Two new species of Cerithiella (Apogastropoda: Cerithiopsidae) for the continental slope of Pernambuco (northeast Brazil)
Author
De, Silvio Felipe B.
Author
De, José Carlos N.
text
Zootaxa
2007
1441
63
68
journal article
10.5281/zenodo.176014
e5fb5e77-a873-49f8-be9c-4ec346fa7edc
1175-5326
176014
Cerithiella pernambucoensis
n. sp.
(
Figures 1–9
)
Type
material:
Holotype
,
MNRJ
10834 [length:
13.3 mm
; width:
2.6 mm
]; 1
paratype
,
MNRJ
10836 [length:
16.1 mm
; width:
2.6 mm
]; 4
paratypes
,
MZSP
80484; 4
paratypes
,
MORG
50.690; 3
paratypes
,
ANSP
413609; 3
paratypes
,
MNRJ
10835. All from
type
locality.
Type
Locality:
Continental slope of Pernambuco (
Brazil
), 08°46.5’00’’S, 34°44.5’00’’W,
690 m
.
Description
: Shell turriform, elongated, multispiral, somewhat slender, white porcelain (
Figs. 1, 9
). Protoconch paucispiral 1½ whorls, smooth, glossy, bulbous, inflated, exceeding contour of first post-nuclear whorl (
Figs. 2, 8
); transition to teleoconch with faint, sparse riblets (
Fig. 2
). Suture linear, faintly marked (
Fig. 3
). Teleoconch of 18 whorls on
holotype
, 23 whorls on
paratype
, flat or faintly concave. Axial ribs generally thin or obscure (
Figs. 3, 5
). First post-nuclear whorl with 22–24 well-delineated axial ribs, extending from suture to suture. Second post-nuclear whorl with two weakly nodular spiral cords at intersection with axial ornamentation. Third whorl with subsutural cord becoming strongest, developing series of strong, raised bulges in intersection with axial ribs, projecting small shoulder. Starting at fifth whorl, all whorls develop four pronounced spiral cords, abapical thicker, strongly nodular, two peripheral cords with low nodules, one smooth suprasutural cord. Suture moderately distinct. Base flat, smooth. Aperture sub-squared. Outer lip straight, thickened, angled at corner of base. Parietal region smooth, faintly convex. Siphonal canal short, oblique, widely opened (
Figs. 4, 6
).
Etymology:
Named in accordance with the locality
type
, Pernambuco, state in northeastern
Brazil
, situated among the states of Ceará and Paraíba (to the north), Piauí (to the west), Alagoas and Bahia (to the south), with the Atlantic Ocean to the east, which presents the record of all
Cerithiella
known for the country thus far.
FIGURES 1–9.
Cerithiella pernambucoensis
n. sp.
(SEM) [holotype, MNRJ]:
1
. Ventral view (length: 13.3 mm),
2
. Apical view,
3
. Detail of ornamentation,
4
. View of body whorl; [paratype, MNRJ 10836]:
5
. Detail of teleococh ornamentation,
6
. Body whorl,
7
. Protoconch and axial ribs of the first post-nuclear whorl,
8
. Apical view,
9
. Ventral view (length: 16.1 mm).
Scale bars
: Figs.
2, 8 =
100 µm;
3, 8
= 200 µm;
4, 6–7
= 500 µm.
Distribution:
Known only from the
type
locality.
Remarks:
Among the
Cerithiella
known for the Atlantic Ocean,
C. pernambucoensis
is doubtlessly the most distinctive taxon due to the presence of a taller spire, with flat or faintly concave whorls, containing a greater number of spiral ornaments than what is commonly found among congeners, which generally develop three pronounced cords per whorl [
C. metula
(Lovén, 1846)
, with sizes of up to
12 mm
, according to
Fretter and Graham (1982)
;
C. martensii
(
Dall 1889: 255, pl. 20, fig. 2, length
11.25 mm
);
C. enodis
(
Watson 1886: 541, pl. 39, fig. 3, length of
syntype
4.8 mm
);
C. amblytera
(
Watson 1886: 542–543, pl. 39, fig. 6, pl. 40, fig. 6, length
5.6 mm
)], with a very thickened subsutural cord originating singular bulges that project a small carina. In rare cases, as with
C. axicostulata
Castellanos, Rolán & Bartolotta, 1987
, the whorls develop only axial ornaments (
Castellanos
et al
. 1987
: 94, fig. 6, length
4.7 mm
).
The general shell morphology of
C. pernambucoensis
is more correlated to that of
C. amblytera
, especially specimens from the Azores (north Atlantic) [see variability in
Bouchet and Warén (1993
: 598, fig. 1322)], than with specimens from
Brazil
due to the presence of a weak axial sculpture and the faint concavity of the whorls. The most obvious characters of the new species to distinguish it from its sympatric congeners
C. amblytera
include reaching a much larger adult size, developing a spire with around 6 (
holotype
–
Fig. 1
) to 13 (
paratype
–
Fig. 9
) whorls, the presence of two additional spiral cords per whorl, a very thick subsutural cord projecting vigorous, raised nodules in the intersection with the weak axial ornamentation. In
C. amblytera
,
the abaxial cord is more pronounced and the protoconch has a smaller number of whorls. All specimens studied presented rather uniform conchological characters, with the exception of one specimen. In
paratype
, MNRJ 10836, the second spiral cord of the subsutural zone is absent and the axial sculpture is nearly obsolete on the whorls (
Figs. 5–6
).
Cerithiella producta
Dall, 1927
has a number of spiral ornaments that is compatible to
C. pernambucoensis
, but was characterized by
Dall (1927: 103)
as having “a fine line at the suture, a small thread a little in advance of the suture and two prominent threads near the periphery”, as well as two other less conspicuous threads at the margin of the base. This species is also similar in the faint or almost obsolete axial ribs and subsquared aperture, but, like the others, it is not as slender as
C. pernambucoensis
.