A key to the genera and species of the transversely-dividing Flabellidae (Anthozoa, Scleractinia, Flabellidae), with a guide to the literature, and the description of two new species Author Cairns, Stephen D. text ZooKeys 2016 562 1 48 http://dx.doi.org/10.3897/zookeys.562.7310 journal article http://dx.doi.org/10.3897/zookeys.562.7310 1313-2970-562-1 D11C6C1E6EE74C8DA560331E75947EC8 Taxon classification Animalia Scleractinia Flabellidae Placotrochides frustum Cairns, 1979 Fig. 12B Placotrochides frusta Cairns, 1979: 152-153, pl. 29, figs 4-6, 8-9, map 43. Placotrochides frustra : Zibrowius 1980 : 159-161, pl. 81E-M. Placotrochides frustum : Cairns 2004 : 307 (key, nom. correct.). New records. CRYOS, Balgim CP85, 34°24'N , 7°39'W , 1378 m, 15 specimens, MNHN; Professor Logachev 37L 165, 16°54.014'N , 46°34.842'W , 2646-2705 m, 6 Mar 2015, 1, USNM 1295415, 1, IOM Moscow; Professor Logachev 37L 188, 17°08.470'N , 46°23.443'W , 2291-2327 m, 12 Mar 2015, 1, IOM Moscow. Distribution. Lesser Antilles, off northeastern Brazil, mid-Atlantic Ridge at latitude of Lesser Antilles, off Morocco, 497-2646 m. Remarks. The specimens reported herein from the mid-Atlantic Ridge are much larger than any previously reported, having a GCD up to 10.2 mm and a height of 13.9 mm, the calice having corresponding more septa, i.e., S1-2>S3>S4, 12:12:12, or 36 septa. The largest previously known specimen was only 5.0 mm in GCD and had 26 septa. They also represent a considerable depth range extension.