Limea lirata Allen, 2004

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 : 55-56

Limea lirata Allen, 2004

Figures 17–19

Limea lirata Allen, 2004: p. 2622 , fig. 36, 37, 46c.

Description: Shell very fragile, translucent, small (height mean = 1.15mm ± 0.07 s.d.; range 1.10–1.20mm; n=2), height/length ratio 1.28, slightly inequilateral, little inflated, oval outline, ornamented with numerous and quite slender concentric lines that are positioned close to each other and cover the entire shell, though the lines are somewhat less evident toward the dorsal region. Axial ornamentation absent, fine internal axial ridge and groove on both valves, and not perceptible on the external side. Auricles small, subauricular sinus absent, postero and antero-dorsal margin curved in the hinge region, ventral margin strongly rounded. Prodissoconch smooth (mean 153.00µm ± 3.00 s.d.; range 150–156 µm; n=2), interdissoconch not distinguishable. Umbones prominent, hinge plate slender, ligamental pit rounded.

Geographic range: Restricted to North American Basin, at 2095 meters. Adapted from Allen (2004). Campos Basin (this study) represents the southernmost and the shallowest (1044m) record of this species, with the first record for Brazilian coast and the southeastern Atlantic Ocean.

Material examined: IBUFRJ 17805, off Bacia de Campos (21°52'43" S, 39°40'42" W, 1941 m), 26. VI.03, [2 valves] .

Remarks: Although this is a rare species in our samples, with only three valves, the characteristic concentric ornamentation with the very conspicuous fine internal axial ridge and groove on both valves makes this a distinct species.

Previously restricted to the North American Basin by Allen (2004) who collected 171 specimens from only one station; since then, this species had not been cited. Our record, the first for the Brazilian and South American coast, expands the area of occurrence to the South Atlantic .

The characterization of the genus Limea includes some characters, such as axial ornamentation and marginal crenulation, which are absent in L. lirata . But, since, as mentioned earlier, the definition of the limid subgroups may be obscure and they probably do not form natural groups and even overlap one another, we prefer not relocate this species now, avoiding the increase of unwarranted taxonomic mistakes.