Oxythrips japonicus, Masumoto, Masami & Okajima, Shûji, 2017

Masumoto, Masami & Okajima, Shûji, 2017, Anaphothrips genus-group: key to world genera, with two new species and three new records from Japan (Thysanoptera, Thripidae), Zootaxa 4272 (2), pp. 201-220 : 212-216

Oxythrips japonicus sp. n.

( Figs 3–4 , 17–38 )

Oxythrips sp.; Okajima, 2000: 102.

Female macroptera ( Fig. 3 ). Distended body length 1.2–1.8 mm. Body uniformly yellowish brown or pale brown; antennal segment I yellow, II–III yellowish brown, IV–VIII brown; all femora yellowish brown with outer margin shaded, all tibiae yellowish with middle of outer margin slightly shaded, all tarsi yellow; fore wings including clavus uniformly weakly shaded with two longitudinal veins often slightly darker; prominent body setae pale or slightly shaded. Head 0.7–0.9 times as long as wide, sculptured with transverse anastomosing striae behind the compound eyes on dorsal surface, smooth within ocellar triangle, slightly rounded at cheeks. Ocellar setae pair III anterior to inner angles of posterior ocelli ( Fig. 17 ). Mouth-cone rounded at apex. Antennae 8-segmented ( Fig. 18 ), an often vestigial oblique suture present on distal fourth to fifth of segment VI ventrally ( Fig. 19 ), segment II without microtrichia, III nearly straight at each side and narrowed at apex, IV rounded on each side, IV–V weakly pedicelate, VI longest, gently rounded on each side of basal half and tapering at distal half. Antennal segments I– VIII length/width ratio as follows: 0.7–1.0, 1.2–1.5, 1.8–2.5, 1.8–2.3, 1.5–2.0, 2.1–2.6, 1.0–1.8, 2.0–3.7. Pronotum 0.6–0.8 as long as wide, sculptured with transverse anastomosing striae, with 18–34 discal setae (25±5, n=21); posteroangular setae, 0.3–0.4 times as long as pronotal median length; posteromarginal setae 3 pairs or 5 setae, setae I longest. Metascutum ( Fig. 20 ) with median pair of setae 0.3–0.5 times as long as metascutal median length. Fore wing costal vein with 25–34 setae, first vein with 6–8 basal and usually 3 setae at distal half, second vein with 6–12 setae. Fore tibiae ( Fig. 22 ) without inner apical tubercle and stout setae, fore tarsi without inner apical claw. Abdominal tergites sculptured with transverse anastomosing striae throughout ( Fig. 24 ); tergite II with 3 lateral marginal setae, but anterior seta (S5) displaced to pleurotergite, median lateral marginal seta (S4) closed to S5 seta ( Fig. 23 ); tergites V–VIII with S4 setae minute; tergite VIII without posteromarginal comb; tergite IX with both anterior and posterior pairs of CPS; tergite X subequal length to tergite IX; sternite III ( Fig. 26 ) usually with 1 or 2 small pore plates, IV also rarely with small one; sternites II (rarely III) to VI with 1–6 discal setae arranged in irregular row at middle ( Fig. 25 ). Ovipositor 2.0–2.3 times as long as pronotal median length.

Measurements (holotype female in microns) Distended body length 1640; head length 118, width across cheeks 138, compound eye dorsal length 65, width 38; ocellar setae III length 26, interval 19. Pronotal median length 108, width 163; posteroangular setae length 37–41. Metascutal median length 73, median pair of setae length 15–18. Fore wing length 800, width at middle 55. Abdominal tergite IX median length 65; tergite X length 65. Ovipositor length 250. Antennal segments I to VIII length (width) as follows: 28 (28), 38 (28), 48 (21), 43 (21), 35 (20), 49 (21), 10 (8), 15 (6).

Male macroptera ( Fig. 4 ). Distended body length 1.0– 1.1 mm. Body colour similar to female. Abdominal tergite IX ( Fig. 27 ) usually with some small tubercles between posterior stout setae; sternites without discal setae, pore plates circular, 25–45 µm wide ( Fig. 28 ).

Measurements (paratype males in microns). Distended body length 980–1110; head length 78–93, width across cheeks 113–120, compound eye dorsal length 48–53, width 43–45; ocellar setae III length 26, interval 19. Pronotal median length 78–90, width 135–150; posteroangular setae length 37–41. Metascutal median length 73, median pair of setae length 15–18. Fore wing length 570–660, width at middle 40–45. Antennal segments I to VIII length (width) as follows: 20–23 (24–25), 33–38 (23–24), 38–45 (19–20), 33–38 (19), 30–33 (18–19), 45–50 (18– 19), 9–10 (6–8), 13–15 (5).

Second instar larva ( Fig. 29 ). Distended body length about 1.3 mm. Body generally white with pink hypodermal pigment; compound eyes with red hypodermal pigment. Head with D1–D4 setae between compound eyes short and acute at apices, almost same in length ( Fig. 30 ). Antennae 7-segmented ( Fig. 31 ); segment III with annulations but no microtrichia; IV without microtrichia, with a long inner sensorium reaching to middle of VI, also a small outer sensorium; V and VI with long outer sensorium. All body setae acute at apex. Pronotum with all seven pairs of setae subequal in length to setae on head, apices acute, D6 setae longest, with transverse lines of granules except medially. Mesonotum with 7 pairs of setae subequal in length to pronotal setae, spiracle with about 25 facets having no internal pore ( Figs 32, 33 ); mesonotum to anterior half of abdominal tergite IX covered with transverse lines of plaques without microtrichia ( Figs 32, 34–36 ). Abdominal tergites II–IX with 3 pairs of setae acute at apices except D1 setae on IX, longer on posterior segments, D2 and D3 setae distinctly longer than D1 setae on V–VIII; tergite II with spiracles having 9–13 facets, no internal pore ( Fig. 34 ); tergite VIII with a pair of CPS medially, with spiracles having about 16 facets, no internal pore; tergite IX with a few weak transverse rows of plaques, D1 setae short and stout, D2 setae much longer than D3 setae, distance of median CPS subequal to interval of D1 setae, no teeth along posterior margin; tergite X almost smooth with a pair of strongly spine-like stout dark setae directed dorsally and slightly curved at apex ( Figs 36–37 ); sternites III–VIII with 3 pairs of setae acute at apices and longer than tergal setae, transverse rows of plaques, plaques apparently with very weak microtrichia at posterior margin ( Fig. 38 ).

Type series. Holotype female, Japan. Honshu, Tokyo, The Imperial Palace Grounds , Fukiage-nishi-dori, on flowers of Pinus thunbergii [ Pinaceae ], 22.iv.1998, S. Okajima.

Paratypes: Japan: Honshu, 56 females, same data as the holotype. Tokyo, The Imperial Palace, Fukiagegyoen : 1 female, host unknown, 15.v.1996; 1 female, host unknown, 16.iv.1997.

Kanagawa Pref., Kawasaki City, Tama-ku, Ikuta-ryokuchi : 10 females on pine flowers, 4.v.1993 ; 68 females & 1 male on flowers of Pinus thunbergii , 4.v.1993. Kanagawa Pref., Yokohama City, all from male cones of Pinus thunbergii : Kanazawa-ku, Namiki , 21 females & 2 males, 17.iv.2004 ; 19 females, 18.iv.2004; 8 females, 24.iv.2004; 11 females, 16.iv.2005; 7 females & 1 male, 23.iv.2006; 12 females, 7.iv.2007; 28 females & 1 male, 14.iv.2007; Kanazawa-ku, Uminokouen Park , 39 females & 18 males, 17.iv.2005 ; 19 females & 2 males, 14.iv.2007; Naka-ku, Honmoku-shiminkouen Park : 69 females & 8 males, 24.iv.2005 ; Kanazawa-shizenkouen Park : 3 females, 1.v.2005. The holotype and most paratypes are deposited in TUA.

Non-paratypic specimens. Japan: Honshu, Chiba Pref., Narita City , Kitasuga , nr. Inba-numa 3 females on flowers of Pinus densiflora , 27.iv.2008 . Kanagawa Pref., Yokohama City, Kanazawa-ku, Namiki : 23 second instar larvae on male cones of Pinus thunbergii , 24.iv.2004 . Shizuoka Pref., Ogasa-gun, Ogasa-cho, Tanno-ike : 2 females and 2 second instar larvae on flowers of Pinus thunbergii , 16.v.1993 . Ryukyus, Okinawa-hontou Is.: Kunigamison, Mt. Yonaha-dake , 1 female on dead leaves and branches, 3.iii.1990 ; Motobu-cho , 1 male on Poaceae , 11.ii.2004 . Amami-ohshima Is., Mt. Yuwan-dake , 5 females and 6 second instar larvae on Pinus flower, 24.iii.1990 .

Comments. Based on information in Mound et al. (1976) and zur Strassen (2003), females of this new species are similar to the European species, O. bicolor by having abdominal sternites with discal setae, small pore plates on sternite III and unarmed tibiae and tarsi. However, O. bicolor has sternite VII with discal setae, sternites III–VI with pore plates and tergite X twice as long as tergite IX, whereas this new species has sternite VII without discal setae, sternite IV usually without pore plate and tergite X subequal in length to tergite IX. Moreover, as a result of comparison of this new species with one female of O. bicolor , S4 seta on abdominal tergite II is situated at middle between S3 and S5 setae in O. bicolor but is close to S5 setae in this new species. Many adults and larvae of this new species emerged during a limited short period in spring when Pinus male-cones flower in Honshu. However, a few adults are often collected from leaves other than Pinaceae , although larvae are found only on the male-cones, after the end of adult-emergence. In early spring before flowering of pine, adults of this new species are often found on young leaves of plants other than pine, such as Magnolia and Salix . It possibly overwinters as an adult or pupa.

According to Stannard (1973), Oxythrips second instar larvae have abdominal tergites with ‘raised pustules’ arranged in transverse rows, and terminal setae less thickened. In contrast, Chilothrips larvae have ‘wavy, thickened, transverse striae’ on the tergites and exceptionally stout terminal setae. However, both Japanese species of Oxythrips and Chilothrips have ‘raised pustules’ arranged in transverse rows on the tergites. Moreover, the median pair of spine-like setae on abdominal tergites IX and X of the Japanese Oxythrips are very similar to those of Chilothrips pini in the United States, but the latter species has abdominal tergal sculpture with ‘wavy, thickened, transverse ridges’ (see Stannard 1973: 113, fig. 10). Second instar larvae of Chilothrips yamatensis emerge in same season as O. japonicus although they do not appear at the same place. Chilothrips yamatensis can be distinguished from O. japonicus by having abdominal tergite IX with a median pair of spine-like setae large and acute at apex and pronotal setae much longer than the latter species.

Etymology. In reference to the locality of this species.

Figures

FIGURES 1 – 5. Adult. (1) Anaphothrips swezeyi, female. (2) Caprithrips melanophthalmus, female. Oxythrips japonicus sp. n., 3 – 4: (3) Female; (4) Male. (5) Rubiothrips galii sp. n., female.

FIGURES 17 – 28. Oxythrips japonicus sp. n. Female 17 – 26. (17) Head & pronotum; (18) Antenna; (19) Antennal segments VI – VIII, ventral aspect, setae and sxulpture omitted; (20) Mesonotum & metascutum; (21) Metapre-episternum, left; (22) Fore tarsus to distal part of tibia, right; (23) Tergite II; (24) Tergites VII-X; (25) Sternites II – IV, sculpture omitted; (26) Middle of sternite III. Male 27 – 28. (27) Tergite IX; (28) Sternite VI, sculpture omitted.

FIGURES 29 – 38. Oxythrips japonicus sp. n., second instar larva. (29) Dorsal aspect; (30) Head & pronotum; (31) Antenna; (32) Mesonotum; (33) Mesothoracic spiracle, lateral aspect, left; (34) Tergite II; (35) Tergite V. Tergites VIII – X 36 – 37: (36) Dorsal aspect; (37) Lateral aspect, left. (38) Middle of sternite V.