Taxonomic review of Inella and Strobiligera (Gastropoda: Triphoridae) from Brazil
Author
Fernandes, Maurício Romulo
Author
Pimenta, Alexandre Dias
text
Zootaxa
2019
2019-06-04
4613
1
1
52
journal article
26607
10.11646/zootaxa.4613.1.1
abf4bd0e-f807-48ce-b161-8fa6e38eae9a
1175-5326
3237989
D3513C1F-B4F6-42EE-BF16-5495B62E9A90
Strobiligera gaesona
(
Dall, 1927
)
Figures 3
S–T, 20
Triphora
(
Strobiligera
)
gaesona
Dall, 1927
: 95
.
Inella unicornium
:
Simone (2006
, fig. 3–4,
partim
).
Inella gaesona
:
Rolán & Fernández-Garcés (2008
: 128
, fig. 20C).
Strobiligera gaesona
:
Fernandes & Pimenta (2014
: 169
)
.
Material examined.
The
type
material and:
Brazil
: off
Ceará
state: MNRJ 30401 [6], MZSP 70305 [6, all with dried soft parts], MZSP 78890 [4, but two shells worn/unidentifiable], MZSP 131829 [8], Canopus Bank, 02º 14ʹ 25ʺ S, 38º 22ʹ 50ʺ W,
240–260 m
, P.M.S. Costa & J. Coltro coll.,
xi/2005
;
MZSP 37077
[2],
MZSP 53685
[2],
MZSP 53697
[2],
MZSP 133332
[1],
MZSP 66850
[1],
MZSP 70300
[6],
MZSP 133341
[4],
MZSP 133331
[6], Canopus Bank, 02º 14ʹ 25ʺ S, 38º 22ʹ 50ʺ W, 240–
60 m
,
J. Coltro
& C.M.
Cunha
coll.,
viii/2005
.
Description.
Shell sinistral, elongated, conical-fusiform, rectilinear profile, reaching
28.56 mm
in length,
4.03 mm
in width, length/width ratio 7.5 to 7.7. Protoconch globose, much to little inflated,
0.66–0.86 mm
in length,
0.41–0.68 mm
in width of its first whorl,
0.45–0.61 mm
in width of its last whorl; 2.75 to 3.5 slightly convex whorls (except first whorl), unclear distinction between protoconch and teleoconch, transition defined by a very fine, sinuous/opisthocline axial mark; initial whorl dome-shaped, broad, smooth; remaining whorls with two main spiral cords, situated at 45–52% and 66–76% of whorl height, with nearly the same strength or with the adapical spiral slightly more prominent, in addition to a small subsutural cord, rapidly enlarging to the end of the protoconch; axial sculpture absent. Teleoconch with up to 24 whorls; three spiral cords in the beginning, all of them continuous with those of the protoconch, the adapical one initially smallest but soon reaching the same size of others; very weak spiral sculpture, almost indistinct even in initial whorls, with only the micro spiral sculpture (composed of several threads) being evident in late whorls, but some shells have a strengthening of the spiral sculpture of median and abapical cords on late whorls; complete absence of axial sculpture over most of the shell, despite sinuous growth lines or discrete threads in some shells; absence of nodules, whorls totally flat, without any convexity; very indistinct suture, only marked by a small sutural cord; narrow, smooth subperipheral cord, two smooth basal cords; no supranumerical cords are distinguishable on the inconspicuous end of the body whorl; ovate aperture, with a moderately expanded outer lip,
1.09–1.32 mm
long,
0.96–1.01 mm
wide, length/width ratio 1.1–1.4; anterior canal very short, directed downwards, and totally open,
0.23–0.29 mm
long,
0.36–0.43 mm
wide, length/width ratio 0.6–0.8; posterior canal a very small notch, almost indistinct,
0.15–0.17 mm
long. White shell, with a translucent initial protoconch whorl.
Remarks.
As mentioned above, the single lot of
paratypes
of
Strobiligera unicornium
is a mix of three species, including
Strobiligera gaesona
(
Fig. 17E
), whose protoconch was illustrated by
Simone (2006
: figs. 3–4).
Shells from
Brazil
(Fig. 20) are remarkably similar to the
lectotype
of
S
.
gaesona
(
Fig. 3S
), without any clear difference, except the bathymetric range of this species is shallower in
Brazil
(
240–260 m
) than in the type locality (
805 m
). Some types also show a moderately strong spiral sculpture on earlier whorls (
Fig. 3T
), fading out later, which is slightly different from the very weak spiral sculpture since the beginning of the teleoconch in Brazilian shells; as mentioned above, shells of
Strobiligera dinea
(
Dall, 1927
)
may be mixed in that lot.
Several shells of
S
.
gaesona
from
Brazil
had drill holes indicative of predation by gastropods. Their smooth shells, without nodules, seem to be prone to suffer attacks.
Geographical distribution.
U.S.A.: off
Georgia
(
type
locality);
Brazil
: off
Ceará
(this study)
.
Bathymetric distribution.
240 m
(this study) to
805 m
(
type
locality).