TOMOHIDE YASUNAGA Okayama University, Japan A REVIEW OF JAPANESE SPECIES OF THE PLANT BUG GENUS PLESIODEMA REUTER (HETEROPTERA: MIRIDAE: PHYLINAE) Yasunaga, T., 2003. A review of Japanese species of the genus Plesiodema Reuter (Heteroptera: Miridae: Phylinae). Tijdschrift voor Entomologie 146: 371-375, figs. 1-12. [ISSN 0040-7496]. Published 1 December 2003. The new species, Plesiodema gotohi, associated with Pinus densiflora, is described from southwestern Honshu and Shikoku, Japan. The genus is diagnosed, and biological notes are given for the genus and the known Japanese species, Plesiodema stlaniki Kerzhner. Tomohide Yasunaga, Zoological Laboratory, Department of Science, Faculty of Education, Okayama University, Okayama, 700-8530 Japan. E-mail: yasunaga@cc.okayama-u.ac.jp Key words. Heteroptera; Miridae; Phylinae; Plesiodema; new species; Japan; Pinus. Plesiodema Reuter, 1875 is a small phyline plant bug genus, previously only by two Palearctic and one Nearctic species (Kerzhner & Josifov 1999, Schuh 1995). In Japan, only a single species, P. stlaniki Kerzhner, 1979, a Japanese stone pine inhabitant, was reported from alpine belts of Hokkaido and central Honshu (Yasunaga et al. 1999, Yasunaga 2001). During recent investigations in the warm temperate zone of southwestern Japan, a unique phyline species was collected by sweeping male inflorescence and branches of Pinus densiflora. Subsequent examination of the male genitalic structures indicated that this mirid obviously represented an undescribed species, related to the alpine Plesiodema stlaniki. This species is here described as new. Brief comments on diagnostic characters and biology are also provided for the genus and P. stlaniki. All measurements are given in millimeters. In the synonymic lists, only selected references are cited for every taxon, as comprehensive catalogs are available (Kerzhner & Josifov 1999, Schuh 1995). The specimens examined for this study are deposited in the collections of National Institute of Agro-Environmental Sciences, Tsukuba, Japan (NIAS); Zoological Institute, Russian Academy of Sciences, St. Petersburg (ZMAS); and Zoological Laboratory, Faculty of Education, Okayama University, Japan (ZEOU). TAXONOMY Plesiodema Reuter Plesiodema Reuter 1875: 171 (n. gen.), type species by monotypy: Phytocoris pinetella Zetterstedt 1828 (NORWAY); Schuh 1995: 393; Kerzhner & Josifov 1999: 395 (cat.); Yasunaga 2001: 171 (note). This small phyline plant bug genus is currently composed of three Palearctic members and one Nearctic, and is characterized by the sexually dimorphic body shape (elongate oval in male; ovoid in female), somber color, shiny dorsum furnished with simple vestiture, narrow, apically pointed head, sharply pointed apex of the phallotheca (fig. 7), and broad, simply C-shaped vesica (figs. 5-6). Additional diagnostic characters were provided by Reuter (1875), Wagner (1952, 1973) and Wagner & Weber (1964). Of the four congeners, all the Palearctic species are restricted to pines, Pinus spp. of the Pinaceae, whereas the Nearctic P. sericea (Heidemann, 1892) is associated with the inflorescence of deciduous lindens, Tilia spp. of the Tiliaceae (Wheeler 2001). Judging from the different host association, the placement of sericea in Plesiodema seems suspicious, but a definitive treatment is beyond a scope of this study. 371
TIJDSCHRIFT VOOR ENTOMOLOGIE, VOLUME 146, 2003 2 1 3 RP 7 VS 4 5 6 Figs. 1-7. Dorsal habitus (1-3), male genital segment (4), vesica (5 & 6) and phallotheca (7) of Plesiodema gotohi sp. n. (1, 4, 6 & 7) and P. stlaniki (2, 3 & 5). 1 & 3, Female; 2, male. Abbreviations: RP, right paramere; VS: vesica. Plesiodema gotohi sp. n. (figs. 1, 4, 6-10, 12) Type material. Holotype, JAPAN: Shimonokae, Tosashimizu City, Kochi Pref., Shikoku, Japan, 28. iv.2002, M. Takai (ZEOU, type no. MR-111). Paratypes: JAPAN: Honshu: 2, Hyoze, Nakahechi T., Wakayama Pref., 1.vi.1997, T. Yasunaga (ZEOU); 1, Mt. Handayama, Okayama City, Okayama Pref., 14.v.2002, T. Yasunaga (ZEOU); 15 2, Kamiyubune, Kawakami Vil., Okayama Pref., 1. vi. 2003, T. Yasunaga (ZEOU). Shikoku: 5 9, same data as for holotype; 1, Tengu-ike, Higashitsuno Vil., Kochi Pref., 21.vii.2000, M. Takai (ZEOU); 10 5, Kinbuchi Park, Takamatsu City, 5.v.2003, S. Akagi (ZEOU); 17 10, same data except for collector, E. Doi (ZEOU). All specimens were collected from Pinus densiflora Sieb. et Zucc. Diagnosis Recognized by the generally fuscous, small body, short antennal segment II that is shorter than basal width of the pronotum, antennal segment III that is shorter than width of the head, and hooked and tapered apical processes (fig. 10) of the small vesica (fig. 6), which distinguishes this species from its assumed 372
YASUNAGA: Japanese Plesiodema 8 9 10 11 Figs. 8-11. Male genitalia of Plesiodema gotohi (8-10) and P. stlaniki (11). 8, Left paramere; 9, right paramere; 10, vesica; 11, the same, apex. Scale bars: 0.1 mm. sister species, P. stlaniki Kerzhner. Significant color variation is not exhibited in the present species. Description Body generally smoky dark brown, elongate oval (male), ovoid (female); dorsal surface shining, with brown or dark brown, simple setae. Head fuscous, somewhat pointed in front, with brown, suberect setae; vertex and frons more or less shagreened. Antenna somber yellowish brown; segment II somewhat thickened in male, shorter than basal width of pronotum; segments III and IV filiform; lengths of segments I-IV (male/ female): 0.21-0.23/ 0.18-0.22, 0.87-0.94/ 0.73-0.75, 0.50-0.57/ 0.46-0.47, 0.31-0.35/ 0.30-0.33. Rostrum shiny dark brown, long, slightly exceeding apex of metacoxa (male), reaching abdominal sternum VI (female). Pronotum with uniformly distributed, dark, suberect setae; scutellum rather flat, with dark, suberect setae; pleura somber brown or dark brown. Hemelytra unicolorously smoky dark brown, with uniformly distributed, dark, reclining setae; membrane pale grayish brown. Coxa and femur somber yellowish brown; tibia somber brown, with dark spines; metatibia and all tarsi dark brown; lengths of metafemur, tibia and tarsus (male/ female): 1.00-1.13/ 0.97-1.00, 1.45-1.63/ 1.25-1.38, 0.42-0.47/ 0.40-0.44. Abdomen entirely fuscous. Male genitalia as in figs. 6-10; vesica bifurcate apically, with hooked and tapered processes. Dimensions. Male/ female: Body length 3.0-3.4/ 2.7-2.9; head width including eyes 0.70-0.72/ 0.68-0.70; vertex width 0.28-0.30/ 0.33-0.35; rostral length 1.37-1.50/ 1.42-1.50; basal pronotal width 1.03-1.09/ 1.02-1.07; width across hemelytra 1.31-1.38/ 1.36-1.49. Etymology Dedicated to Mr. Shin Gotoh (Tanabe City), who was an enthusiastic heteropterist and helped with the discovery of this species at Hyoze, Nakahechi but regrettably passed away on January 27, 2003; a noun in the genitive case. Distribution Japan (SW. Honshu and Shikoku). Occurrence of this species appears to be restricted to the warm temperate zone. Biology This species is associated with Pinus densiflora Sieb. et Zucc. The adults are found from late April to mid July. It seems to have a univoltine life cycle, and, presumably, the eggs hibernate. Plesiodema stlaniki Kerzhner (figs. 2, 3, 5, 11, 12) Plesiodema stlaniki Kerzhner 1979: 43 (n. sp.); Schuh 1995: 394 (cat.); Kerzhner & Josifov 1999: 396 (cat.); Yasunaga et al. 1999: 3 (list); Yasunaga 2001: 171 (desc., biol.). Holotype, S. KURIL ISLANDS: Golovnina Volcano, 13. vi. 1973, I. M. Kerzhner (ZMAS) [examined]. Diagnosis Recognized by having the largest size among its congeners, variable general coloration from somber olive green to fuscous, long antennal segment II that is as long as basal width of the pronotum, antennal segment III that is subequal in length to width of the head, and unique apical shape (fig. 11) of the long vesica (fig. 5). A detailed description was provided by Kerzhner (1979), and color habitus photographs of 373
TIJDSCHRIFT VOOR ENTOMOLOGIE, VOLUME 146, 2003 Fig. 12. Distribution of two Plesiodema species in Japan. both adult and a final- instar nymph were also given by Yasunaga (2001). Dimensions. male/ female: Body length 4.0/ 3.5; head width including eyes 0.78/ 0.76; vertex width 0.38/ 0.39; rostral length 1.78/ 1.83; basal pronotal width 1.23/ 1.16; width across hemelytra 1.56/ 1.69. Distribution Japan (alpine belts of Hokkaido and Honshu where Pinus pumila grows), Kuril Islands (Kunashiri Is.), Russia (Far East, including E. Siberia and Sakhalin). The present record from Mt. Oblachnaja of the Sikhotealin mountains represents the southernmost distribution in continental Eurasia (see below material examined). Biology This boreal mirid is known to inhabit Japanese stone pine, Pinus pumila Regel, growing only at alpine elevations in temperate and cold temperate zones of the eastern Asia, including Japan and the southern Primorskij Territory of Russia. One generation per year is assumed for P. stlaniki. The eggs appear to hibernate, and the nymphs are found from June to July. Material examined. 80 specimens (NIAS, ZEOU, ZMAS) collected between Jun. 11 and Aug. 10 from the following localities: JAPAN: Hokkaido: Kamikawa, Daisetsu Mts., Mt. Tokachidake (1,400-1,500 m alt.), Tokachidake hot spa; Daisetsu Mts., Mt. Midori (1,500-1,700 m alt.); Sorachi, Mt. Yubari. Honshu: Nagano Pref., Japan Alps, Mt. Kiso-Ontake. KURIL ISLANDS: Kunashiri Is., Golovnina Volcano (type series, ZMAS). RUSSIA: S. Primorskij Kraj, Chugevskij District, Sikhotealin Mts., Mt. Oblachnaja (1,700 m alt.). ACKNOWLEDGMENTS Special thanks are due to Dr. S. Miyamoto (Fukuoka City) for continuous advice and encouragement. I also thank Dr. I. M. Kerzhner (ZMAS) and Mr. M. D. Webb (the Natural History Museum, London) for kind permission to examine invaluable material. I am indebted to the following individuals for offering material and/or for kind assistance in the field research: the late Mr. S. Gotoh (Tanabe City, Wakayama); Mr. M. Takai (Kochi Agricultural Experimental Station, Nankoku); Mr. M. Wataji (Takuhoku High School, Sapporo); Drs. A. S. Lelej, Y. Tsuistjakov, E. Kanyukova and V. Makarkin (Institutes of Biology and Pedology, Russian Academy of Sciences, Vladivostok); my students, S. Akagi and E. Doi (ZEOU); and my wife Miho-Arare. Thanks are extended to reviewers of the 374
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