Bactrothrips honoris (Bagnall)

Okajima, Shûji & Masumoto, Masami, 2025, Two idolothripine genera, Bactrothrips and Megalothrips (Thysanoptera, Phlaeothripidae), from Asia between India and Taiwan, with descriptions of two new species, Zootaxa 5696 (4), pp. 491-516 : 498-500

Bactrothrips honoris (Bagnall)

( Figs 1 , 6, 11 & 13–43)

Megathrips honoris Bagnall, 1921: 359 .

Bactrothrips elongatus Dang & Qiao, 2012: 51 . Syn. nov.

This species was originally described based on a unique holotype female collected from Kobe, Japan, by J. E. A. Lewis. It is widely distributed in the warm temperate zone and subtropical Ryukyu Islands in Japan, and had subsequently been recorded from Taiwan ( Chen 1982) and China ( Dang & Qiao 2012). In addition, several populations widely distributed in tropical Southeast Asia may also be local populations of the same species. The female Bournier’s Apparatus of this species is particularly characteristic, small with the tufted area vestigial (Fig.6). Moreover, the reticulation of the pelta of honoris is peculiar among the Asian Bactrothrips species: the pattern of reticles clearly different between the anterior and posterior portions of the pelta ( Fig. 22 ). The antennal segment III is comparatively short ( Fig.17 ), 0.46–0.52 times as long as head in female (means±SD=0.49±0.01, n=30), 0.46– 0.55 times in male (means±SD=0.52±0.02, n=30), and with somewhat longer sense cones which are usually much longer than one-third the segment length. The male abdominal tubercles on tergite VI are weakly curved outwardly at least in medium to large sized individuals (cf. Fig. 26 ), and tergite VII is without distinct tubercles even in large individuals. The male subgenital plate is comparatively wide and tongue-shaped (Figs 11 & 40), broadest near base and gradually narrowed towards apex. Interestingly, when alive, this species has a pair of bright red spots on both sides of each abdominal segment in both sexes ( Fig. 1 ). Of the seven species distributed in Japan, only two species, B. honoris and B. pictipes ( Fig. 2 ), have such spots. These red spots are not the color of cuticle, but the color beneath it seems to show through. Therefore, in macerated specimens, the cuticle has transparent ‘faded windows’ in the areas of red spots ( Fig. 39 ), but this is not always clearly observable in compressed specimens. These ‘faded windows’ are also found in B. luteus from India.

The specimens from Taiwan are very similar to the specimens from Japan, but sometimes there is variation in the color of the hind tibiae even within the same colony ( Figs 27–29 ). Usually, the basal three-fifths is brown and the apical two-fifths is yellow ( Fig. 27 ), but sometimes more widely brown ( Fig. 28 ) or almost entirely brown ( Fig. 29 ). Dang and Qiao (2012) distinguished B. elongatus from B. honoris for several reasons as follows: sensecones on antennal segment III obviously shorter than half of this segment; prothoracic epimeral accessory setae much longer than half of epimeral setae; all tibiae uniformly dark brown. However, all of these characteristics show variation, and all of them also apply to the range of variations in B. honoris , and are thus not appropriate as distinguishing features for dividing species. Moreover, the reticulation pattern of the pelta in elongatus is clearly different between the anterior and posterior portions (see Fig. 6 in Dang & Qiao). The anterior half of this pelta has a longitudinal reticulation, while the posterior half has a transverse reticulation, and this pattern is consistent with that characteristic of typical honoris ( Fig. 22 ). Furthermore, one female and one male paratypes of elongatus were probably collected together with honoris . At least they were collected from the same place on the same day as honoris was obtained (from Guangxi, Wuming County, Daming Mountain at 28.v.2011). Judging from these facts, elongatus is not distinguishable from honoris , and is here treated as a synonym. If the female Bournier’s Apparatus of elongatus could be observed, this problem would be easily solved.

Several populations from tropical Southeast Asia are very similar to this species, and it is very difficult to decide whether these are different species or local populations of a single species. They share the short antennal segment III ( Figs 18–21 ), outwardly curved male abdominal tubercles (cf. Fig. 26 ), pelta with two patterns of reticulations (cf. Figs 23–25 ), reduced female Bournier’s Apparatus (cf. Figs 42 & 43 ), and tongue-shaped male subgenital plate (cf. Fig. 41 ). However, there are some differences from the populations of Japan and Taiwan in the color of antennal segments IV–VIII, and the relative length of head and postocular setae pair II. These differences may simply be regional variations, and the difference may not be significant enough to divide the species. For example, the relative length of the head tends to be longer in these populations ( Figs 15 & 16 ), but this may be related to the size of the body. This is because the specimens of these populations tend to be larger than the specimens from Japan and Taiwan. There is another possibility that populations exhibiting intermediate character states will be found in the future. As a result, in this time, we have determined these populations as honoris , but further investigation is needed. Moreover, there are slight differences in color and structure in each population. For example, the mid and hind tibiae of the specimens from Sulawesi are largely brown ( Figs 33 & 38 ), but those of the specimens from Java and Peninsular Malaysia are bicolored, brown at basal half and yellow at apical half ( Figs 30, 31, 35 & 36 ). There is a slight difference in the shape of female Bournier’s Apparatus between the populations from Java ( Fig. 42 ) and Peninsular Malaysia ( Fig. 43 ). The length of cephalic setae such as the two pairs of postoculars also differs slightly in each population.

In consequence, honoris are recorded here from Peninsular Malaysia, Thailand, Vietnam, Java, Sulawesi, Mindanao, for the first time. Finally, the Figures 19 and 37 in Eow et al. (2011), which were identified as B. idolomorphus , are possibly this species, because the tubercles on the tergite VI are curved outwards and tergite VII has no lateral small tubercles.

Specimens examined. Japan, numerous females and males from Honshu, Shikoku, Kyushu and the Ryukyu Islands (detailed data are omitted, see Haga & Okajima 1989). Taiwan, many females and males (detailed data are omitted). Indonesia, E. Java, 16 females and 8 males, 19km N from Batu Cangat, Mt. Arjuna, alt. about 1200m, on dead Quercus leaves, 24.viii.1984, SO; 2 females and 1 male, Mt Arjuna , on dead leaves, 19.iv.1981, T. Senoh; 1 male, Mt. Tengger , 2.v.1981, W. Suzuki. Indonesia, S. Sulawesi (= Celebes), 9 females and 1 male, Malino, alt. about 900m, on dead Palmae , 3.viii.1984, SO. Peninsular Malaysia, about 20km from Kuala Lumpur, 1 female, on dead leaves, 12.viii.1990, 1 female, on dead leaves and branches, 12.ix.1990, TN & SO; 5 females and 5 males, Cameron Highland, nr. Brinchang, on dead leaves and branches, 25.viii.1990, TN & SO; 2 females and 1 male, Cameron Highland, foot of Gnung Brinchang, on dead leaves and branches, 26.viii.1990, TN & SO; 1 female, Cameron Highland, nr. Tanah Rata, on dead leaves and branches, 30.viii.1990, TN & SO; 4 females, Fraser’s Hill, on dead leaves and branches, 13.ix.1990, TN & SO. Thailand, nr. Chiang Mai, Doi Suthep , 1100m alt., 3 females, on dead leaves, 13.viii.1976, SO. Vietnam, 1 male, Lam Dong Province, Bao Loc, Dam Bri , on dead leaves, 28.xii.2001, SO. The Philippines, Mindanao, Mt. Apo, Agko , alt. about 1300m, on dead leaves, 1 female and 3 males, 30. vii.1979, 7 females and 4 males, 3.viii.1979, SO; 1 male, locality similar to above, but alt. about 1100m, 5.viii.1979, W. Suzuki.

Figures

FIGURES 1–2. Bactrothrips species: (1) B. honoris, male; (2) B. pictipes, female.

FIGURES 13–26. Bactrothrips honoris. Head 13–16: (13) female from Taiwan; (14) male from Taiwan; (15) female from Java; (16) male from Java. Antennal segments III–VIII, female 17–21: (17) Taiwan; (18) Java; (19) Peninsular Malaysia; (20) Mindanao Is., the Philippines; (21) S. Sulawesi. Pelta 22–25: (22) female from Taiwan; (23) female from Java; (24) male from Java; (25) male from Peninsular Malaysia. (26) Abdominal tubercle, male from Java.

FIGURES 27–43. Bactrothrips honoris. Hind tibia, female 27–33: (27–29) Taiwan; (30) Java; (31) Peninsular Malaysia; (32) Mindanao Is., the Philippines; (33) S. Sulawesi. Mid tibia, female 34–38: (34) Taiwan; (35) Java; (36) Peninsular Malaysia; (37) Mindanao Is., the Philippines; (38) S. Sulawesi. (39) Abdominal segments VI and VII, female (arrows indicate ‘faded windows’), female from Java. Male subgenital plate 40–41: (40) Taiwan; (41) Java. Female Bournier’s Apparatus 42–43: (42) Java; (43) Peninsular Malaysia.