Mesandrothrips ichikaianus, Okajima & Masumoto, 2025

Mesandrothrips ichikaianus sp. nov.

( Figs 60 View FIGURES 57–69 , 86–93 View FIGURES 86–93 )

Female (macroptera). Distended body length: about 2.2mm. Body dark brown ( Fig. 60 View FIGURES 57–69 ). Femora brown, fore femora with distal half yellowish, mid and hind femora with apical one-third yellowish; fore tibiae yellowish, tinged with pale brown, mid and hind tibiae brown, with extreme bases and apices yellowish; tarsi yellow. Antennal segments I– II and VII – VIII brown, somewhat paler than head, segment II yellowish antero-externally; segment III yellowish, segments IV – VI yellowish at basal half, weakly shaded with brown at apical half, segment VI scarcely darker than segment V. Fore wings very weakly shaded with brown at basal half. Major body setae pale. Head ( Fig. 86 View FIGURES 86–93 ) longer than wide, about 1.2 times as long as wide, 1.23 times in holotype; dorsal surface weakly sculptured with transverse striae at posterior half, almost smooth between eyes. Cheeks very weakly rounded, weakly constricted at base, weakly serrated. Eyes well developed, about 0.4 times as long as head, 0.39 times in holotype. Ocelli developed; posterior pair 25µm apart from each other in holotype. Postocular setae shorter than eyes, expanded; 131µm apart from each other, about 18–22µm apart from eyes in holotype. Antennae ( Fig. 93 View FIGURES 86–93 ) 1.8–1.9 times as long as head, 1.86 times in holotype (the right antennae aberrantly 7-segmented in holotype); segment VIII relatively slender, very weakly constricted at base, about 0.8 times as long as segment VII; segments III and IV subequal in length, much longer than VII; segments III and IV with three (1+2) and four (2+2 +1) sense cones respectively. Maxillary stylets reaching postocular setae, rather wider apart; maxillary bridge distinct, narrower than 1/2 of head width, 0.44 times as wide as head in holotype. Pronotum ( Fig. 86 View FIGURES 86–93 ) about 0.7 times as long as head, 1.6–1.7 times as wide as long, 1.66 times in holotype; almost smooth; four pairs of prothoracic setae expanded; am setae reduced to discal setae, ml and pa subequal in length, epim much longer than pa. Basantra ( Fig. 87 View FIGURES 86–93 ) relatively small; prospinasternum relatively small, 28µm wide in holotype; mesopresternum reduced medially, very narrowly boat-shaped. Mesonotal lateral setae developed, weakly expanded, 35µm long in holotype. Metanotum ( Fig. 88 View FIGURES 86–93 ) weakly sculptured with reticulation; median pair of setae blunt or bluntly pointed, 18–20µm long, distance between both median setae narrower than distance between each seta and anterior margin of metanotum, 55µm apart from each other,72–80µm apart from anterior margin in holotype. Fore femora ( Fig. 90 View FIGURES 86–93 ) somewhat enlarged; fore tarsus with a well-developed apical tooth. Fore wing with 7–9 duplicated cilia; three sub-basal setae well developed, expanded, S1 and S2 weakly expanded, S3 blunt or very weakly expanded, the longest. Pelta ( Fig. 89 View FIGURES 86–93 ) trapezoid, distinctly sculptured, 1.44 times as wide as long in holotype. Tergites III – VIII S2 setae: III very weakly expanded, IV and V blunt, VI – VIII pointed or bluntly pointed. Tergite IX S1 and S2 setae pointed, S1 shorter than tube, S2 almost as long as tube; intermediate setae much shorter than half of Sl. Tube ( Fig. 92 View FIGURES 86–93 ) longer than 0.6 times as long as head, 0.64 times in holotype, about 2.1 times as long as wide; terminal setae almost as long as tube .

Measurements (holotype female in µm). Body length 2230 (distended). Head length 218, from anterior margin of eyes 203, width across eyes 174, maximum width across cheeks 177, minimum width across base 151; eyes length 85; diameter of posterior ocelli 18–20; postocular setae 53–54. Maxillary bridge width 78. Antenna total length 405, segments III–VIII length (width) as follows: 65 (30), 65 (32), 55 (29), 50 (26), 43 (22), 35 (12). Pronotum length 153, width 254. Setae on prothorax: aa 35, ml 47, pa 52, epim 75–90. Fore wing length 900. Sub-basal wing setae: S1 57, S2 70–72, S3 105. Pelta length 95, width 137. Tergite IX setae: S1 130–132, S2 140–142. Tube length 140, maximum width 66; terminal setae 140.

Male (macroptera). Distended body length: about 1.9mm. Very similar to macropterous female in color and structure. Head 1.24 times as long as wide; maxillary bridge 0.47 times as wide as head; pronotum 0.72 times as long as head, about 1.6 times as wide as long; fore wing with 7 duplicated cilia; tube 0.67 times as long as head.

Measurements (paratype male in µm). Body length about 1900 (distended). Head length 197, from anterior margin of eyes 180, width across eyes 158, maximum width across cheeks 159, minimum width across base 132; eyes length 82; diameter of posterior ocelli 16–18; postocular setae 50–54. Maxillary bridge width 75. Antenna total length 380, segments III–VIII length as follows: 58, 58, 49, 45, 40, 32. Pronotum length 142, width 225. Setae on prothorax: aa?35, ml?35, pa about 50, epim 60–65. Fore wing length 790. Sub-basal wing setae: S1 44 –46, S2 53 –55, S3 82–85. Pelta length 79, width 125. Tergite IX setae: S1 120–130, S2 40. Tube length 132, maximum width 64; terminal setae 115.

Type material. Holotype: macropterous female, Japan (Honshu), Tochigi-ken, Ichikai-machi, on Phyllostachys heterocycle ( Poaceae ), 17.v.2023, SO. Paratypes: Japan (Honshu), 2 females and 1 male, collected together with holotype.

Comments. This species is somewhat similar to M. inquilinus from Java, Indonesia in color and structure. However, it can be distinguished by the following features (in parentheses are the features of inquilinus ): head about 1.2 times as long as wide (about 1.4 times); maxillary bridge narrower than half of head with (a little wider than half of head width); prosternal basantra small, inner margin bluntly pointed (normally developed, inner margin broadly rounded); fore femora somewhat enlarged (not enlarged); fore tarsus with a well-developed apical tooth (with a minute apical tooth); tube longer than 0.6 times as long as head (a little shorter than half of head length). This species was taken from a common bamboo species in Japan, Phyllostachys heterocycle , together with Xylaplothrips togashii . The feeding behavior is uncertain, but the species is possibly predaceous.