Gonimyrtea ferruginea, Taylor, John D. & Glover, Emily A., 2013

Taylor, John D. & Glover, Emily A., 2013, New lucinid bivalves from shallow and deeper water of the Indian and West Pacific Oceans (Mollusca, Bivalvia, Lucinidae), ZooKeys 326, pp. 69-90 : 78-80

Gonimyrtea ferruginea sp. n. Figs 9A, 10

Gonimyrtea ferruginea UGS-3, unidentified genus & species - Taylor et al. 2011, fig. 7J.

Type material.

Holotype: paired valves, live collected (MNHN IM-2009-10376) L 24.5 mm H 23.2 mm T whole shell 15.0 mm. Paratypes: 1 paired valve (MNHN IM-2009-10376) L 24.0 mm H 22.0 mm T 6.5 mm (single valve); 1 pv (MNHN IM-2009-10376) L 15.9mm H 14.2 mm T 7.7 mm.

Type locality.

New Caledonia, Chesterfield Bank, 19°35'S, 158°48'E, 680-722 m. N/O Alis campagne EBISCO 2005 stn CP2614.

Material examined.

All MNHN material from several deep water cruises in South west Pacific (for details see - www.mnhn.fr/musorstom/). New Caledonia, MUSORSTOM 4: 1 valve,stn CP158, 18°49'S, 163°15'E, 625 m. 2 valves, stn CP179 18°57'S, 163°14'E, 475 m.1 paired valve, stn CP 236, 22°11'S, 167°15'E, 495-550 m. BATHUS 2: 1 paired valve, stn DW740, 22°36'S, 166°27'E, 570-605 m. BATHUS 4: 1 valve, stn CP 900, 20°17'S, 163°50'E, 580 m. 2 valves, stn DW 908, 18°58'S, 163°11'E, 502-527m. 1 valve, stn CP905, 19°02'S, 163°16'E, 294-296 m. 1 valve, stn CP954, 21°44'S, 166°36'E 250-255 m. BIOCAL: 1 valve, stn DW40, 22°55'S, 167°24"E, 650 m. Chesterfield Bank, MUSORSTOM 5: 5 valves, stn 380, 19°38'S, 158°44'E, 555-570 m. 24 valves, stn 381, 19°38'S, 158°47'E, 620 m. Coral Sea, Kelso Bank, MUSORSTOM 5: 2 valves, stn 284, 24°10'S, 159°33'E, 225-230 m. Vanuatu, MUSORSTOM 8: 1 valve, stn DW1072, 15°40'S, 167°20'E, 622-625 m. SW Pacific, Wallis Island, MUSORSTOM 7: 3 valves, stn DW526, 13°13'S, 176°15'E, 355-360 m. 5 valves, stn DW527, 13°24'S, 176°15'W 540-560 m. 10 valves, stn DW 528, 13°24'S, 176°13'W, 435-515 m. 8 valves, stn DW601, 13°19'S, 176°17'W, 350 m. Bank Bayonnaise, MUSORSTOM 7: 1 valve, stn DW626, 11°54'S, 179°32W 597-600 m. 2 valves, stn CP629, 11°54'S, 179°32'W, 400-420 m. Tuscarora Bank, MUSORSTOM 7: 35 valves, stn DW556, 11°49'S, 178°18'W, 440 m.

Description.

Shell white, L to 25 mm H to 23.5 mm;subcircular, H/L 0.91 ± 0.017 (n=10), inflated T/L 0.28 ± 0.02 (n=10), sculpture of fine, low, rounded, regular, closely spaced, commarginal lamellae, radial sculpture absent, dorsal areas characteristically with ferruginous encrustations. Lunule short, lanceolate, symmetric. Protoconch (Fig. 10L): PI+PII 275 µm, PII, a narrow, 19 µm rim with fine increments. Ligament inset in narrow groove. Hinge (Figs 10J, K) LV with 2 cardinal teeth the posterior larger, can be obscure, lateral teeth not visible, RV with 2 cardinals, very small anterior lateral tooth, posterior lateral absent. Anterior adductor muscle scar long detached for ½ length, at an angle of 10-15°. Posterior adductor scar ovoid. Pallial line continuous, shell margin smooth.

Distribution.

New Caledonia, Vanuatu, and banks and islands in SW Pacific, in deeper water between 350 and 650 m (Fig. 4).

Remarks.

Compared to the genotype, Gonimyrtea concinna from New Zealand, at depths to 200 m, Gonimyrtea ferruginea occurs in much deeper water, is larger, the lateral teeth are less distinct, and commarginal lamellae are more closely spaced. Another deeper water species of Gonimyrtea is known from the Philippines ( Glover and Taylor in press) occurs at depths of 500-1000 m but is smaller than G. ferruginea, more elongate, lamellae are narrower, the interspaces wider, and the lunule deeper and longer.

Both Gonimyrtea ferruginea and the new species from the Philippines typically have dense iron-rich encrustations on the dorsal areas of the shell (Fig. 10 A–D). This also occurs in Dulcina guidoi from central Philippines at similar depths ( Cosel and Bouchet 2008) but is an unusual feature of lucinids that otherwise often exhibit some brown staining around the anterior inhalant area and posterior apertures.

Molecular analyses show that Gonimyrtea ferruginea (as UGS-3 in Taylor et al. 2011) aligns in the subfamily Leucosphaerinae close to species of Dulcina . GenBank numbers FR 686701, FR 686779, FR 686606

Etymology.

Derived from Latin ferrugineus meaning rust-coloured. Adjective in nominative singular.