Description As Karnekampia bruei: Shell almost as long as wide, generally longer than wide, sometimes the reverse. Left valve 11 primary ribs almost equally pronounced, one secondary rib in between. Right valve always with 2 "groups" of ribs more than primary ribs of left valve, all ribs almost equally pronounced. Ribs of right valve single or arranged in groups of two. Microsculpture of ribs of left and right valve composed of coalesced hollow rows of tubercles. Anterior auricles 1.57-1.86 times as large as posterior ones. Anterior auricles right and left valve 4 ribs. Posterior auricles right and left valve 4 ribs also. Byssal notch broad, ctenolium relatively broad too. Top angle between 85°-90°. Colour lemon yellow, sometimes orange or white. Colour pattern consist of an almost uniform colouration, somewhat lighter to the apex.
Dimensions. - The largest specimen I have examined is one of the syntype specimens preserved in the Museum National d'Histoire Naturelle at Paris, measuring 20.3 mm height x 20.5 mm width x 6.3 mm depth. Distribution. - This species can be found throughout the Mediterranean and the (?) adjacent area of the Atlantic Ocean north to the Galicia Bank, northeast of Spain. Remarks. - Strangely the specimen examined from the Galicia Bank is quite different from the K. bruei examined from the Mediterranean; In which the primary and secondary tuberculous ribs are always coalesced to more or less continuous ribs, while in the specimen from the Galicia Bank the secondary ribs are formed by rows of separate tubercles. A more detailed study of more material from the Galicia Bank can solve the identity of the species living there. At this instance I consider it a form of K. bruei.

Description as Karnekampia sulcata. - Shell always longer than wide. Left valve 9 primary ribs equally pronounced, one secondary rib in between, 1 or 2 tertiary ribs in-between primary and secondary ribs. Right valve always 1 or 2 groups of ribs less than primary ribs of left valve, all ribs almost equally pronounced. Ribs of right valve more or less arranged in groups of 3-5. Microsculpture of primary and secondary ribs of left valve and ribs of right valve composed of coalesced hollow rows of tubercles, tertiary ribs of left valve formed likewise, but tubercles separately implanted. Anterior auricles 1.88-2.33 times as large as posterior ones. Anterior auricle right valve 5 ribs, left valve 4 ribs. Posterior auricles right valve 5 ribs, left valve 4 ribs. Byssal notch broad, ctenolium relatively broad too. Top angle between 85°-91°. Colour generally white and/or wine-red. Colour pattern consist of winered bands in various gradations towards the top, becoming more and more creamy white of colour to its edges.
Dimensions. - Largest valve measured is 23.5 mm height x 22.2 mm width; largest complete specimen examined measures 22.6 mm height x 21.3 mm width x 5.7 mm depth. Distribution. - Arctic Ocean from Norway to Iceland, and south to the Irish Sea.
Remarks. - Although the height x width ratio's can differ considerably within this species, it has always the wine-red colour and tuberculate ribs and riblets. This in contrary to K. bruei, which is mostly white to yellow of colour and has the tuberculous ribs more coalesced to continuous ribs.