Deep-sea “ cephalaspidean ” heterobranchs (Gastropoda) from the tropical southwest Pacific Author Valdés, Ángel John T. Huber text Mémoires du Muséum national d'Histoire naturelle 2008 196 587 792 journal article 978-2-85653-614-8 1243-4442 Retusa lenis n. sp. Figs 75A, B, 76 TYPE MATERIAL . — Holotype MNHN 20419 and 4 paratypes MNHN 20420-20422, 3 paratypes LACM 3003 . TYPE LOCALITY . — East coast of New Caledonia , Passe de Hienghu , 20°33’S , 165°00’E , 270-282 m [ BATHUS 1 : stn DW 688 ] . MATERIAL EXAMINED. — New Caledonia proper . VAUBAN : stn ratype ( MNHN 20420 ) . — BATHUS 2 : stn DW 717 , Ile des Pins , 40, 22°30’S , 166°24’E , 250-350 m , 2 dd, paratypes ( MNHN 20421 ). 22°44’S , 167°17’E , 350-393 m , 1 dd, paratype ( MNHN 20422 ) . — BATHUS 1: stn DW 688, Passe de Hienghu, 20°33’S , 165°00’E , Loyalty Ridge . MUSORSTOM 6: stn DW 442, 20°54’S , 167°17’E , 270-282 m , 2 dd, holotype ( MNHN 20419; Figs 75A, B) and pa- 200 m , 2 dd, paratypes ( LACM 3003). DISTRIBUTION . — Collected only from New Caledonia (Fig. 76), in 200-350 m . DESCRIPTION. — Shell morphology . Length 2 mm , width 0.8 mm ( holotype ). Shell fragile, elongate, wider anteriorly and narrower posteriorly, with nearly parallel sides (Fig. 75A). In some specimens, including the holotype , the left side is slightly concave. Only 1 whorl visible, forming nearly the entire shell, except for a small visible portion of the spire. Apex deeply umbilicate (Fig. 75B), with the aperture lip rising from the right side. The aperture lip forms a rounded wing connected to the columellar margin. Anterior end of the shell rounded. Aperture as long as the shell, wider anteriorly and narrowing abruptly at about 1/4 of its length. Columellar margin slightly thickened. Columella with an inconspicuous fold. Umbilicus closed. Sculpture of a number of faint, simple spiral lines crossed by growth lines. Colour uniformly whitish. Anatomy . Unknown. All shells collected lacked soft parts. REMARKS. — The shell morphology of Retusa lenis is similar to that of Retusa succinta A. Adams, 1862 , redescribed by Hori (2000c). Differences between these species include the presence of grey spiral lines and the more quadrangular shape of the shell in the latter. Additionally, R. lenis has a more developed aperture lip. This species is placed in Retusa , based on the shell morphology, pending availability of complete specimens. ETYMOLOGY. — From the Latin lenis (soft, smooth), in reference to the smooth, shiny shell of this species.