Mesandrothrips eximius, Okajima & Masumoto, 2025

Mesandrothrips eximius sp. nov.

( Figs 59 View FIGURES 57–69 , 78–85 View FIGURES 78–85 )

Female (macroptera). Distended body length: 2.2mm. Body dark brown ( Fig. 59 View FIGURES 57–69 ). Femora dark brown, fore femora with apices yellowish; fore tibiae yellow, mid tibiae brown, with apical one-third yellowish, hind tibiae dark brown, with apical one-fifth yellowish; tarsi yellow. Antennal segments I and II brown, segment II scarcely paler antero-externally; segments III – VIII yellow, but segments VII and VIII very weakly shaded. Fore wings almost transparent, but brownish at base. Major body setae pale. Head ( Fig. 78 View FIGURES 78–85 ) longer than wide, 1.28 times as long as wide; dorsal surface weakly sculptured with transverse striae at posterior half, almost smooth between eyes. Cheeks weakly rounded, weakly rounded, gradually narrowed to base, gradually narrowed to base, weakly serrated. Eyes well developed, 0.42 times as long as head. Ocelli well developed; posterior pair in contact with eyes, 32µm apart from each other. Postocular setae shorter than eyes, weakly expanded; 156µm apart from each other, 16–17µm apart from eyes. Antennae ( Fig. 85 View FIGURES 78–85 ) about 1.8 times as long as head; segment VIII slender, very weakly constricted at base, narrowly joined to segment VII, 0.84 times as long as VII; segments III almost as long as segment IV, much longer than VII; segments III and IV with three (1+2) and four (2+2 +1) sense cones respectively, these sense cones shorter than the width of the segments (shorter than those of inquilinus ). Maxillary stylets probably retracted to postocular setae (the stylets are bringing out in holotype), wider apart; maxillary bridge distinct, 0.45 times as wide as head. Pronotum ( Fig. 78 View FIGURES 78–85 ) about 0.7 times as long as head, about 1.4 times as wide as long; almost smooth; four pairs of prothoracic setae well developed, expanded; aa and ml subequal in length, pa a little longer than aa, epim much longer than postocular setae. Basantra ( Fig. 80 View FIGURES 78–85 ) largely developed. Prospinasternum relatively small, about 30µm wide; mesopresternum reduced medially, separated into two triangle plates. Mesonotal lateral setae developed, expanded, 25µm long. Metanotum distinctly sculptured with reticulation; median pair of setae pointed, about 20µm, distance between them much narrower than distance between these setae and anterior margin of metanotum, 45µm apart from each other, 67–68µm apart from anterior margin. Fore tarsus ( Fig. 82 View FIGURES 78–85 ) with a well-developed apical tooth. Fore wing with 7 duplicated cilia; three sub-basal setae expanded, S1 the shortest, S3 the longest. Pelta ( Fig. 81 View FIGURES 78–85 ) trapezoid, 1.36 times as wide as long, sculptured distinctly. Tergites III – VIII S2 setae bluntly pointed. Tergite IX S1 setae probably longer than tube (tips of these setae are missing in holotype), S2 much longer than tube; intermediate setae shorter than half of Sl. Tube ( Fig. 84 View FIGURES 78–85 ) 0.59 times as long as head, about 2.0 times as long as wide; terminal setae about 1.4 times as long as tube .

Measurements (holotype female in µm). Body length about 2200 (distended). Head length 220, from anterior margin of eyes 203, width across eyes 170, maximum width across cheeks 172, minimum width across base 140; eyes length 92; diameter of posterior ocelli 18–20; postocular setae 50–56. Maxillary bridge width 77. Antenna total length about 400, segments III–VIII length (width) as follows: 56 (32), 56 (33), 50 (28), 50 (25), 43 (21), 36 (12). Pronotum length 153, width 214. Setae on prothorax: aa about 40, ml about 40, pa 45, epim 80. Fore wing length 850. Sub-basal wing setae: S1 47 –48, S2 60 –63, S3 80. Pelta length 83, width 113. Tergite IX setae: S1 128–132 (tips missing), S2 165. Tube length 129, maximum width 65; terminal setae about 180.

Male (macroptera). Distended body length: 1.70–1.85mm. Very similar to macropterous female in color and structure. Antennal segments VII and VIII pale brown, somewhat darker than those of female; fore tibia largely yellow or largely brown with apical half yellowish; head 1.36 times as long as wide; maxillary stylets retracted to eyes; maxillary bridge about half of head width; fore wing with 5–8 duplicated cilia; fore tarsal apical tooth ( Fig. 83 View FIGURES 78–85 ) well developed, similar to those of Karnyothrips species; tergite IX S1 setae almost as long as tube or a little longer.

Measurements (paratype male in µm). Body length 1840 (distended). Head length 206, from anterior margin of eyes 190, width across eyes 151, maximum width across cheeks 151, minimum width across base 126; eyes length 87; diameter of posterior ocelli 16–18; postocular setae 45–50. Maxillary bridge width 75. Antenna total length 380, segments III–VIII length as follows: 52, 55, 49, 49, 42, 35. Pronotum length 142, width 193. Setae on prothorax: aa about 40, ml about 40, pa 48–50, epim 55. Fore wing length 750. Sub-basal wing setae: S1 40, S2 50 –55, S3 60 –64. Pelta length 70, width 101. Tergite IX setae: S1 125–133, S2 37 –38. Tube length 125, maximum width 58; terminal setae 172.

Type material. Holotype: macropterous female, Vietnam, Lam Dong Province, Finom Ward, Don Duong, on leaves of Quercus sp. ( Fagaceae ), 25.xii.2001, SO. Paratypes: Vietnam, 2 males, collected together with holotype.

Doubtful specimen. Thailand, 1 female, Chiang Mai, Farm of Chiang Mai University , 26.viii.1992, TN .

Comments. This species was collected from Quercus sp. leaves together with undetermined Liothrips species. It is closely related to M. inquilinus , but can be distinguished by the following features: intermediate antennal segments clear yellow; sense cones on the antennal segments III and IV much shorter than width of segment; prosternal basantra larger; fore tarsal apical tooth larger; tergite IX S1 setae longer, almost as long as tube or longer; tube about 0.6 times as long as tube. It is also very similar to a synonymous species, Xylaplothrips longus Ananthakrishnan & Jagadish which was synonymized with X. inquilinus (= M. inquilinus ) by Pitkin (1976), in having the intermediate antennal segments entirely yellow. However, there is a possibility that longus is a distinct species (see M. inquilinus ). According to the original descriptions ( Ananthakrishnan & Jagadish 1967), eximius can be distinguished from longus by the antennal segments III and IV broader, the prothoracic major setae shorter, and the major body setae pale. A female collected from Thailand listed under the doubtful specimen is very similar to eximius , but the head is somewhat broader and the mid and hind tibiae largely yellow.