Mycterothrips egonoki, Okajima, 2006

Okajima, Masami Masumoto And Shûji, 2006, A revision of and key to the world species of Mycterothrips Trybom (Thysanoptera, Thripidae), Zootaxa 1261 (1261), pp. 1-90 : 43-48

Mycterothrips egonoki sp. nov.

( Figs. 60–69)

Mycterothrips consociatus (nec. Targioni­Tozzetti, 1887); Okajima & Urushihara, 1992: 160.

Description. Female. Distended body length 1.3–1.6 mm. Body almost uniformly brown to dark brown; head sometimes slightly darker in basal third; antennal segments I to VIII uniformly dark brown; thorax sometimes slightly darker in part; abdominal terga usually with slightly darker patches lateral to B2 setae ( Fig. 63); fore femora yellowish brown or pale brown with slightly darker posterior margin, mid­ and hind femora yellowish brown or pale brown, sometime slightly darker at base; fore tibiae yellowish brown or pale brown, sometimes slightly darker at base, mid­ and hind tibiae yellowish brown or pale brown, sometimes slightly darker at middle; all tarsi yellowish; fore wings and scales uniformly pale brown; prominent body setae brown to dark brown.

Head 1.2–1.6 times as wide as long, cheeks almost straight. Ocellar setae I rarely absent or only one seta, setae III situated between posterior ocelli and usually 2.9–5.2 times as long as distance between their bases ( Fig. 60). Antennal segment III usually the longest, sometimes subequal to IV ( Fig. 61). Antennal segments I to VIII length/width as followings; 0.9–1.2, 1.2–1.7, 2.4–3.3, 2.5–3.3, 1.7–2.7, 2.4–3.3, 1.0–1.7, 3.0–4.5.

Pronotum 1.3–1.6 times as wide as long, weakly sculptured with transverse anastomosing striae medially, with 26–51 (mean 36, n=27) discal setae (33 in holotype); posteroangular setae I (=inner setae) almost as long as setae II (=outer setae) and 0.4–0.5 times as long as pronotal median length; posteromarginal setae I 1.0–2.1 times as long as setae II and 0.2–0.4 times as long as pronotal median length ( Fig. 60). Mesonotum without CPS anteromedially; median pair of setae near posterior margin ( Fig. 62). Metascutal sculpture weak and irregular at middle; median pair of setae near anterior margin and 0.4– 0.6 times as long as metascutal median length ( Fig. 62). Fore wings with 25–37 (mean 32, n=38) setae on costal vein (holotype 32) and 10–17 (mean 14, n=38) setae on second vein (holotype 14).

Abdominal terga and laterotergites without ciliate microtrichia on lines of sculpture, a few lines of sculpture slightly extending mesad of B2 setae on terga II to VIII ( Figs. 63– 64); tergum II with four lateral marginal setae; terga VI to VIII with B4 setae minute ( Fig. 64); tergum IX with posterior pair of CPS only, B1 setae, B2 setae and B3 setae 0.8–1.2 times, 1.1–1.4 times and 1.0–1.3 times as long as tergum IX median length, respectively ( Fig. 64); tergum X with median slit at distal half to third or often only at middle ( Fig. 64); sterna without discal setae. Ovipositor 1.5–2.2 times as long as pronotal median length.

Measurements (in µm). Holotype (female). Distended body length 1,530. Head length (width across cheeks) 103 (145), compound eye dorsal length (width) 65 (45), ocellar setae III length (interval) 46 (15). Pronotal median length (width) 128 (175), posteroangular setae I length 59, setae II length 59, posteromarginal setae I length 43, setae II length 27. Metascutal median length 90, median setae length 43. Fore wings length 895. Tergum IX median length 88, B1 setae length 98, B2 seta length 118, B3 setae length 108. Ovipositor length 275. Antennal segments I to VIII length (width) as follows: 28 (28), 43 (25), 60 (20), 55 (20), 38 (18), 58 (18), 10 (8), 20 (5).

Male. Body colour and general structure very similar to female, but smaller and more slender than female. Head slightly narrower at base than in female and pronotal discal setae slightly fewer ( Fig. 66). Antennal segment VI much longer than that of female, about 1.4 times as long as combined length of segments I to V, with numerous long setae and without microtrichia ( Fig. 68). Abdominal tergum IX with small setae near posterior margin ( Fig. 67); sterna with discal setae ( Fig. 65). Hypomere expanded at apex ( Fig. 67).

Measurements (in µm). Paratype (male). Distended body length 1,150. Head length (width across cheeks) 93 (138), compound eye dorsal length (width) 60 (38), ocellar setae III length (interval) 55 (8). Pronotal median length (width) 108 (158), posteroangular setae I length 55, setae II length 48, posteromarginal setae I length 38, setae II length 23. Metascutal median length 73, median setae length 33. Fore wings length 670. Antennal segments I to VIII length (width) as follows: 25 (28), 33 (28), 35 (20), 30 (20), 15 (20), 195 (25), 5 (5), 10 (5).

Type series. Japan: Holotype (female), Kanagawa Pref., Kawasaki City, Tama­ku, Ikuta­ryokuchi, on leaves of Styrax japonica [ Styracaceae ], 27­iv­1993, S. Okajima. Paratypes: 13 females, same data as the holotype. 1 female, same locality and date as the holotype, on leaves of Artemisia princes [Compositae], S. Okajima. 10 females, same locality as holotype, on leaves of Cocculus orbiculatus [ Menispermaceae ], 7­ix­1994, S. Okajima. 1 female, same locality as holotype, flowers of Liliope graminifolia [ Liliaceae ], 21­ix­1994, S. Okajima. 1 female, Kanagawa Pref., Zushi City, Jinmuji Forest Res., in leaf­litter, 17­v­1990, T. Nonaka & H. Urushihara. 1 male, Kanagawa Pref., Hayama­cho, Mt. Futago­yama, on leaves of Pleioblastus chino [ Poaceae ], 25­viii­1996, M. Masumoto. 1 female, Kanagawa Pref., Hayama­cho, Mt. Futago­yama, on leaves of Pleioblastus chino , 24­viii­1997, M. Masumoto. 1 female, Kanagawa Pref., Hayama­cho, Mt. Futagoyama, on leaves of Cinnamomum japonicum [ Lauraceae ], 25­v­2002, M. Masumoto. 4 females, Kanagawa Pref., Hayama­cho, Mt. Futago­yama, on leaves of Styrax japonica , 23­vi­2002, M. Masumoto. 1 female and 1 male, Kanagawa Pref., Hayama­cho, Mt. Futago­yama, on leaves of Ficus erecta [ Moraceae ], 2­x­2005, M. Masumoto. 14 females, Tokyo, Kodaira City, on dead wood, 18­xii­1983, Satake. 43 females, Chiba Pref., Narita City, Otake, near Inba­numa, on leaves of Styrax japonica , 5­viii­2001, M. Masumoto. 33 females, Chiba Pref., Narita City, Otake, near Inba­numa, on leaves of Styrax japonica , 17­viii­2001, M. Masumoto. 16 females, Fukushima Pref., Kitashiobara­mura, alt about 800 m, on leaves of Morus bombycis [ Moraceae ], 11­viii­2002, M. Masumoto. 2 females, Fukushima Pref., Kitashiobara­mura, alt about 800 m, on leaves of Morus bombycis , 20­ viii­2003, M. Masumoto. 1 female, Fukushima Pref., Fukushima City, Matsukawa­cho, Fukushima University, leaf­litter ( Quercus serrata , Prunus sp. , Pinus densiflora ), 24­viii­ 1999, T. Tsutsumi. 1 female, Nagano Pref., Maruko­cho, on leaves of Betula platyphylla [ Betulaceae ], 2005, M. Masumoto. 1 female, Miyagi Pref., Mt. Zao, sweeping, 12­ vi­ 1976, S. Okajima. 1 female, Nagasaki Pref., Kitamatsuura­gun, Tabira­cho, Ogitamen, on leaves of Machilus thunbergii [ Lauraceae ], 27­x­1994, S. Okajima.

Non­paratypic specimens. Japan: 1female, Kagoshima Pref., Amami­ohshima Is., Uken­son, Fureainomori, on dead leaves and branches, 28­iii­1990, S. Okajima ( TUA). 1 female, Kagoshima Pref., Amami­ohshima Is., Kinsakubaru, on leaves of Stylax sp., 30­vi­ 2000, M. Masumoto ( TUA). 4 males, Okinawa Pref., Okinawa­hountou Is., on bush, 10­ iv­2004, K. Minoura ( TUA). 1 female, Okinawa Pref., Ishigaki­jima Is., Takeda­rindou, on leaves of Fraxinus griffithii [ Oleaceae ], 16­i­1991, S. Okajima ( TUA). 1 female. Okinawa Pref., Ishigaki­jima Is., Takeda­rindou, host unknown, 18­i­1991, S. Okajima ( TUA). 1 female, Okinawa Pref., Ishigaki­jima Is., Mt. Banna­dake, on leaves of Machilus thungergii , 17­i­1991, S. Okajima ( TUA). 1 male, Kanagawa Pref., Hayama­cho, Mt. Futago­yama, on leaves of Pleioblastus chino , 20­vii­2002, M. Maumoto ( TUA). 1male, Fukushima Pref., Fukushima City, Matsukawa­cho, Fukushima University, leaf­litter ( Quercus serrata , Pinus densiflora , Pinus densiflora ), 10­x­2000, T. Tsutsumi ( FU).

The holotype and most paratypes are deposited in TUA, Atsugi , Japan .

Comments. This species is very similar to M. consociatus , but in addition to the character states in the key they differ as follows: M. egonoki head with dorsal sculpture more reticulate posteromedially ( Fig. 60), fore wing costal vein usually with more than 30 setae. M. consociatus , head with dorsal sculpture transverse ( Fig. 51), fore wing costal vein with 23–28 setae. Moreover, the female of this new species has the antennal segment VI with the lateral margins not rounded ( Fig. 61), whereas antennal segment VI in M. consociatus is slightly rounded laterally ( Fig. 52). There also seems to be a difference in their habitats, because this species has been collected from a comparatively wide range of environments, such as low to high altitude and from north to south, including from dead leaves, grass, bamboo and living leaves. In contrast, M. consociatu is usually collected from living leaves such Betulaceae or Fagaceae plants in the north, or at high altitude places in Japan. Although Okajima and Urushihara (1992: 160) listed a female from leaf litter at Kanagawa Prefecture in Honshu as M. consociatus , it is here recognized as this new species. The males of M. egonoki can barely be distinguished from M. consociatus ­ group by the head with dorsal sculpture lines relatively distinctly reticulated ( Fig. 66), and the antennal segments III and IV with each sense­cone long and reaching the middle of the next segment ( Fig. 68).

In Mycterothrips , especially the consociatus ­group, it is often difficult to associate males with females because fewer males are collected and they are not usually taken together with females. Two males listed above as non­paratypic specimens, collected from Fukushima University (Fukushima Pref.) and Mt. Futago­yama (Kanagawa Pref.), have antennal segments III and IV more slender than two paratype males ( Fig. 69) with the length (width) 40 (18) and 38 (18). However, these two males were recognized as this new species here despite being excluded from the type­series, because two paratypic males were also collected from Mt. Futago­yama although other Rhopalandrothrips ­type species of consociatus ­group have never been collected there.

Etymology. In reference to the Japanese name of the host plant, Styrax japonica .