Deep-water Raphitomidae (Mollusca, Gastropoda, Conoidea) from the Campos Basin, southeast Brazil
Author
Figueira, Raquel Medeiros Andrade
Author
Absalão, Ricardo Silva
text
Zootaxa
2012
3527
1
27
journal article
10.5281/zenodo.210977
8eba0512-d65c-4c36-8c30-6d629fabfff8
1175-5326
210977
Gymnobela xaioca
n. sp.
(
Figs. 33–34
)
Type
material
:
Holotype
MNRJ
30287 [1] OP I # 3 (
22°35'S
,
39°58'W
–
22°32'S
,
39°56'W
),
20.94 mm
,
1620–1623 m
.
Paratype
IBUFRJ 16460 [1] OP I # 9 (
22°41'S
,
40°02'W
–
22°39'S
,
40°01'W
),
14.34 mm
,
1609–1621 m
.
Paratype
MNHN
[1] OP I # 9 (
22°41'S
,
40°02'W
–
22°39'S
,
40°01'W
),
17.14 mm
,
1609–1621 m
.
Type
locality
:
22°35'S
,
39°58'W
–
22°32'S
,
39°56'W
, Campos Basin, Southeast
Brazil
, Southwestern Atlantic,
1620–1623 m
.
Material examined
: The
type
material.
Description
: Shell slender, biconical-fusiform, yellowish, up to
20.94 mm
long. Protoconch not observed. Teleoconch whorls with a low-set shoulder forming a pagoda-like profile. Axial sculpture consists of many short fine axial riblets below the suture but not reaching the whorl shoulder, and 16–18 axial folds (on the fifth whorl). Except for the body whorl, the axial folds are angled on the whorl shoulder. Body whorl with about 28 very faint opisthocline axial ribs which extend onto the base, feebly reaching the aperture. Numerous weak and flattened spiral cords sculpture the entire surface of the whorls evenly, including the base. Suture shallow. Base elongated. Anal sinus wide and shallow. Inner lip reflected over parietal wall. Outer lip very thin. Anterior siphonal canal long and narrow. Aperture elliptical.
Etymology
:
Xaioca
is a word in Tupy, a major language of Brazilian indigenous peoples, and means “unwrinkle”, referring to the fact that his species has strong axial ornamentation on the earlier whorls that tend to vanish as the animal grows.
Geographic distribution
: Only known from Campos Basin, off Rio de Janeiro,
1609–1623 m
.
Discussion
: This species can be characterized by its very long anterior siphonal canal, faint spiral sculpture, axial sculpture strong and forming a shoulder on the earlier whorls and vanishing on the later whorls. Our material resembles Dall’s illustration of
Gymnobela emertoni
(
Verrill & Smith, 1884
)
(
Dall, 1889: pl. X, fig. 9
); however, the original illustration of this species (
Verrill, 1884, pl. XXXI, fig. 6
) is actually quite different, as is the material illustrated by
Bouchet & Warén (1980: 60, fig. 130)
. Our material is also similar to
Theta chariessa
as represented in the original illustration (
Watson, 1886: PL. XX, fig. 6
) and by
Bouchet & Warén (1980: 60, fig. 130)
. However, upon examination of the figures of the
type
material, it is clear that both
Gymnobela emertoni
and
Theta chariessa
are larger than our material and have shorter anterior siphonal canals.