DEEP-SEA PROTOBRANCHIA (BIVALVIA) 



13 



Fig. 1 Yoldiella lucida. Lateral views of 

 shells of different size seen from the 

 right side to show variation in shell 

 outline. Collected by R.V. Dana 1922; a 

 & b, 50°20'N 9°00'E, 350 m; c & d, 

 58°13'N, 9°34'E, 650 m. (Scale = 1.0 

 mm). 



Subfamily Yoldiellinae Allen & Hannah 1986 



Shell small, usually compressed, ovate or elongate subovate, 

 occasionally with ill-defined rostrum, not gaping, smooth, or 

 very fine concentric sculpture; ligament amphidetic, largely 

 internal; combined siphons with various degrees of tissue 

 fusion, siphonal embayment small; hind gut with various 

 configurations. 



Leda lucida Jeffreys 1869, p. 173. pi. 100, Fig. 1; Jeffreys 



1879, p. 578;Locard 1898, p. 351, 362. 

 Portlandia lucida Sars G.O. 1878, p. 37. pi. 4, Figs. 8a, 8b; 



Norman 1893, p. 364; Posselt 1898, p. 36; Ockelmann 



1958, 122, p. 29. 

 Yoldiella iris Verrill & Bush 1898, 20, p. 863-864, pi. 80. Fig. 



1,2, pi. 82, Fig. 11; Type specimen U.S., Natl. Mus. 



159722. 

 Yoldiella lucida Tebble 1966, p. 29, Fig. 156. 



Genus Yoldiella Verrill & Bush 1897 



Type species. By original designation, Yoldia lucida Loven, 

 1846. 



Shell small, fragile, usually slender, subovate, usually 

 glossy, no escutcheon or lunule, no carina, not gaping, 

 occasionally fine concentric sculpture, postero-ventral margin 

 may be slightly sinuate, postero-dorsal margin usually slightly 

 convex, maybe posteriorly angulate; umbo usually anterior 

 occasionally posterior or central; chevron-shaped hinge teeth 

 may or may not extend beyond the inner limit of adductor 

 muscles; no chondrophore; except for very small external 

 componant, ligament internal and amphidetic, but may 

 extend anteriorly and/or posteriorly to a small degree, hind- 

 gut with various configurations, mostly deep-water species 

 beyond shelf-slope break. 



Note. A detailed account of an internal morphology is given under 

 Y. lata (p. 34). 



Yoldiella lucida (Loven 1846) 



Type locality. Hammerfest, northern Norway (desig. A. 

 Waren, 1989). 



Type specimen. Lectotype (desig. A. Waren, 1989), Swed- 

 ish Museum of Natural History, No. 1533. 



Yoldia lucida Loven 1846, p. 34. 



Material. 











Cruise Sta Depth No 



Lat 



Long 



Geai 



Date 



(m) 











NORWEGIAN BASIN 











Thor 273 610 











350 50 



58°20'0N 



09°00'0E 







Dana 2896 60 



58<T3'0N 



09°34'0E 







NORTH AMERICAN BASIN 











Chain 58 105 530 124 



39°56'6N 



71°03'6W 



ET 



5.5.66 



Chain 88 207 805- 264 



39°51'3W 



70°54'3W 



ES 



21.2.69 



811 



39°51'0W 



70°56'4W 







WEST EUROPEAN BASIN 











Incal DS03 609 2 



57°57'0N 



10°43'0W 



CP 



16.7.76 



DS04 619 1 



57°58'0N 



10°43'0W 



CP 



16.7.76 



Museum material examined is listed in the text. 



Specimens of Yoldiella lucida have most subtle differences 

 in shape that taxed the descriptive powers of our predecessors 

 and as they do ours. Jeffreys (1879) recognized three varieties 

 {lucida, declivis and truncata) while Locard (1898), accepting 

 the form figured by Sars (1878) as the type, recognized five 

 varieties {truncata - the form figured by Jeffreys, intermedia, 

 minor, depressa, and ventricosa). 



Three thousand miles to the west, and in the same year as 

 Locard, Verrill & Bush (1898) described what they thought to 



