Trichromothrips dorsalis Masumoto & Okajima

Masumoto, Masami & Okajima, Shûji, 2011, A new species of the genus Trichromothrips (Thysanoptera, Thripidae) from bamboo in Thailand, Malaysia and Vietnam, Zootaxa 3118, pp. 45-50 : 46-50

Trichromothrips dorsalis Masumoto & Okajima , sp. n.

( Figs 1–8 )

Female macroptera. Body distinctly bicoloured ( Fig. 1 ). Head almost uniformly dark brown, sometime slightly paler at middle along posterior margin of dorsal surface; antennal segments I and II dark brown, III and IV yellowish white with distal fourth and distal third brown, respectively, V yellowish white, VI–VIII brown. Pronotum yellowish white at median large triangular area with lateral dark stripes; pterothorax almost uniformly yellowish white, slightly shaded at lateral part of mesonotum and shaded at tegula; fore wing including clavus uniformly dark brown with a small transparent spot near base; all legs yellowish white. Abdominal segments I–VII yellowish white with tergites III–VII ( Fig. 4 ) each having a transverse diamond-shaped dark area at middle, segments VIII and IX dark brown, segment X shaded.

Head ( Fig. 2 ) slightly produced in front of fore ocellus, almost as long as wide, slightly concave behind compound eyes and slightly rounded at cheeks; dorsal surface sculptured with anastomosing striae at basal third. Compound eyes bulged, without pigmented ommatidia on ventral surfaces. Ocellar setae I absent, setae III situated between hind ocelli and well-developed, more than twice longitudinal diameter of hind ocelli. Mouth-cone rounded at apex with 3-segmented maxillary palpi. Antennae ( Fig. 3 ) 8-segmented, segment I with two dorso-apical median setae, III and IV with forked sensoria and each with apical neck at distal fourth, IV and V slightly pedicelate, III– VI with some microtrichial rows on both dorsal and ventral surfaces. Ratio length/width of antennal segments I– VII as follows: 0.8–1.1, 1.2–1.5, 2.4–3.4, 2.7–3.6, 2.8–4.4, 3.3–4.7, 1.3–2.0, 3.5–5.0.

Pronotum ( Fig. 2 ) 0.6–0.8 times as long as wide, smooth medially, weakly sculptured at lateral dark areas, with 20–23 discal setae, median pair of setae near anterior margin slightly long; two pairs of posteroangular setae developed, setae I (=inner pair) 0.4–0.7 times as long as pronotal median length and longer than setae II (=outer pair); posteromarginal setae two pairs, setae I about twice as long as setae II. Mesonotum ( Fig. 4 ) almost smooth; CPS absent anteromedially; median pair of setae situated in front of submedian pairs. Metascutum ( Fig. 4 ) almost smooth medially, sculptured longitudinally at each side; median pair of setae situated at anterior margin and 0.3– 0.4 times as long as metascutal median length; CPS absent. Metapre-episternum developed and with a seta. Metaepisternum without setae. Metaepimeron with a seta. Prosternal ferna undivided. Mesosternum without sternopleural suture. Spinula present on mesothoracic endofurca only. Fore wing first vein with a median long gap in setal row, usually 7 (rarely 6, 8 or 9) basal setae and two distal setae, costal vein with 20–29 setae on, second vein with 10–14 setae; clavus with usually 4 (rarely 3 or 5) veinal setae and a discal seta; posterior fringe cilia wavy. Tarsi 2-segmented.

Abdominal tergites ( Fig. 5 ) and sternites without posteromarginal fringe; tergites without ctenidia, almost smooth and with only a few short transverse line at each side; tergites II–VII with three setae (S3 to S5 setae) arranged in straight line along lateral margin, S4 setae (middle setae) minute on tergites VI–VIII; tergite IX without campaniform sensilla, with S1 setae, S2 setae, S3 setae and MD setae each 0.7–0.8 times, 1.2–1.4 times, 1.2 times and 0.6 times as long as median length of the tergite; tergite X without median split, with S1 setae and S2 setae each 2.0–2.4 times and 1.9–2.3 times as long as median length of the tergite; sternites without discal setae; sternites II–VII with all three pairs of setae inserted on posterior margin; laterotergites indistinctly divided from tergites and without discal setae. Ovipositor 2.3–2.8 times as long as pronotal median length.

Measurements (holotype female in microns). Distended body length 1500. Head length 115 (length including anterior prolongation 125), width of behind compound eyes 115, width across cheeks 120; compound eye dorsal length 75, width 43; ocellar setae III length 41–44, interval 5. Pronotal median length 108, width, 168, posteroangular setae I length 53–54, setae II length 46–49, posteromarginal setae I length 28–29, setae II length 23; metascutal median length 78, median setae length 28–30; fore wings length 740, width at middle 40. Abdominal tergite IX median length 106, S1 setae length 81–85, S2 setae length 143–149, S3 setae length 125–126, MD setae length 63–68; tergite X median length 47, S1 setae length 114–115, S2 setae length 101–108. Ovipositor length 260. Antennal segments I–VIII length (width) as follows: 30(30), 38(25), 55(18), 58(18), 48(15), 63(15), 13(8), 20(5).

Male macroptera. General structure and colour same with in female, but slightly smaller and paler. Abdominal tergite IX ( Fig. 6 ) with a pair of slender horn-like processes (=drepanae), posterior margin eroded between drepanae; sternites III–VIII ( Fig. 8 ) with numerous scattered glandular areas; phallus ( Figs. 6 & 7 ) with sclerotized spikes.

Measurements (paratype male in microns). Distended body length 1420. Head length 103 (length including anterior prolongation 110), width of behind compound eyes 105, across cheeks 113; compound eye dorsal length 65, width 38; ocellar setae III length 35–38, interval 5. Pronotal median length 105, width 160, posteroangular setae I length 61–64, setae II length 44, posteromarginal setae I length 23–24, setae II length 19–?; metascutal median length 68, median setae length 28; fore wings length 740, width at middle 40. Antennal segments I–VIII length (width) as follows: 28(28), 30(25), 55(15), 53(18), 48(15), 60(15), 15(8), 23(5).

Material studied. Holotype female, Thailand, nr. Chiang Mai, Phrow, on bamboo, 22.viii.1992, T. Nonaka & S. Okajima (T-146).

Paratypes: Thailand: 2 females, collected together with holotype (T-146). nr. Chiang Mai, Doi Inthanon, 11 females, 1 male on bamboo, 29-viii-1992, T. Nonaka & S. Okajima (T-208); nr. Chiang Mai, Doi Pui, Farm of Chiang Mai University, 1 female, 2-ix-1992, P. Jangvitaya (T-166); Doi Suthep, 1 male on bamboo, 1-ix-1991, T. Nonaka & S. Okajima; nr. Chiang Mai, foot of Doi Suthep, 1 female on grass, 24-viii-1992, S. Okajima (T-224); nr. Chiang Mai, Ka Jan, 14 females, 1 male on bamboo, 3-ix-1992, S. Okajima (T-234); Chiang Rai, 1 female on bamboo, 4-ix-1992, S. Okajima (T-232); Chiang Rai, 1 female in leaf-litter, 5-ix-1992, H. Urushihara (T-148); Fang, 1 female on bamboo, 23-viii-1992, S. Okajima (T-158); Phuket Is., 4 females on bamboo, 24-viii-1991, T. Nonaka. The types are deposited in Laboratory of Insect Resources, Faculty of Agriculture, Tokyo University of Agriculture, Atsugi, Kanagawa Pref., Japan.

Non-paratypic specimens. South Vietnam, Lam Dong Province, Bao Loc, Dam Bri, 2 females on bamboo, 26- xii-2001, S. Okajima (V-55). West Malaysia, Tapah, 1 female on bamboo, 17-ix-1990, T. Nonaka & S. Okajima (M-72). These are deposited together with type series.

Etymology. In reference to the abdominal tergites with dark areas.

Comments. Using the key in Bhatti (2000), this species runs to T. alis Bhatti from India, but it can be distinguished easily from that species by lacking a corn-shaped pale area on the dorsal surface of the head, and having a dark median area on each of abdominal tergites III–VII. According to Bhatti (2000), this species appears to be included in bellus section, which is one of his 10 subdivision within this genus, together with T. alis , T. arorai Bhatti , T. bellus Priesner by having the following features: body strongly bicoloured and abdominal segments VIII–IX dark brown, ocellar setae III situated between hind ocelli, pronotum with lateral dark stripes, mesonotum with median setae in front of submedian setae, metascutum without sculpture and campaniform sensilla, fore wings uniformly dark brown, abdominal sternite II with three pairs of posteromarginal setae, abdominal sternites with numerous scattered glandular areas and phallus with a pair of spikes in male.

Moreover, this section was also characterized by lacking seta on metaepimeron, all setae situated far from posterior margin of abdominal sternite VII and lacking drepanae on abdominal tergite IX of male. However, this species has a seta on each metaepimeron, abdominal sternite VII with three pairs of setae inserted at posterior margin and has abdominal tergite IX with slender drepanae in male.

Figures

FIGURE 1. Trichromothrips dorsalis sp. n., holotype female.

FIGURES 2 – 4. Trichromothrips dorsalis sp. n. (2) Head & pronotum; (3) Antenna, right; (4) Mesonotum & metascutum.

FIGURES 5 – 8. Trichromothrips dorsalis sp. n., 5. Female. 6 – 8. Male. (5) Abdominal tergites VI – VII; (6) Abdominal tergites IX – X with phallic spike of genitalia; (7) Phallic spike of genitalia; (8) Abdominal sternite VIII.