Research Article |
Corresponding author: Khine Mon Mon Kyaw ( khinemon09yau@gmail.com ) Academic editor: Erik J. van Nieukerken
© 2019 Khine Mon Mon Kyaw, Sadahisa Yagi, Jouhei Oku, Yositaka Sakamaki, Toshiya Hirowatari.
This is an open access article distributed under the terms of the Creative Commons Attribution License (CC BY 4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
Citation:
Kyaw KMM, Yagi S, Oku J, Sakamaki Y, Hirowatari T (2019) Taxonomic study of Thiotricha Meyrick (Lepidoptera, Gelechiidae) in Japan, with the description of two new species. ZooKeys 897: 67-99. https://doi.org/10.3897/zookeys.897.38529
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A part of Japanese species of the genus Thiotricha Meyrick, 1886 are reviewed. Three species described by
distribution, host plants, morphology, new species, portable case, pupa, taxonomy
The family Gelechiidae is one of the largest families of Microlepidoptera in the world and includes more than 4,700 described species belonging to approximately 500 genera (van
The subfamily Thiotrichinae includes the genera Thiotricha Meyrick, 1886, Macrenches Meyrick, 1904, Palumbina Rondani, 1876 and Polyhymno Chambers, 1874. Among them, Thiotricha Meyrick, 1886 and Polyhymno Chambers, 1874 have a long taxonomic history with various opinions about their separation. The genus Thiotricha includes globally nearly 100 described species and is most diverse in Asia (
Another genus, Cnaphostola Meyrick, 1918, was described for the single species C. adamantina Meyrick, 1918, collected in Assam, North India. Three additional species; C. biformis Omelko, 1984, C. angustella
Although the phylogenetic relationship and synonymy of the genera Cnaphostola, Thiotricha and Polyhymno is not fully resolved to date, we place all Japanese species here in Thiotricha, we review the Japanese species and compare the morphological characters, including head parts, wing marking, venation, and genitalia, to solve the aforementioned taxonomic problems. Further, we describe two new species with photographs of male and female adults, wing venation, and genitalia. We also report the biology of immature stages of some species, the pupal morphology of T. chujaensis (Park, 2016) comb. nov. and T. elaeocarpiella Kyaw, Yagi & Hirowatari sp. nov. and discuss the larval feeding mode of this group.
Dried specimens deposited in the Entomological Laboratory, Kyushu University, Fukuoka (
Unless otherwise noted, the specimens are deposited in the Entomological Laboratory of Kyushu University (
The descriptive terminology follows
Thiotricha thorybodes Meyrick, 1886 designated by Meyrick, 1925:101.
Cnaphostola biformis
Omelko, 1984: 32;
Thiotricha biformis:
Japan – Hokkaido [Hokkaido] • 1♂,1♀; Katsuranosawa, Uryu-cho, Uryu-gun; 20 Jul. 2018; S. Yagi leg. • 1 ♂; Katsuranosawa, Ishikari city; 15 Jul. 2007; H. Kogi leg. • 1♂; Manzi, Kurisawa; 8 Jul. 2001; H. Kogi leg.; gen. slide no. KM-143 • 1 ♂, 1♀; same locality and collector; 28 Jul. 2003; gen. slide no. KM-144(♂) • 1♂; Kotan Atuta; 10 Jul. 2003; H. Kogi leg. • 1♀; Nopporo (Atsubetsu); 27 Jul. 1993; T. Hirowatari leg. • 2♀♀; Kamisibun, Iwamizawa; 9 Jul 2011; 8 Aug. 2012; H. Kogi leg.; gen. slide no. KM-145 • 1♀; Hukui, Niseko; 4 Aug. 2006; H. Kogi leg. • 1♀; Tiyosibetu, Hamamasu; 14 Jul. 2000; H. Kogi leg. • 1♀; Asari Pass, Otaru; 28 Jul. 2012; H. Kogi leg.; gen. slide no. KM-146. – Honshu [Iwate] • 1♀; Atei-Sanso Niisato vill.; 6 Jul. 2002; T. Oku leg. (TO).
The forewing is white with broad, dark brown fascia, a rather large yellow patch before the apex, and a black rounded apical spot demarcated by a white line. The anellus lobe of the male genitalia is a short and heavily sclerotized beak-shaped lobe basally, armed with a small claw-like process apically, which is a unique characteristic of this species. The apopyhsis posterioris of the female genitalia is ca. 1/2 the length of the papilla analis and approx. two times longer than the apophysis anterioris; the signum is absent in the corpus bursae.
Male. (Figs
Head : covered with shiny, creamy white appressed scales. Antennae filiform; basal segment (scape) elongate without pecten, creamy white; flagellum creamy white on dorsal surface before middle, then entirely grayish brown beyond on its dorsal and ventral surface, with rather long and fine cilia ventrally. Labial palpus white, long, and recurved; first segment shortest with creamy white scales; second segment thickened, ca. 2.5 the thickness times of first, covered entirely with white scales; third segment white on dorsal surface, sparse brown scales medially on ventral surface, as long as second segment, apex sharply acute.
Thorax : creamy white. Tegula shiny, creamy white dorsally, with brown scales along anterior margin.
Legs : white; forefemur, tibia, and tarsus suffused inwardly with brownish tinge, white on outer surface; mid legs entirely white; hind femur and tibia white, with a row of long, stiff, stout white bristles on upper and lower surfaces; all tarsal segments brownish gray.
Forewing
: eleven veins, R3 + R4 stalked, M1 separate, R5 absent, anal veins furcate (Fig.
Hindwing : darker grayish brown with tiny black apical dot at apex; cilia well-fringed, grayish brown, with dark brown at tip of wing.
Male genitalia
: (Figs
Female. (Figs
Female genitalia
: (Fig.
Japan (Hokkaido, Honshu), Russia, Korea.
Unknown.
Cnaphostola angustella
Omelko, 1984: 32;
Japan – Hokkaido [Hokkaido] • 1♀; Yamato, Erimo; 15 Jul. 2002; H. Kogi leg.; Host: Quercus dentata; TO • 1♂; same locality and collector; 19 Jul. 2003; Host: Quercus dentata • 1♂; Syoya, Erimo; 30 Jun. 2002; H. Kogi leg. • 1♂; Tomikawa, Monbetu; 21 Jul. 2004; H. Kogi leg.; Host: Quercus dentata; TO • 3♀♀; same locality and collector; 23–25 Jul. 2006; 6 vii 2007 • 2♀♀; Higasihayakita, Hayakita; 20 Jul. 2005; H. Kogi leg. • 1♂; Tiyosibetu, Hamamasu; 13 Jul. 2002; H. Kogi leg. • 1♂; Katsuranosawa, Atuta; 21 Jul. 2002; H. Kogi leg. • 1♂; Uenai, Tomakomai; 26 Jul. 2002; H. Kogi leg. – Honshu [Iwate] • 1♀; Iwayama, Morioka; 2 Jul. 2009; T. Oku leg.; Host: Quercus mongolica; 13 Jul. 2009 em.; TO. – Honshu [Nagano] • 1♀; Kojiro, Tenryu-mura; N. Hirano leg.; 5 Jul. 2008; gen. slide no. KM-118 • 1♂; same locality and collector; 28 Aug. 2009; gen slide no. KM-106. – Honshu [Aichi] • 1♂; Asahikogen, Asahi-cho; 7 Jul. 2001; T. Mano leg.;
The forewing is white with pale brown in the distal part, without an apical black spot. The anellus lobe of the male genitalia is a pear-shaped lobe basally, long, strongly sclerotized, and spine-like apically; the valva is narrow and elongate. The apophysis posterioris of the female genitalia is approx. two times of the length of papilla analis and approx. three times longer than the apophysis anterioris; the signum is long, narrow, and arch-shaped.
Male (Figs
Head : shiny creamy white with appressed scales. Antennae filiform, basal segment elongate without pecten and creamy white; flagellum creamy white on dorsal surface before middle, then grayish brown beyond, with extraordinarily long and fine cilia on its ventral surface. Labial palpus white, long, and recurved; first segment shortest, creamy white suffused with brown scales on outer surface; second segment thickened, up to 2.5 times the length of the first and white; third segment nearly as long as second, creamy white evenly on both surfaces, apex sharply acute.
Thorax : creamy white. Tegula shiny, creamy white dorsally, ornamented with bronze-brown scales along anterior margin.
Legs : white; forefemur, tibia, and tarsus suffused inwardly with brown; hind tibia creamy white, with a row of long, stiff, stout white bristles at approx. the midpoint anteriorly, with dark brown bristles at ca. 1/4 posteriorly on dorsal surface, with white bristles ventrally.
Forewing
: eleven veins, R4 + M1 stalked, R5 absent, anal vein furcate (Fig.
Hindwing : narrower than forewing, white to whitish brown; cilia well-fringed, white to brownish white; apex produced conspicuously.
Male genitalia
: (Figs
Female (Fig.
Female genitalia
: (Fig.
Japan (Hokkaido, Honshu), Russia, Korea.
Quercus dentata (
Cnaphostola venustalis
Omelko, 1984: 32;
Japan – Hokkaido [Hokkaido] • 2♂♂; Katsuranosawa, Uryu-cho, Uryu-gun; 20 Jul. 2018; S. Yagi leg. • 1♂, 1♀; Tomuraushi, Shintoku town; 20 Aug. 2000; H. Kogi leg.; gen. slide no. KM-148 (♂) • 2♂♂; Tokachigaoka, Otofuke-cho; 13 Jul. 2000; T. Hirowatari; N.H. Ahn; Y. Miyamoto; H. Okamoto; K. Yamada leg.; gen. slide no. KM-4, 47;
The forewing is white with a small orange patch and a black rounded spot apically. The anellus lobe of the male genitalia is narrow, slender, and longer than the valva, with a sharp and thorn-like spine at the apex, which is a unique characteristic of this species. The apopyhsis posterioris of the female genitalia is ca. 1/3 of the length of papilla analis and approx. half the length of the apophysis anterioris; the signum is absent in the corpus bursae.
Male (Figs
Head : shiny, creamy white with appressed scales. Antennae filiform, basal segment elongate and white; flagellum whitish brown on dorsal surface before middle, then entirely grayish brown beyond, with rather long and fine cilia ventrally. Labial palpus white, long, and recurved; first segment shortest, creamy white; second segment thickened, as much as 2.5 times the length of the first, covered evenly with creamy white scales; third segment as long as second, creamy white, apex sharply acute.
Thorax and tegula : creamy white.
Legs : white; forefemur, tibia, and tarsus suffused inwardly with dark brown, white on outer surface; mid legs entirely white; hind femur and tibia white, dispersed inwardly with brown; with compact ventral and dorsal rows of long, stiff, stout white bristles; all tarsal segments grayish brown.
Forewing
: eleven veins, R3 + R4 stalked, M1 separate, R5 absent, anal vein furcate (Fig.
Hindwing : narrower than forewing, brown with tiny dark brown apical dot; fringe around apex darker in color, long, and brown, cilia well-fringed on inner region of hind wing.
Male genitalia
: (Figs
Female (Fig.
Female genitalia
: (Fig.
Japan (Hokkaido, Honshu, Kyushu), Russia, Korea.
Quercus dentata (
Cnaphostola chujaensis:
Japan – Honshu [Chiba] • 1♀; Kayano, Orikisawa, Kimitsu-shi; 4 Sep. 2013; O. Saito leg. • 1♂; Otake, Narita-shi; 23 Jul. 2016; O. Saito leg. • 1♀; same locality and collector; 20 Aug. 2016 • 1♂; same locality and collector; 3 Jun. 2017 • 1♀; same locality and collector; 9 Sep. 2017 • 1♀; same locality and collector; 7 Oct. 2017. – Honshu [Ishikawa] • 1♀; Hodatsushimizu cho, Shikinami; 16 Jun. 2018; S. Tomura leg. – Honshu [Nagano] • 2♀♀; Kojiro, Tenryu-mura; 19 Jun. 2009; 28 Aug. 2009; N. Hirano leg. • 1♂; Hiraoka, Tenryu-mura; 16 Jun. 2007; N. Hirano leg. [Gifu] • 1♀; Yamagata-gun, Miyama-cho, Iodo; 17 Jun. 1994; T. Mano leg.; gen. slide no. KM-140;
This species is similar to T. biformis, which is known in the Russian Far East and Japan but can be distinguished by markings in the distal yellow zone of the forewing with a distinct black streak below the middle of the yellow zone. The male genitalia is similar to those of T. epiclista Meyrick, 1908 described from Khasi Hills, India, but can be distinguished by the basally broadened valva and the presence of a thumb-like basal process bearing numerous setae, the lack of a pre-apical spine on the costal process of the valva, and the slender posterior part of the phallus.
Male (Figs
Male genitalia
: (Figs
Female (Fig.
Female genitalia
: (Fig.
Japan (Honshu, Shikoku, Kyushu, Ryukyus), Korea.
Mallotus japonica (Euphorbiaceae).
(Fig.
(Figs
This species was described by Park (in
Cnaphostola
sp. 2:
Holotype
: Japan – Kyushu • 1 ♂, Fukuoka Pref., Kyushu Univ. Ito Campus, Nishi-ku; 7 Aug. 2017; S. Yagi, T. Hirowatari, K. M. M. Kyaw & C. Tsuji leg.; case on Rhaphiolepis indica (case made from flower bud of Elaeocarpus zollingeri); 19 Aug. 2017 em.; gen. slide no. KM-88; in
Paratypes
: Japan – Kyushu [Fukuoka] • 1♂; same locality and collectors as holotype; 26 May. 2017; portable case on Rhaphiolepis indica; 17 Jul. 2017 em.; gen. slide no. KM-40 • 3♂♂; same locality and collectors as holotype; 31 Jul. 2017; Host: Rhaphiolepis indica; 7 Aug. 2017 em.; gen. slide no. KM-104,105 • 2♂♂; same locality and collector as holotype; 22 Jul. 2017; Host: Rhaphiolepis indica; 31 Aug. 2017 em. • 1♀; same locality; 22 Jul. 2017; Host: Rhaphiolepis indica; 27 Aug. 2017; K.M.M.Kyaw leg.; gen. slide no. KM-132. – Kyushu [Kagoshima] • 1♀; Satahetsuka (L), Minamiousumi Town; 9–10 Jul. 2011; T. Terada leg. (
At a glance, the external features are similar to those of T. chujaensis (Park, 2016) comb. nov. but it can be distinguished by wing markings in the distal yellow zone of the forewing, which lacks a distinct blackish streak below the middle of the yellow zone and features grayish scales at the costal margin before the apex and the area beyond the tornus. Additionally, it can easily be distinguished based on the male genitalia; the uncus is more rounded apically; the gnathos is U-shaped and acute apically; the valva is narrowly elongate with a sharped pre-apical process ca. 1/4 of the way along its length and the vinculum lacks thumb-like lobes posteriorly; the saccus has a rounded base. The shape of the phallus is also different. However, the male genitalia are similar to those of Thiotricha clidias Meyrick, 1918, which was described from Khasi Hills, India, although they differ in the shape of the phallus. In T. clidias Meyrick, 1918, the phallus is rounded basally, abruptly sinuate and slender in distally but as a cucurbit-shaped in T. elaeocarpiella sp. nov.
Male (Figs
Head
: shiny creamy white with appressed scales. Antennae filiform, basal segment elongate and creamy white, sparsely speckled with brown scales; flagellum grayish white on dorsal surface before midpoint, then brownish gray beyond on its dorsal and ventral surfaces, with extraordinarily long and fine cilia ventrally. Labial palpus white, moderately long and recurved; first segment approximately half the length of the second, with blackish gray scales on lateral surface; second segment as much as 1.5 times the length of the first, creamy white throughout on outer surface; bundle of hair pencils arising from apex of first and second segment, appressed on dorsal surface to near the end of the third segment; third segment as thick as second, with blackish gray scales medially on lower surface ventrally, shiny creamy white evenly on both surfaces, apex sharply acute (Fig.
Thorax : creamy white. Tegula shiny, creamy white dorsally, ornamented with blackish gray scales along anterior margin.
Legs : white; forefemur, tibia, and tarsus suffused inwardly with blackish brown; scattered with white scales on outer surface; mid femur entirely white; mid tibia and tarsus white but slightly speckled with blackish brown scales on outer surface; hind femur white; hind tibia creamy white, with a row of long, stiff, stout, creamy white bristles above and below, suffused with a small blackish gray scale on lateral outer surface posteriorly; first tarsal segment entirely blackish gray; second and third segment white with blackish gray apical ring; last two segments white.
Forewing
: eleven veins, R4 + M1 stalked, R5 absent, anal vein furcate (Fig.
Hindwing : narrower than forewing, creamy white to grayish white, with pale orange apical zone; apex sharply produced, with small apical black spot; cilia well-fringed to base, fringe around apex creamy white, with broad, dark brown median band.
Male genitalia
: (Figs
Female (Figs
Female genitalia
: (Fig.
Japan (Kyushu, Ryukyus).
The name refers to its main host plant, Elaeocarpus zollingeri.
Elaeocarpus zollingeri (Elaeocarpaceae), Rhaphiolepis indica (Rosaceae).
(Fig.
(Figs
Although this new species was found on two different plants in the present study, it may be that E. zollingeri is mainly utilized as the host plant and occasional feeding on R. indica occurs when individuals happen to come into contact with this plant. See discussion.
Cnaphostola
sp. 1:
Holotype
: Japan – Ryukyu • 1 ♂; Okinawa Pref., Kunigami vill., Ookunirindo; 26, 27 May. 2000; T. Mano leg.; gen. slide no. KM-100; in
Paratypes
: Japan – Ryukyus [Kagoshima] • 1♂; Tokara Island, Nakanoshima Is, Takao; 15 Nov. 2018; K. Sakagami leg. • 1♂; Mt. Akatuti-yama, Uken-son vill., Amamioshima Is.; 21 May. 2013; S. Sameshima leg.;
Male genitalia of Thiotricha spp. A, B T. biformis A male genitalia, gen. slide no. KM-143 B phallus C, D T. angustella comb. nov. C male genitalia, gen. slide no. KM-106 D phallus E, F T. venustalis comb. nov. E male genitalia, gen. slide no. KM-1 F phallus G, H T. chujaensis (Park, 2016) comb. nov. G male genitalia, gen. slide no. KM-43 H phallus I, J T. elaeocarpiella sp. nov., holotype I male genitalia, gen. slide no. KM-88 J phallus K, L T. flavitermina sp. nov., holotype K male genitalia, gen. slide no. KM-100 L phallus. Scale bars: 0.4 mm (genitalia), 0.2 mm (phallus).
The external morphological character of this new species is quite similar to that of T. angustella; the wings of both species are shaded brown apically. However, the two can be differentiated based on the brightness of the color of the apical wing markings. In the new species, the wings feature a huge dark brown area distally, so it can be recognized easily at a glance. Likewise, in the male genitalia, the anellus lobe is a small membranous spherical lobe basally with a delicate, thread-like spine apically. Also, the size of apophyses and shape of the signum in the female genitalia are different to those of T. angustella. On the other hand, the male genitalia are quite similar to those of Thiotricha xanthodora Meyrick, 1923, which was described from Pyinmana, Myanmar, but differ in terms of the uniformly elongate valva, spherical-shaped and straight phallus. In T. xanthodora, the shape of the valva is dilated along 1/3 of its length apically whereas the phallus is slightly rounded basally and twisted forward.
Male (Figs
Head : shiny creamy white with appressed scales. Antennae filiform, basal segment rather large and elongate, white, sparsely speckled with brown scales on dorsal surface; flagellum creamy white on dorsal surface before middle, then entirely grayish brown beyond on both surfaces with extraordinarily long and fine cilia ventrally. Labial palps white, long, and recurved; first segment shortest, creamy white with brown scales medially on outer surface; second segment thickened with white scales evenly on both surfaces, as much as 2.5 times the length of the first; third segment as long as second segment, entirely grayish brown, considerably acute and slender.
Thorax and tegula : creamy white.
Legs : white; forefemur and tibia inwardly suffused with brown and white on outer surface; fore tarsus completely brown; mid femur and tibia entirely white; mid tarsus with brown; hind femur and tibia creamy white, with long, stiff, white bristles until the midpoint anteriorly, brown bristles on upper surface at ca. 1/4 beyond half of its length posteriorly, with white bristles ventrally; all tarsal segments dark grayish in color.
Forewing
: eleven veins, R3 + R4 stalked, M1 separate, R5 absent, anal veins furcate. (Fig.
Hindwing : narrower than forewing, brownish white, pale brown; cilia well-fringed around apex and then white to anterior rim of base.
Male genitalia
: (Figs
Female (Fig.
Female genitalia
: (Fig.
Japan (Ryukyus).
The name refers to the coloration of the forewing (yellow apically).
Unknown.
There are two alternative types of wing markings at the distal portion: the brown form collected from Okinawa-jima Island, and the yellow ones from Amami-oshima Island. As mentioned above, individuals with these wing color variations were separately collected from these two islands in the same season. Therefore, this difference may be due to geographical variation.
Female genitalia of Thiotricha spp. A T. biformis, gen. slide no. KM-145 B T. angustella comb. nov., with close up of signum, gen. slide no. KM-118 C T. venustalis comb. nov., gen. slide no. KM-52 D T. chujaensis (Park, 2016) comb. nov. with close up of signum, gen. slide no. KM-128 E T. elaeocarpiella sp. nov. with close up of signum, paratype, gen. slide no. KM-132 F T. flavitermina sp. nov. with close up of signum, paratype, gen. slide no. KM-55. Scale bars: 0.5 mm.
Biology of Thiotricha chujaensis (Park, 2016) comb. nov. and its host plant A habitat at Kyushu Univ., Fukuoka Pref. B host plant, Mallotus japonica (Euphorbiaceae) C larval portable case made of flower bud attached to the underside of the leaf D larva within the portable case E a young shoot of host plant F Infested part of the shoot G Larva inside of the petiole H Pupa exuviae I Resting posture of adult, lateral view.
In terms of male genitalia, T. chujaensis, T. elaeocarpiella, and T. flavitermina have a similar-shaped anellus lobe and gnathos, as some other Thiotricha species.
Judging from figures given by
In addition, we studied the pupal morphology, and found that characters of T. chujaensis and T. elaeocarpiella were congruent with those of T. prunifolivora as described by
Based on the reasoning above, we conclude that Japanese species of Cnaphostola should be treated in the genus Thiotricha, because they share morphological characters of the antenna, labial palps, wing venation and the anellus lobe in the male genitalia with the type species Thiotricha thorybodes Meyrick, 1886 and with some other species in that genus (Table
Species | Ciliation of male antenna (-) minute (+) rather long (++) extraordinarily long | Labial palps 2nd joint thickened with appressed scales, terminal joint as long as 2nd and acute | Wing venation R4 + M1 (6 and 8) stalked | Sternum VIII bifurcate | Anellus lobe in male genitalia |
---|---|---|---|---|---|
T. biformis | + | + | - | - | + |
T. venustalis comb. nov. | + | + | - | - | + |
T. pontifera | - | + | - | - | + |
T. attenuata | - | + | - | - | + |
T. flavitermina sp. nov. | ++ | + | - | - | + |
T. celata | ++ | + | - | - | + |
T. pancratiastis | ++ | + | - | - | + |
T. synodonta | ++ | + | - | - | + |
T. angustella comb. nov. | ++ | + | + | - | + |
T. chujaensis comb. nov. | ++ | + | + | - | + |
T. elaeocarpiella sp. nov. | ++ | + | + | - | + |
T. prunifolivora | ++ | + | + | - | + |
On the other hand, species of Thiotricha are also similar to those of Polyhymno.
In the present study, although we could not find any definite diagnostic character for separating each genus, we confirmed that the presence of anellus lobe in the male genitalia would provide one of the possible characters for Thiotricha which is also shared by all examined species. Furthermore, the pupal morphological characters also support the genus Thiotricha. In future studies, a molecular analysis would hopefully clarify the phylogenetic relationships between genera and species and solve the taxonomic problems of the generic delimitation.
Although Thiotrichinae are known to utilize plants of ten families (all in eurosids), the host range of each species is usually restricted to one genus or a few related genera (
In the present study we observed T. elaeocarpiella larvae making portable cases on two different unrelated host plants, Elaeocarpus zollingeri (Elaeocarpaceae) and Rhaphiolepis indica (Rosaceae), in Okinawa-jima Island and Kyushu. First, we discovered that this species made portable cases with parts of R. indica in May 2017 in Fukuoka, Kyushu (Fig.
Biology of Thiotricha elaeocarpiella sp. nov. and its host plant A host plant, Elaeocarpus zollingeri (Elaeocarpaceae) B host plant, Rhaphiolepis indica (Rosaceae) C larval portable case made of a young shoot of R. indica on the underside of the leaf D larval portable cases made with flower buds of E. zollingeri E close up of larval portable cases F different types of portable cases. Left arrow indicates the portable case made of E. zollingeri, right arrow indicates the portable case made of R. indica G larva within the flower bud H pupa exuviae I resting posture of adult, dorsal view.
However, whether the larvae of T. elaeocarpiella consumed both plants or accidentally shifted host plants is a controversial matter. Based on shape, the portable case found in May seems to be made of a young shoot of R. indica, and we also observed some holes on the leaf near the portable case. These holes are similar to the feeding trace made by T. prunifolivora, and the larvae of T. elaeocarpiella actually feed on the leaf of R. indica. Therefore, we concluded that this species can utilize both of these two plants. In T. chujaensis, we found that the larva penetrates the leaf bud (young shoot) of the host plant and then enters entirely and feeds inside (Fig.
Some Thiotricha species showing similar larval feeding habits have been identified.
Pupa of Thiotricha chujaensis (Park, 2016) comb. nov. A head, lateral view Arrow indicates many minute spines on vertex B seventh abdominal segment, ventral view Arrow indicates oval pad armed with a row of spines C seventh abdominal segment, dorsal view Arrow indicates a row of spines on both anterior and caudal margin D seventh abdominal segment, lateral view Arrow indicates oval pad armed with a row of spines and rows of tergal spines. Scale bar: 0.1 mm.
In T. elaeocarpiella, T. chujaensis, T. prunifolivora, and T. pancratiastis, the larval feeding mode and behavior are different among generations. These species occur in Honshu, Kyushu, and Ryukyus, have more than two generations a year, and utilize different parts of host plants that grow in temperate climates. On the other hand, T. venustalis, T. angustella, and some species of Thiotricha in the cool climate of the East Palearctic have one generation a year and one mode of feeding (
Hence, we presume that the larval feeding mode in Thiotricha usually involves the creation of portable cases on host plants, whereas the larvae of Polyhymno are leaf-spinners and leaf-webbers (
From the results of our taxonomic study together with an exploration of the biology of these species, the evolution of host plant utilization can be elucidated based on species relationships in this genus and its relatives. In future studies, it will be necessary to clarify the biology and DNA sequences of most species.
Pupa of Thiotricha elaeocarpiella sp. nov. A head, lateral view. Arrow indicates many minute spines on vertex B seventh abdominal segment, ventral view Arrow indicates oval pad armed with a row of spines C seventh abdominal segment, dorsal view Arrow indicates a row of spines on both anterior and caudal margin D seventh abdominal segment, lateral view Arrow indicates oval pad armed with a row of spines and rows of tergal spines. Scale bar: 0.1 mm.
We express our cordial thanks to Kyu Tek Park (The Korean Academy of Science and Technology) and Tatsuya Ueda (Regional Environmental Planning, Inc.) for providing us with valuable information on Thiotrichinae. We thank Utsugi Jinbo (