Scirtothrips albidus, Masumoto, Masami & Okajima, Shûji, 2007

Masumoto, Masami & Okajima, Shûji, 2007, The genus Scirtothrips Shull (Insecta, Thysanoptera, Thripidae) and three related genera in Japan, Zootaxa 1552, pp. 1-33 : 19-22

Scirtothrips albidus n. sp.

( Figs. 9 A, 11B, 12D, 13C–D, 15A & 17A)

Female. Distended body length 1.0– 1.2 mm. Body uniformly yellowish white; antennal segment I to II pale, III pale with apex shaded, IV pale with distal third pale brown, V pale brown with extreme base pale, VI to VIII pale brown; fore wings uniformly pale; all legs yellowish white; prominent body setae pale.

Head 1.6–2.2 times as wide as long. Ocellar setae III situated near or anterior to tangent of anterior margin of hind ocelli ( Fig. 9 A). Two pairs of postocular setae mesad of compound eyes slightly longer than ocellar setae III, minute setae usually present between two long setae. Compound eyes without pigmented ommatidia. Antennae 8-segmented, segment III with a mid-dorsal seta below CPS, III the longest, barely widest near apex and nearly straight at each side ( Fig. 11 B). Antennal segments I to VIII length/width ratio as follows: 0.9–1.0, 1.3–1.5, 2.6–3.5, 2.4–2.8, 2.1–2.3, 2.5–3.2, 0.9–1.3, 2.0–2.5.

Pronotum 1.6–1.8 times as wide as long, space between lines of sculpture as wide as diameter of socket of discal setae, with 12–22 discal setae (including anteromarginals and lateralmarginals) (17 in the holotype); posteromarginal setae four pairs, B2 setae 0.6 times as long as pronotal median length and 2.9–4.0 times as long as B1 setae ( Fig. 9 A). Mesonotum without CPS anteromedially ( Fig. 12 D). Metascutum sculptured with transverse reticulations anteriorly and longitudinal oblong reticulations medially, smooth within reticulations; median pair of setae situated behind anterior margin ( Fig. 12 D). Fore wings with 22–25 setae on costal vein (25 on left, 24 on right, in the holotype), with five to six basal and three to four distal setae on first vein (six and four on left, five and three on right, in the holotype), with two or three setae on second vein (two on left, three on right, in the holotype); clavus with four veinal and one discal setae; posteromarginal fringe hair slightly wavy, not straight.

Abdominal terga with B1 setae much wide apart each other than their length and much smaller than B2 setae on terga II to VI ( Figs. 13 C–D, 15A); lateral microtrichial fields each with three discal setae ( Figs. 13 C– D); terga II to VI with posteromarginal microtrichia at out side of B2 setae ( Fig. 13 C); tergum VII often with posteromarginal microtrichia throughout, at least out side of B1 setae, or small posteromarginal microtrichia between B1 setae ( Fig. 13 D); terga VIII without microtrichia anteromedially ( Fig. 15 A); tergum IX without microtrichia ( Fig. 15 A), B1 setae, B2 setae and B3 setae each 0.7–0.9, 0.9–1.0 and 0.7–0.9 times as long as median length of the tergum; tergum X without microtrichia ( Fig. 15 A), B1 setae and B2 setae each 1.2–1.5 and 1.1–1.4 times as long as median length of the tergum; sterna with discal microtrichial rows at out side of B1 setae; sternum VII with B1 setae in front of posterior margin ( Fig. 17 A). Ovipositor 2.0–2.4 times as long as pronotal median length.

Measurements of holotype female in microns. Distended body length 1160. Head length 71, width across cheeks 129; compound dorsal length 53, width 38. Pronotal median length 93, width 153; posteromarginal setae I length 18–20, setae II length 58–60. Metascutal median length 68, median setae length 19–25. Fore wings length 670, width at middle 40. Abdominal tergum IX median length 75; B1 setae length 60, B2 setae length 70–?, B3 setae length 63–66, mid-dorsal setae length 43–45; tergum X median length 48, B1 setae length 63, B2 setae length 59–60. Ovipositor length 210. Antennal segments I to VIII length (width) as follows: 23 (25), 35 (25), 50 (18), 43 (18), 38 (16), 45 (16), 8 (8), 10 (5).

Male. Unknown.

Type series. Holotype female: Japan, Honshu, Kanagawa Pref., Yokosuka City, Kannonzaki, on leaves of Neolitsea serica [ Fagaceae ], 28-v-2005, M. Masumoto. Paratypes: 11 females collected together with the holotype. 9 females, same locality and date as the holotype, on leaves of Machilus thunbergii [ Lauraceae ], M. Masumoto. 1 female, same locality as the holotype, on leaves of Castanopsis sieboldii [ Fagaceae ], 5-v-2005, M. Masumoto. 1 female, same locality as the holotype, on leaves of Machilus thunbergii , 5-vi-2005, M. Masumoto. 2 females, same locality as the holotype, on leaves of Castanopsis sieboldii , 14-v-2006, M. Masumoto. 6 females, Kanagawa Pref., Hayama-cho, Mt. Futago-yama, on leaves of Castanopsis sieboldii , 15-v- 2005, M. Masumoto.

The holotype and most paratypes are deposited in Laboratory of Entomology, TUA, Atsugi, Japan. Etymology. In reference to the body colour of the species.

Comments. This species is somewhat common on young leaves of the plants listed above, but it is difficult to collect because of the pale body colour and activity. Moreover, the specimens are often very difficult to prepare onto slides because of their fragile bodies.

Figures

FIGURE 9. Scirtothrips species, head & pronotum (female). (A) S. albidus n. sp.; (B) S. dorsalis.

FIGURE 11. Scirtothrips species (female). (A) S. machili n. sp., Head & pronotum; B – C, Antenna: (B) S. albidus n. sp.; (C) S. dorsalis.

FIGURE 12. Scirtothrips species (female). A – C, Antenna: (A) S. flavus n. sp.; (B) S. katsura n. sp.; (C) S. machili n. sp., (D) S. albidus n. sp., mesonotum & metascutum. E – F, Metascutum: (E) S. dorsalis; (F) S. flavus n. sp.

FIGURE 13. Scirtothrips species (female). A – B, Metascutum: (A) S. katsura n. sp.; (B) S. machili n. sp. C – E, Abdominal terga: (C) S. albidus n. sp., tergum VI (microtrichial row omitted on left side); (D) S. albidus n. sp., tergum VII (microtrichial row omitted on left side); (E) S. dorsalis, left side of tergum VI (microtrichial row omitted.).

FIGURE 15. Scirtothrips species, terminal abdominal terga (female). (A) S. albidus n. sp., terga VIII – X (microtrichial row omitted on left side of tergum VIII); (B) S. flavus n. sp., terga VIII – XI (microtrichial row omitted on left side of tergum VIII).

FIGURE 17. Scirtothrips species, abdominal sternum (female). (A) S. albidus n. sp., sternum VII; (B) S. dorsalis, sternum VI (microtrichial row omitted on left side.); (C) S. flavus n. sp., right side of sternum VI; (D) S. katsura n. sp., sternum VI (microtrichial row omitted on left side.); (E) S. machili n. sp. sternum V (microtrichial row omitted on left side.).