Taxonomical study on the mollusks collected in Marion-Dufresne (MD 55) and other expeditions to SE Brazil: the Fissurellidae (Mollusca, Vetigastropoda)
Author
Simone, Luiz Ricardo L.
Author
Cunha, Carlo M.
text
Zootaxa
2014
3835
4
437
468
journal article
10.11646/zootaxa.3835.4.2
01da15e5-14ca-4506-89fd-2055b906f4ff
1175-5326
249622
F492B5ED-0CA7-436B-94AF-EE4C99D630AF
Cranopsis apostrema
new species
Figures 56–65
Types
.
Holotype
MNHN 25300.
Paratypes
: MNHN 25301, 25 shells, MZSP 105509, 10 shells, MNRJ 25961, 4 shells; all from
type
locality.
Brazil
. Espírito Santo; continental slope of Abrolhos (MD55; Bouchet, Leal & Métivier col.;
27/v/1987
); off Itaúnas,
18°59’S
37°48’W
,
607–620 m
, MNHN 25302, 3 shells (sta. DC73),
18°58’S
37°48’W
,
682 m
, MNHN 25303, 1 shell (sta. SY74); off Regência,
19°40’S
37°48’W
,
790–940 m
, MNHN 25304, 1 shell (sta. CB77). Rio de Janeiro; Campos Basin,
22°42’33.8”S
40°40’84.2”W
,
110–120 m
, MNRJ 17234, 1 shell (
19/ix/2009
).
Type
locality.
Brazil
. Espírito Santo; off Itaúnas, continental slope of Abrolhos,
18°59’S
37°50’W
,
295 m
(MD55 sta. DC75; Bouchet, Leal & Métivier col.,
27/v/1987
).
Diagnosis.
Apex curved posteriorly, located in middle level in profile. Height ca. 45% of length; width 66% of length. Sculptured by 53 radial cords, with pustules. Foramen flanked by low edges; located high on shell.
Description.
Shell size ca.
5 mm
; bluntly conical; height ca. 45% of length. Pure white. Protoconch of 1.5 rounded whorls (Fig. 60, 65); situated on right (Figs 57, 59); smooth, glossy; size 240 µm. Foramen cuneiform (pointed anteriorly), width 13% of length; located dorsally, preceding anterior slope; ca. 6% of shell width, ca. 25% of shell length; edges irregular (Figs 56, 61, 63). Groove anterior to fissure very narrow; flanked by cords of similar strength as neighbor cords. Beak curved dorso-posteriorly, located anterior to posterior 1/3 of shell length (in dorsal view), in middle of shell height in profile; teleoconch of one whorl, overall angle in lateral view ca. 110° (Figs 57, 59, 62, 64). Sculpture of ca. 53 (range 50–55) narrow primary radial cords (Figs 56–57, 59–64), with small pustules; gradually increasing in strength towards aperture; in ventral half secondary cords gradually appearing; each pustule separated from neighboring pustules in line by space ca.1/2 of its width; interspaces ca. twice as wide as cord; ca. 60 pustules along threads close to median line. Selenizone short, narrower than foramen; edges simple, low; smooth internally (Figs 56, 61, 63). Aperture planar (Figs 57, 59, 64) to slightly concave (
Fig. 62
); outline elliptical, width approximately 66% of length; edges smooth. Inner surface smooth, glossy (Fig. 58). Septum ca. 40% of shell height; twice as high as wide, ventral edge slightly concave, ca. 25% of aperture width; gradually narrowing up to posterior edge of fissure.
Measurements (in mm).
Holotype
: 4.8 by 2.5;
Paratype
MZSP 105509#1: 4.8 by 2.5 (
Figs 61–62
).
Distribution.
Continental slope off Espírito Santo to Rio de Janeiro,
Brazil
.
Habitat.
Sandy mud bottoms,
110–940 m
(dead specimens).
Material examined.
Types
.
Etymology.
The specific epithet is derived from the Greek,
apo
, meaning separate, and
extrem
, related to strike; an allusion to delicate radial sculpture of the shell.