Japanese Journal of Systematic Entomology, 26 (2): 294–300. December 30, 2020.
A New Species of the Genus Laccophilus (Coleoptera: Dytiscidae) from Eastern Honshu, Japan, with Biological Notes
Kohei WATANABE 1) and Yuuki KAMITE 2) 1) Ishikawa Insect 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, taxonomy.
Introduction in the following collections: CKH: Collection of Kei Hirasawa, Iwaki, Japan The diving beetle 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.
December 30, 2020, JJSE 26 (2) 296 Watanabe, K. and Y. Kamite
(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.
December 30, 2020, JJSE 26 (2) A New Laccophilus from Eastern Honshu, Japan 297
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).