124 



J. A. ALLEN AND H.L. SANDERS 



is widely distributed throughout the Mediterranean and lusitanean 

 Atlantic. Prior to the paper by Carrozza ( 1 987) there had been debate 

 as to whether N. fragilis and N. commutata were the same species 

 (Locard, 1891, 1898; Bucquoy et al, 1887-98). It is not possible to 

 determine whether this earlier debate was a presage to the study of 

 Carrozza (1987). In contrast N. acuta is even more widely distrib- 

 uted off the eastern North America, West Indies and off Brazil 

 (Abbott, 1974). It must be assumed that these are three sibling 

 species. 



Nuculana vestita (Locard 1898) 



Type specimen. MNHN 



Type LOCALITY. Talisman stas 96-98 & 101, West of Senegal, 

 2324-3200m, 19'12'N 1757'W - 16°38'N 18°24'W 



Cited specimens. BMNH 1 995056 and 1 9952 1 1 



Leda vestita Locard 1898, 340, pl.XIV, figs 12-18 



Nuculana vestita Clarke 1962, 53. 



Leda macella Barnard 1963, 448, fig. lid; type locality: West off 



Cape Point, S.W.Africa, Africana II stas A 190, A 192, A3 17, 



A3 19, 2268-3200m, SAM (not seen). 



MATERIAL: 













Cruise Sta Depth 

 (m) 



No 



Lat 



Long 



Date 



Gear 



SIERRA LEONE BASIN 













Atlantis II 146 2842 



1 



10"39.5'N 



17°44.5'W 



6.2.67 



ES 



31 -2891 













ANGOLA BASIN 













Atlantis II 201 1964 



1 



09"29.0'S 



1 1°34.0'E 



23.5.68 



ES 



42 -2031 













203 527 



742 



0846.0'S 



12'47.0'E 



23.5.68 



ES 



-542 













Specimens taken by the Galathea Expedition described by 

 Knudsen (1970) examined by JAA, ZMUC. Knudsen (1970) fol- 

 lowing examination of specimens synonymized L. macella with N. 

 vestita. 



Nuculana vestitais a well-described species (Locard, 1 898;Theile 

 and Jaeckel, 1931; Knudsen, 1970) occurring off West and South- 

 west Africa at lower slope depths (71 5-289 lm) in the Sierra Leone, 

 Guinea and Angola basins. 



Shell description (Figs 36 & 37) 



Shell moderately large, inflated, somewhat elongate, rostrate, 

 ornamented with concentric ridges, pale brownish-yellow 

 periostracum; umbos large, inwardly directed, anterior to midline; 

 antero-dorsal distal margin horizontal for short distance, proximal 

 margin broadly convex forming smooth curve with anterior margin, 

 ventral margin broadly convex to rostrum, postero-dorsal margin, 

 raised in small specimens but less so in large, proximally straight or 

 slightly concave, in small specimens angulate at limit of posterior 

 hinge plate, distally slightly concave to posterior limit of rostrum; 

 broad ridge extends from umbo to rostrum forming outer limit of 

 escutcheon; anterior and posterior hinge plates broad, meet shell 

 margin ventral to umbo, hinge teeth broad chevrons, up to 19 and 16 

 in anterior and posterior series respectively in specimen 8.3mm total 

 length; ligament internal, amphidetic, pear-shaped in sagittal verti- 

 cal section, extends ventral to hinge plate. The maximum length of 

 the present specimens is 13.8mm. 



Internal morphology (Fig. 38) 



The adductor muscles are moderately large and oval. The siphonal 

 embayment is deep with the siphonal tentacle to the right side. The 

 siphons are entire. The feeding aperture is small but well-defined 

 with the mantle surface ridged internally. Radial mantle muscles 

 are well-developed forming a broad band internal to the inner lobe 



Fig. 36. Nuculana vestita. External right lateral and dorsal view of a large adult shell and a lateral view of the hinge plate of a right valve. Specimens are 

 from Atlantis II station 203 from the Angola Basin. Scale = 1 mm. 



