First fossil records of the Recent Ovulid genus Pseudocypraea Schilder, 1927 (Mollusca, Gastropoda) with description of a new species
Author
Pacaud, J. - M.
text
Geodiversitas
2003
25
3
451
462
journal article
10.5281/zenodo.5375302
1638-9395
5375302
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.