Hanging on - lucinid bivalve survivors from the Paleocene and Eocene in the western Indian Ocean (Bivalvia: Lucinidae) Author Taylor, John D. Author Glover, Emily A. text Zoosystema 2018 2018-04-10 40 7 123 142 journal article 10.5252/zoosystema2018v40a7 26ac6a51-9d0a-4cb0-8502-230b45cf66e6 1638-9387 3738245 urn:lsid:zoobank.org:pub:7652DEC7-3C6C-414F-AF2C-7C396D78F6F6 Retrolucina voorhoevei ( Deshayes, 1857 ) n. comb. ( Figs 6A-H ; 7A, B ) Lucina voorhoevei Deshayes, 1857: 106 , pl. 2, fig, 1. Holotype not located. Dance (1986: 154) lists 1872 sales catalogue of J. Voorhoeve collection where the holotype of Lucina voorhoevei was sold to H. C. R. van Lannep and then later listed in the 1876 sale catalogue of his collection ( Jutting 1939 ) but its subsequent whereabouts is unknown. Lucina mirabilis Dunker, 1865: 77 , pl. 26, figs 7-9. Gibbolucina ( Eomiltha ) voorhoevei – Chavan 1938: 93 . — Kilburn 1974: 343 , figs 6, 7. Eomiltha voorhoevei – Oliver 1995: 236 , fig. 1029. — Huber 2015: 106, 458. TYPE LOCALITY. — Not given in original but cited as Mozambique by Heukolom 1866 . MATERIAL EXAMINED. — Algoa Bay (unlikely) ( NHMUK 20170373) ; Mozambique ( USNM 628930) ; Mozambique ( ANSP 234103) ; Mozambique : Mucoque , near Vilanculos ( MNHN ) . DISTRIBUTION. — Mozambique : Mucoque (MNHN), Inhassoro, Mucoque and Bazaruto Island ( Kilburn 1974 ); Madagascar : NW Madagascar (ANSP); Kenya : Ukunda ( Huber 2015 ); Oman : Masirah ( Oliver 1995 ), Muscat (NMW BV6059). HABITAT. — No live collected specimens are known. Most records are beach collected and the species is assumed to live subtidally but Huber (2015) records dead shells at 5 m depth in southern Kenya . DESCRIPTION Shell large, L to 80 mm , ovoid, tapering to anterior and posterior, thin shelled, relatively flat T 8.3 mm single valve. Umbones small, low. Posterior dorsal area faintly delineated by shallow sulcus. Sculpture generally smooth with irregular growth lines. Lunule small, narrow, triangular. Ligament short, set in shallow groove. Hinge line thin, RV with two cardinal teeth the posterior bifurcate, anterior tooth smaller, LV with two cardinal teeth, anteriormost bifurcate; lateral teeth absent in both valves. Anterior adductor muscle scar long, narrow, curved, extends ventrally to past mid-line of shell, detached and widely separated from pallial line for nearly all of length. Posterior adductor scar reniform. Pallial line narrow, entire. Pallial blood vessel scar visible, terminating ventrally at lower part of anterior adductor scar. Shell interior with fine radial ridges and sometimes exposed organic layers. Shell outside pallial line glossy, margin smooth. REMARKS Among living Lucinidae Retrolucina voorhoevei n. comb. has an unusual, elongate, laterally compressed shell shape that is only matched by some deep water taxa such as Gloverina and Elliptiolucina ( Cosel & Bouchet, 2008 ) or Jorgenia (Tay - lor & Glover, 2009) but these have short anterior adductor muscle scars and molecular results show they belong in the Myrteinae ( Taylor et al. 2014 , 2016 ). By contrast, although details of habitat are lacking, the presence of dead shells on beaches suggests that R. voorhoevei n. comb. is a shallow subtidal species. The Eocene congener, R. defrancei , was also a shallow water species recorded by Courville et al. (2012) from the Paris Basin at Damery (Lutetian), in beds associated with cerithiid and potamidid gastropods.