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The black-brown underside of Colymbetes fuscus. A part of the right epipleur is visible in the lower left corner of the picture, more to the front we see the notopleural sutures, which are also light-brown. The male has suckerdisc-like structures on the broadened tarsi of the front and middle legs, as with many species of the Dytiscidae. With these they have a hold on the wingcases of the female, when the mating. The femur has a depression, in which the leg can be folded. On the head we see: the labial palps (resting on the beetles ventral side on this picture), the maxillary palps (pointing up) and the right antenna (on the picture: lying almost against the front leg). The middle legs have a relatively large fringe of swimming hairs.
As with all diving beetles, the 'hips' of the powerful swimming legs are flattened and incorporated in the body shell (they are called metacoxae). The legs are also flattened and have swimming hairs, which are fold out when the legs are thrust backwards. This specimen has fringes of swimming hairs on both sides of the legs, it may be that the female has only one fringe of hairs on each leg, at least the great diving beetle has that sex-difference.
Walking is more difficult with such specialized legs, but a pair of sturdy spurs help the beetle when crawling. On the inset picture you can see that the end of the leg also has some prominent spines.
Pictures below: on the overview picture again we see the wide epipleura. If the mouse cursor is brought over the middle picture, the metasternum is outlined. The figure reminds of a bird or maybe a bat symbol. The wings of that figure are broad on this beetle species. The right pictures shows the surface structures on the sternites. The insets are of another photo, on which some parts were better in focus.
