Hyalopecten hadalis

(Knudsen, 1970)



Holotype (figured lv)

Original name   Cyclopecten (Hyalopecten) hadalis Knudsen, 1970
Autoreference   Knudsen, 1970: 98, pl. 13, fig. 2, text-figs 61, 62.
Reference   Knudsen, J. 1970. The systematics and biology of abyssal and hadal Bivalvia. Reprinted from Galathea Report, volume 11. Danish Science Press, Copenhagen. 241 pp., 20 pls.
Type data   Holotype (pr: H 20.9 mm, L 18.2 mm) Zoological Museum, University of Copenhagen, Copenhagen (ZMUC, not yet registered). Type locality: Kermadec Trench, 32*20'S, 176*54'W, 6620-6730 m, alive, brown clay with pumice, 15.ii.1952 ("Galathea" stn 650).

  Shell up to ca. 21 mm high, thin, semi-transparent, weakly inflated, commarginally undulated, left valve more convex than right valve, higher than wide, inequivalve, inequilateral, auricles nearly equal in size and unequal in shape, umbonal angle ca. 90 degrees, colour dirty white.

  Left and right valve regularly, commarginally undulated and sculpture with numerous delicate, closely spaced, overrunning radial lirae, somewhat coarser on the left valve. Auricles small, posterior continuous with disc, anterior auricle of right valve demarcated from disc and sculptured with commarginal lamellae.

Byssal notch deep, byssal fasciole broad, inactive and active (functional) ctenolium well-developed.



Kermadec Trench (TL)

Habitat   Living hadally on soft bottom assemblages.