Bactrothrips serraticornis Okajima & Masumoto 2025, stat. rev.

Bactrothrips serraticornis (Bagnall), stat. rev. (Figs 79–89) Bactridothrips serraticornis Bagnall, 1921: 397. This species was described from Ceylon (= Sri Lanka)based on a unique holotype male.Subsequently, Ananthakrishnan (1973) treated this species as a synonym of B. idolomorphus. However, the present study reveals the existence of at least two species that have been previously identified as B. idolomorphus. These two species can be easily distinguished by the difference in shape of the female Bournier’s Apparatus, but, unfortunately, this species was described from a unique male, and it is impossible to compare this structure in the original specimens. However, according to the original description, the mid and hind tibiae of serraticornis differs from that of idolomorphus, basal half or two-fifths being brown, respectively. This color pattern of tibiae is very similar to the population of Java (Figs 83 & 84) which was previously identified as idolomorphus (Mound & Palmer 1983). In addition, the population from Kerala, South India, which was identified as idolomorphus by Ananthakrishnan (1970 & 1973), is also very similar. At present, it seems best to tentatively identify these populations as B. serraticornis, but it is necessary to re-examine this suggestion based on sufficient specimens (see above under B. idolomorphus). There are some small differences between populations from Java and South India. According to Ananthakrishnan (1973), the specimens from Kerala, South India, have antennal segment III and postocular as well as prothoracic epimeral setae shorter. Two females and 10 males from Sulawesi are very similar to the population from Java, but have longer cephalic setae and darker tibiae. The female Bournier’s Apparatus and male subgenital plate are indistinguishable. However, the length of cephalic setae is highly variable and more samples are needed to provide an accurate determination of this population. Diagnosis and measurements (specimens from Java). Female: distended body length 6.7–8.5 mm. Fore tibiae largely yellow, shaded with brown externally in basal half; mid tibiae dark brown in basal half (Fig. 83), hind tibiae brown in basal one-third (Fig. 84). Antennal segment III with pedicel yellow, but scarcely shaded medially, club-head brown (Fig 81). Head widest across eyes (Fig. 79), 2.2–2.4 times as long as wide. Cephalic setae variable in length; postocular setae pair II elongate, usually longer than interocellar setae; postocellar setae usually the shortest; postocular setae pair I variable in length, usually shorter than interocellar setae, but longer than postocellar setae. Antennal segment III 0.63–0.71 (means±SD=0.66±0.03, n=16) times as long as head. Prothoracic epim longer than pa; epim-a short, usually shorter than one-quarter the length of epim. Bournier’s Apparatus well-developed (Fig. 88), tufted area triangular, somewhat similar to that of pictipes, but somewhat slender. Male: distended body length 6.6–8.4mm. Antennal segment III 0.65–0.76 (means±SD=0.72±0.03, n=14) times as long as head. A pair of lateral tubercles on tergite VI curved inwards (Fig. 87), tubercles on tergite VII well-developed, directed backwards, those on tergite VIII stout and directed diagonally backwards. Subgenital plate slender and tie-shaped. Measurements (female in µm). Body length about 7700 (distended). Head length 780, from anterior margin of eyes 688, width across eyes 340, maximum width across cheeks near base 290, minimum width across basal constriction 262; eyes length 220. Cephalic setae: interocellars 140–150, postocellars 65–85, postoculars pair I about 150, postoculars pair II about 220. Antenna total length 1900, segments III–VIII length as follows: 530, 380, 326, 280, 100, 100. Pronotum length 310, width 498. Setae on prothorax: am about 70, aa 80–95, ml about 120, pa 160–178, epim 190–200, epim-a about 30. Pelta length 160, width 670. Tube length 1410, maximum width 180. Measurements (male in µm). Body length about 8200 (distended). Head length 840, from anterior margin of eyes 750, width across eyes 350, maximum width across cheeks near base 294, minimum width across basal constriction 270; eyes length 240. Cephalic setae: interocellars 180, postocellars 70–75, postoculars pair I 150–100, postoculars pair II 125–140. Antenna total length 2150, segments III–VIII length as follows: 635, 430, 380, 260, 110, 103. Pronotum length 350, width 527. Setae on prothorax: am?, aa 40–50, ml 135–145, pa about 150, epim 185–200, epim-a 45. Pelta length 190, width 740. Tube length 1380, maximum width 168. Specimens examined. Indonesia, E. Java, 3 females and 4 males, Mt. Arjuna, 1400–1600m alt., on dead leaves, 19-iv.1981, T. Senoh; 1 female and 4 males, data very similar to above, but 27.iv.1981, W. Suzuki; 13 females and 6 males, 19km N from Batu, Cangar, Mt. Arjuna, alt. about 1200m, on dead Quercu s leaves, 24.viii.1984, SO. Indonesia, C. Sulawesi, 8 males, 31km W from Palopo, Puncak, alt. About 1300m, on dead leaves and branches, 16.viii.1984, SO; 2 females and 2 males, near Rantepao, Pedamaran, alt. about 1000m, on dead leaves and branches, 11.viii.1984, SO.