Thrips griseus Bagnall

Masumoto, Masami & Okajima, Shûji, 2013, Review of the genus <i> Thrips </ i> and related genera (Thysanoptera, Thripidae) from Japan, Zootaxa 3678 (1), pp. 1-65 : 34-35

Thrips griseus Bagnall

( Figs. 123–129 )

Female macroptera. Distended body length 1.4–1.6 mm. Body uniformly dark brown; antennal segments I to II dark brown, but paler than head, III to V brownish yellow with distal third to half pale brown, VI pale brown with basal third yellowish, VII pale brown; fore wings uniformly brown, clavus brown; all femora dark brown, fore tibiae and gradually yellowish forward to apex,, mid and hind tibia dark brown, all tarsi brownish yellow; prominent body setae dark. Head ( Fig. 123 ) 0.7–0.8 times as long as wide, convex just behind compound eyes and narrowed forward to base; cheeks nearly straight. Compound eyes large, dorsal length more than twice as long as distance between their posterior margin and posterior margin of head, dorsal width as wide as distance between both compound eyes. Ocellar setae III at outside of ocellar triangle and just anterior to hind ocelli. Postocular setae short and subequal in length to or slightly shorter than longitudinal diameter of hind ocelli, setae II and III minute. Antennae ( Fig. 124 ) 7-segmented, II with microtrichial rows very weak on dorsal surface, III to IV gently rounded at each side, IV to V pedicelate, VI nearly parallel at each side of basal two-thirds and tapering to apex, with 11 setae. Antennal segments I to VII length/wide ratio as follows: 0.9–1.0, 1.1–1.4, 2.0–2.5, 1.8–2.3, 1.3–1.7, 1.9–2.4, 1.8–2.4. Pronotum ( Fig. 123 ) 0.6–0.8 times as long as wide, sculptured with transverse striae, with 23–30 discal setae; posteroangular setae 2 pairs, setae I 0.4–0.5 times as long as pronotal median length and longer than setae II; posteromarginal setae 3 pairs, all setae small and almost same size. Mesonotum sculptured with transverse anastomosing striae; CPS present anteromedially. Metascutum ( Fig. 125 ) sculptured with longitudinal anastomosing striae; median pair of setae far from anterior margin, 05–0.7 times as long as metascutal median length; CPS absent. Fore wing costal vein with 20–25 setae, first vein with long gap in setal row, seven or eight basal and three distal setae (four distal setae on left of lectotype), second vein with 10–15 setae. Abdominal tergites III to VII with no lines of sculpture reaching at median CPS; tergite II with 3 lateral marginal setae, a small seta at pleurotergite II near tergite; tergite VIII ( Fig. 126 ) with posteromarginal comb complete, but irregular spaced; tergite IX with 2 pairs of CPS; sternite I with three microsetae; sternites III to VII ( Fig. 127 ) with 5–11 discal setae arranged in irregular line; sternite VII with S1 setae far from posterior margin; pleurotergites III to VII without discal setae, often with small dentate microtrichia along lines sculpture. Ovipositor 1.0–1.5 times as long as pronotal median length .

Measurements of female (lectotype in parenthesis). Distended body length 1350–1630 (1450). Head length 108–128 (128) (length including anterior prolongation 113–130 (–)), width across cheeks 138–173 (173); compound eye dorsal length 75–88 (88), width 45–58 (53). Pronotal median length 118–150 (138), width 158–223 (213); posteroangular setae I length 45–65 (63), setae II length 38–60 (53), posteromarginal setae I length 18–22 (–). Metascutal median length 63–85 (85), median setae length 38–50 (50). Fore wing length 610–820 (820), width at middle 50–70 (70). Abdominal tergite IX median length 58–68 (68); S1 setae length70–115 (113), S2 setae length 94–133 (120), S3 setae length 93–133 (133), MD setae length 28–40 (38); tergite X length 48–68 (63), S1 setae length 106–125 (125), S2 setae length 96–125 (125). Ovipositor length 150–200 (200). Antennal segments I to VII length/width as follows: 252–30 (28)/25–30 (30), 30–38 (35)/25–29 (28), 43–50 (48)/20–24 (23), 38–45(45)/20–23 (21), 25–33 (33)/18–20 (19), 38–48 (48)/19–20 (20), 14–18 (15)/6–9 (6).

Male macroptera. Distended body length 1.0– 1.1 mm. Body colour almost uniformly yellow with ocellar triangle shaded, fore wings uniformly pale, antennal segments I to II yellow. Abdominal tergite VIII without posteromarginal comb; tergite IX ( Fig. 128 ) with S1 setae at level of S2 setae and subequal in length to S2 setae, their bases equidistant; sternites III to VII ( Fig. 129 ) each with a transverse or oblong pore plate, pore plates gradually smaller toward posterior sternites, 8–45 microns wide.

Measurements of male. Distended body length 1090. Head length 90, width across cheeks 135; compound eye dorsal length 63, width 45. Pronotal median length 110, width 153; posteroangular setae I length 35–41, setae II length 28–41, posteromarginal setae I length 15. Metascutal median length 58, median setae length 28–30. Fore wing length 540, width at middle 45. Antennal segments I to VII length (width) as follows: 20 (25), 33 (24), 43 (19), 35 (19), 23 (19), 38 (19), 15 (9).

Specimens examined. Lectotype female & paralectotype female, JAPAN, Honshu , Kobe, vi-1915, J. E. A. Lewis ( NHM). JAPAN, Honshu: 106 females, 25 males ( TUA).

Distribution. Japan (Honshu).

Biology. This species is associated with Cirsium flowers.

Comments. This species almost has not been studied by any authors since the original description and was reported as Thrips sp. 3 ( Tsutsumi, 1995) and Thrips sp. 1 ( Okajima, 2000) . It is closely related to the European species, T. physapus Linnaeus and T. trehernei (= T.hukkineni Priesner ). These European species cannot be distinguished from each other satisfactorily as females. Pitkin (1971) indicated the difference between females of physapus and hukkineni by using a principal component analysis ( Ward, 1968) as follows: X 1 +2X 2 +X 3 (X 1 =pronotal posteroangular seta I length, X 2 =S3 seta length on ninth tergite, X 3 =tenth tergite length) less than 430 in physapus , more than 450 in trehernei . Moreover, in female physapus abdominal tergite X is usually shorter than 80 microns with the median split almost complete, but in trehernei tergite X is usually longer than 80 microns with the median split ending far from the anterior margin (zur Strassen, 2003). In contrast, their males are distinct in body colour, physapus is uniformly pale but trehernei is dark. Thrips griseus and T. physapus are probably same species because in griseus X 1 +2X 2 +X 3 is much smaller than 430 (286–358, mean=328±23, n=34) and median split of abdominal tergite X is almost complete, and the male is uniformly pale.

Figures

FIGURES 116–129. Thrips species. T. fuscicornis, holotype male 116–122: (116) Head & pronotum; (117) Antennal segments III–VII, right; (118) Metascutum; (119) Tergite II, left side, sculpture omitted; (120) Tergites VIII–IX, sculpture omitted; (121) Sternite VI, sculpture omitted. (122) Pleurotergite V, right, sculpture omitted. T. griseus, female. 123–127: (123) Head & pronotum; (124) Antenna, right; (125) Metascutum; (126) Tergites VIII–X; (127) Sternite VII. T. griseus, male 128– 129: (128) Tergite IX; (129) Sternites VI–VII, sculpture omitted.