Mycterothrips albiziae sp. n., 2024

Masumoto, Masami & Okajima, Shûji, 2024, Further study of the genus Mycterothrips Trybom (Thysanoptera: Thripidae) in Japan, with description of a new species and a new record, Zootaxa 5489 (1), pp. 107-124 : 111-116

Mycterothrips albiziae sp. n.

( Figs 1–6, 12 , 16–34 )

Female macroptera. Body length 1.3–1.5 mm. Body brownish yellow, with shaded patches on mesonotum anteriorly, on metascutum laterally, on median half and outside of S2 setae of abdominal tergites II–VIII ( Figs. 1, 2 , 5 ); antennal segment I brown, at least shaded, never yellow, II–VIII brown; fore wings uniformly weakly shaded ( Fig. 18 ); all legs yellowish; major setae dark. Head 0.7–0.9 times as long as width, sculptured with transverse anastomosing striae ( Fig. 16 ); ocellar setae pair I rarely a single seta, III situated between hind ocelli, about 5.2–8.3 times as long as their interval. Antennae 8-segmented, segment III and IV with short apical neck, III straight at each side, IV slightly rounded at each side, IV and V pedicelate, VI not pedicelate, basal half weakly rounded with extreme base rounded and tapering distal half ( Fig. 17 ). Ratio length/width of antennal segments I–VIII as follows: 1.0–1.1, 1.3–1.6, 2.4–3.2, 2.1–2.5, 1.8–2.2, 2.5–2.9, 1.0–1.3, 2.4–3.5. Pronotum about 0.8 times as long as width, sculptured with transverse anastomosing striae, with 47–65 discal setae (means 55±4, n=27); posteroangular setae pair I (=inner pair) 0.4–0.5 times as long as pronotal median length and slightly longer than pair II (=outer pair); posteromarginal S1 setae about 0.3 times as long as pronotal median length and about 1.5 times as long as S2 setae. Mesonotum sculptured with wide spaced transverse anastomosing striae, without CPS anteromedially; median pair of setae near posterior margin ( Fig. 19 ). Metascutum irregularly reticulate medially; median pair of setae at or near anterior margin, 0.6–0.7 times as long as metascutal median length. Fore wing costal vein with 23–31 (means 27±2, n=54) setae, second vein with 11–16 setae (means 13±1, n=54). Abdominal tergite I with S1 setae minute; tergite II with 4 lateral marginal setae; tergites II–VIII laterally with ciliate microtrichia, microtrichia usually reaching to next sculpture on posterior segments and at least exceeding mid-point between sculpture lines on anterior segments; tergites III–VII laterally with transverse striae slightly exceeding S2 setae but not reaching median CPS, with posteromarginal microtrichia outside of S2 setae ( Fig. 20 ); tergite VI–VIII with S4 setae minute; tergite IX with 2 pairs (often 3) of CPS; tergite X with longitudinal slit distally; sternites without discal setae; sternite VII with S1 setae in front of posterior margin. Pleurotergites with ciliate microtrichia arising from sculpture. Ovipositor 1.8–1.9 times as long as pronotal median length.

Measurements (holotype female in microns). Body length 1510. Head length 115, width across cheeks 135; compound eye dorsal length 73, width 43; ocellar setae pair III length 60–63, interval 6.3. Pronotal median length 140, width 170; posteromarginal setae pair I length 67–70, pair II length 55–62; posteromarginal S1 setae length 40–43. Metascutum median length 85; median pair of setae length 48–53. Fore wing length 740, width at middle 55. Ovipositor length 250. Antennal segments I–VIII length (width) as follows: 30 (29), 38 (25), 55 (21), 53 (21), 35 (20), 54 (19), 10 (9), 18 (6).

Male macroptera. Body length 1.0– 1.1 mm. Body grayish brown ( Figs 3 , 6 ); all antennal segments brown ( Fig. 25 ); fore wings uniformly pale brown. Head 0.7–0.9 times as long as width. Antennae 8-segmented, segments IV and V pedicelate, VI much elongate, 85–105 microns long and 0.54–0.70 times as long as combined length of I–V and with numerous long setae and a few microtrichia near base on ventral (often also on dorsal) surface ( Figs 24a, b ). Ratio length/width of antennal segments I–VIII as follows: 1.0–1.1, 1.2–1.6, 2.1–2.6, 1.5–2.1, 1.0–1.5, 4.4–6.0, 0.5–1.0, 2.0–3.3. Pronotum with 37–49 (means 42±4, n=23) discal setae ( Fig. 23 ). Fore wing costal vein with 23–27 (means 24±2, n=40) setae, second vein with 7–12 (means 10±1, n=40) setae. Abdominal tergite II with 4 lateral marginal setae; tergites II–VIII laterally with transverse reaching median CPS, a few short ciliate microtrichia arising from the striae ( Fig. 27 ); tergite IX with S1 setae slightly shorter than S2 setae and slightly behind S2 setae, a pair of minute setae near posterior margin ( Fig. 26 ); sternites III (or usually V)–VIII with 1–7 discal setae, more discal setae on posterior segments than on anterior segments ( Fig. 27 , Table 3 ); pleurotergites not separated from tergites clearly and with rough microtrichia. Hypomere dilated at apex.

Measurements (paratypes male in microns). Body length 930–1060. Head length 87–95, width across cheeks 110–115; compound eye dorsal length 53–60, width 30–35; ocellar setae pair III length 40–53, interval 8–9. Pronotal median length 95–103, width 170; posteromarginal setae pair I length 48–52, pair II length 45–54; posteromarginal S1 setae length 27–33. Metascutum median length 58–63; median pair of setae length 28–40. Fore wing length 470– 580, width at middle 35–40. Antennal segments I–VIII length (width) as follows: 23–28 (25–28), 28–35 (21–24), 38–50 (16–19), 30–38 (18–20), 18–24 (15–19), 85–105 (16–20), 3–5 (5–6), 10–13 (4–5).

Material examined. Holotype female, JAPAN, Honshu, Kanagawa-ken, Hayama-machi, nr. Mt. Futago-yama (alt. 135m), on young leaf of Albizia julibrissin [ Fabaceae ], 9.vii.2017, M.Masumoto.

Paratypes. All from leaves of Albizia julibrissin : JAPAN, Honshu : 2 females collected together with holotype. Iwate-ken, Ichinohe-machi, Iwate-kodomono-mori (alt. 640m), 3 females & 1 male, 29.vii.2023 , T. Yasuoka. Same place and host plant with holotype: 2 males, 19.ix.2014 . 3 females, 9.vii.2017 . 3 females & 1 male, 15.vii.2017 . 4 females & 9 males, 25.viii.2018 . 4 females & 1 male, 11.vii.2020 . 1 female, 25.vi.2022 . 4 females & 2 males, 30.vii.2022 . 5 females & 2 males, 2.ix.2023. (all collected by M.Masumoto). Kanagawa-ken , Hadano-shi, Togawakôen park, 1 female, 4.viii.2007 , M.Masumoto. Gunma-ken, Nakanojo-machi , Ichishiro, side of the river Agatsumagawa, 5 females, 10.viii.2007 , M. Masumoto. Yamanashi-ken , Hokuto-shi: Shibusawa (alt. 650m), 6 females & 1 male, 19.vii.2015 . Akeno-cho (alt. 800m), 17 females, 25.vi.2015 ; 21 females & 1 male, 23.vii.2022 ; 24 females, 15.vii.2023 . Fuefuki-shi , Kanegawanomori park (350m), 2 females, 10.ix.2022. (all collected by M.Masumoto) . Toyama-ken , Toyama-shi, Wariyama-shinrinkôen park, 7 females, 15.viii.2017 , M.Masumoto. Ishikawa-ken, Kahoku-shi , Ishikawa-ken shinrinkôen park, 10 females & 4 male s, 16.viii.2017 , M.Masumoto. Hyôgo-ken, Tanbashinoyama-shi (alt. 220m): 19 females & 6 males, 31.viii.2022 ; 38 females, 15.vii.2023 . Yabu-shi , Hachikôgen (770m), 5 females & 2 males, 23.vii.2023. (all collected by T. Yasuoka) . The holotype and paratypes are deposited in TUA.

Non-paratypic specimens. All from leaves of Albizia julibrissin : JAPAN, Honshu : Gifu-ken, Mino-shi, 3 females, 26.vii.2010; 2 females, 14.ix.2010. (all collected by K.Minoura). Okayama-ken, Maniwa-shi, 1 female, 6.viii.2015. Hiroshima-ken: Hiroshima-shi, Hongô-cho, 3 females & 2 males, 31.viii.2008. Higashi-hiroshima-shi, Takaya-cho, 20 females & 5 males, 23.vii.2008. (all collected by Y.Kojima). All specimens are deposited in TUA .

Second instar larva. Body dull creamy yellow ( Fig. 12 ), head weakly shaded gray anteromedially, abdominal tergite IX shaded dark gray along posterior margin, shaded area reaching but not exceeding setal base, tergite X shaded gray on posterior third, shaded area exceeding setal base but not reaching CPS; antennal segment I pale, II shaded gray below setae, III shaded gray in median half, IV – VII shaded gray; basal half of femora and tibiae shaded gray; dorsal setae on head to abdomen shaded dark gray but slightly pale on tergite X. Head with D1 setae small and acute at apex, D2 and D4 setae expanded and multifid at apex, 2.0 and 2.5 times as long as D1 setae respectively, D3 setae subequal in length to D4 setae and acute at apex ( Fig. 30 ). Antennae 7-segmented ( Fig. 29 ), segment III with two and three rows of microtrichia on dorsal and ventral surfaces, respectively, IV with five and six rows of microtrichia on dorsal and ventral surfaces, respectively. Thoracic nota with strong setae expanded and multifid at apex, sternal setae slender and acute at apex; pronotum with longitudinal granules and large smooth areas at each side, meso- and metanota with more than 10 transverse rows of longitudinal granules; mesothoracic spiracle about 15 microns in major axis, with small peridrome and a posteromedian peridrome larger than spiracle opening in major axis ( Fig. 31 ). Abdominal tergites I– VIII throughout covered with longitudinal granules having minute microtrichia posteriorly, microtrichia conspicuous laterally, D1–D3 setae strong, expanded and multifid at apex, spiracles on II and VIII small; tergite IX with minute teeth along posterior margin and two or three transverse rows of longitudinal granules having minute microtrichia, interval of CPS slightly narrower than interval of D1 setae ( Fig. 32 ); tergite X with D1 setae weakly expanded apex and about 2.6 times as long as D2 setae blunt at apex; sternites throughout covered with longitudinal granules, microtrichia more conspicuous than on tergites ( Fig. 33 ), smooth at posterior half of X ( Fig. 34 ), all ventral setae slender and acute at apex.

Specimens of second instar larvae examined. All from leaves of Albizia julibrissin : JAPAN: Honshu: 2 larvae collected together with holotype. Same place as holotype: 4 larvae, 15.vii.2017. Yamanashi-ken, Hokuto-shi: Shibusawa (alt. 650m), 2 larvae, 19.vii.2015. Akeno-cho (alt. 800m), 8 larvae, 23.vii.2022. Toyama-ken, Toyama-shi, Wariyama-shinrinkôen park, 1 larva, 15.viii.2017. (all collected by M.Masumoto). Okayama-ken, Maniwa-shi, 7 larvae, 6.viii.2015, Y.Kojima. All specimens are deposited in TUA .

Comments. This species is very similar to M. glycines as follows: female body colour brownish yellow often with pale brown markings ( Figs 5, 10 ), abdominal tergites with ciliate microtrichia, usually antennal segment VI longer than IV; male antennal segment VI much longer than that of female but much shorter than combined length of segments I–V. However, females can be somewhat weakly distinguished from M. glycines as in the key above, although M. glycines is usually much paler than the new species, and it may be distinguished from the new species by degree of development of tergal microtrichia: i.e. the microtrichia of M. glycines are rougher and usually not exceeding middle between sculpture lines ( Fig. 22 ), especially on anterior segments. In contrast, males are distinctly distinguishable from each other in the key above. Moreover, there is a difference in distribution of discal setae on male abdominal sternites: i.e. in the new species these setae are present on sternites III–VIII (usually V–VIII), whereas in the latter species these setae are present on IV–VIII (usually VII –VIII) ( Table 3 ). In second instar larva, this new species can be distinguished from M. glycines as follows: in the new species basal half of femora and tibiae dark gray, and D1 setae on head acute at apex, whereas all legs not shaded ( Fig. 14 ) and D1 setae on head blunt at apex in the latter species ( Fig. 48 ). Miyazaki & Kudo (1986) stated that D1 setae on head was “pointed”, but the setae are at least not acute in specimens studied here. The host plants of both species are also different as follows: this new species seems to be specific to Albizia julibrissin ( Fig. 4 ), whereas M. glycines breeds on beans such as Glycine max and Phaseolus angularis , but it has ever been collected from A. julibrissin .

This new species is also similar to M. desleyae Masumoto & Okajima from Australia and M. nilgiriensis (Ananthakrishnan) from India to Taiwan and Australia. However, it can be distinguished from the latter two species as followings: in desleyae female abdominal tergite VI with S4 setae not minute and male antennal segment VI without microtrichia, whereas in this new species female abdominal tergite VI with S4 setae minute and male antennal segment VI with a few microtrichia at least ventrally; in nilgiriensis female antennal segment VI shorter than IV and mouth-cone slender and 1.3–1.5 times as long as dorsal length of head, and male antennal segment VI longer than combined length of segments I–V, whereas the female of this new species has antennal segment VI as long as or longer than IV and mouth-cone wider and shorter, and male antennal segment VI shorter than combined length of segments I–V. This new species may be included in the consociatus -group together with M. glycines based on much elongate male antennal segment VI, but it has male antennal segment VI with a few microtrichia. Alternatively, it may be included in the salicis-group based on the following character states: male antennal segment VI often without microtrichia dorsally and hypomere dilated at apex.

Figures

FIGURES 1–4. Mycterothrips albiziae sp. n. & host plant: (1) Female, dorsal aspect; (2) Female, lateral aspect; (3) Male, dorsal aspect; (4) Host plant of M. albiziae, Albizia juribrissin.

FIGURES 5–15. Mycterothrips species, slide-mounted specimens. Adult 5–11. M. albiziae sp. n.: (5) Female; (6) Male. M. auratus: (7) Female; (8) Male. M. glycines: (9) Female; (10) Female, dark type; (11) Male. Second instar larvae, 12–15: (12) M. albiziae, sp. n.; (13) M. fasciatus; (14) M. glycines; (15) M. japonicus.

FIGURES 16–22. Mycterothrips species, female. M. albiziae sp. n., 16–20: (16) Head and pronotum; (17) Antenna; (18) Antenna, slide-mounted specimen; (19) Mesonotum and metascutum: (20) Abdominal segments V and VI, lateral aspect, right. M. glycines, 21–22: (21) Antenna, slide-mounted specimen; (22) Abdominal tergites and pleurotergites, V and VI, sculptures on pleurotergites omitted.

FIGURES 23–28. Mycterothrips species, male. M. albiziae sp. n., 23–27: (23) Head and pronotum; (24a) Antenna; (24b) Base of antennal segment VI, ventral aspect; (25)Antenna, slide-mounted specimen; (26) Abdominal tergite IX and apex of hypomere; (27) Abdominal segments VI–X, lateral aspect, right. (28) M. glycines, antenna, slide-mounted specimen. hy=hypomere.

FIGURES 29–34. Mycterothrips albiziae sp. n., second instar larva:(29)Antenna; (30) Head–mesonotum; (31)Anterior angle of mesonotum. (32) Abdominal tergites VII–XI: (33) Abdominal sternites III–IV; (34) Abdominal sternites VIII–X. spl=spiracle.

FIGURES 43–49. Mycterothrips species, second instar larva. M. fasciatus, 43–47: (43) Antenna; (44) Head–mesonotum; (45) Anterior angle of mesonotum; (46) Abdominal tergites VII–XI: (47) Abdominal sternites III–VI. M. glycines, 48–49: (48) Head and pronotum; (49) Abdominal sternites IV–VI. spl=spiracle.