Coptothyris adamsi Davidson, 1871
Terebratula grayi Davidson, 1852: 76 (preocc. Davidson, 1848, fide Allan, 1947).
Magasella adamsi Davidson, 1871: 307.
Waldheimia grayi Davidson, 1886: 54, pl. 10, fig. 4.
Coptothyris grayi Thomson, 1927: 247; Markovskaya-Avdeeva, 1976: 113, figs. 264, 265.
Coptothyris adamsi Allan, 1947: 497–498; Zezina, 1997: 68.
Description. Large roughly ribbed shells, variable in shape from round or almost pentagonal to semicircular and triangular, from oval to transversely stretched. Hinge margin is straight or slightly curved, being longer or shorter than the width of shell. Beak is short, almost straight, foramen is large transversely oval, deltidial plates are triangular disjunct, usually destructed. Side ribs of beak are well expressed and form triangular almost plain area. Rough radial ribs bifurcate near the shell margins, concentric growth-lines are well seen marked out with intensive rose colour on the general yellowish background of shell. Cardinal process is narrow transversal, hinge platform fused with middle septum, which reaches half of shell-length in young specimens, but is reduced in adults. Free loop in adults stretches anteriorly to 4/5 of the length of brachial valve.
Distribution. The species is known around the Japanese Islands from southern shores of Hokkaido to Kyushu and along continental slopes of Asia from the Korea Straight to 48° N (Konzhukova, 1957).
Ecological data. Vertical range is 2–353 m. The species is known well in Peter the Great Bay from Furugelm Island to Povorotnyi Cap at the depths of 3–20 m, but it is not numerous. Maximal density 4 sp./m2 is found in Vostok Bay at the of depth 3–4 m. Beautiful shells of the species often become a prey of tourists and fanciers of marine rarities. At the same time, the species is subtropical endemic with confined geographic range, and its ontogenesis has principal significance for systematics. So Coptothyris adamsi is included in the Red Book of Russian Federation (Zezina, 2001).
References:
The World Register of Marine Species