Cybister Explained

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 2021 there are 96 species and 9 additional subspecies among four subgenera in the genus.[3]

Description by Muthiah R

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 from 13 mm (C. parvus from Brazil) 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.

Larvae have a frontal tooth on the head and lack cerci. North American species can grow up to 80 mm long.

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 backswimmer Notonecta 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]

The swimming behaviour of C. lateralimarginalis has inspired (biomimetics) the design of a legged underwater robot.[10]

List of species

Subgenus Cybister Curtis, 1827

Subgenus Megadytoides Brinck, 1945

Subgenus Melanectes Brinck, 1945

Subgenus Neocybister K.B. Miller, Bergsten & Whiting, 2007

Subgenus unknown

Fossil species

These seven extinct species are known only from fossils:

External links

Notes and References

  1. Book: Miller, K.B. . J. Bergsten . Diving Beetles of the World: Systematics and Biology of the Dytiscidae . 2016 . 131–132 . 978-1-4214-2054-7 .
  2. The Distinctive Characters of the Eastern Species of the Genera Dytiscus and Cybister . Roberts . C H . 1905 . . 13 . 103–107 .
  3. Web site: Anders N. . Nilsson . Jiří . Hájek . A World Catalogue of the Family Dytiscidae or the Diving Beetles (Coleoptera, Adephaga) . 2021 . 1.I.2021 .
  4. Web site: Genus Cybister . 2023-03-02 . bugguide.net.
  5. Arce-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 . en . 5061 . 2 . 323–339 . 10.11646/zootaxa.5061.2.5 . 1175-5334.
  6. Web site: Liao . Wenfei . 2018-08-19 . Cybister, an Immigrant in Finland . 2023-03-02 . Wenfei's Blog . en.
  7. Ohba . Shin-Ya . 2009-06-01 . Ontogenetic Dietary Shift in the Larvae of Cybister japonicus (Coleoptera: Dytiscidae) in Japanese Rice Fields . Environmental Entomology . en . 38 . 3 . 856–860 . 10.1603/022.038.0339 . 0046-225X. free .
  8. 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 . en . 25 . 2 . 10.1111/ens.12510 . 1343-8786.
  9. Pemberton . R. W. . 1990 . The Korean water beetle game . Pan-Pacific Entomologist . 66 . 2 . 172-174.
  10. Kim . Heejoong . Lee . Jihong . 2017 . Design, swimming motion planning and implementation of a legged underwater robot (CALEB10: D.BeeBot) by biomimetic approach . Ocean Engineering . en . 130 . 310–327 . 10.1016/j.oceaneng.2016.11.006.

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