Japanese Journal of Systematic Entomology, 26 (2): 294–300. December 30, 2020.

A New Species of the Genus Laccophilus (Coleoptera: ) from Eastern Honshu, Japan, with Biological Notes

Kohei WATANABE 1) and Yuuki KAMITE 2) 1) Ishikawa Museum, Inu–3, Yawata-machi, Hakusan-shi, Ishikawa, 920–2113 Japan; e-mail: [email protected] 2) Nagoya City Public Health Research Institute, Anagahora 2266–132, Shimoshidami, Moriyama-ku, Nagoya, 463–0003 Japan; e-mail: [email protected]

Abstract Laccophilus hebusuensis Watanabe et Kamite, sp. nov. is described from the eastern part of Honshu, Japan. Laccophilus hebusuensis Watanabe et Kamite, sp. nov. is similar to L. kobensis Sharp, 1873, but is distinguishable from the latter by the fol- lowing characteristics: body darkish brown and penis not swollen at apical 1/6 in dorsal view. Under laboratory rearing conditions, Laccophilus hebusuensis Watanabe et Kamite, sp. nov., collected from the type locality, laid eggs singly into the main axes of Pogostemon sp. (Lamiaceae). The developmental stadium for each immature stage was as follows: egg, within 6 days; 1st instar larva, 3–4 days; 2nd instar larva, 2–5 days; 3rd instar larva, 3–8 days; emergence from the water to pupate, 6 days; and exiting the pupal chamber, 10–11 days. Key words: egg, immature stage, Laccophilus kobensis species group, larva, .

Introduction in the following collections: CKH: Collection of Kei Hirasawa, Iwaki, Japan The diving genus Laccophilus Leach, 1815 CKW: Collection of Kohei Watanabe, Nomi, Japan (Coleoptera, Dytiscidae) has been known 285 species across CYI: Collection of Yasuyuki Iwata, Tokorozawa, Japan the world (Nilsson & Hájek, 2020). In Japan, 12 species of the CYK: Collection of Yuuki Kamite, Nagoya, Japan genus have been recorded (Mori & Kitayama, 2002; Kamite et EUMJ: Ehime University Museum, Matsuyama, Japan al., 2005; Watanabe & Kamite, 2018; Nakajima et al., 2020). IIM: Ishikawa Insect Museum, Hakusan, Japan The Japanese species of the L. kobensis species group have NMNS: National Museum of Nature and Science, Tsukuba, been reexamined by Kamite et al. (2005) and Watanabe and Japan Kamite (2018). In this series of studies, Kamite et al. (2005) TPM: Tochigi Prefectural Museum, Utsunomiya, Japan pointed out that Laccophilus kobensis Sharp, 1873 has three types of the male genital structures (types 1–3). Watanabe and Rearing study Kamite (2018) revealed that the types 1 and 2 are L. kobensis Three adults (one male and two females) were collected and L. yoshitomii Watanabe et Kamite, 2018, respectively. from the type locality (Hebusu-pond, Kamikawauchi, However, the type 3 (sensu Kamite et al., 2005) has not been Kawauchi-mura, Futaba-gun, Fukushima Prefecture, Japan), studied taxonomically. on April 24, 2020 by Kei Hirasawa. All the individuals were As a result of our research with specimens of L. kobensis reared in a plastic rearing cup (13 cm in diameter, 10 cm in and its related species in Japan, we concluded that the type height, and approximately 7 cm in water depth) at the Ishikawa 3 (sensu Kamite et al., 2005) is an independent species. We Insect Museum, Hakusan, Ishikawa Prefecture, Japan, from describe it here as a new species. April 29, 2020. First author placed Pogostemon sp. ‘dassen’ (Lamiaceae) in the rearing cup, and the set-up was maintained Material and Methods at 26°C with 9 h of light (from 8:15 am to 5:15 pm, JST) and 15 h of darkness (9 L:15 D). Frozen chironomid larvae were Morphological study provided to the adults as prey every 2–3 days. The cup was Specimens were observed using stereoscopic microscopes checked every day. The date and developmental stages were (Nikon SMZ-745 and SMZ-1000 with ED Plan 2×) and recorded for any larvae that were found. For the eggs we scanning electron microscopes (SEM; HITACHI Miniscope® recorded the oviposition locations and situation by means of TM3030Plus). The photographs of the habitus were taken photography. Photographs were captured using a Nikon D500 using a Nikon D500 digital camera with the Laowa ULTRA digital camera equipped with a Nikon AF-S VR MICRO- MACRO 25 mm f/2.8 2.5–5× lens. Photographs of the penis NIKKOR 105 mm f/2.8G ED and Laowa ULTRA MACRO and parameres were taken using a Nikon SMZ-1000 with ED 25 mm f/2.8 2.5–5× lens. Multiple digital photographs were combined by focus stacking, using the digital image processing Multiple digital photographs were combined by focus stacking, software Zerene Stacker version 1.04 for Fig. 10G. using the digital image processing software Zerene Stacker Nineteen larvae were transferred to plastic larval cups (8 version 1.04 (Zerene Systems LLC, USA) for Figs. 1–6. cm in diameter, 4 cm in height, ca. 5 mm water depth), and Abbreviations: were then reared individually in the cups. Live water fleas EW: maximum width of elytra and chironomid larvae, from cultures in the Ishikawa Insect TL: anterior margin of clypeus to posterior margin of elytra Museum were used as larval food. Plastic pupation cups (the The mean and standard deviation of the measurements are same size as larval cups) with had crushed and moistened peat indicated in parenthesis after the ranges. moss (1 cm in depth) provided as a pupation medium. Third Type specimens and the material examined are deposited instar larvae were carefully placed in the pupation cups when

Ⓒ Japanese Society of Systematic Entomology A New Laccophilus from Eastern Honshu, Japan 295 they stopped eating prey and began walking without stopping. Taxonomy The dates of molting, transition to the pupation medium, and emergence of new adults were recorded in detail. Laccophilus hebusuensis Watanabe et Kamite, sp. nov. [Japanese name: Hirasawa-tsubu-gengorô]

Figs. 1–7. Laccophilus hebusuensis Watanabe et Kamite, sp. nov. ––––– 1, Holotype, male; 2, paratype, female; 3–4, penis; 5, left paramere; 6, right paramere; 7, living specimen. ––– 1–2, 4–7, from the type locality; 3, from Kawayatsu, Kimitsu-shi, Chiba Pref. ––– 1–4 & 7, Dorsal view. Photographs by Kohei Watanabe.

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(Figs. 1–8 & 10) Type material Kamikawauchi, Kawauchi-mura, Futaba-gun, Fukushima Laccophilus kobensis Sharp, 1873: Kamite et al., 2005: 620 Pref., Japan, 24.IV.2020, K. Hirasawa leg. Paratypes: [Type 3 of Fig. 12; misidentification]; Watanabe and EUMJ, IIM), same locality as for the holotype, 16.VI.2019,

Fig. 8. SEM photographs of Laccophilus hebusuensis Watanabe et Kamite, sp. nov. ––– A & B, Habitus; C, medial surface of left elytron; D, metacoxal process; E & F, abdomen, comparison of short grooves of abdominal ventrites 6 (E, male; F, female). ––– A & C, Dorsal view; B, D–F, ventral view. Photographs by Yuuki Kamite.

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Fig. 9. Distribution map of Laccophilus hebusuensis Watanabe et Kamite, sp. nov., L. kobensis Sharp, 1873, and L. yoshitomii Watanabe et Kamite, 2018. ––– Triangle, L. hebusuensis; square, L. kobensis; circle, L. yoshitomii. Data from Watanabe and Kamite (2018), Mori and Wakimura (2019), Watanabe and Hoshina (2019), Uchida and Watanabe (2019), Watanabe et al. (2019), and Iwata et al. (2019).

while alive), densely microreticulate in integument. Anterior Futaba-machi, Futaba-gun, 29.V.2010, K. Hirasawa leg.; 1 outline not margined. Apical 1/2 of antennomere 11 darkish. Apical 1/5 of maxillary palpomere 4 darkish (Figs. 1 & 7). Pronotum gently convex, about 2.7 times as wide as long, densely microreticulate in integument, medial part slightly dent, yellowish brown, middle yellowish green (only while alive), numa, Kiwadajima, Imaichi-shi, 6.V.1991, K. Satoh leg.; 2 middle of anterior and posterior margins darkish (Figs. 1 & 7). Elytra gently convex, about 1.4 times as long as wide, widest at basal 2/5, darkish brown, densely microreticulate in integument; each elytron with six dark vittae; 1st sutural vitta longest from base to apex, 2nd from basal 1/5 to near apex, 3rd TPM), alt. ca 510 m, Takakuhei, Nasu Town, 23.IX.2014, from basal 1/10 to apical 1/10, 4th from basal 1/10 to apical 1/10, 5th from base to apical 1/10, 6th inarticulate (Figs. 1, 7 & 8C). Mawaritani, Takakukou, Nasu-machi, 27.IV.1991, K. Satoh Ventral aspect: Darkish brown. Metacoxal process sparsely pubescent (Fig. 8D). Abdomen densely striate (Fig. 8E); two parallel, densely setiferous puncto-striae in middle of ventrite 6 (Fig. 8E); strongly lustrous. river, Kawamura, funyu, Shioya-machi, 25.VIII.1995, K. Legs: Fore and middle legs yellowish brown, hind legs adhesive setae (Fig. 1). Male genitalia: Penis (Figs. 3–4): Sides gradually spread 11.XI.1990, S. Ohmomo leg. from apical 1/6 to base in dorsal view; strongly curved from Non-type material base to apex in lateral view; apical 1/4 curved outside; apical 1/6 IIM), Kawayatsu, Kimitsu-shi, 11.III.2020, S. Yamasaki leg.; and 1/2 slightly swollen; apex with diagonal dent in dorsal view, not forming a crest. Parameres asymmetrical. Right paramere Description. M a l e. Dorsal aspect: Body broadly oval, (Fig. 6) squamous, with a short seta near apex. Left paramere gently convex, about 1.8 times as long as wide; almost darkish (Fig. 5) crescentiform, wides in middle, with a long seta (about brown, weakly lustrous (Figs. 1, 7 & 8A). 2/5 the length of left paramere) near the apex. Head almost yellowish brown, middle yellowish green (only F e m a l e: Externally similar to as male but pro- and

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Fig. 10. Laccophilus hebusuensis Watanabe et Kamite, sp. nov. ––– A, Two eggs laid in Pogostemon instar larva; D, third instar larva; E, third instar larva immediately before seeking pupation site; F, third instar larva preying on a living chironomid larva; G, pupa in a pupal chamber; H, newly emerged adult emerging on the soil surface. Scale bars: 1.0 mm for A–G. Photographs by Kohei Watanabe.

December 30, 2020, JJSE 26 (2) A New Laccophilus from Eastern Honshu, Japan 299

Table 1. Character matrix of Laccophilus kobensis species group. Character states and distribution are corded as the following alphabet, A: apex; Ab: absent; An: angulate; As: apical sixth; Bt: basal transverse black band; C: clarity; Cr: crest; Do: dorsal lateral view; Ne: not extended to apex; Ns: not swollen; P: present; Ry: Ryukyu Isls.; S: small; Sh: Shikoku; Sl: slender; Sw: swollen; Tl: total length; Ts: Tsushima Isls.; V: vague; Vi: vitta. elytra penis species/characters Tl distribution in Japan references Bt Vi Fv AsLa AsDo ADl L Ab V Ab Sl Ns Sl Hk, Hn, Sh, Ky, Ry Kamite . (2005) L Ab C Ne An Ns Sl Hn Kamite . (2005) S P C E Sl Sw Sl Hn, Sh, Ky, Ts, Ry Watanabe & Kamite (2018) L Ab C Ne Sl Ns Sl Ry Kamite . (2005) S P C Ne An Ns Sl Hn Kamite . (2005) S P C Ne Sl Ns Cr Hn, Sh, Ky Watanabe & Kamite (2018) S P C E Sl Ns Sl Hn present study

Diagnosis. Laccophilus hebusuensis Watanabe et Kamite, 2 & 8B). Sparce punctures with setae in middle of ventrite 6 sp. nov. is similar to L. kobensis and L. yoshitomii, but can be (Fig. 8F). distinguished from the latter two by the following combination Measurement data and ratios. TL, males (n = 8) 3.69–3.92 of characteristics: body darkish brown (yellowish brown in (3.77 ± 0.08) mm, females (n = 10) 3.69–3.91 (3.77 ± 0.07) L. kobensis and L. yoshitomii); sutural vitta of each elytron mm; EW, males (n = 8) 2.09–2.25 (2.15 ± 0.05) mm, females extended to apex (Figs. 1–2 & 7; Table 1) (not extended to (n = 10) 2.11–2.20 (2.15 ± 0.03) mm; TL/EW, males (n = 8) apex in L. yoshitomii); penis not swollen at apical 1/6 in dorsal 1.69–1.82 (1.76 ± 0.04) mm, females (n = 10) 1.73–1.82 (1.75 view (swollen at apical 1/6 in L. kobensis) (Figs. 3–4; Table ± 0.03) mm. 1). In some individuals the elytral vittae may be not well Distribution. Japan (eastern part of Honshu) (Fig. 9). developed, so the elytral vittae should be carefully used for Biological notes. Laccophilus hebusuensis Watanabe et Kamite, sp. nov. has been collected mainly from eastern Notes. From the results of this report and Watanabe and part of Honshu (Fig. 9), and has not been collected with L. Kamite (2018), the male genital structures mentioned by kobensis or L. yoshitomii in the same locality. Kamite et al. (2005) may be organized as follows: the type The eggs were laid singly into the main axes of Pogostemon 1 is L. kobensis; the type 2 is L. yoshitomii; the type 3 is L. sp. (Fig. 10A). The egg stadium was within 6 days. All larvae hebusuensis Watanabe et Kamite, sp. nov. However, the type 2 ate live chironomid larvae (Fig. 10F) and water fleas in the hatching day. The stadium of each developmental stage was as et al., 2005) could be L. kobensis. follows: 1st instar (Fig. 10B), 3–4 days (mean ± SD = 3.2 ± 0.4 The body length and penis size of L. hebusuensis Watanabe days, n = 19); 2nd instar (Fig. 10C), 2–5 days (3.8 ± 0.8 days, et Kamite, sp. nov. from Chiba Prefecture were smaller than the n = 19); 3rd instar (Fig. 10D–F), 3–8 days (5.8 ± 1.4 days, n = population from the type locality (Figs. 3–4). 19). The total larval stadium was 10–15 days (12.8 ± 1.7 days, n = 19). The body of the third instar Laccophilus hebusuensis Acknowledgements Watanabe et Kamite, sp. nov. larvae turned green two days We express our sincere gratitude to Dr. Hiroyuki before seeking a pupation site, the same as L. nakajimai Yoshitomi (EUMJ) and Dr. William D. Shepard (University Kamite, Hikida et Satô, 2005 (Watanabe, 2019). However of California) for a critical reading of the manuscript, Mr. Kei the body color is lighter than L. nakajimai (Fig. 10E). After Hirasawa (Aquamarine Inawashiro Kingfishers Aquarium), transitioning to land, the larvae dug into the pupation medium, Dr. Takashi Kurihara (Tochigi Prefectural Museum), Mr. made a pupal chamber, and pupated. One pupa was obtained by Yasuyuki Iwata (Japan Institute of Insect and Fungal Damage dissecting a pupal chamber three days after (Fig. 10G) it was to Cultural Properties), Mr. Daiki Uchida (NPO birth), Mr. made. Adult emergence was observed six days (n = 1) after the Shun Yamasaki, Mr. Katsumi Akita, Dr. Toshimasa Mitamura pupal chamber was made. The period staying a pupal chamber (Fukushima Agricultural Technology Centre Hama-dori was 10–11 days (10.3 ± 0.5 days, n = 17). All the adults Research Centre), Mr. Shigeyuki Yoshii (Fukushima Insect which were moved to the larval cups began to feed on frozen Society), Mr. Takamitsu Yoshino (Futaba Town Board chironomid larvae from the day they entered the water. of Education), Mr. Osamu Inaba (Iitate Village Board of The specimen collected in Tochigi Prefecture on June 25, 1988 was teneral, and the total immature stadia, under of specimens and collecting, Dr. Ryota Saiki, Mr. Masataka laboratory conditions, was 21–25 days (23.0 ± 1.9 days, n = Suda and Mr. Wataru Yoshida at the Ishikawa Insect Museum 17), suggesting that the reproductive season of Laccophilus hebusuensis Watanabe et Kamite, sp. nov. is from spring to larval stages, Dr. Shûhei Nomura (NMNS) for his consenting early summer. to deposit the specimen in the Museum, the whole staff of Etymology. The species name hebusuensis is derived from the Ishikawa Insect Museum for showing great cooperation the type locality "Hebusu-numa" of this species. during this research.

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References Version 1.I.2020. http://waterbeetles.eu/documents/W_CAT_ Dytiscidae_2020.pdf (downloaded on 26 April 2020). Iwata, Y., K. Arai, T. Iwata & K. Watanabe, 2019. [A new record of Uchida, T. & K. Watanabe, 2019. [A new record of Laccophilus Laccophilus yoshitomii Watanabe et Kamite, 2018 (Coleoptera, yoshitomii Watanabe et Kamite, 2018 (Coleoptera, Dytiscidae) Dytiscidae) from Saitama Prefecture, Japan, and deleting L. from Nagano Prefecture, Japan] Sayabane, New Series, (34): kobensis Sharp, 1873 records] Sayabane, New Series, (35): 28. (In Japanese.) 46–47. (In Japanese.) Watanabe, K., 2019. Ecological notes on Laccophilus nakajimai Kamite, Y., N. Hikida & M. Satô, 2005. Notes on the Laccophilus Kamite, Hikida & Satô, 2005 (Coleoptera, Dytiscidae). Elytra, kobensis species-group (Coleoptera, Dytiscidae) in Japan. Tokyo, (n. ser.), 9: 279–283. Elytra, Tokyo, 33: 617–628. Watanabe, K., H. Fujimoto, T. Dejima & Y. Kitagawa, 2019. [A Mori, M. & A. Kitayama, 2002. Dytiscoidea of Japan (2nd edition). new record of Laccophilus yoshitomii Watanabe et Kamite, 231 pp. Bun-ichi Sogo Shuppan, Tokyo. (In Japanese, with 2018 (Coleoptera, Dytiscidae) from Shikoku, Japan] English book title.) Sayabane, New Series, (34): 64. (In Japanese.) Mori, M. & R. Wakimura, 2019. [Records of Laccophilus Watanabe, K. & H. Hoshina, 2019. [A new record of Laccophilus yoshitomii Watanabe et Kamite, 2018 (Coleoptera, Dytiscidae) yoshitomii Watanabe et Kamite, 2018 (Coleoptera, Dytiscidae) from Kobe-shi, Hyogo Prefecture, Japan] Gekkan-Mushi, from Fukui Prefecture, Japan] Sayabane, New Series, (34): 18. (580): 40–42. (In Japanese.) (In Japanese.) Nakajima, J., M. Hayashi, K. Ishida, T. Kitano & H. Yoshitomi, Watanabe, K. & Y. Kamite, 2018. A new species of the genus 2020. Aquatic Coleoptera and Hemiptera of Japan, 351 pp. Laccophilus (Coleoptera, Dytiscidae) from Japan. Elytra, Bun-ichi Sogo Shuppan, Tokyo. (In Japanese, with English Tokyo, (n. ser.), 8: 417–427. book title.) Nilsson, A. N. & J. Hájek, 2020. A World Catalogue of the Family [Received: July 22, 2020; accepted: November 22, 2020] Dytiscidae, or the Diving (Coleoptera, Adephaga).

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