Taxonomy of tropical West African bivalves. VI. Remarks on Lucinidae (Mollusca, Bivalvia), with description of six new genera and eight new species Author Cosel, Rudo von Muséum national d’Histoire naturelle, Département Systématique et Évolution, Unité Taxonomie et Collections, case postale 51, 57 rue Cuvier, F- 75231 Paris cedex 05 (France) cosel @ mnhn. fr cosel@mnhn.fr text Zoosystema 2006 28 4 805 851 journal article 6343 10.5281/zenodo.4689802 cb4d8e3b-abd4-4a73-b074-8dd9ab59f5a6 1638-9387 4689802 Lucinoma atalantae n. sp. ( Figs 15C, D ; 16 ) TYPE MATERIAL. — Holotype :W of Mauritania , 20°32’N , 18°36’W , 2042 m , dredged RV Atalante , EUMELI 4, stn CP 16, 5.VI.1992 , an alcohol preserved spm ( MNHN ). Paratypes : same locality, 2 sh. ( MNHN ). TYPE LOCALITY. — Cape Verde Basin, W of Cap Blanc, Mauritania . ETYMOLOGY. — Named after the RV Atalante , from which the type material was taken. OTHER MATERIAL EXAMINED. — Mauritania . W of Cap Blanc, 20°41’N , 18°33’W , 2114 m , dredged RV Atalante , EUMELI 2, stn CP 03, 5.II.1992 , 3 spm, 1 adult , 1 juv. sh. (MNHN). — 20°33’N , 18°35’W , 2003 m , dredged RV Atalante , EUMELI 2, stn CP 04, 5.II.1992 , 1 juv. sh. (MNHN). — NW of Cap Blanc, 20°58.9’N , 18°13.6’W , 2112-2160 m , RV Discovery , stn 9133#5, 25.II.1976 , 2 spm, 2 sh. (BMNH). — Same locality, 20°57.0’N , 18°11.0’W , 2110-2130 m , RV Discovery stn 11540, 2.IX.1987 , 1 spm (BMNH). DISTRIBUTION. — Only known from the Cape Verde Basin. FIG. 16. — Lucinoma atalantae n. sp. : A , holotype, W of Mauritania, 20°32’N, 18°36’W, 2042 m, dredged RV Atalante , EUMELI 4, stn CP 16, 5.VI.1992, 29.1 mm (MNHN), exterior and interior of rv., exterior and interior with soft parts of lv., dorsal view; B , paratype 1, same locality, 29.1 mm (MNHN), interior and exterior of lv.; C , paratype 2, same locality, 26.7 mm (MNHN), interior of both v. DESCRIPTION Shell to 29mm long, rather solid, variable in outline and sculpture, subcircular (length/height ratio between 1.1 and 1.2), compressed.Anterior margin rather narrowly rounded, posterior margin more or less conspicuously truncated, occasionally slightly sinuous, with rounded corners.Ventral margin convex, nearly semi-circular. Beaks just in front of the vertical midline. TABLE 7. — Lucinoma atalantae n. sp. : measurements in mm and length/height ratio. All non type specimens are voucher specimens.

Shell length × height × tumidity	Specimen	Length/height ratio
31.7 × 28.5 × 13.7	Mauritania, Discovery , stn 9133#5	1.1
29.1 × 24.9 × 11.6	Mauritania, holotype	1.2
29.0 × 24.6 × 9.5	Mauritania, paratype 1	1.2
28.7 × 24.1 × 11.1	Mauritania, Discovery , stn 11540	1.2
27.0 × 23.7 × 10.2	Mauritania, EUMELI 2, stn CP 03	1.1
26.7 × 24.1 × 11.4	Mauritania, paratype 2	1.1
25.1 × 21.0 × 9.7	Mauritania, EUMELI 2, stn CP 03	1.2
20.3 × 18.9 × 8.4	Mauritania, EUMELI 2, stn CP 03	1.1
11.7 × 10.3 × 4.4	Mauritania, EUMELI 2, stn CP 04	1.1
11.3 × 9.8 × 3.8	Mauritania, EUMELI 2, stn CP 03	1.2
10.7 × 9.0 × 3.7	Mauritania, EUMELI 2, stn CP 03	1.2
10.5 × 9.0 × 3.4	Mauritania, Discovery , stn 9133#5	1.2

Exterior with numerous, very fine, irregular growth lines and commarginal lamellae which in juvenile specimens are very close-set and evenly spaced, in adult and subadult specimens they are more irregularly and wider spaced, obsolete or entirely missing. Earlier part of the valves often eroded. Posterior area delimited by gently rounded posterior angle, anterior angle absent. Lunule sunken, with rather thick layer of periostracum on it. Escutcheon long and very narrow, ligament slightly sunken. Hinge plate moderately broad, with two well developed cardinal teeth in each valve; posterior cardinal in the left valve rather thin and laminar. Laterals more or less indistinct. Diverging part of anterior adductor scar long. Inner margin smooth. Valves white. Periostracum very strong, yellowish brown, on the earliest parts of the valve thinner to obsolete. Measurements are provided in Table 7. BIOTOPE In soft sediment, most probably mud, found between 2003 and 2160 m . REMARKS Lucinoma atalantae n. sp. is distinguished from L. vestita , the most similar species, by its larger size, the thinner and slightly longer valves, the narrower hinge plate and the sculpture. Lucinoma atalantae n. sp. shows dense commarginal lamellae on the earlier part of the valve whereas L. vestita is smooth. Juveniles of L. atalantae n. sp. are closer in outline to L. vestita but the narrower hinge line and the presence of commarginal lamellae remain distinguishing features. Both species have a different depth preference: L. vestita on the shelf slope at about 600 m , L. atalantae n. sp. much deeper, at about 2000 m . The two species have been taken at their type localities only, and we do not know their actual distribution range. Apart from an Indo-West Pacific species (under description by Cosel & Bouchet) which was found at 2570 m , L. atalantae n. sp. is the deepest-recorded lucinid species.