Elytra, Tokyo, New Series, 10 (1): 5–18
July 7, 2020

Japanese Weevils Associated with Ferns

5

Weevils (Coleoptera, Curculionoidea) Associated with Ferns in Japan
Hiroaki Kojima 1), Sae Furuhashi 1), Hiraku Yoshitake 2) and Futoshi Miyamoto 3)
1)

Laboratory of Entomology, Tokyo University of Agriculture, 1737 Funako, Atsugi,
Kanagawa, 243–0034 Japan
2)
Kyushu Okinawa Agricultural Research Center (Itoman residence), NARO, 820 Makabe,
Itoman, Okinawa, 901–0336 Japan
3)
Laboratory of Plant Diversity, Tokyo University of Agriculture, 1737 Funako, Atsugi,
Kanagawa, 243–0034 Japan
Abstract Weevils associated with ferns (pteridophytes) in Japan are studied taxonomically and enumerated with plant association records for the first time. Three families, four genera and seven species
are recognized including a new species, Caenosilapillus morimotoi Kojima et Furuhashi, sp. nov. Ten
genera and eleven species in six families of ferns are utilized by weevils as adult food plants.

Ferns (pteridophytes) are primitive plants that were already well represented during the Carboniferous Period, approximately 350 million years ago (mya) (Taaffe, 2002). The first weevils arethought to have appeared in the late Jurassic Period and to have undergone rapid diversification as theangiosperms began to diversify during the Cretaceous Period, approximately 100 mya (Oberprieler
et al., 2007). The association between weevils and ferns is known only in the more derived weevil
groups, such as Erirhinidae and Curculionidae. Consequently, it has been proposed that the association between weevils and ferns may have arisen secondarily, after having been associated primarily
with angiosperms (Oberprieler et al., 2007).
In Japan, approximately 700 taxa of ferns have been recorded to date, making this one of themost biodiverse groups for which information has been collected (Ebihara, 2010). Nonetheless, relatively little is currently known about the weevil fauna associated with ferns in Japan.
In this paper, we will enumerate the Japanese weevil taxa associated with ferns for the first time.
Although several curculionid species in the subfamily Cossoninae are known to associate with ferns(Kuschel et al., 2000), these taxa have been excluded from this treatment and are currently understudy. This manuscript is dedicated to the late Dr. Katsura Morimoto, who was a global authority on
weevil systematics.
Material and Methods
Standard technique for the examination of dry, pinned specimens were used. Classification system of weevils is followed Alonso-Zarazaga and Lyal (1999).
Specimens studied were based on the collections of the following institutions: ELKU (Entomological Laboratory, Kyushu University, Fukuoka); KUM (Kyushu University Museum, Fukuoka); NIAES (Institute for Agro-Environmental Sciences, NARO, Tsukuba); TUA (Tokyo University of Agriculture, Atsugi).

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Hiroaki Kojima, Sae Furuhashi, Hiraku Yoshitake and Futoshi Miyamoto

Enumeration with Description of a New Species
Family Dryophthoridae
Subfamily Cryptodermatinae
Cryptoderma Ritsema, 1885
Oxyrhynchus Schoenherr, 1823: c.1137 (type species: Calandra discors Fabricius, 1801; Orthoceri, Oxyrhynchides).
Cryptoderma Ritsema, 1885: 54 (revision; Curculionidae, Cryptoderminae); Alonso-Zarazaga & Lyal, 1999: 63 (cataloged;
Dryophthoridae, Cryptodermatinae).
See Alonso-Zarazaga & Lyal (1999) for other synonymy.

Remarks. This Oriental apterous genus currently constitutes its own subfamily. While little is
known about the biology of the genus, previous records from Japan suggest a strong association between this genus and ferns (Kojima & Miyamoto, 2020, in press).
1. Cryptoderma fortunei (Waterhouse, 1853)
Oxyrhynchus Fortunei Waterhouse, 1853: 172 (type locality: “China Boreali”).
Cryptoderma fortunei: Bovie, 1908: 2, fig.2; Morimoto, 1978: 114; 1984: 346, pl. 68, fig. 12; Ohno, 1992: 55 (bibliography);Lyal, 2011: 185 (cataloged); Alonso-Zarazaga et al., 2017: 238 (cataloged).

Specimens examined. Japan: Honshu. [Aichi-ken] 3 males, Inuyama-shi, Aichi, 13.IX.1981, T.
Nohira (KUM). [Fukui-ken] 1 male, Nakaikemi, Fukui, 25.VII.1995, O. Kishimoto (KUM). Shikoku. [Tokushima-ken] 1 male, Mt. Daisen-zan, Miyoshi-gun, 31.VII.1950, M. Chûjô (KUM). Kyushu. [Fukuoka-ken] 1 female, Wakitabaru, Kurate, 30.VII.1948, M. Yano, on sap of Ulmus sp.
(KUM); 1 female, Tashiro, Yame-gun, 16.VI.1953, Y. Miyatake (KUM); 1 ex., Mt. Fukuchi, Kokura
City, 9.VI.1948, T. Matsuda (KUM); 1 male, Mt. Inunaki, 23.VI.1970, S. Ogata (KUM); 1 male & 1
female, Mt. Abura, 29.VII.1970, S. Ogata (KUM); 1 female, Mt. Miikeyama, Ômuta-shi, 19.V.1973,
H. Kinoshita (KUM). [Nagasaki-ken] 1 male, Mt. Konpira, Nagasaki City, 26.VII.1953, S. Ikushima;
1 female, same locality, 30.VII.1954, S. Ikushima; 1 male, same locality, 55.-.-, Yamaishi (KUM); 1
male, Mt. Iwaya, Nagasaki City, 31.VIII.1955, Y. Nonaka; 1 male, same locality, 17.VII.1965, Y.
Nonaka (KUM); 1 male, Takashima, Nagasaki, Nishisonogi, 22.VII.1954 (KUM); 2 males & 2 females, Mt. Yahirodake, Sasebo-shi, 26.VI.1977, J. Okuma (TUA); 1 female, Mekuragaharu, Shikamachi-chô, 19.VI.1983, J. Okuma (TUA). [Tsushima Is.] 1 female, Hikage, Izuhara-chô, 2.VII.1983, J.
Okuma (TUA); 1 female, Waita, 17.VI.1991, Y. Okushima (TUA). [Ôita-ken] 1 male, Sobosan (Bungo), 29.VI.1932, Hori, Fujino & Cho; 1 male, same locality, 5.VII.1932, Hori, Fujino & Cho; 1 female, same locality, 14.VII.1932, Hori, Fujino & Cho (KUM). [Kumamoto-ken] 1 male, Iwano,
Higo, 5.V.1950 (KUM); 2 females, Tensui-cho, 31.VII.1988, K. Kido (KUM); 1 male & 3 females,
Yamatsukuri, Soyô-machi, 10.VII.1994, I. Ohtsuka (KUM); 42 exs., 12.VII.1994, I. Ohtsuka, fromgutter (KUM). [Kagoshima-ken] 1 male, Cape Sata, Ôsumi Penn., 2–5.V.1958, K. Morimoto (KUM).
Korea: Chejudo Is. 1 male & 1 female, Yongshil, Mt. Hallasan, 24.VII.1990, Y.-C. Yeol (KUM); 1
male & 1 female, Ora-dong, Cheju City, 26.VII.1990, K. Yoshizawa, by banana trap (KUM).
Distribution. Japan: Honshu, Ie-shima Isls., Oki Isls., Shikoku, Kyushu, Hirado-jima Is., Tsushima Is., Gotô Isls.; Korea, China.
Biology. Adults of this weevil were collected on Pteridium aquilinum (Warabi in Japanese;
Dennstaedtiaceae), Thelypteris torresiana var. clavata (Himewarabi in Japanese; Thelypteridaceae)
and Diplopterygium glaucum (Urajiro in Japanese; Gleicheniaceae) (Ohno, 1992). Adults were alsoJapanese Weevils Associated with Ferns

7

occasionally found feeding on the sap of trees and in fruit traps baited with banana and pineapple.
Remarks. This species is distinguished from the next species by having narrow oblique elytral
bands, maximally as broad as the distance between the punctures of the striae, and each band notreaching the suture.
2. Cryptoderma kuniyoshii Morimoto, 1978
(Fig. 27)
Cryptoderma kuniyoshii Morimoto, 1978: 106 (type locality: “Hateruma-mori, Iriomote Is.”); 1984: 346 (diagnosis & distribution); Tanikado, 1985: 6 (Okinawa-jima Is.); Hori, 1986: 234 (on Thelypteris acuminata); Hayakawa, 1988: 6 (Ishigaki-jima Is.); Yoshitake, 1997: 13 (Miyako-jima Is.); Lyal, 2011: 185 (cataloged); Alonso-Zarazaga et al., 2017: 238(cataloged).

Specimens examined. Japan: Ôsumi Isls. [Satsuma-Kuroshima Is.] 1 male & 4 females, Ôsato,
7–9.VIII.1990, K. Yoshizawa (KUM); 4 males & 7 females, same locality, 3–5.VII.2016, H. Kojima(TUA); 1 female, same locality, 11.IX.2016, H. Kojima (TUA); 1 female, Kaminakazato, 10.IX.2016,
H. Kojima (TUA); 4 males & 2 females, Sondô Ôsato-Katadomari, 5.VII.2016, H. Kojima (TUA); 3
males, same locality, 11.IX.2016, H. Kojima (TUA); 1 male & 6 females, same locality, 10.V.2017, H.
Kojima (TUA); 1 male & 1 female, Mt. Kamugoyama, 14.IX.2016, H. Kojima (TUA); 1 male, same
locality, 15.IX.2016, H. Kojima (TUA); 1 female, Nakazato-rindô (Kaminakazato-Katadomari),
15.IX.2016, H. Kojima (TUA); 2 males & 3 females, Mt. Yaguradake, 4–5.VII.2016, H. Kojima(TUA). Ryukyus. [Okinawa-jima Is.] 1 male, Izumi, 30.IV.1984, M. Tanikado (KUM); 1 ex., Namizato, Motobu-chô, 12.VI.2018, H. Yoshitake (NIAES); 1 ex., Kanekadan, Uruma-shi, 29.VI.2019,
H. Yoshitake (NIAES); 8 exs., Yamada, Onna-son, 3–4.VII.2019, H. Yoshitake (NIAES). [Ishigaki-jima Is.] 4 males & 1 female, Kabira, 17.VI.1996, T. Fukaishi, by pineapple trap (KUM); 1 male,
Mt. Yarabudake, 17–20.IV.1998, S. Ohmomo (KUM); 1 female, Mt. Omoto, 8.V.1990, T. Hanatani(TUA). [Iriomote-jima Is.] Holotype, male, Hateruma-mori, 5.X.1963, S. Kuniyoshi (ELUK); 1 male
& 1 female (paratypes), same data as the holotype (KUM); 1 female, Shirahama-rindô, 31.V.1977, J.
Okuma (TUA); 2 exs., Ôtomi-yûhodô, 2.IV.2019, H. Yoshitake (NIAES).
Distribution. Japan: Ôsumi Isls. (Satsuma-Kuroshima Is.), Ryukyus (isls. of Okinawa-jima, Miyako-jima, Ishigaki-jima and Iriomote-jima).
Biology. Adults of this weevil were collected on Diplopterygium glaucum, Microlepia strigosa(Ishikaguma in Japanese; Dennstaedtiaceae), Odontosoria chinensis (Horashinobu in Japanese; Lindsaeaceae) and Woodwardia prolifera (Hachijyôkaguma in Japanese; Blechnaceae) on Satsuma-Kuroshima Island during the day time (Kojima & Miyamoto, in press), and Thelypteris acuminata (Hoshida in Japanese; Thelypteridaceae) on the islands of Okinawa-jima and Iriomote-jima, where they wereusually found on the plant at night.
Remarks. Body varies from 8.3 to 16.7 mm in length. This species is distinguished from C. fortunei by broad oblique elytral band, much wider than the distance between the punctures of the striae,
and each band reaches the suture.
Family Erirhinidae
Subfamily Erirhininae
Caenosilapillus Chûjô et Morimoto, 1962
Caenosilapillus Chûjô & Morimoto, 1959: 147 (type species: Caenosilapillus babai Chûjô et Morimoto; Curculionidae, No-8Hiroaki Kojima, Sae Furuhashi, Hiraku Yoshitake and Futoshi MiyamotoFigs. 1–4. Dorsal habitus images of Caenosilapillus spp. — 1 & 2, C. babai Morimoto; 3 & 4, C. morimotoi sp.
nov. (1 & 3, male; 2 & 4, female; 1, Gumma-ken; 2, Fukushima-ken; 3 & 4, Yamanashi-ken).
tarinae, Orthocaetini); Morimoto, 1962 a: 345 (checklist; Curculionidae, Hyperinae, Notarini); 1962 b: 56 (in key; Hyperinae, Notarini, Orthocaetina); 1989: 505 (checklist; Curculionidae, Erirhininae); Alonso-Zarazaga & Lyal, 1999: 69(cataloged; Erirhinidae, Erirhininae, Erirhinini).

Redescription. Medium-sized (4.0–6.0 mm) apterous erirhinid Curculionoidea with exposed surface of body closely punctate and sometimes partly covered with amorphous incrustation or coating,each puncture bearing fine recumbent hairy scale, but often filled with incrustation. Elytra with yellowish brown recumbent lanceolate scales, which are condensed to form spots.
Head broader than long, forehead between eyes broader than base of rostrum, with frontal pit.
Eyes not convex from outline of head. Rostrum weakly curved, nearly as long as (male) or longer
than (female) pronotum, sides narrowest slightly before base, parallel-sided on median part andbroader than median part before antennal insertion. Mandibles each with two large and one external
small teeth, of which the last one is obscure in left mandible. Antennae inserted at or before apicalJapanese Weevils Associated with Ferns

9

Figs. 5–8. Dorso-lateral habitus images of Caenosilapillus spp. — 5 & 6, C. babai Morimoto; 7 & 8, C. morimotoi sp. nov. (5 & 7, male; 6 & 8, female; 5, Gumma-ken; 6, Fukushima-ken; 7 & 8, Yamanashi-ken).

third; scape not reaching base of rostrum and anterior margin of eye; funicle with basal two segments
elongate, 3–7th segments quadrate, at least 7th transverse; club visible three-segmented.
Prothorax weakly rounded laterally, subapical constriction weak, post-ocular lobes present andconcealing posterior margin of each eye when in repose. Scutellum absent. Elytra oblong-ovate,shoulder obsolescent; striae with large punctures, 7th and 8th striae obsolete on basal fourth of elytra,
10th stria obsoleting above 2nd segment of abdomen; odd intervals more or less costate. Pygidium
concealed. Legs with femora unarmed, isometric; tibiae distinctly mucronate, without spurs, withspiny setae on apical 2/3 along ventral margin; tarsi with 3rd segment bilobed; claws simple, free,each with minute seta.
Pro- and mesocoxal cavities continuous. Procoxae contiguous, lying posterior third of prosternum, anterior margin of prosternum weakly concaved. Mesocoxae almost contiguous. Metacoxae
reaching lateral margin of elytra, metepisternum very narrow. First and 2nd ventrites weakly depressed in male or inflated in female, disc of 3rd to 5th ventrites finely punctate and smooth, 5th ventrite with pair of hairy tufts on posterior margin. Metendosternite without lateral arms, anterior tendons widely distant.
Terminalia. Male: 8th sternite reduced to pair of small pigmentations without setae, and with apically forked spiculum relictum, spiculum gastrale Y-shaped. Dorsal plate of tegmen bilobed both posteriorly and anteriorly, manubrium straight. Median lobe with pair of orificial sclerites, tectum narrow,less than half as long as pedon, internal sac without any large sclerites, except for pair of pigmented
patches, extending beyond tip of apodemes. Female: 8th sternite Y-shaped. Spermatheca with curved
cornu, more or less developed ramus and undeveloped collum.
Remarks. This apterous genus is currently endemic to Japan, and belongs to the tribe Erirhinini.
Caenosilapillus was previously considered to be very rare and initially regarded as a soil-dwelling
species as the holotype of the type species was collected by shifting of litter (Morimoto, 1984, 1993).

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Hiroaki Kojima, Sae Furuhashi, Hiraku Yoshitake and Futoshi Miyamoto

However, an association between this genus and ferns was initially suggested by Oberprieler (2014)
based on personal communication with the first author, Kojima. Recently, Caenosilapillus weevils
have been collected from several localities on some ferns, mainly in the mountainous areas of easternJapan, east of the Kinki District. Further taxonomic study is required to clarify whether local speciation has occurred due to atrophy of the hind wings.
Chûjô and Morimoto (1959) compared this genus with Orthocaetes Germar, 1824, currently
placed in the curculionine tribe Styphlini (Alonso-Zarazaga & Lyal, 1999). However, there is no
phylogenetic relationship between these taxa and the closest relative of Caenosilapillus is currently
uncertain.
3. Caenosilapillus babai Chûjô et Morimoto, 1959
(Figs. 1, 2, 5, 6 & 9–18)
Caenosilapillus babai Chûjô & Morimoto, 1959: 148 (by monotypy; type locality: “Miyahisa, Niigata, Pref.”); Morimoto,
1984: 289, pl. 57, fig. 3 (by shifting of leaf-litter; Niigata, Yamagata); 1993: 22 (Niigata, Yamagata, Iwate); Caldara,
2011: 193 (cataloged) ; Alonso-Zarazaga et al., 2017: 112 (cataloged).

Redescription. M a l e and F e m a l e. Length: 4.2–5.3 mm (male); 4.2–5.7 mm (female).
Brownish black, antennae and tarsi, often legs dark reddish brown, elytra with yellowish brown scales
forming pair of spots on declivities of 3rd intervals and irregularly condensed to form smaller spots.
Head sparsely and finely punctate and smooth, forehead between eyes about 1.5 times as wide as
narrowest part of rostrum. Rostrum as long as or slightly longer than (male) or 1.25 times as long as(female) pronotum, dorsum with median keel on basal 2/3 and with punctured several shallow sulci
on each side, apical part sparsely with fine and shallow punctures. Antennae inserted at apical fourth(male) or third (female) of rostrum, scape a little longer than funicle, funicle with basal two segments
subequal in length, 1.5–2.0 times as long as wide, 3rd and 4th subequal in length, a little longer thanwide, 5th to 7th subequal in length, 5th and 6th as long as wide, 7th transverse; club as long as basal
three segments of funicle combined, 1st segment a little longer than 2nd.
Prothorax as long as wide, widest at apical third, dorsum closely with large punctures, punctures
become smaller near anterior margin. Elytra 1.6–1.7, rarely 1.5 times as long as wide, gently rounded
laterally and widest behind middle, sometimes subparallel-sided behind shoulders to apical third insmall individuals; striae with deep separated large punctures, punctures become smaller and striae become narrower towards apex; intervals uneven especially on costate odd intervals, 3rd interval tuberculate on declivity.
Specimens examined. Japan: Honshu. [Akita-ken] 1 male & 1 female, Dakigaeri-keikoku, Tazawako-machi, 31.VII.2006, I. Matoba (KUM). [Iwate-ken] 1 female, Getô-onsen, Waga-chô, 8.VI.1986,
Y. Takahashi (KUM); 1 female, Toyosawa-rindô, Hanamaki-shi, 8.VI.2007, I. Matoba (TUA). [Yamagata-ken] 9 males & 5 females, Arakawa River, Oguni-machi, 12.VI.2011, Y. Fujisawa (TUA); 2
males & 2 females, Kotamagawa Oguni-machi, 23.VIII.2019, H. Kojima (TUA); 1 male, same locality,
23.VIII.2019, S. Furuhashi (TUA). [Fukushima-ken] 13 males & 9 females, Misawa-yaeijyô, Yamato-chô, Kitakata-shi, 3.VIII.2016, Y. Fujisawa (TUA); 1 male & 5 females, same locality, 14.
VIII.2018, S. Shimamoto (TUA); 5 males & 4 females, same locality, 10.X.2019, H. Kojima (TUA).
[Gumma-ken] 1 female, Akayagawa, 22.VIII.1999, K. Takahashi (KUM); 2 females, Hôshi Spa(600m), Niiharu-mura, 19.X.2001, S. Nomura (KUM); 13 males & 5 females, Ichinokura, Minakami-machi, 8.VI.2008, H. Kojima (TUA). [Niigata-ken] Holotype, male, Miyahisa, 3.VI.1955, K. Baba
(ELKU); 1 male, Mt. Narumi, N-Echigo, 14.VI.1970, K. Baba (KUM); 3 males, Kamikawa-chô,Japanese Weevils Associated with Ferns

Figs. 9–26. Male and female terminalia, mesosternum and metendosternite of Caenosilapillus spp. — 9–18, C.
babai Morimoto (9–14, male; 15–18, female; 9–12, 15 & 17, Fukushima-ken; 13 & 18, Yamagata-ken; 14 &16, Gumma-ken); 19–26, C. morimotoi sp. nov. (19–24, male; 25 & 26, female; Yamanashi-ken). — 9 & 21,
Aedeagus and tegmen, lateral; 10 & 22, aedeagus, dorsal; 11 & 23, tegmen, dorsal; 12 & 24, sternite 8 andspiculum gastrale, ventral; 13 &14, median column of 8th sternite; 15 & 25, 8th sternite, ventral; 16–18, spermatheca; 19, mesosternum, ventro-lateral (mp: mesosternal process; mc: mesocoxal cavity); 20, metendosternite, dorsal; 26, ovipositor. Scale = 0.5 mm.

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Hiroaki Kojima, Sae Furuhashi, Hiraku Yoshitake and Futoshi Miyamoto

3.VI.2000, K. Takahashi (KUM); 1 male, Yomogisawa, Yuzawa-machi, 10.X.2019, S. Furuhashi(TUA).
Distribution. Japan: Honshu (Akita, Iwate, Yamagata, Fukushima, Gumma and Niigata-ken).
Biology. Adults of this species were collected on Arachniodes standishii (Ryômenshida in Japanese; Dryopteridaceae).
Remarks. Matoba (2008) recorded this species from Nara-ken, western Japan. However, basedon photographic evidence of the specimen, this record is considered to have been misidentified, andhis species is considered to be more closely affiliated with the following species or its allies. Taxonomic treatment of this specimen will be maintained until the material and additional specimens are
obtained.
4. Caenosilapillus morimotoi Kojima et Furuhashi, sp. nov.
(Figs. 3, 4, 7, 8, 19–26, 28 & 29)

Description. M a l e and F e m a l e. Length: 4.5–5.0 mm (male); 4.4–6.0 mm (female). Resembles to C. babai except prothorax widest at middle, elytra 1.5–1.6 times as long as wide, subparallel-sided behind shoulders to apical third, with yellowish brown lanceolate scales not condensed toform spots except on declivities of 3rd intervals, and median lobe with pedon roundly tapered apically.
Type series. Holotype: male. Japan: Honshu. [Yamanashi-ken] Kanayamadaira, Sutama-chô,16.VII.2018, S. Furuhashi (TUA). Paratypes. 3 males & 4 females, same data as the holotype (TUA);
1 male & 1 female, same locality as the holotype, 28.VI.2008, H. Kojima (TUA); 1 female, same locality as the holotype, 27.IX.2008, H. Kojima (TUA); 6 males & 8 females, same locality as the holotype, 23.VI.2013, H. Kojima (TUA); 1 male, same locality as the holotype, 15.X.2019, H. Kojima, by
Tullgren funnel (TUA); 1 male & 1 female, Nr. Mt. Gorisan, Sutama-chô, 3.X.2016, Y. Fujisawa(TUA); 2 males & 1 female, Nr. Mt. Mizugaki, Sumata-chô, 22–24.VII.2016, Y. Fujisawa (TUA).
Distribution. Japan: Honshu (Yamanashi-ken).
Etymology. This new species is named after the late eminent Japanese curculionologist, Dr. Katsura Morimoto.
Biology. Adults of this weevil were collected on Arachniodes standishii and Dryopteris crassirhizoma (Oshida in Japanese) in the family Dryopteridaceae.
Family Curculionidae
Subfamily Baridinae
Pteridobaris Morimoto et Yoshihara, 1996
Pteridobaris Morimoto & Yoshihara, 1996: 8 (in key), 27 (type species: Baris maritima Roelofs, 1875); Yoshihara, 2016:
11 (in key), 34.
See Yoshihara (2016) for other synonymy and diagnosis.

Remarks. This Oriental genus is currently monotypic, but several undescribed species are present in Southeast Asia (Morimoto & Yoshihara, 1996). Association of this genus with forked ferns
has been confirmed (Morimoto, 1984; Morimoto & Yoshihara, 1996; Yoshihara, 2016).
5. Pteridobaris maritima (Roelofs, 1875)
Baris maritima Roelofs, 1875: 181 (type locality: “Japon”); Morimoto, 1984: 309, pl. 61, fig. 3.

Japanese Weevils Associated with Ferns

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Figs. 27–30. Habitus photos of Japanese fern weevils. — 27, Cryptoderma kuniyoshii Morimoto on Woodwardia prolifera (Satsuma-Kuroshima Is.); 28 & 29, Caenosilapillus morimotoi sp. nov. on Arachniodes standishii (Yamanashi-ken); 30, Euthycus inaequalicollis Morimoto on Thelypteris acuminata (Ishigaki-jima Is.).
Pteridobaris maritima: Morimoto & Yoshihara, 1996: 28; Yoshihara, 2016: 35 (revision); Alonso-Zarazaga et al., 2017:
128 (cataloged).
See Yoshihara (2016) for other synonymy and diagnosis.

Specimens examined. 66 exs. collected from Mie-ken (Kumano-shi) and Wakayama-ken (Hikigawa-chô, Taiji-chô) of Honshu, Kagawa-ken (Mt. Zohzusan) and Kôchi-ken (Kuroson) of Shikoku,
Fukuoka-ken (Mt. Inoyama, Magaribuchi, Yame-gun, Mt. Wakasugi, Kôrasan, Mt. Hôman, Mt. Jôyama, Kumagahata), Nagasaki-ken (Mt. Yahirodake, Omura-shi), Kumamoto-ken (Ashikita) and Kagoshima-ken (Izashiki, Sata) of Kyushu (KUM & TUA).
Distribution. Japan: Honshu, Awajishima Is., Shikoku, Kyushu; China.
Biology. Adults of this weevil were collected on young shoots of Diplopterygium glaucum and Dicranopteris pedata (Koshida in Japanese; Gleicheniaceae) from April to July.
Subfamily Molytinae
Euthycus Pascoe, 1885
Euthycus Pascoe, 1885: 220 (type species: Euthycus macilentus Pascoe, 1885; Molytinae); Morimoto, 1982: 55 (in key); 97(revision of Japanese spp.; Hylobiinae, Hylobiini); Alonso-Zarazaga & Lyal, 1999: 195 (cataloged; Molytinae: Molytini: Molytina); Alonso-Zarazaga, 2013: 486 (cataloged).

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Hiroaki Kojima, Sae Furuhashi, Hiraku Yoshitake and Futoshi Miyamoto

Euthicus [sic!]: Heller, 1922: 10 (key to spp.).
Stenanchonus Voss, 1937: 263 (type species: Stenanchonus angustus Voss, 1937).

Remarks. Association of this apterous genus with ferns was recently reported by Yoshitake(2016). This genus is nocturnal. Host feeding and copulation on ferns occurs at night, with resting on
and in the ground occurring during the daytime. Thanatosis behavior is also observed frequently after
being caught or when resting in the ground during the daytime (Kojima et al., in press).
6. Euthycus japonicus Heller, 1922
Euthycus japonicus Heller, 1922: 11 (type locality: “Japonia septentrionali”); Morimoto, 1982: 97 (redescription with figures;
Is. Amami-Oshima); 1984: 330, pl. 65, fig. 10; Saitô, 1991: 14 (Kagoshima-ken); Yoshitake, 2009: 12 (Kumamoto-ken);Ôgai, 2016: 30 (Tokunoshima Is.); Alonso-Zarazaga, 2013: 486 (cataloged); Alonso-Zarazaga et al., 2017: 478 (cataloged).

Specimens examined. Japan: Kyushu. [Kumamoto-ken] 1 male, Hitoyoshi, 8.IX.2008, N. Take-da & Y. Matsubara, by pit-fall trap (NIAES). Ôsumi Isls. [Yakushima Is.] 1 male, Anbô-rindô (750m), 17.VII.2001, H. Hoshina, by shifting leaf-litter (KUM); 1 female, Hanyama, 250 m alt., 25.VIII–
28.IX.2007, T. Yamauchi et al., by Malaise trap (TUA). 2 males, Kankake, 220 m alt., 26.IX.–24.
X.2006, T. Yamauchi et al., by Malaise trap (TUA); 1 male, same locality, 27.X–28.XI.2006, T. Yamauchi et al., by Malaise trap (TUA); 1 male, same locality, 30.VII–25.VIII.2007, T. Yamauchi et al.,by Malaise trap (TUA); 1 male, Mt. Aikodake, 150 m alt., 25.IX–23.X.2006, T. Yamauchi et al., by
Malaise trap (TUA); 1 male, same locality, 26.X–27.XI.2006, T. Yamauchi et al., by Malaise trap
(TUA); 1 female, same locality, 2.V.–5.VI.2007, T. Yamauchi et al., by Malaise trap (TUA); 1 male,same locality, 2.XI–1.XII.2007, T. Yamauchi et al., by Malaise trap (TUA). Ryukyus. [Amami-Ôshima Is.] 1 female, Yuwan, 5.IV.1958, M. Takahashi (KUM); 1 male & 1 female, Mt. Yuwan, 16–18.
VII.1963, C. M. Yoshimoto (KUM); 2 females, same locality 30.VII.1963, L. Gressitt (KUM); 1 female, Sumiyô, 9.VIII.1963, T. Okada (KUM); 1 male, Chûô-rindô, nr. Kinsakubaru, 16–17.V.2007,
H. Yoshitake, on Ctenitis subglandulosa (NIAES); 1 male, Chinase, Naze-shi, 2.VII.2011, H. Sawada (TUA).
Distribution. Japan: Kyushu (Kumamoto-ken), Ôsumi Isls. (Yakushima Is. — new record),
Ryukyus (isls. of Amami-Ôshima and Tokunoshima).
Biology. An adult of this weevil was collected by the third author from Ctenitis subglandulosa(Katsumouinode in Japanese; Dryopteridaceae) on Amami-Ôshima Island. Adult weevils were alsocollected by Malaise traps on Yakushima Island.
Remarks. Body length (7.8–10.5 mm; 6.5–8.7 mm in E. inaequalicollis) overlaps with next species, E. inaequalicollis, but antennae with the 7th segment of the funicle trapezoidal, pronotum with a
medial irregular carina on apical two-thirds, and elytra with the 3rd and 5th intervals convex with
dense granules in this species. As the examined specimens from Kyushu and Yakushima Island seemto be slightly different from those from the islands of Amami-Ôshima and Tokunoshima, further study
is needed to confirm their taxonomic identity.
7. Euthycus inaequalicollis Morimoto, 1982
(Fig. 30)
Euthycus inaequalicollis Morimoto, 1982: 98 (type locality: “Okinawa”); Matoba, 1983: 7 (Yonaguni-jima Is.); Morimoto,
1984: 330; Hori, 1986: 229 (on Thelypteris acuminata); Alonso-Zarazaga, 2013: 486 (cataloged); Yoshitake, 2016: 45(biology); Alonso-Zarazaga et al., 2017: 478 (cataloged).

Japanese Weevils Associated with Ferns

15

Table 1. Adult host plants of Japanese fern weevils.

Specimens examined. Japan: Ryukyus. [Okinawa-jima Is.] Holotype, male, Okinawa, VII.1960,
S. Kuniyoshi (ELKU); 1 ex., Yonahadake, 29.V.1978, H. Makihara (KUM); 6 males & 3 females,
Mt. Nagodake, Nago-shi, 16.VIII.2019, H. Yoshitake (NIAES). [Ishigaki-jima Is.] 1 female, 1983,
Masaki (paratype; KUM); 1 female, Mt. Omotodake, 25–30.IV.1997, K. Takahashi (KUM). [Iriomote-jima Is.] 2 males, 8.VII.1995, K. Takahashi (KUM); 1 male & 1 female, Shirahama-rindô,30.V.1998, K. Takahashi (KUM); 1 male, Airagawa, 18.V.2010, K. Akita (TUA). Taiwan. 1 male,
Hungyeh Wenchuan, Hualien Hsien, 13.VI.1976, H. Makihara (paratype; KUM).
Distribution. Japan: Ryukyus (isls. of Okinawa-jima, Ishigaki-jima, Iriomote-jima and Yonaguni-jima); Taiwan.
Biology. Adults of this weevil were collected on leaves of Thelypteris acuminata (Thelypteridaceae) at night all year around.
Remarks. This species is distinguished from E. japonicus by having antennae with the 7th segment of the funicle subglobular, pronotum with a fine median carina along almost entire length except
at the base, and elytra with the 3rd and 5th intervals costate at the base.
Discussion
Weevil associations with ferns
Pteridophagy, or fern-feeding, is not very common among weevils and the number of lineages
that are monophagous or oligophagous with respect to pteridophytes is restricted. These lineages are
members of Erirhinidae and Curculionidae (i.e., Baridinae, Cyclominae and Molytinae). In Erirhinidae, the Palaearctic genus Grypus Germar (Erirhinini) is known to associate with horsetail, Equisetum (Equisetaceae), and the New World genera Cyrtobagous Hustache and Stenopelmus Schoenherr(Tanysphyrini (= Stenopelmini)) with water fern, Salvinia, and aquatic fern, Azolla (both in Salviniaceae), respectively (Oberprieler, 2014). In Curculionidae, the Oriental baridine genus Pteridobaris is
known to be associated with forked ferns, Gleicheniaceae (Yoshihara, 2016), and the Neotropical16

Hiroaki Kojima, Sae Furuhashi, Hiraku Yoshitake and Futoshi Miyamoto

genera Lamprobaris Champion and Lissobaris Champion (Madopterini) with ferns, but which fern
species is uncertain (Prena et al., 2014). In Cyclominae, the Australian genus Neosyagrius Lea (Notiomimetini, formerly in Rhythirrhinini) is known to be associated with maiden-hair fern, Adiantum(Pteridaceae) (Marshall, 1922). In Molytinae, Gondwanan genera, such as Megacolabus Broun(New Zealand), Rystheus Broun (New Zealand), Syagrius Pascoe (Austaralia) and Germainius Kuschel (Chile) (all in Phrynixini), are known to be associated with ferns (Lyal, 2014).
In this study, Cryptoderma (Dryophthoridae), Caenosilapillus (Erirhinidae, Erirhinini), and Euthycus (Curculionidae, Molytinae, Molytini) are newly enumerated as fern weevils. Cryptoderma is thefirst representative of Dryophthoridae known to be associated with ferns. The family is mainly associated with terrestrial monocotyledons, such as palms, bananas, orchids and grasses (Anderson & Marvaldi, 2014). Caenosilapillus is the third representative of Erirhinidae known to be associated withferns. This family is also mainly associated with monocotyledons, particularly semiaquatic and aquatictaxa (Oberprieler, 2014). The phylogenetic affinity of Caenosilapillus is uncertain, but the genus is
not considered to be related to other erirhinid genera associated with ferns. Euthycus is the second
member of the curculionid subfamily Molytinae known to be associated with ferns. This genus is oneof the most taxonomically diverse weevil subfamilies and include the majority of the wood-boring taxa
(Oberprieler et al., 2007); the biological traits of this subfamily are also very diverse. Euthycus is notconsidered to be related to Gondwanan fern weevil genera of Phrynixini mentioned above.
All of the associations between the aforementioned weevil taxa and ferns are regarded as having
occurred secondarily, that is, after a host shift from their ancestral association with angiosperms, most
likely from monocotyledons, as was proposed by Oberprieler et al. (2007) and Oberprieler (2014).
Further, this association with ferns may have evolved independently in each taxon.
Association between Japanese weevils and ferns
In Japan, the association between weevils and ferns is recognized in three families, four generaand seven species. The adults of these taxa utilize ten genera and eleven species in six families offerns as host plants (Table 1). A wide range of fern families (five of six families) are utilized by the
dryophthorid genus Cryptoderma, while the hosts utilized by other weevil groups is restricted to one
or two fern families.
Regarding the larval biology of the Japanese weevil taxa, no information is available on larval
habitat except that the baridine weevil Pteridobaris maritima may be a stem-borer. Due to their adultbody size of fern weevils, which can reach 10.0–17.0 mm in length, the underground parts of ferns,
such as the underground stem (rhizome) may serve as their habitat. In addition to their cryptic larval
habitats, the nocturnal behavior of these species, certainly in Euthycus species complicates elucidation
their biology. Further study will be required in order to thoroughly understand the relationship between weevils and ferns.
Lastly, except for species of Pteridobaris, three of the four Japanese weevil genera that are
known to be associated with ferns are apterous. Although the reason for this is currently uncertain, it
may be attributed to the preference of ferns for stable humid forest habitats.
Acknowledgments
HK thanks Dr. M. Maruyama, Mr. N. Tsuji and Mr. S. Imada of the Kyushu University Museum, Fukuoka for their kind care during his visit. The authors thank two anonymous referees for theirvaluable suggestions. This study was supported in part by a research grant from TUA (to HK andFM).

Japanese Weevils Associated with Ferns

要
小島弘昭・古橋紗瑛・吉武

啓・宮本

17

約

太：日本産のシダを利用するゾウムシ類（鞘翅目ゾウムシ上科）．

— 日本におけるシダ植物利用のゾウムシをリストアップするとともに，成虫の加害植物記録をまとめた．イネゾウムシ科の 1 新種フタホシニセイネゾウムシ Caenosilapillus morimotoi Kojima et Furuhashi, sp. nov.
を含む，3 科 4 属 7 種のゾウムシを確認し，計 6 科 10 属 11 種のシダ植物を成虫が利用していることが明らかとなった．これらゾウムシ類のシダ植物への適応は，被子植物からの二次的な寄主転換の結果と考えられている．

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Manuscript received 29 February 2020;
revised and accepted 14 May 2020.