Bactrothrips malayanus, Okajima & Masumoto, 2025

Okajima, Shûji & Masumoto, Masami, 2025, Two idolothripine genera, Bactrothrips and Megalothrips (Thysanoptera, Phlaeothripidae), from Asia between India and Taiwan, with descriptions of two new species, Zootaxa 5696 (4), pp. 491-516 : 504-506

Bactrothrips malayanus sp. nov.

( Figs 68–78 )

Female (macroptera). Distended body length 5.4–8.3mm. Body dark brown, abdominal segments without lateral transparently faded windows (see B. honoris ). All femora dark brown; fore and mid tibiae dark brown in basal two-thirds, yellowish in apical one-third (cf. Fig. 72 ); hind tibiae dark brown in basal three-fifths, yellow in apical two-fifths ( Fig. 73 ). Antennal segments I and II dark brown, segments V–VIII brown ( Fig. 71 ), segments IV and V largely pale brown, but more or less yellowish at bases of both club-head and pedicel, segment III largely yellowish brown, but scarcely shaded with brown at apex of club-head and anterior half of pedicels ( Fig. 70 ). Wings scarcely shaded with brown, with a distinct longitudinal brown streak on basal three-fifths. Prominent body setae pale. Head widest across eyes ( Fig. 68 ), more than twice as long as wide, 2.38 times as long as wide in holotype. Postocular setae pair II almost as long as interocellar setae, or longer; postocellar setae and postocular setae pair I much shorter than interocellar setae, but variable in length, usually postocellar setae more or less longer than postocular setae pair I. Eyes 0.28 times as long as head in holotype; posterior ocelli 45µm apart from each other, 95–97µm apart from anterior one in holotype. Antennae about 2.2–2.5 times as long as head, 2.36 times in holotype; segment III 0.56–0.63 (means±SD=0.60±0.02, n=22) times as long as head, 0.59 times in holotype; sense cones on segment III about one-third of the segment length. Pronotum 0.39 times as long as head, about 1.6 times as wide as long in holotype. Prothoracic aa setae usually reduced, much shorter than am, epim and pa subequal in length; epim-a short, usually shorter than one-third of epim. Hind tibiae 1.18 times as long as head in holotype. Fore wings with about 50 duplicated cilia; sub-basal setae S2 usually shorter than S1, S3 much longer than S1. Metanotal median pair of setae about 180µm apart from each other, 65–70µm apart from anterior margin of metanotum. Pelta typical of the genus ( Fig. 74 ). Dorsal length of tube 1.67 times as long as head in holotype. Bournier’s Apparatus well-developed, tufted area triangular ( Fig. 78 ), somewhat similar to that of pictipes (Fig. 8), 100–120µm long.

Measurements ( holotype female in µm). Body length about 7400 (distended). Head length 742, from anterior margin of eyes 650, width across eyes 312, maximum width across cheeks near base 277, minimum width across basal constriction 250; eyes length 210; diameter of posterior ocelli 30–33. Cephalic setae: interocellars about 80, postocellars 45–50, postoculars pair I about 30, postoculars pair II 80–90. Antenna total length 1750, segments III–VIII length (width) as follows: 440 (53), 352 (58), 310 (50), 228 (40), 100 (30), 100 (18). Pronotum length 287, width 460. Setae on prothorax: am less than 30, aa 65–75, ml 80–100, pa 140, epim 135, epim-a 40–50. Fore wing length 2800. Sub-basal wing setae: S1 130, S2 70, S3 215–225. Pelta length 145, width 610. Tergite IX setae: S1 lost, S2 310–320. Tube length 1240, maximum width 169; terminal setae 340.

Male (macroptera). Distended body length 4.6–7.5mm. Color very similar to female; tubercles on tergite VI uniformly dark brown. Antennal segment III 0.52–0.64 (means±SD=0.60±0.03, n=19) times as long as head. A pair of lateral tubercles on tergite VI curved inwards near apex, tubercles on tergite VII well-developed, directed backwards, those on tergite VIII stout and directed diagonally backwards ( Fig. 75 ). Tube 1.5–1.6 times as long as head. Subgenital plate slender and tie-shaped, but rather variable in shape ( Figs 76 & 77 ).

Measurements ( paratype male in µm). Body length about 7000 (distended). Head length 730, from anterior margin of eyes 645, width across eyes 311, maximum width across cheeks near base 260, minimum width across basal constriction 235; eyes length 200; diameter of posterior ocelli 27–32. Cephalic setae: interocellars 70–90, postocellars 25–45, postoculars pair I 25–45, postoculars pair II 50–60. Antenna total length 1725, segments III– VIII length as follows: 435, 340, 302, 237, 98, 90. Pronotum length 300, width 460. Setae on prothorax: am about 20, aa 60–63, ml 75–90, pa 100–120, epim 100–120, epim-a 30–42. Fore wing length 2800. Sub-basal wing setae: S1 120, S2 115, S3 200–220. Pelta length 160, width 600. Tergite IX setae: S1 190–230, S2 110–130. Tube length 1160, maximum width 155; terminal setae about 300.

Type material. Holotype macropterous female: Peninsular Malaysia, about 20km N from Kuala Lumpur, Templer Park , on dead leaves, 12.viii.1990, TN & SO . Paratypes: 21 females and 17 males, collected together with holotype ; 1 male, data very similar to holotype, but 15.viii.1990.

Non-paratypic specimens. Peninsular Malaysia, 1 female and 1 male, Fraser’s Hill, on dead leaves and branches, 13.ix.1990, TN & SO.

Remarks. This species has the male tubercles on abdominal tergite VI curved inwards, the female Bournier’s Apparatus with well-developed tufted area and the male subgenital plate tie-shaped, and is included in the idolomorphus -group. It is very similar to B. brevitubus , B. idolomorphus and B. serraticornis . It can be distinguished from brevitubus by the following features: antennal segment III shorter, about 0.6 times as long as head in both sexes (about 0.65 times in male in brevitubus ); antennal segments III and IV with club head paler, with pedicel shaded ( Fig. 70 ) (club head brown, pedicel usually clear yellow in brevitubus ); antennal segments V and VI largely brown ( Fig. 71 ) (with yellow pedicel in brevitubus ); mid and hind tibiae with extreme bases brown ( Figs 72 & 73 ) (yellow in brevitubus ); female Bournier’s Apparatus finer ( Fig. 78 ). From idolomorphus , it can easily be distinguished by the following features: mid and hind tibiae darker ( Figs 72 & 73 ); postocellar setae shorter than interocellar setae; antennal segment III shorter ( Fig. 70 ), about 0.6 times as long as head in both sexes; female Bournier’s Apparatus with tufted area triangular, not spread laterally ( Fig. 78 ). From B. serraticornis , it can be distinguished by the key above. The female Bournier’s Apparatus is similar to that of serraticornis from Java, but rather weaker. Moreover, the male abdominal tubercles are relatively shorter in malayanus even in the large individuals ( Fig. 75 ). One female and one male listed as non-paratypic specimens may represent this species, but somewhat larger.

Figures

FIGURES 68–78. Bactrothrips malayanus sp. nov.: (68) head, female; (69) head, male; (70) antennal segments III & IV, female; (71) antennal segments V–VIII, female; (72) mid tibia, femle; (73) hind tibia, female; (74) pelta, female; (75) abdominal segments VI–VIII, male; (76 & 77) subgenital plate, male; (78) Bournier’s Apparatus, female (a: tufted area, b: hilt).