Limatula laminifera ( Smith, 1885 )

Oliveira, Cléo Dilnei De Castro & Absalão, Ricardo Silva, 2008, The genera Limatula and Limea (Mollusca, Pelecypoda, Limidae) from deep waters off Brazil, Zootaxa 1940, pp. 48-58 : 55

Limatula laminifera ( Smith, 1885)

Figure 16

Lima (Limatula) laminifera Smith, 1885: p. 293 , pl. XXIV, fig. 7, 7a.

Limatula laminifera: Stuardo, 1968: p. 226 . pl. 14, fig. 65; Abbott, 1974: p. 454; Allen, 2004: p. 2616. fig. 29–32, 46b.

Description: Shell fragile, white, small (height mean = 2.15mm ± 0.17 s.d.; range 2.04–2.40mm; n=4), height/length ratio 1.37, equivalve, slightly inequilateral, moderately inflated. Ornamented with very fine, irregularly spaced concentric striae and slender concentric lamellae, which become more foliaceous toward the ventral margin. Internally with two thickened axial ridges, which correspond to two internal grooves in the opposite valve. Auricles relatively small, subauricular sinus hardly visible. Dorsal margin straight and little inclined from antero-posterior axis. Prodissoconch barely visible (mean 95.00µm ± 5.77 s.d.; range 90– 100µm; n=4), interdissoconch not distinguishable. Umbones prominent and triangular. Hinge plate narrow, edentulous, with an elongated triangular ligamental pit.

Geographic range: Western North Atlantic, Florida to the West Indies, off the Azores, off Fernandina, off Sombrero Island, off Culebra Island. Depths ranging between 137 to 1590 meters. Adapted from Smith (1885), Abbott (1974), Allen (2004). Campos Basin (this study) represents the first record of this species for the Brazilian coast and for the southeastern Atlantic Ocean.

Material examined: IBUFRJ 17808, off Bacia da Foz do Amazonas (03º25 'N, 48º03' W, 700 m), 14.XII.05, [1 valve]; IBUFRJ 17823, off Bacia da Foz do Amazonas (03º25 'N, 48º03' W, 700 m), 14.XII.05, [4 valves] .

Remarks: Both the original description of L. laminifera ( Smith 1885) and a later redescription ( Allen 2004) pointed out the near absence of axial sculpture, except for very faint lirae that may occur on the central portion of the valves. In fact, the axial sculpture is barely visible in our specimens.