Podothrips bicolor Seshadri & Ananthakrishnan, 2025

Okajima, Shûji & Masumoto, Masami, 2025, Some Poaceae-inhabiting Phlaeothripinae (Thysanoptera, Phlaeothripidae) in East Asia, with descriptions of six new genera and 18 new species, Zootaxa 5726 (1), pp. 1-68 : 37-39

Podothrips bicolor Seshadri & Ananthakrishnan , stat. rev.

( Figs 136–137 )

Podothrips bicolor Seshadri & Ananthakrishnan, 1954: 221 .

This species was described from Madras, India, and recorded subsequently from Singapore ( Ritchie 1974). In this study, it is recorded from Peninsular Malaysia, Thailand and Minamidaitô Is., the Daitô group of Islands, Japan, for the first time. Minamidaitô Is. is a small oceanic island located about 340km east of Okinawa Is. The population of this island is somewhat isolated, and there is a possibility that it has invaded recently from elsewhere. P. bicolor is very similar to P. sasacola from Japan, and Ritchie distinguished it from sasacola by the following features: antennal segment IV with (1+1 +1) sense cones (with (1+1) in sasacola ); sub-basal wing setae S1 and S2 expanded, S3 pointed (all sub-basal wing setae pointed in sasacola ); fore wing with a median brown shading (generally scarcely shaded with brown in sasacola ); prothoracic midlateral setae short and pointed (usually short and pointed, rarely weakly expanded in sasacola ). Recently, however, Tyagi et al. (2020) synonymized P. bicolor with P. sasacola , because when they examined 50 bicolor specimens from India, 10 specimens had (1+1 +1) sense cones but the remaining specimens had (1+1) on the antennal segment IV. They may have considered bicolor and sasacola to be the intraspecific variation in same species, but they did not seem to compare them with sasacola from Japan, according to the specimens described in the text. Furthermore, they did not mention the other morphological differences that Ritchie had indicated at all. In our careful observations, bicolor can be distinguished from sasacola by the following character states: antennal segments I and II brown, almost concolorous with head ( Fig. 137 ) (yellow, distinctly paler than head in sasacola ( Fig. 143 )); head a little broader, distinctly narrowed towards base ( Fig. 137 ) (a little narrower, weakly narrowed towards base in sasacola ( Fig. 143 )); prothoracic major setae except for posteroangulars expanded (prothoracic major setae except for epimerals pointed or very weakly expanded in sasacola ); sub-basal wing setae S1 and S2 usually expanded (all three sub-basal setae pointed in sasacola ); tergite IX setae S2 1.4 –1.7 times as long as tube (1.0–1.1 times as long as tube in sasacola ); tube shorter than 130µm in female, about 0.5 times as long as head (usually about 140µm in female, about 0.6 times as long as head in sasacola ). Because of these differences we here recall bicolor from synonymy with sasacola . We do not know if the specimens with (1+1) sense cones examined by Tyagi et al. from India are an intraspecific variation of bicolor or a different species.

The specimens examined listed below from India, Southeast Asia and Japan exhibit structural variation in the shape and form of certain setae, such as postocular setae, prothoracic setae and sub-basal wing setae. It is difficult to know whether these specimens contain additional distinct species or not. The postocular setae are long and pointed in the specimens from India but those are rather shorter and expanded in the specimens from Singapore ( Ritchie, 1974). In our observation, the prothoracic posteroangular setae are usually expanded in the specimens from Southeast Asia and Japan, and are rarely pointed. The sub-basal wing setae S1 are rarely pointed in the specimens from Singapore. The postocular setae are rarely blunt or pointed in the specimens from Peninsular Malaysia. Moreover, the male posteromarginal setae S1 on tergite IX of the specimens from India are pointed, whereas those setae are expanded, or at least blunt, in the specimens from Singapore, Peninsular Malaysia, Thailand and Japan. In a long series of specimens from Thailand examined here, a few specimens have (1+1) sense cones on the antennal segment IV, but it is difficult to determine whether the small outer sense cone is absent or missing.

The description of this species is given below based on the specimens from Thailand, because the original description is insufficient for the present study.

Female (macroptera). Distended body length 1.7–2.3mm. Body bicolored ( Fig. 136 ). Head, prothorax and abdominal segments VIII–X brown but segment VIII slightly yellowish in anterior to antecostal suture; pterothorax yellow with pleural areas shaded, abdominal segments I–VII yellow, tergites III–VI each with a brown marking anteromedially. All legs yellow. Antennal segments I–II brown with apex of II yellowish, III–V yellow, VI yellow with distal third shaded, VII brown with base yellowish, VIII brown. Fore wings pale, slightly shaded with brown at middle. Head widest just behind compound eyes ( Fig. 137 ), without lateral tooth. Postocular setae developed, pointed, blunt or expanded. Cheeks rounded and somewhat distinctly narrowed towards base, slightly constricted near base.Antennal segment III with (1+1) sense cones, IV usually with (1+1 +1) sense cones, but often with (1+1), V with (1+1 +1) sense cones; segment VIII not constricted at base. Maxillary stylet reaching postocular setae. Prothoracic aa, ml and epim expanded, pa pointed, blunt or expanded. Fore femora unarmed; fore tibial inner apical tooth weak. Fore wings without duplicated cilia, sub-basal setae short, S1 and S2 expanded, S3 setae pointed. Pelta hut-shaped. Abdominal tergite VIII S1 setae expanded; tergite IX S1 and S2 setae pointed, S1 about 0.7 times as long as tube, S2 about 1.7 times as long as tube. Tube almost straight-sided, tapered to apex, about 0.5 times as long as head, 2.2 times as long as basal width.

Male (macroptera). Distended body length 1.6–2.0mm. Very similar in color and structure to female, but smaller; abdominal tergite IX with S1 setae pointed or expanded.

Specimens examined. India, 2 males, Bangalore, Lal Bagh , on bamboo, 25.iii.1964, T. N. Ananthakrishnan ; 1 female, Chalakudi , on bamboo, 5.xii.1964, T. N. Ananthakrishnan . Thailand, 1 female and 1 male, Kamphaeng Saen, Campus of Kasetsart University , on bamboo, 12.i.1988, SO ; 4 females, Nakornprathom, Puttamonton , on bamboo, 18.ix.1991, J.Pornthip ; 1 male, Hang Dong, on bamboo, 25.viii.1992, SO; Bangkok, Bangkhen, Campus of Kasetsart University , NBCRC, on bamboo , 4 females, 28.xii.1987, SO, 4 females and 2 males, 11.i.1988, SO, 5 females and 2 males, 22.viii.1990, TN &SO; 2 females and 1 male, Chiang Mai, on bamboo, 2.ix.1991, TN & SO ; 56 females and 17 males, Phuket, Gu gu suri Road , on bamboo, 24.viii.1991, TN & SO ; 7 females and 4 males, Phuket Is., nr. Rawai Beach , on bamboo, 15.ix.1992, TN & SO ; 14 females and 8 males, nr. Rawai Beach , on bamboo, 26. Viii.1991, TN & SO . Singapore, 11 females and 7 males, Macritchie Res. , on bamboo, 17.viii.1990, TN & SO. Peninsular Malaysia, 21 females and 2 males, Tapha , on bamboo, 17.ix.1990, TN & SO . Japan, Okinawaken , Minamidaitô-jima Is., on bamboo , 1 females, 21.iii.2008, K. Minoura. 12 females and 6 males 22.iii.2016, K. Minoura. 9 females and 6 males, 22.iii.2016, Kurahashi.

Figures

FIGURES 134–143. Podothrips species, female. P. bellatulus 134–135: (134) whole body; (135) head. P. bicolor 136–137: (136) whole body; (137) head. P. luteus 138–139: (138) whole body; (139) head. P. odonaspicola 140–141: (140) whole body; (141) head. P. sasacola 142–143: (142) whole body; (143) head.