA extraction, amplification, sequencing, sequence alignment, and phylogenetic analysis were followed from Cho et al. (2020). In addition to the material of Anomoneura, two Acizzia species (Psyllidae, Acizziinae) were included in the phylogenetic analysis as outgroups (Table 1). K2P distance and p-distance were computed using MEGA 6 (Tamura et al. 2013). Nomenclature for genetic sequences in Table 1 follows Chakrabarty et al. (2013).

Anomoneura mori was described from Japan by Schwarz in Uhler (1896) and subsequently reported from the Korean Peninsula (Chon 1963; Klimaszewski 1963), the Russian Far East (Gegechkori and Loginova 1990; Labina 2006), China (Li 2011), and most recently from Taiwan (Liao and Yang 2018). The Taiwanese population of Anomoneura showed some morphological differences from A. mori specimens from other countries, but unfortunately, this was overlooked (Liao and Yang 2018).

Anomoneura taiwanica sp. nov. resembles A. mori in the structure of the head, the general structure of the forewing, and a similar host association with plants of the genus Morus. Anomoneura taiwanica sp. nov. differs from A. mori in the details of the forewing, paramere, distal segment of aedeagus, and female proctiger (see the key above, Table 2, and Figs 1–10). The shape of the vein Cu_1a of the forewing is quite variable, curved at 90° to 100° in examined Anomoneura material, including Taiwanese populations, which likely reflects an intraspecific variation in both species (Figs 1, 2). No significant morphological differences were found between immatures of these taxa. We analysed DNA sequence fragments of A. mori from Japan and Korea and A. taiwanica sp. nov. from Taiwan. Sequences from Japan and Korea showed no significant genetic divergence from each other (1.8% p-distance and K2P distance). However, the difference of those populations from A. taiwanica sp. nov. was significantly higher (9.0% p-distance, 9.7% K2P distance) (Fig. 11). A 3% genetic distance has been considered supportive for diagnosis of taxa at the species level for psyllids in general (Percy 2003; Martoni et al. 2018).

Figure 11. 

A neighbor-joining tree based on the Kimura 2-parameter genetic distance between COI-tRNA^leu-COII sequences. Bootstrap support values are shown at the branch points and are based on 1,000 replications.

Mulberry (Morus spp.) is important to sericulture as it is also the host plant for silkworms. Due to this, damage caused by Anomoneura can significantly affect the silkworm industry in both Taiwan and abroad. Populations of A. mori can remove large quantities of plant sap, produce masses of wax threads, and secrete a large amount of honeydew. This causes negative effects on plant growth and diminishes mulberry leaves which devalues the silkworms cocoons (Kuwayama 1971; Kim and Park 2016). A recent field survey by Liao and Yang (2018) in Taiwan showed that A. taiwanica has the same life history as A. mori, which indicates that both species are serious pests of mulberry trees. However, at present, A. taiwanica may not cause serious economic loss in Taiwan due to a decline of the silk industry in the late 1990s. Just a few silkworm farmers remain in Taiwan, and these are merely for traditional or educational purposes (Jiang 2007).

Liao and Yang (2018) considered A. taiwanica sp. nov. (which they had misidentified as A. mori at the time) as an exotic invader in Taiwan because earlier surveys of Morus trees did not identify this species as present in the country (Yang 1984; Yang et al. 1986). Furthermore, A. mori is widely distributed in the temperate climatic zone of East Asia at higher latitudes than A. taiwanica, which is known only from the subtropical climate of northern Taiwan. The recent increase in the import of various plant seedlings from China to Taiwan has often accelerated the establishment of exotic species, such as Cacopsylla chinensis (Yang et al. 2004). Given this fact, A. taiwanica may have originated in southern China. To confirm this hypothesis, more material of Anomoneura from China should be examined to reveal a potentially wider distribution of A. taiwanica.

We are grateful to Daniel Burckhardt (Naturhistorisches Museum, Basel, Switzerland), Igor Malenovský and Liliya Štarhová Serbina (both Department of Botany and Zoology, Faculty of Science, Masaryk University, Brno, Czech Republic), and David Ouvrard (Anses, Plant Health Laboratory, Montferrier-sur-Lez, France) for helpful comments on earlier versions of this manuscript, and Hiromitsu Inoue (Institute of Fruit Tree and Tea Science, National Agriculture and Food Research Organization, Japan), Eugenia Labina (Zoological Institute, Academy of Sciences, St Petersburg, Russia) for helping us to examine Anomoneura material from China, Japan and Russia, and Wesley Hunting (Department of Entomology, National Chung Hsing University, Taichung, Taiwan) for his help in English editing. Thanks are extended to Dávid Rédei (Institute of Entomology, College of Life Sciences, Nankai University, China) for checking Chinese mulberry psyllids. This work was partly supported by a grant from the Korea National Arboretum ‘Development of an integrated identification system of Korean insects’ (project no. KNA 1-1-20, 16-1).