Thrips atactus Bhatti

Masumoto, Masami & Minoura, Kazushige, 2011, Thrips atactus (Thysanoptera, Thripidae): first records of the male and host plant, intercepted in quarantine at Japan, Zootaxa 2920, pp. 65-68 : 65-67

Thrips atactus Bhatti

Thrips atactus Bhatti, 1967: 17 ; 1980: 126; 1990: 259; Palmer, 1992: 25.

Female macroptera. Distended body length 1.3–1.5 mm. Body distinctly bicoloured ( Fig. 1 ), head, pronotum, abdominal segments I and VIII–X yellow, pterothorax dark brown with meso and metasterna yellowish, abdominal segments II–VII dark brown with tergite VII yellowish at both sides and posterior fourth; antennal segments ( Fig. 4 ) largely brown but segment I and basal fourth of III paler; fore wing ( Fig. 6 ) including clavus brown with sub-basal and distal areas pale; all legs yellow; prominent body setae brown.

Head ( Fig. 3 ) rounded at cheeks; ocellar setae I absent, setae III much longer than setae II, and lateral to fore ocellus and just outside of or on anterior margins of ocellar triangle; postocular setae I the longest. Antennae ( Fig. 4 ) 7- segmented, segments III and IV with short apical neck, sensoria on III and IV forked.

Pronotum ( Fig. 3 ) with transverse anastomosing lines of sculpture, with 23–28 discal setae; two pairs of posteroangular setae developed; two or three pairs of posteromarginal setae, setae I the longest. Mesonotum without anteromedian CPS. Metascutum ( Fig. 5 ) with longitudinal anastomosing lines of sculpture except anteromedian area sculptured transversely, lines widely-spaced medially; median pair of setae far from anterior margin; CPS absent. Fore wing first vein with long gap in setal row, seven basal and three distal setae, costal vein with 21–24 setae, second vein with 8–12 setae; clavus with five to six marginal and a discal setae.

Abdominal tergites V to VIII with paired ctenidia, ctenidia posteromesad of each spiracle on VIII; tergites smooth medially ( Figs. 8–9 ); tergite II ( Fig. 7 ) with four lateral marginal setae, third seta often mesad to posteromesad of second seta; tergite VIII ( Fig. 9 ) with complete, fine and long posteromarginal comb; tergite IX with two pairs of CPS; sternites without discal setae; sternite I without anteromedian microsetae; sternites III to VII each with two pairs of posteromarginal setae, but two pairs on II; sternite VII with median pair of setae much in front of the posterior margin; laterotergites without either discal setae or ciliate microtrichia.

Male macroptera. General body colour and structure almost as that of female ( Figs. 1–2 ), but smaller. Fore wing clavus with six marginal and a discal setae. Antennal segments III and IV slightly rounded at each side ( Fig. 10 ), sensoria each 25μm long and 23μm long. Abdominal tergites with small scallops along the posterior margins ( Fig. 11 ); tergite VIII with posteromarginal comb irregular, microtrichia small and irregular-spaced ( Fig. 12 ); tergite IX with S1 setae slightly anterior to level of S2 setae, equidistant from each other and S2 setae and length subequal to S2 setae ( Fig. 13 ); sternites III to VII each with a large transverse pore plate ( Fig. 14 ), 98–120 μm width.

Measeurements in microns. Distended body length 1110. Head length 93, width across cheeks 120; compound eye dorsal length 58, width 38. Pronotal median length 100, width 150; posteroangular setae I (inner pair) length 58–61, setae II (outer pair) length 47–51; posteromarginal setae I length 33–34. Metascutal median length 58; median setae length 33.

Fore wing length 530, width at middle 40. Abdominal tergite IX median length 55; S1 setae length 43–45, S2 setae length 38. Antennal segments I–VII length (width) as follows: 23 (28), 29 (25), 45 (20), 45 (18), 35 (16), 50 (16), 19 (8).

Specimens examined. LAOS, on leaf of Eryngium foetidum : 1 female, 5-ii-2007, H. Naitoh (NR); 1 female, 21-iv- 2008, H. Hattori (NR); 1 female, 1-ii-2010, O. Hirahara (NR); 1 female, 22-xi-2010, T. Hiramoto (NR); 1 female, 6-xii- 2010, S. Sato (NR); 1 female and 1 male, 14-ii-2011, T. Hiramoto. NEPAL, on cut flower of Rosa sp., 1 female, 27-ii- 2009, J. Miyoshi (CB). THAILAND, on leaf of Eryngium foetidum , 1 female, 25-vi-2007, T. Inagaki (NR).

Comments. Deciding the true host plant of Thysanoptera species is difficult, because plants on which adults are found are not always the same as those on which larvae can develop. However, most specimens of T. atactus , both female and male, were intercepted only on leaves of Eryngium foetidum , although many kinds of plants are imported into Japan from Laos and Thailand. Thus, this thrips may be a leaf-feeder rather than flower-living, and this plant is apparently one of the host plants of this thrips .

This species shares the following character states with many species such as T. flavus Schrank , T. formosanus Priesner , T. nigropilosus Uzel , T. palmi Karny , T. tabaci Lindeman , T. sukki Bhatti & Lee and T. urticae Fabricius : metascutum with longitudinal sculpture, at least not reticulated polygonaly, median pair of setae far from anterior margin, fore wing first vein with long gap in the setal row, abdominal tergite VIII with posteromarginal comb complete, sternites and pleurotergites without discal setae, sternite II with two pairs of posteromarginal setae and 7-segmented antenna (often 8-segmented in flavus ). However, these species are either uniformly dark or pale, and although some of the pale species often have dark markings, they are never strongly bicoloured as in T. atactus .

In contrast, many species with discal setae on the sternites (and pleurotergites) are often bicoloured. For example, T. hawaiiensis (Morgan) and T. parvispinus (Karny) are usually yellowish in head to thorax but with a dark brown abdomen. T. darwini Mound & Masumoto has characteristic bicoloured body, mainly yellow but abdominal segments VI to X dark. Thrips atactus is thus apparently unique in this genus in the body colour pattern.

We thank our co-workers in Japan quarantine for supplying the specimens detailed above, and also Laurence Mound of CSIRO, Australia, for editorial advice.

Figures

FIGURES 1 – 2. Thrips atactus, adult. (1) Female; (2) Male.

FIGURES 3 – 9. Thrips atactus, female. (3) Head & pronotum; (4) Antenna, left; (5) Metascutum; (6) Fore wing, left; (7) Abdominal tergite II, right side; (8) Abdominal tergite V; (9) Abdominal tergites VII – X.

FIGURES 10 – 14. Thrips atactus, male. (10) Antenna, left; (11) Abdominal tergites V – VI; (12) Abdominal tergite VIII; (13) Abdominal tergite IX; (14) Abdominal sternites III – V.