Pseudocypraea Schilder, 1927

Pacaud, J. - M., 2003, First fossil records of the Recent Ovulid genus Pseudocypraea Schilder, 1927 (Mollusca, Gastropoda) with description of a new species, Geodiversitas 25 (3), pp. 451-462 : 454

Genus Pseudocypraea Schilder, 1927

TYPE SPECIES. — Cypraea adamsonii Sowerby, 1832 , by original designation.

DISTRIBUTION. — Indo-Pacific Province, Galapagos and Coco islands.

DIAGNOSIS. — Small and subglobose shell. Involuted protoconch. Terminal fold lamellar, exceedingly elongated, straight and adaxial (absolutely unique to the

Cypraeoidea ), adapical acuminate ridge, canaliculated excurrent channel, forming a protruding bridge, neck forming an adaxial obtuse bottom, spiral incision developing into narrow ribs on the entire surface of the shell.

REMARKS

Schilder (1927: 13, 71) erected the subgenus Pseudocypraea with Cypraea adamsonii as the type species, within the genus Cyproglobina de Gregorio, 1880 . This fossil genus of Cypraeidae ( Dolin & Dolin 1983: 26-29, fig. 9a-c) is in fact related to Cypraeorbis Conrad, 1865 ( Dolin 1991a: 4-11, figs 2-9). In an attempt at accommodating the anatomical features of the animal and the morphological features of the shell, Schilder (1936: 77, 81, pl. 11) reassigned it to a subgenus of Eocypraea Cossmann, 1903 . In fact, the morphology of Pseudocypraea strikingly resembles only that of Eovolva nigeriensis ( Newton, 1922) , type species of the monospecific genus Eovolva Schilder, 1932 . However E. nigeriensis ( Fig. 2B ) from the Bartonian (middle Eocene) of Bende Ameki, Nigeria ( Newton 1922: 18, 19, pl. 3, figs 14, 15; Eames 1957: 39, pl. 6, figs 2, 3; Adegoke 1968: 48, figs 23, 24), displays the characteristic terminal fold and costulation of Eucypraedia Schilder, 1939 ( Dolin 1991b: 30, figs 1a, b, 3-5), although it shows the same curvature and canaliculate excurrent channel as in Pseudocypraea . Furthermore, Schilder & Schilder (1971) inexplicably synonymized Cypraea (Cypraeovulva) eratoformis Hoernes & Auinger, 1880 from the Langhian (middle Miocene) of Lapugiu de Sus ( Rumania) with Apiocypraea hoernesi (Neugeboren, 1853) . However, the holotype (NHMW 1999Z0077/ 0027) ( Fig. 4 D-F) of Cypraea (Cypraeovula) eratoformis is a typical Pseudocypraea , as evidenced by all its morphological characters, such as the globose shell, lamellar terminal folds, exceedingly elongated, straight and canaliculate excurrent channel, and body whorl with numerous, fine, and evenly spaced spiral threads. The genus Pseudocypraea was obviously considered as monotypic ( Cernohorsky 1968: 51, fig. 14; 1972: 91, pl. 23, fig. 6; Keen 1971: 499, fig. 94; Cate 1973: 4, 5). Petuch (1979: 6, figs 5, 6) described the holotype of P. exquisita (DMNH 126392) from the deep-waters of the Philippines, which differs from the holotype of P. adamsonii (BMNH 1969139), the type species of the genus, in having a more slender shell, well developed anterior and posterior terminal and posterior labial teeth, which give the outer lip a serrated edge. P. adamsonii has a heavily sculptured columella and base, whereas P. exquisita contrasts greatly with the latter in having a smooth and highly polished basal area (see Petuch 1979: 6). P. exquisita lives about 250 m deep on sponge and soft coral-bearing substrates. P. adamsonii occurs in intertidal, shallow water, among corals ( Rosenberg 1992: 73). The genus Pseudocypraea is distributed throughout the Indo-Pacific, including the Japan and South-Africa provinces ( Liltved 1989: 98, fig. 155; 2000: 98, fig. 155-155a) ( Fig. 6 ). The new species described herein cannot be referred to the genus Eocypraea Cossmann, 1903 . This genus ( Fig. 2A ) appears as early as the Cenomanian ( Schilder & Schilder 1971: 9, 66, 67) and represents the ancestral group for the Ovulidae ( Dolin & Ledon 2002: 331) . It is characterized by a globulous, callous and smooth, cypraeiform shell, an open siphonal canal, a thin terminal fold, a marginate, trigonal fossula, a columellar denticulation that is restricted to the angular area, and a short and poorly delineated excurrent channel.

Figures

FIG. 2. — A, Eocypraea (s.s.) dollfusi (de Laubrière, 1881), Lutetian (middle Eocene) of Fontenay-en-Vexin (Eure) (MNHN- DHT R63541) (leg. Pons); B, Eovolva nigeriensis (Newton, 1922), Bartonian (middle Eocene) of Bende Ameki (Nigeria) (MNHN- DHT R63539) (leg. Brébion). Scale bar: 5 mm.

FIG. 4. — A-C, Pseudocypraea dolini n. sp., Bartonian (Marinesian, middle Eocene) of Le Quoniam (Val d’Oise), holotype (MNHN- DHT R63008) (leg. J.-M. Pacaud); D-F, Pseudocypraea eratoformis (Hoernes & Auinger, 1880) n. comb., Langhian (middle Miocene) of Lapugiu de Sus (Rumania), holotype (NHMW 1999Z0077/0027). Scale bar: A-C, 5 mm; D-F, 3 mm.

FIG. 6. — Geographic distribution of the genera Pseudocypraea Schilder, 1927 and the fossil occurences.