Article Review of Japanese Pine Bast Scale, Matsucoccus matsumurae (Kuwana) (Coccomorpha: Matsucoccidae), Occurring on Japanese Black Pine (Pinus thunbergii Parl.) and Japanese Red Pine (P. densiflora Siebold & Zucc.) from Korea Jinyeong Choi 1,2, Deokjea Cha 3, Dong-Soo Kim 3 and Seunghwan Lee 1,2,* 1 Insect Biosystematics Laboratory, Department of Agricultural Biotechnology, Seoul National University, Seoul 151-921, Korea 2 Research Institute of Agriculture and Life Sciences, Seoul National University, Seoul 151-921, Korea 3 Forest Biomaterials Research Center, National Institute of Forest Science, Jinju 52817, Korea * Correspondence: [email protected]; Tel.: +82-2880-4703; Fax: +82-2873-2319 Received: 11 June 2019; Accepted: 16 July 2019; Published: 29 July 2019 Abstract: Matsucoccus matsumurae (Kuwana, 1905), commonly known as Japanese pine bast scale, is a destructive pest on pine trees in North America, East Asia, and Northern Europe. The spread of damage to black pine trees, Pinus thunbergii Parl., due to M. matsumurae has been reported throughout Southern and some Eastern and Western coastal regions in Korea, under the name M. thunbergianae, which was described by Miller and Park (1987). Recently, M. thunbergianae was synonymized with M. matsumurae by Booth and Gullan (2006), based on molecular sequences and morphological data. However, M. thunbergianae is still considered a valid species in Korea. Since supporting data for the synonyms are unavailable in any DNA database (e.g., GenBank and BOLD), we performed morphological and molecular comparisons to review the results of Booth and Gullan (2006) using samples of M. matsumurae collected from Japan and topotype materials of M. thunbergianae from Korea. Our study supports the opinion of Booth and Gullan (2006), as the morphological features of the adult female and male of M. thunbergianae are identical to those of M. matsumurae, and DNA sequences (18S and 28S) of M. thunbergianae show identical or very low genetic distances with those of M. matsumurae. Additionally, regional sampling of Korea produced the first documented occurrence of M. matsumurae in Jeju. Keywords: Matsucoccus thunbergianae; black pine bast scale; taxonomy; synonym 1. Introduction The genus Matsucoccus Cockerell [1], belonging to the archaeococcoid family Matsucoccidae, comprises about 38 species worldwide [2]. Except for six fossil species described from Baltic amber, all 32 extant species exclusively occur on Pinus spp. in the Holarctic and Neotropical regions [2]. Among them, some species are the most destructive pests on pine trees; for example, Matsucoccus acalyptus Herbert on pinyon pine (Pinus edulis Engelm.) and single-leaf pinyon (P. monophylla Torr. and Frém.); M. bisetosus Morrison and M. vexillorum Morrison on ponderosa pine (P. ponderosa P. and C. Lawson); and M. matsumurae (Kuwana) on Chinese pines (P. tabuliformis Carrière and Pinus massoniana D. Don.), Japanese black pine (P. thunbergii Parl.), and red pine (P. resinosa Sol. ex Aiton) [3–7]. Females and males of Matsucoccus species have sexually dimorphic life cycles after the second-instar nymphs, which are known as “cysts” in the feeding and overwintering stages (Figure1). The females Forests 2019, 10, 639; doi:10.3390/f10080639 www.mdpi.com/journal/forests Forests 2018, 8, x FOR PEER REVIEW 2 of 15 Forests 2019, 10, 639 2 of 14 Females and males of Matsucoccus species have sexually dimorphic life cycles after the second- instar nymphs, which are known as “cysts” in the feeding and overwintering stages (Figure 1). The arefemales neotenic, are includingneotenic, including three stages three (occasionally stages (occasionally four in M. four vexillorum in M. Morrison),vexillorum Morrison), whereas the whereas males havethe males five stages, have five including stages, aincluding prepupa a and prepupa pupa, and and pupa, grow and functioning grow functioning wings as wings adults as (for adults the life (for cyclethe life details cycle of detailsMatsucoccus of Matsucoccus, see Foldi, see [5]). Foldi [5]). Adult male (♂) Adult female (♀) Pupa (cocoon) Egg sac rd st 3 instar 1 instar or prepupa (crawler) nd 2 instar (cyst) FigureFigure 1. 1.General General life life cycle cycle of ofMatsucoccus Matsucoccusspecies. species. TheThe Japanese Japanese pine pine bast bast scale, scale,Matsucoccus Matsucoccus matsumurae matsumurae,, was was described described by by Kuwana Kuwana [ 8[8]] as as a a new new speciesspecies on on Japanese Japanese black black pine pine (Pinus (Pinus thunbergii thunbergiiParl.) Parl.) in Tokyo, in Tokyo, Japan, Japan, and was and mainly was mainly found infound China, in Japan,China, and Japan, Korea. and In Korea. China, In more China, than more 70,000 than km 70,0002 of pine km forest2 of pine damage forest by damageM. matsumurae by M. matsumuraehad been reportedhad been each reported year between each year the between 1970s–1980s the 1970s–1980 despite attemptss despite at attempts chemical at control chemical [7,9 ].control [7,9]. InIn Korea, Korea, there there had had been been no no reports reports of of significant significant damage damage by byMatsucoccus Matsucoccus matsumurae matsumuraeafter after the the speciesspecies was was first first found found by by Kanda Kanda [ 10[10],], until until a a heavy heavy infestation infestation was was detected detected on on about about 12,000 12,000 ha ha of of JapaneseJapanese black black pine pine in thein the Southwestern Southwestern coastal coastal area ofarea Korea of Korea [11]. This [11]. damage This damage was found was to found be caused to be bycaused a new by species, a newM. species, thunbergianae M. thunbergianaeMiller & Park Miller [11], & which Park was [11], distinguished which was distinguished based on differences based inon morphologicaldifferences in morphological characteristics andcharacteristics in the number and in of the generations number of from generations the congeners, from theM. congeners, matsumurae M. andmatsumuraeM. resinosae andBean M. resinosae & Godwin. Bean However, & Godwin. several However, studies several implied studies that M. implied matsumurae that M., M. matsumurae resinosae, , andM. resinosae,M. thunbergianae and M. thunbergianaecould be the could same be species. the same For species. example, For theexample, three the species three showed species showed strong cross-attractivenessstrong cross-attractiveness to sex pheromones to sex pheromones [12,13], the[12,13], main the component main component of which of was which identical was identical for the threefor the species three [14 species,15]. Finally, [14,15].M. Finally, thunbergianae M. thunbergianaeand M. resinosae and M.were resinosae synonymized were synonymized with M. matsumurae with M. bymatsumurae Booth and Gullanby Booth [16 ],and mainly Gullan based [16], on theirmainly similarities based on in morphologytheir similarities and molecularin morphology sequences and ofmolecular 18S and 28S sequences rDNA. However,of 18S andM. 28S thunbergianae rDNA. However,is still considered M. thunbergianae a valid speciesis still inconsidered Korea [6, 17a –valid19] despitespecies suggestions in Korea that[6,17–19] the two despite species suggestions are synonymous, that the and two an evaluation species are between synonymous,M. thunbergianae and an collectedevaluation from between Korea andM. thunbergianaeM. matsumurae collectedwas not from possible Korea due and to M. the matsumurae absence of DNAwas not data possible from any due availableto the absence database. of DNA data from any available database. InIn this this study, study, we we collected collected true trueMatsucoccus Matsucoccus matsumurae matsumuraefrom from Fukuoka, Fukuoka, Japan, Japan, and and topotype topotype materialsmaterials of ofM. M. thunbergianae thunbergianaefrom from Goheung, Goheung, Korea, Korea, on on the the Japanese Japanese black black pine pine to to compare compare their their morphologiesmorphologies and and molecular molecular sequences. sequences. To To examine examine the the spread spread of ofM. M. matsumurae matsumurae, regional, regional sampling sampling Forests 2019, 10, 639 3 of 14 Forests 2018, 8, x FOR PEER REVIEW 3 of 15 waswas performed performed inin Korea.Korea. Based Based on thoseon those data, wedata, provide we morphologicalprovide morphological and molecular and characteristics molecular characteristicsof M. matsumurae of M.and matsumurae its current and distribution its current indistribution Korea. in Korea. 2. 2.Materials Materials and and Methods Methods 2.1.2.1. Sample Sample Collection Collection EightEight populations populations of ofMatsucoccusMatsucoccus sp.sp. from from Japan Japan and and Korea Korea were were sampled sampled for for morphological morphological andand molecular molecular analyses analyses (Figure (Figure 2;2; Table Table 11).). ToTo samplesample M. matsumurae,, aa populationpopulation ofofMatsucoccus Matsucoccussp. sp.(assumed (assumed to to be beM. M. matsumurae matsumurae) on) Pinuson Pinus thunbergii thunbergiiwas was collected collected from from Fukuoka Fukuoka in Japan. in Japan. To sample To sampleM. thunbergianae M. thunbergianae, a population, a population of Matsucoccus of Matsucoccussp. (assumed sp. (assumed to be topotype to be materials topotype of materialsM. thunbergianae of M. ) thunbergianaeon P. thunbergii) on wasP. thunbergii collected was from collected Goheung from in Korea. Goheung For in regional Korea. sampling For regional in Korea, sampling six populations in Korea, sixof populationsMatsucoccus ofsp. Matsucoccus