Cybister ('kybistētēr' = diver, tumbler), is a genus of beetle in family Dytiscidae. They are found in much of the world, including all continents except Antarctica.[1][2] As of 2024 there are 98 species and 9 additional subspecies among four subgenera in the genus.[3]
Description
Adult Cybister have broad hind legs with unequal tarsal claws (the inner claw being smaller and sometimes absent) and a fringe on the outer margin of the tarsus.[4] They range in length up to 43 mm (C. bimaculatus from the Afrotropics).[5] Adult males of the North American species have several ridges on the coxae of the hind legs, forming a stridulatory device.[5]
Larvae have a frontal tooth on the head and lack cerci. North American species can grow up to 80 mm long.[4]
Ecology
Cybister live in lentic (still fresh water) habitats that have vegetation.[6]
Like other diving beetles, Cybister are predatory. Larvae of C. japonicus prey on insects (mainly Odonata nymphs and the backswimmerNotonecta triguttata) in their first two instars, while third-instar larvae prey on vertebrates (tadpoles and fish).[7] Larvae of C. rugosus feed on both invertebrates and vertebrates in all instars.[8]
Importance
Cybister chinensis (sometimes misidentified as C. japonicus) is used in a game in Korea. The water beetle game (mul bang gae nori) is played in an oval, water-filled tank with vertical flanges along its inner edge and prizes on the tank rim. The game is played by dropping a C. chinensis through a funnel into the center of the tank, after which it swims towards the edge of the tank and stops in one of the slots formed by the metal flanges. If a prize is above this slot, the player wins it.[9]
These seven extinct species are known only from fossils:
†Cybister agassizi Heer, 1862
†Cybister atavus Heer, 1862
†Cybister fractus Riha, 1974
†Cybister imperfectus Riha, 1974
†Cybister mancus Riha, 1974
†Cybister nicoleti Heer, 1862
†Cybister rotundatus Riha, 1974
References
^Miller, K.B.; J. Bergsten (2016). Diving Beetles of the World: Systematics and Biology of the Dytiscidae. JHU Press. pp. 131–132. ISBN978-1-4214-2054-7.
^Nilsson, Anders N.; Hájek, Jiří (2024). "A World Catalogue of the Family Dytiscidae or the Diving Beetles (Coleoptera, Adephaga)" (PDF) (1.I.2024 ed.).
^ a b"Genus Cybister". bugguide.net. Retrieved 2023-03-02.
^ a bArce-Pérez, Roberto; Novelo-Gutiérrez, Rodolfo; Fery, Hans (2021-11-04). "Cybister (s. str.) poblanus sp. n. from Mexico and notes on other species of Cybistrinae (Coleoptera: Dytiscidae)". Zootaxa. 5061 (2): 323–339. doi:10.11646/zootaxa.5061.2.5. ISSN 1175-5334. PMID 34810625.
^Liao, Wenfei (2018-08-19). "Cybister, an Immigrant in Finland". Wenfei's Blog. Retrieved 2023-03-02.
^Ohba, Shin-Ya (2009-06-01). "Ontogenetic Dietary Shift in the Larvae of Cybister japonicus (Coleoptera: Dytiscidae) in Japanese Rice Fields". Environmental Entomology. 38 (3): 856–860. doi:10.1603/022.038.0339. ISSN 0046-225X. PMID 19508796.
^Yamasaki, Shun; Watanabe, Kohei; Ohba, Shin-ya (2022). "Larval feeding habits of the large-bodied diving beetle Cybister rugosus (Coleoptera: Dytiscidae) under laboratory conditions". Entomological Science. 25 (2). doi:10.1111/ens.12510. ISSN 1343-8786.
^Pemberton, R. W. (1990). "The Korean water beetle game". Pan-Pacific Entomologist. 66 (2): 172–174.
^Kim, Heejoong; Lee, Jihong (2017). "Design, swimming motion planning and implementation of a legged underwater robot (CALEB10: D.BeeBot) by biomimetic approach". Ocean Engineering. 130: 310–327. doi:10.1016/j.oceaneng.2016.11.006.