Mesandrothrips brevisetis, Okajima & Masumoto, 2025

Mesandrothrips brevisetis sp. nov.

( Figs 57, 62–69 View FIGURES 57–69 )

Female (macroptera). Distended body length: 1.80–2.14mm. Body dark brown ( Fig. 57 View FIGURES 57–69 ). Femora dark brown, fore femora with apices slightly paler; fore tibiae yellowish, shaded with brown, mid and hind tibiae dark brown, with apices slightly paler; tarsi yellow. Antennal segments I– II and VII – VIII brown, a little paler than head; segment III largely yellow, scarcely shaded with brown anteriorly, segments IV – VI yellow at basal half, shaded with brown at anterior half. Fore wings very weakly shaded with brown. Major body setae pale. Head ( Fig. 62 View FIGURES 57–69 ) longer than wide, a little shorter than 1.2 times as long as wide; dorsal surface very weakly sculptured with transverse striae at posterior half, sculpture somewhat distinct near base, almost smooth between eyes. Cheeks weakly rounded, gradually narrowed to base, finely serrated. Eyes a little longer than one-third of head length. Ocelli well developed; posterior pair in contact with eyes, about 30µm apart from each other in holotype. Postocular setae much shorter than eyes, weakly expanded; 127µm apart from each other, about 15µm apart from eyes in holotype. Antennae ( Fig. 69 View FIGURES 57–69 ) about 2.0 times as long as head, 1.97 times in holotype; segment VIII very weakly constricted at base, 0.78 times as long as segment VII; segments III almost symmetrical, a little shorter than IV, much longer than VII; segments III and IV with three (1+2) and four (2+2 +1) sense cones respectively. Maxillary stylets retracted to postocular setae, sub-parallel at middle; maxillary bridge distinct, narrower than 1/2 of head width, 0.42 times as wide as head in holotype. Pronotum ( Fig. 62 View FIGURES 57–69 ) more than 0.6 times as long as head, 0.66 times in holotype, about 1.7 times as wide as long; almost smooth, median apodeme very weak; four pairs of prothoracic setae expanded, but relatively short; am reduced to discal setae, pa much shorter than postocular setae, epim almost as long as eyes. Prospinasternum ( Fig. 63 View FIGURES 57–69 ) comparatively small, narrowly fan-shaped, about 25µm wide in holotype; mesopresternum reduced medially, separated into lateral triangle plates. Mesonotal lateral setae developed, weakly expanded, about 25µm long. Metanotum ( Fig. 64 View FIGURES 57–69 ) sculptured with reticulation; median pair of setae pointed, shorter than 20µm, 56µm apart from each other, 54–60µm apart from anterior margin in holotype. Fore tarsus ( Fig. 66 View FIGURES 57–69 ) with a small apical tooth. Fore wing with 8–9 duplicated cilia; three sub-basal setae weakly expanded, S3 about 1.7 times as long as S2. Pelta ( Fig. 65 View FIGURES 57–69 ) trapezoid or triangle, with irregular lateral margins, sculpture weak at middle, 1.43 times as wide as long in holotype. Tergites III – VIII S2 setae relatively short, bluntly pointed. Tergite IX S1 and S2 setae pointed, a little shorter than tube, S2 a little longer than S1; intermediate setae shorter than half of Sl. Tube ( Fig. 68 View FIGURES 57–69 ) longer than 0.5 times as long as head, 0.55 times in holotype, 1.75 times as long as wide; terminal setae about 1.1 times as long as tube .

Measurements (holotype female in µm). Body length 2140 (distended). Head length 206, from anterior margin of eyes 187, width across eyes 175, maximum width across cheeks 177, minimum width across base 147; eyes length 73; diameter of posterior ocelli 18–20; postocular setae 45. Maxillary bridge width 75. Antenna total length 405, segments III–VIII length (width) as follows: 62 (33), 65 (35), 51 (30), 46 (28), 40 (19), 31 (13). Pronotum length 135, width 230. Setae on prothorax: aa?20, ml?25, pa?35, epim 70–73. Fore wing length 860. Sub-basal wing setae: S1 37 –38, S2 43 –45, S3 75. Pelta length 89, width 127. Tergite IX setae: S1 98–100, S2 105. Tube length 114, maximum width 65; terminal setae 123.

Male (macroptera). Distended body length: about 1.5mm. Very similar to macropterous female in color and structure. Head 1.13 times as long as wide; maxillary bridge 0.40–0.49 times as wide as head; fore wing with 6–7 duplicated cilia; tube 0.61 times as long as head; terminal setae almost as long as tube.

Measurements (paratype male in µm). Body length 1470 (distended). Head length 160, from anterior margin of eyes 147, width across eyes 137, maximum width across cheeks 141, minimum width across base 119; eyes length 60; diameter of posterior ocelli 13–15; postocular setae 38–39. Maxillary bridge width 56. Antenna total length 320, segments III–VIII length as follows: 45, 46, 41, 38, 33, 28. Pronotum length 97, width 184. Setae on prothorax: aa?20, ml 25, pa 28, epim 48. Fore wing length 600. Sub-basal wing setae: S1 32 –33, S2 32 –38, S3 48 –52. Pelta length 64, width 90. Tergite IX setae: S1 82–88, S 2 28. Tube length 97, maximum width 53; terminal setae 97.

Type material. Holotype: macropterous female, Japan, Ryukyus, Amami Is., Uken-son, Fureainomori, on Elaeocarpus sylvestris leaves, 23.iii.1990, SO. Paratypes: Japan, Ryukyus, 1 female, Okinawa-hontou Is., Nahashi, Sueyoshi, Sueyoshi Park, on leaf of Piper kadzura ( Piperaceae ), 7.ix.2003, K. Minoura; 1 male, Okinawa-hontou Is., Uruma-shi, Katsuren-haebaru, on Poaceae , 21.i.2002, T. Tasuoka; 1 female and 1 male, Miyako-jima Is., Gusukube, on dead leaves and branches, 8.iii.1990, TN.

Doubtful specimens. Japan, Ryukyus, Iriomote-jima Is., Nakamagawa-rindou, on Ilex integra (Aquiforiaceae), 12.iii.1990, TN . Taiwan, 1 male, Nantou Hsien, Nanshanchi, on dead leaves, 31.vii.1986, SO; 1 female, same locality as above, on grass, 3.iv.1993, TN & SO; Nantou Hsien, Meifeng , about 2000m alt., 1 male, habitat uncertain, 2.ix.1993, 1 male, on dead leaves and branches, 1.ix.1994, TN & SO .

Comments. This species was collected together with Liothrips horutonoki from the leaves of Elaeocarpus sylvestris ( Elaeocarpaceae ), and seems to be a predator. It is somewhat similar to M. inquilinus , but it can be distinguished by the following features (in parentheses are the features of inquilinus ): head somewhat broader, about 1.2 times as long as wide (about 1.4 times); maxillary bridge much narrower than half of head width in female, 0.40–0.49 times as wide as head in male (wider than half of head width); four pairs of prothoracic setae relatively short (well developed); tergite IX S2 setae shorter than tube (a little longer than tube); tube 0.55 times as long as head (a little shorter than half of head width). One male from Iriomote Is. listed above under the doubtful specimen is very similar to this species, but has antennal segment III weakly swollen sub-basally. One female and three males collected from Taiwan have the antennal segments and fore tibiae somewhat darker and the ocelli somewhat smaller.