Limatula louiseae Clarke, 1974

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 : 49-51

publication ID	11755334
persistent identifier	https://treatment.plazi.org/id/03ED2102-8412-FF8E-FF06-F8DBFC3DD704
treatment provided by	Felipe
scientific name	Limatula louiseae Clarke, 1974
status

Treatment

Figures 1–5

Limatula louiseae Clarke, 1974: p.17 , fig. 9; Allen, 2004: p. 2601, fig. 10–12, 45a. Description: Shell fragile, white or translucent, small (height mean = 1.61mm ± 0.38 s.d.; range 0.91– 2.23mm; n=50), height/length ratio 1.53, equivalve, equilateral, very inflated, elongated, ornamented externally with unevenly spaced concentric lines that are less apparent in the dorsal region, and many concentric microscopic striae between these lines. Microscopic diagonal striae, which vary in number, on anterior and posterior parts of shell. Internal median axial fold absent, auricles small and usually short and rounded, subauricular sinus absent, ventral margin strongly rounded or angulated. Prodissoconch smooth and somewhat detached (mean 109.00µm ± 7.38 s.d.; range 100–120 µm; n=50), interdissoconch not distinguishable. Umbones prominent, hinge plate somewhat broad, ligamental pit triangular.

Geographic range: At Mid-Atlantic Ridge, close to equator and west of Newfoundland, off Surinam, North America Basin. Depths ranging between 1500 and 4793 meters. Adapted from Clarke (1974) and Allen (2004). Campos Basin (this study) represents the southernmost and the shallowest (1330 m) record of this species, and the first record in the southeastern Atlantic Ocean.

Material examined: IBUFRJ 17809, off Bacia de Campos (21°58'36" S, 39°46'30" W, 1700 m), 10. VIII.01, [1 valve]; IBUFRJ 17810, off Bacia de Campos (22°37'02" S, 39°56'21" W, 1950 m), 23.XI.02, [1 spec.]; IBUFRJ 17811, off Bacia de Campos (21°58'36" S, 39°46'30" W, 1700 m), 10. VIII.01, [1 valve]; IBU- FRJ 17824, off Bacia de Campos (22°38'53" S, 40°04'16" W, 1342 m), 14. VI.03, [1 valve]; IBUFRJ 17825, off Bacia de Campos (22°03'28" S, 39°45'07" W, 1730 m), 08. V.02, [7 valves]; IBUFRJ 17826, off Bacia de Campos (22°05'12" S, 39°42'41" W, 1930 m), 08. V.02, [4 valves]; IBUFRJ 17827, off Bacia de Campos (22°09'11" S, 39°44'51" W, 1930 m), 08. V.02, [17 valves]; IBUFRJ 17828, off Bacia de Campos (22°04'53" S, 39°49'04" W, 1330 m), 09. V.02, [1 valve]; IBUFRJ 17829, off Bacia de Campos (22°05'45" S, 39°45'55" W, 1730 m), 09. V.02, [1 spec. + 4 valves]; IBUFRJ 17830, off Bacia de Campos (21°58'36" S, 39°46'30" W, 1700 m), 08.X.01, [3 valves]; IBUFRJ 17831, off Bacia de Campos (22°06'53" S, 39°44'14" W, 1930 m), 08. V.02, [17 valves]; IBUFRJ 17832, off Bacia de Campos (22°08'24" S, 39°46'24" W, 1730 m), 09. V.02, [3 valves]; IBUFRJ 17833, off Bacia de Campos (22°41'04" S, 40°02'30" W, 1650 m), 23.XI.02, [1 spec.]; IBUFRJ 17834, off Bacia de Campos (21°52'44" S, 39°40'46" W, 1950 m), 11. XII.02, [8 valves]; IBUFRJ 17835, off Bacia de Campos (21°57'16" S, 39°47'44" W, 1650 m), 14. XII.02, [20 valves]; IBUFRJ 17836, off Bacia de Campos (21°57'27" S, 39°40'34" W, 1942 m), 27. VI.03, [23 valves]; IBUFRJ 17837, off Bacia de Campos (22°30'22"S, 39°56'54" W, 1353 m), 21. VI.03, [2 valves]; IBUFRJ 17838, off Bacia de Campos (22°31'37" S, 39°55'14" W, 1630 m), 16. VI.03, [3 valves]; IBUFRJ 17839, off Bacia de Campos (21°52'41" S, 39°46'17" W, 1688 m), 26. VI.03, [12 valves]; IBUFRJ 17840, off Bacia de Campos (22°11'16" S, 39°43'45" W, 1968 m), 22. VI.03, [27 valves]; IBUFRJ 17841, off Bacia de Campos (22°28'46" S, 39°53'28" W, 1621 m), 17. VI.03, [7 valves]; IBUFRJ 17842, off Bacia de Campos (22°04'45" S, 39°41'58" W, 1910 m), 27. VI.03, [28 valves]; IBUFRJ 17843, off Bacia de Campos (22°36'12" S, 39°58'23" W, 1670 m), 13. VI.03, [2 valves]; IBUFRJ 17844, off Bacia de Campos (22°04'34" S, 39°52'05" W, 1030 m), 30. VI.03, [1 valve]; IBUFRJ 17845, off Bacia de Campos (22°41'32" S, 40°00'47" W, 1906 m), 12. VI.03, [44 valves]; IBUFRJ 17846, off Bacia de Campos (22°33'08" S, 39°54'21" W, 1934 m), 15. VI.03, [26 valves]; IBUFRJ 17847, off Bacia de Campos (21°52'43" S, 39°40'42" W, 1941 m), 26. VI.03, [40 valves]; IBUFRJ 17848, off Bacia de Campos (22°41'11" S, 40°02'20" W, 1623 m), 13. VI.03, [7 valves]; IBUFRJ 17849, off Bacia de Campos (22°30'35" S, 39°51'45" W, 1970 m), 16. VI.03, [12 valves]; IBUFRJ 17850, off Bacia de Campos (22°04'45" S, 39°46'32" W, 1643 m), 27. VI.03, [3 valves]; IBUFRJ 17851, off Bacia de Campos (22°37'03" S, 39°56'20" W, 1945 m), 13. VI.03, [31 valves]; IBUFRJ 17852, off Bacia de Campos (22°36'12" S, 39°58'23" W, 1670 m), 13. VI.03, [4 valves]; IBUFRJ 17853, off Bacia de Campos (22°11'04" S, 39°47'05" W, 1654 m), 22. VI.03, [3 valves] GoogleMaps .

Remarks: The presence of diagonal striae on the anterior and posterior parts of the shell is the most important diagnostic character of this species, and distinguishes it from all other species in the Atlantic Ocean. According to Allen (2004), although rare, L. louiseae is widely distributed in the North Atlantic and south of the equator. This taxon was abundant in our samples, with a total of 368 valves collected. The number of diagonal striae on the anterior and posterior parts of the shell is quite variable, and depends on the size of the shell; often, small shells tend to have less conspicuous diagonal striae.