Mesandrothrips crassicornis, Okajima & Masumoto, 2025

Mesandrothrips crassicornis sp. nov.

( Figs 58 View FIGURES 57–69 , 70–77 View FIGURES 70–77 )

Female (macroptera). Distended body length: about 1.6mm. Body bicolored yellow and brown ( Fig. 58 View FIGURES 57–69 ). Head, prothorax, mesothorax and tube brown; metathorax yellow, abdomen largely yellow, segments III–VII each with a median brown marking, segments VIII and IX pale brown, but yellowish anteriorly. Legs yellow, except for brown fore coxae. Antenna pale brown to brown, segments I–II and VI–VIII brown, segment III pale brown, with basal one-third yellowish. Fore wing scarcely shaded with brown. Major body setae pale. Head ( Fig. 70 View FIGURES 70–77 ) longer than wide, 1.38 times as long as wide; dorsal surface smooth. Cheeks almost straight, sub-parallel, weakly serrated. Eyes well-developed, a little longer than one-third of head length, 0.37 times as long as head. Ocelli well developed; posterior pair in contact with eyes, about 20µm apart from each other. Postocular setae much shorter than eyes, expanded; about 100µm apart from each other, about 10µm apart from eyes. Antennae ( Fig. 77 View FIGURES 70–77 ) 1.79 times as long as head; segment VIII slender, weakly constricted at base, narrowly joined to segment VII, about 0.9 times as long as VII; segments III and IV subequal in length, thick, much longer than VII; segments III and IV with three (1+2) and four (2+2 +1) stout sense cones respectively. Maxillary stylets not reaching postocular setae, wider apart, V-shaped; maxillary bridge weak, wide and slender, wider than half of head width. Pronotum ( Fig. 70 View FIGURES 70–77 ) 0.65 times as long as head, about 1.45 times as wide as long; almost smooth, median apodeme weak; four pairs of prothoracic setae expanded, am setae reduced; aa almost as long as postocular setae, pa much longer than aa, epim the longest. Prospinasternum ( Fig. 71 View FIGURES 70–77 ) relatively wide, 60µm wide; mesopresternum reduced medially. Mesonotal lateral setae developed, expanded. Metanotum ( Fig. 72 View FIGURES 70–77 ) weakly sculptured with reticulation; median pair of setae minute and relatively far apart from anterior margin of metanotum, 42µm apart from each other, 45–46µm apart from anterior margin. Fore tarsus ( Fig. 74 View FIGURES 70–77 ) with a well-developed apical tooth, similar to that of Karnyothrips species. Fore wing with 4 duplicated cilia; three sub-basal setae expanded, S1 the longest. Pelta ( Fig. 73 View FIGURES 70–77 ) trapezoid, with indistinct lateral wings, weakly reticulate, 1.42 times as wide as long. Tergites III–VIII S2 setae: III–VI and VIII expanded, VII finely pointed. Tergite IX S1 setae expanded, shorter than tube, 0.76–0.80 times as long as tube, S2 sharply pointed, a little longer than tube; intermediate setae almost half of Sl. Tube ( Fig. 76 View FIGURES 70–77 ) about 0.5 times as long as head, 1.88 times as long as wide; terminal setae 1.4–1.5 times as long as tube.

Measurements (holotype female in µm). Body length 1630 (distended). Head length 183, from anterior margin of eyes 166, width across eyes 132, maximum width across cheeks 133, minimum width across base 117; eyes length 67; diameter of posterior ocelli 15–17; postocular setae 25–30. Maxillary bridge width 80. Antenna total length 327, segments III–VIII length (width) as follows: 47 (32), 45 (32), 41 (25), 40 (22), 38 (20), 34 (12). Pronotum length 119, width 172. Setae on prothorax: aa 26–28, ml 30–32, pa 37–38, epim 47–48. Fore wing length?. Sub-basal wing setae: S1 30 –31, S2 25 –28, S3 27 –28. Pelta length 65, width 92. Tergite IX setae: S1 68–72, S2 95–98. Tube length 90, maximum width 48; terminal setae 130–136.

Male (macroptera). Distended body length: about 1.6mm. Very similar to macropterous female. Antennal segment VIII almost as long as segment VII; pronotum about 0.8 times as long as head; fore leg ( Fig. 75 View FIGURES 70–77 ) relatively enlarged, fore tarsal hamus stout; fore wing with 5 duplicated cilia; sub-basal wing setae S1 and S2 subequal in length, S3 the longest; tergite IX S1 setae weakly expanded.

Measurements (paratype male in µm). Body length 1580 (distended). Head length 171, from anterior margin of eyes 156, width across eyes 124, maximum width across cheeks 126, minimum width across base 113; eyes length 62; diameter of posterior ocelli 13–15; postocular setae?27. Maxillary bridge width 68. Antenna total length about 320, segments III–VIII length as follows: 46, 42, 37, 35, 35, 35. Pronotum length 135, width 177. Setae on prothorax: aa about 30, ml 35, pa 38, epim 48. Fore wing length 640. Sub-basal wing setae: S1 30, S2 30 –31, S3 38 –39. Pelta length 60, width 87. Tergite IX setae: S1 63–83, S2 30 –32. Tube length 87, maximum width 50; terminal setae 130.

Type material. Holotype: macropterous female, Peninsular Malaysia, about 20km N from Kuala Lumpur, on dead branches, 11.viii.1990, TN & SO . Paratype: Peninsular Malaysia, 1 male, collected together with holotype .

Comments. This species is easily discriminated from congeners by a combination of the following features: body bicolored; intermediate antennal segment relatively thick; antennal segment VIII slender, about 0.9 times as long as segment VII in female, almost as long as VII in male; antennal segments III and IV with three (1+2) and four (2+2 +1) thick sense cones respectively; maxillary bridge wide, more than half of head width; S2 setae on tergite VIII and S1 on tergite IX expanded. Moreover, the fore tarsus has a well-developed apical tooth like that of Karnyothrips species. Unfortunately, the feeding habit of this species is uncertain.