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 famelica
Watson, 1883
Figs 71A, B, 72
Retusa famelica
Watson, 1883: 338
.
TYPE MATERIAL
. —
One
syntype
BMNH
1887.2.9.2216-7
.
TYPE
LOCALITY
. —
Levuka
,
Fiji
,
22 m
[
Challenger
]
.
MATERIAL
EXAMINED. —
New Caledonia
proper
.
BATHUS 1
: stn
DW 674
,
Grande Passe de Touho
,
20°49’S
,
165°19’E
,
105-110 m
, 5 dd; stn
DW 677
,
20°49’S
,
165°19’E
,
96-109 m
, 3 dd (Figs 71A, B).
Fiji
.
The
type
material
.
DISTRIBUTION
. —
Originally
described from
Levuka
,
Fiji
, in
22 m
(Watson 1883).
Specimens
herein collected in
New Caledonia
(Fig. 72), in
105-109 m
.
DESCRIPTION. —
Shell morphology
. Length 2.5 mm, width
1 mm
(largest specimen examined). Shell fragile, very elongate, wider anteriorly and narrower posteriorly, with nearly parallel sides (Fig. 71A). Only 1 whorl visible, forming nearly the entire shell, except for a visible portion of the top of the spire and the apex of the protoconch, which is partially embedded. Apex deeply umbilicate (Fig. 71B), with the aperture lip conspicuously 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 simple, with no folds. Umbilicus closed. Sculpture of a number of strong, simple spiral lines crossed by conspicuous growth lines, more marked near the apex. Colour uniformly whitish.
Anatomy
. Unknown. All shells collected lacked soft parts.
REMARKS. —
Retusa famelica
, originally described from
Fiji
, is an elongate species with a rounded and conspicuous wing on the right side of the apex and a strong sculpture of spiral lines crossed by growth lines, more marked near the apex (Watson 1883, 1886). Examination of the original
type
material and the detailed drawings and text of the redescription by Watson (1886) allowed a positive identification of the present material from
New Caledonia
.
FIG. 71
. Shell morphology of species of
Retusa
Brown, 1827
.
A
,
Retusa famelica
Watson, 1883
, (2.5 mm), ventral view,
New Caledonia
, BATHUS 1 stn DW 677;
B
, same shell, posterior view.
C
,
Retusa sulcata
(Watson, 1883)
, (
6 mm
), ventral view,
Fiji
, SUVA 2 stn DW 04;
D
, same shell, posterior view.
E
,
Retusa crispula
(Watson, 1883)
, (
4 mm
), ventral view,
New Caledonia
, MUSORSTOM 4 stn CC 175;
F
, same shell, posterior view.
G
,
Retusa waughiana
Hedley, 1899
, (
2 mm
), ventral view;
New Caledonia
, BATHUS 1 stn DW 697;
H
, same shell, posterior view.
Retusa concentrica
A. Adams
in
Sowerby, 1850, originally described from the
Philippines
and subsequently reported from
Japan
(Hori 2000c), is similar to
Retusa famelica
in shell morphology. However,
Retusa concentrica
is proportionately shorter and has the growth lines well marked along the entire shell.
Since the anatomy of this species is unknown, it is provisionally maintained in the genus
Retusa
until complete specimens become available for study.