Large diving beetle, elytra with yellow margin. Similar to
Dytiscus species, but metatarsal claws different. (See guide for genus.) Elytra and pronotum smooth in male. Unique structure on male protarsi, used for grasping female during mating.
Dytiscus male has similar structure, but differing in details--two large disks are obvious. White, fig. 33, and Papp
(1), figs. 178, 179 illustrate this well
(4). Female
Cybister has fine furrows on pronotum. Male
Cybister has, apparently, two rows of punctures on each elytron, lacking in
Dytiscus (4).
Blatchley
(5) gives the following description of this species:
Ovate, more or less wedge-shaped. Above brown with a faint greenish tinge; thorax and elytra with a broad yellow margin; front of head, four front legs and spots at sides of abdominal segments 3 to 6, also yellow. Thorax and elytra of female, except along the suture, with numerous fine short impressed lines. Length 30-33 mm. Throughout the State (Indiana); frequent. May 27-September 20. In autumn sometimes found beneath rubbish on the beaches of lakes.
