Notostomum cyclostomum from a deep-sea fish Biogeography 19. 167–170. Sep. 20, 2017 Notes on the preimaginal stages of the ground beetle Chlaenius (Epomis) nigricans Wiedemann, 1821 (Coleoptera: Carabidae) Kôji Sasakawa1,2* 1 Laboratory of Zoology, Department of Science Education, Faculty of Education, Chiba University, 1-33 Yayoi-cho, Inage-ku, Chiba-shi, Chiba, 263-8522 Japan 2 Department of General Systems Studies, Graduate School of Arts and Sciences, The University of Tokyo, 3-8-1 Komaba, Meguro-ku, Tokyo, 153-8902 Japan Abstract. The carabid beetle Chlaenius (Epomis) nigricans Wiedemann, 1821 was reared in the laboratory to investigate its preimaginal stages. Each egg was enclosed in mud and placed on a soil surface. Larvae fed ectoparasitically at all instars on two anuran species provided, Bufo japonicus Temminck & Schlegel, 1838 (Bufonidae) and Pelophylax nigromaculatus (Hallowell, 1861) (Ranidae), and reached adulthood. All of the instars exhibited color variability; however, the color pattern of the first instar differed from that of two previ- ously examined Epomis species. Key words: Chlaenius circumscriptus, Chlaenius dejeani, life history, larval feeding habits, color variability Epomis Bonelli, 1810 (Coleopera: Carabide), 2007) are available. This short communication reports comprising approximately 20 species, is a subgenus additional notes on the preimaginal stages of C. nigri- of Chlaenius Bonelli, 1810 (Kirschenhofer, 2003) and cans, as revealed in a laboratory rearing experiment. is mainly distributed in the Afrotropical and Oriental Laboratory rearing began on July 20, 2010, with regions (Yanai et al., 2015). This group includes two females collected from Mt. Inari, Numanotawa, species whose larvae feed exclusively on anurans in Nasushiobara-shi, Tochigi Prefecture, Japan, during an ectoparasitic manner (Wizen & Gasith, 2011a). July 19–20. Rearing was performed in a laboratory To date, the larval stages of three species have been at the University of Tokyo (Komaba, Meguro-ku, studied. Among these, C. circumscriptus (Duftschmid, Tokyo), at room temperature (approximately 25°C) and 1812) and C. dejeani (Dejean, 1831) have been well under the natural photoperiod. Females were reared studied, and their prey species (Elron et al., 2007; individually in plastic boxes (17.0 × 8.5 × 4.5 cm) Wizen & Gasith, 2011a; Yanai et al., 2015), feeding following the technique described by Sasakawa (2011), behavior (Wizen & Gasith, 2011a), micromorphology which simulates a wetland environment, the habitat (Brandmayr et al., 2010), and color variability (Wizen of C. nigricans. Commercial mealworms (Tenebrio & Gasith, 2011b) have been reported for all instars. molitor larvae, cut into pieces) were provided as a food In the remaining species, C. nigricans Wiedemann, source ad libitum. Food was replaced daily, and the 1821, only the macromorphology of the last instar presence of eggs and/or hatchlings were checked at the (Kurosa, 1959) and a preliminary report of the prey same time. species (Shiina & Tachikawa, 1998 cited in Elron et al., Egg-laying started on July 21. Each egg was ——————————————————————— enclosed in mud (Figs. 1, 2) and placed on the soil *Corresponding author: [email protected] surface. These mud cells were individually transferred − 167 − Preimaginal stages of Chlaenius (Epomis) nigricans Kôji Sasakawa Fig. 1–13. Developmental stages of Chlaenius nigricans. 1: Egg in a mud cell; 2: Egg in a mud cell with cover removed; 3: Pale-yellow first-instar larva; 4: Black first-instar larva; 5: Black first-instar larva climbing a plant; 6: Pale- yellow first-instar larva feeding on Bufo japonicus; 7: Black first-instar larva after feeding on B. japonicus; 8–9: Second-instar larva; 10–11: Third-instar larva; 12: Third-instar larva feeding on Pelophylax nigromaculatus; 13: Newly emerged adult (female). Image magnification varies. to a Petri dish (diameter: 6.0 cm, height: 1.5 cm) filled retains high humidity and serves as a shelter for larvae, to a depth of 0.5 cm with moistened garden soil, and was placed on the soil surface. Two anuran species, checked daily for hatching. Some individuals could not Bufo japonicus Temminck & Schlegel, 1838 (Bufo- be found at the egg stage because the mud cells and nidae) from Hiroshima Prefecture and Pelophylax soil clods were similar in appearance; these individuals nigromaculatus (Hallowell, 1861) (Ranidae) from Aichi were found on the soil after hatching. Hatchlings were Prefecture, were provided as prey for beetle larvae. In reared individually in the Petri dish or a plastic bottle some individuals, prey species differed between instars (diameter: 6.5 cm, height: 7.5 cm) filled to a depth of 0.5 due to availability. cm with moistened garden soil. Moistened moss, which In total, 53 larvae were obtained from the two − 168 − Preimaginal stages of Chlaenius (Epomis) nigricans Kôji Sasakawa females. First-instar larvae had mandibles with hooked the sample size was small, the durations of the egg, apices and retinacula (Figs. 3, 4). Color variability first-instar, second-instar, and third-instar stages were was observed in the head and pronotum, with pale apparent (Table 2). yellow (Fig. 3) and black (Fig. 4) types; the other These results are notable in the following aspects. body sclerites were blackish. Unfed first-instar larvae First, this experiment revealed a novel type of color were often observed to climb (Fig. 5). First-instar variability in Epomis larvae. Compared to the two larvae accepted both B. japonicus (Figs. 6, 7) and P. species examined to date, first-instar C. nigricans nigromaculatus, and reached the second instar. In the individuals were peculiar in that color variability second and third instars, mandibles were unhooked was conspicuous and only occurred in the head and (Figs. 8–11). Second- and third-instar larvae also pronotum. In first-instar C. circumscriptis individuals, exhibited color variability, but the pattern differed color variability was observed over the entire body; from that of the first instar, with variation in the size of however, the color range (pale yellow to brown) was the orange and black spots on the pale-yellow dorsal narrower than that of first-instar E. nigricans (pale side (Figs. 8–11). Second- and third-instar larvae also yellow to black). In first-instar C. dejeani individuals, accepted both B. japonicus and P. nigromaculatus variability was observed in only one abdominal (Fig. 12). All of the instars exhibited “luring behavior”, segment (Wizen & Gasith, 2011b). This between- which was characterized by waving of the antennae and species difference in the color variability pattern mandible (Figs. 3 and 8; note movement afterimage of the first instar contrasted that of the second and of antennae and mandibles; see also Wizen & Gasith, third instars, where the color variability pattern was 2011a). Although most larvae were killed as specimens similar among the three Epomis species. Whether the for future morphological studies (Table 1), two were difference in color variability between species and/ selected to rear to the adult stage. Of these, one died or instars in Epomis larvae has ecological significance during pupation, and the other reached adulthood (Fig. should be addressed in future studies. The results 13). The former was fed B. japonicus at all instars, and also provide new insights into the prey species of the latter was fed B. japonicus at the first instar and P. Epomis larvae. To date, the following amphibian nigromaculatus at the second and third instars. In the species have been reported as prey of Epomis larvae: larva that reached adulthood, the total duration of the Bufotes viridis (Anura: Bufonidae; as Pseudepidalea egg, larval, and pupal stages was 36 days. Although viridis), Hyla savignyi (Anura: Hylidae), Pelophy- Table 1. Number of Chlaenius nigricans individuals reared in the laboratory, at each developmental stage. First larval instar Second larval instar Third larval instar Pupa Adult Number of individuals Initial phase 53 33 18 2 1 Mortality 0 1 1 1 0 Killed as specimens 20 14 15 0 – Table 2. Developmental duration of Chlaenius nigricans individuals. Note that larvae typically molted in the soil; in such cases, the molting dates or resulting duration of each developmental stage could not be determined. Data represent means ± standard deviations, with n in parentheses. Egg First larval instar Second larval instar Third larval instar Duration (days) 6.0 ± 0 (13) 5.5 ± 1.3 (16) 4.5 ± 0.8 (11) 12 (1) − 169 − Preimaginal stages of Chlaenius (Epomis) nigricans lax bedriagae (Anura: Ranidae), Ommatotriton 49–58. vittatus, and Salamandra infraimmaculata (Caudata: Elron, E., Shlagman, A. & Gasith, A. 2007. First Salamandridae) for C. circumscriptus and C. dejeani detailed report of predation on Anuran metamorphs (Wizen & Gasith, 2011a), Hyla sp. (Anura: Hylidae), by terrestrial beetle larvae. Herpt. Rev. 38: 30–33. and Rhacophorus schlegelii (Anura: Rhacophoridae) Kirschenhofer, E., 2003. Tribe Chlaeniini Brullé, 1834. for C. nigricans (Shiina & Tachikawa, 1998 cited in In Löbl, I. & Smetana, A. (Eds), Archostemata– Elron et al., 2007). Therefore, the results of the current Myxophaga–Adephaga. Catalogue of Palaearctic study represent the first report of a Bufo species as prey Coleoptera: 347–356. Apollo Books, Stenstrup. for larvae of the subgenus Epomis, and also the first Kurosa, S. 1959. Illustrated insect larvae of Japan. 712 report of Bufo and Pelophylax species as prey for C. pp. The Hokuryukan Co., Ltd., Tokyo.