Leptandrothrips nigrescens, Okajima & Masumoto, 2025

Leptandrothrips nigrescens sp. nov.

( Figs 10 View FIGURES 6–17 , 41-48 View FIGURES 41–48 )

Female (microptera). Distended body length: about 1.5–1.8mm. Body brown to dark brown ( Fig. 10 View FIGURES 6–17 ). Femora brown to dark brown, with apices yellowish; fore and mid tibiae pale brown, paler than femora, with bases and apices yellowish, often largely yellowish; hind tibiae brownish yellow, often largely yellowish; tarsi yellow to brownish yellow. Antennae dark brown, segments II and III somewhat paler, segment III with extreme base yellowish. Major body setae pale. Head ( Fig. 41 View FIGURES 41–48 ) longer than wide, about 1.2 times as long as wide, 1.22 times in holotype, widest across cheeks at middle; dorsal surface almost smooth, weakly sculptured with transverse reticles at base. Cheeks weakly rounded, weakly serrated. Eyes a little shorter than 0.3 times as long as head, 0.27 times in holotype. Ocelli small; posterior pair 35µm apart from each other in holotype. Postocular almost as long as eyes, expanded; 108µm apart from each other, about 17µm apart from eyes in holotype. Antennae ( Fig. 48 View FIGURES 41–48 ) about 2.0 times as long as head in holotype; segment VIII about 0.6 times as long as VII, 0.63 times in holotype; segments III and IV each with two (1+1) sense cones. Maxillary stylets rather close together, 48µm apart from each other at a level of maxillary bridge; maxillary bridge rather distinct, about one-third as wide as head. Pronotum about 0.7 times as long as head, 0.69 times in holotype, 1.5–1.6 times as wide as long, 1.55 times in holotype; almost smooth; five pairs of prothoracic setae expanded, am well developed, almost as long as aa, epim the longest. Prospinasternum ( Fig. 43 View FIGURES 41–48 ) inverted triangle, about 38µm wide in holotype; mesopresternum transverse, but narrow. Mesonotal lateral setae well developed, expanded, 25µm long. Metanotum almost smooth at middle; median pair of setae pointed, longer than 30µm, widely apart from each other, 46µm apart from each other, about 30µm apart from anterior margin in holotype. Pelta ( Fig. 44 View FIGURES 41–48 ) trapezoid, but with lateral margins rounded, 1.35 times as wide as long in holotype. Abdominal tergites II – VII each with two pairs of minute wing retaining setae. Tergites III – VIII S2 setae: III – VI expanded, VII and VIII pointed. Tergite IX S2 setae much longer than S1; intermediate setae shorter than half of Sl. Tube ( Fig. 47 View FIGURES 41–48 ) about 0.6 times as long as head, 1.7–1.8 times as long as wide; terminal setae about 1.7 times as long as tube .

Measurements (holotype female in µm). Body length 1770 (distended). Head length 163, from anterior margin of eyes 150, width across eyes 124, maximum width across cheeks 134, minimum width across base 120; eyes length 44; diameter of posterior ocelli 8–10; postocular setae 43–48. Maxillary bridge width 46. Antenna total length 332, segments III–VIII length (width) as follows: 40 (25), 41 (27), 45 (23), 42 (21), 40 (21), 25 (17). Pronotum length 112, width 174. Setae on prothorax: am 27–28, aa 30, ml 35–37, pa 38–42, epim 44–48. Fore wing length 87. Sub-basal wing setae: S1 30 –32, S2 31 –32, S3 41 –43. Pelta length 63, width 85. Tergite IX setae: S1 125, S2 170. Tube length 97, maximum width 55; terminal setae 163.

Female (macroptera). Distended body length: 1.65mm. Very similar to micropterous female in color and structure. Fore wing shaded with brown; head ( Fig. 42 View FIGURES 41–48 ) 1.29 as long as wide; eyes 0.28 times as long as head; fore wing with 4–5 duplicated cilia, sub-basal setae S2 shorter than S1, S3 the longest; wing retaining setae normally developed.

Measurements (paratype female in µm). Body length 1640 (distended). Head length 159, from anterior margin of eyes 143, width across eyes 112, maximum width across cheeks 123, minimum width across base 104; eyes length 45; diameter of posterior ocelli 10–12; postocular setae 40–45. Maxillary bridge width 47. Antenna total length 290, segments III–VIII length as follows: 37, 40, 39, 35, 39, 25. Pronotum length 100, width 158. Setae on prothorax: am 24–25, aa 23, ml 30–35, pa 38–40, epim 45. Fore wing length 530. Sub-basal wing setae: S1 38, S2 32 –33, S3 45. Pelta length 55, width 82. Tergite IX setae: S1 110–117, S2 155–158. Tube length 92, maximum width 49; terminal setae?170.

Male (microptera). Distended body length: 1.2–1.4mm. Very similar to micropterous female in color and structure. Tibiae somewhat paler; maxillary bridge somewhat wider, about 0.4 times as wide as head; tergite IX S2 setae comparatively longer, about 1/2 of tube length.

Measurements (paratype male in µm). Body length 1350 (distended). Head length 141, from anterior margin of eyes 130, width across eyes 108, maximum width across cheeks 120, minimum width across base 105; eyes length 40; diameter of posterior ocelli 7–8; postocular setae 38–40. Maxillary bridge width 49. Antenna total length 295, segments III–VIII length as follows: 35, 36, 39, 37, 36, 26. Pronotum length 96, width 154. Setae on prothorax: am 25–28, aa 25, ml 35, pa 33–37, epim 42. Fore wing length 57. Sub-basal wing setae: S1 24, S2 27, S3 28. Pelta length 50, width 75. Tergite IX setae: S1 103–107, S2 35 –40. Tube length 82, maximum width 47; terminal setae 155.

Type material. Holotype: micropterous female, Taiwan, Nantou Hsien, Nanshanchi , on dead branches, 30.iii.1984, SO . Paratypes: Taiwan, 1 male (mic.), collected together with holotype; same locality and habitat as holotype , 1 female (mic.) and 1 male (mic.), 24.iii.1984, 1 male (mic.), 25.iii.1984, 1 female (mic.), 29.iii.1984, SO; 1 female (mic.), Nantou Hsien, foot of Mt. Nankao , nr. Wanta, on dead branches, 1.iv.1984 , SO; 2 males (mic.), Taitung Hsien, Chihpen, on dead wood, 10.ix.1993 , TN & SO; 1 female (mac.) and 2 females (mic.), Taoyuan, on dead wood, 24.viii.1975 , SO.

Non-paratypic specimen. Taiwan, 1 male (mic.), Nantou Hsien, Meifeng , on dead leaves and branches, 1.ix.1994, TN & SO .

Doubtful specimens. Taiwan, 1 female, Nantou Hsien, foot of Mt. Nankao, nr. Wanta , on dead branches, 1.iv.1984, SO ; 1 female (mic.), Taipei Hsien, Mt. Tatung shan, on dead branches, 4.iv.1984, SO .

Comments. This species was collected mainly from dead branches. It is somewhat similar to L. robustus and L. zelkovae from Japan, but can easily be distinguished from robustus by antennal segment III darker, the maxillary stylets wider apart and the mesopresternum not divided. From zelkovae , it can also be distinguished by the compound eyes somewhat larger and the maxillary stylets wider apart. Moreover, although ocelli are present in the microptera of nigrescens , they are absent in robustus and zelkovae . A non-paratypic female listed above may represent this species, but is much larger than the type series (about 1.8mm). Two females listed under the doubtful specimens are very similar to this species, but have some differences in coloration and the length of setae.