Eight new species of Scissurellidae and Anatomidae (Mollusca: Gastropoda: Vetigastropoda) from around the world, with discussion of two new senior synonyms
Author
Geiger, Daniel L.
text
Zootaxa
2006
1128
1
33
journal article
50738
10.5281/zenodo.273358
ba17466e-c23e-4583-ae92-0bf956c83ca3
11755326
273358
Scissurella maraisorum
new species
:
Figures 7–8
Type
material.
Holotype
(
NMSA
W3498/T1616:
Fig. 7
).
Paratypes
(
NMSA
W3499/ T1617, 2).
Paratypes
(Coll. A & J.P. Marais, 3: including
Fig. 8
A).
Paratypes
(
SBMNH
359327, 2.
Fig. 8
B.
SBMNH
359324:
Fig. 8
C). Unfigured
paratypes
(AMS C.447877, 1;
BMNH
20050274, 1;
MNHN
type
collection, 1;
UMUT
RM29043, 1;
USNM
1081939, 1).
Type
locality.
20 m
, Aliwal Shoal, KwazuluNatal south coast,
Republic of South Africa
.
June 2003
.
30.250°S
,
30.817°E
.
Etymology.
Named after Dr. Johan P. and Alwyn P. Marais of
South Africa
, who collected the specimens and generously made them available for study, and for their continuing accomplishments to further the understanding the South African malacofauna. Genitive masculine plural of surname.
FIGURE 7.
Holotype of
Scissurella maraisorum
new species
(NMSA W3498/T1616). Aliwal Shoal, KwazuluNatal south coast, SCUBA 20 m. June 2003. 30.250°S 30.817°E. Uncoated specimens, variable pressure, VPSE detector. Scale bar shell = 500 µm. Scale bar protoconch = 100 µm.
Description.
Shell small (to
0.72 mm
:
holotype
), trochiform depressed. Protoconch of 1 whorl, fine axial sculpture with median ridge, no apertural varix, apertural margin convex. Teleoconch I of 1–1.125 whorls, approximately 14–18 strong axial cords, no spirals, interstices with fine irregular axials. Teleoconch II of 0.33 whorls. Shoulder flat, suture deep, near suture indistinct axial cords of same spacing as on teleoconch I, mainly fine irregular axials. Base with strong axial cords of same spacing as on teleoconch I from selenizone to lowermost base, fading towards umbilicus; no spirals; interstices with fine irregular axials; base continuously sloping with umbilical wall. Umbilicus wide, open, protoconch visible through umbilicus. Selenizone above periphery, keels moderately strongly elevated, strong, inclined approximately 45° towards coiling axis. Aperture subquadratic, adumbilical wall straight, roof almost straight, base curved with adumbilical projection.
FIGURE 8.
Paratypes of
Scissurella maraisorum
new species
. A. Collection J.P. & A.P. Marais, South Africa. B. (SBMNH 359327). C. (SBMNH 359324). All specimens from Aliwal, Kwazulu Natal south coast, SCUBA 20 m. June 2003. 30.250°S 30.817°E. Uncoated specimens, variable pressure, VPSE detector. Scale bars shell = 200 µm. Scale bars protoconch = 100 µm.
Differential diagnosis.
Scissurella maraisorum
is characterized among the African species by its flat spire, the absence of spiral sculpture, and the widely open umbilicus which shows the lower surface of the protoconch.
Scissurella jucunda
Smith, 1890
from
South Africa
has a distinctly elevated spire, a closed umbilicus, and some spiral sculpture on shoulder as well as base.
Scissurella rota
Yaron, 1983
from East Africa has spirals on shoulder and base, the umbilicus is bordered by an edge towards base.
Scissurella sudanica
Bandel, 1998
from East Africa has an elevated spire, spirals on shoulder and base, and a narrower umbilicus that is bordered by a strong cord towards the base.
Sinezone doliolum
Herbert, 1986 from
South Africa
has the slit closed to a foramen in adults, has an elevated spire, has indistinct spirals on shoulder and base, and an almost closed umbilicus.
Sinezona insignis
(Smith, 1890)
from
South Africa
has a closed foramen in adults, fewer but stronger axial cords to low lamellae, has strong axials on the protoconch, and has a much more narrow umbilicus bordered by a cord towards base.
Sukashitrochus maraisi
Herbert, 1986
from
South Africa
has distinct spiral keels on base, a closed foramen in mature specimens, and the umbilicus is bordered by a keel.
Distribution
. Known from
type
locality only.
Sinezona garciai
new species
:
Figures 9–10
Type
material
.
Holotype
(
USNM
1081940: ex
UMML
30.12043.
Fig. 9
).
Paratypes
(
SBMNH
359317, 2: ex
UMML
30.12043.
Fig. 10
A, B), same data as
holotype
.
Paratype
(
UMML
30.12043, 1), same data as
holotype
.
Paratype
:
16 m
, St. Croix,
US
Virgin Islnads,
17.800°N
,
64.800°W
(
UMML
30.12051, 1.
Fig. 10
C).
Type
locality
.
1.5 m
, behind outer reef, Courtown Cays, San Andres y Providencia,
Colombia
,
12.383°N
,
81.433°W
.
Etymology
. Named for Emilio Garcia of Lafayette, Louisiana,
USA
, for his continuing contribution to the knowledge of the Caribbean malacofauna, and his generous support of ongoing research.
Description
. Shell small (to
0.76 mm
), trochiform depressed, last 0.125 whorl distinctly descending. Protoconch of one whorl, fine, sharp axials in outer half of whorl, inner half smooth, no apertural varix, apertural margin convex. Teleoconch I of 0.66 whorls. Shoulder slightly convex, suture distinct; approximately 10–12 axial cords, no spirals, interstices with fine irregular growth marks. Teleoconch II of 0.66 whorls, same density and strength of axials as on teleoconch I, onset of broad, low axial cords slightly after onset of selenizone, increasing in number to approximately 10–12, somewhat unevenly spaced. Base with distinct constriction below selenizoen, same density of more distinct axial cords as on shoulder, crossed by approximately 16–18 weaker spiral cords, cords mirror increase in strength and number with growth to those on shoulder. Selenizone above periphery, keels strong, moderately elevated, growth marks very distinct; foramen elongated. Umbilicus wide, bordered by strong spiral cord, walls straight, with fine axial growth marks. Aperture obliquely Dshaped, roof overhanging. Animal unknown.
Differential diagnosis
.
Sinezona confusa
Rolán & Luque, 1994
[=
Sin.
columbiana
(
Bandel, 1998
)
] from the Caribbean has a more elevated overall shape and spire, a very narrow, barely open umbilicus, and a protoconch with fewer and broader axials as well as an apertural varix.
Scissurella electilis
Montouchet, 1972
from
Brazil
has a much narrow umbilicus, lacks the strong cord separating the umbilicus from the base, and retains an open slit at maturity.
Satondella brasiliensis
(Mattar, 1987)
[=
Sat.
tabulata
(Watson, 1886)
?] from
Brazil
and
Sat.
tabulata
from the Caribbean have a more strongly descending aperture on the last quarter whorl and the foramen is drawn out into a strongly elevated chimney.
Satondella tabulata
has microhexagonal microsculpture, which is often eroded and looks smooth; the protoconch sculpture of the nominal taxon
Sat.
brasiliensis
is unknown.
FIGURE 9.
Holotype of
Sinezona garciai
new species
. Behind outer reef, Courtown Cays, W. Caribbean, Colombia, 12.383°N, 81.433°W (USNM 1081940: ex UMML 30.12043). Scale bar shell = 500 µm. Scale bar protoconch = 100 µm.
Distribution
.
Colombia
to
Bahamas
.
Specimen Records
.
18 m
, Samphire Cay, NW Nassau,
Bahamas
,
25.183°N
,
77.017°W
(HLC, 1).
Remarks
.
Sinezona garciai
is considered distinct from
Sin.
confusa
, and not simply a form with more depressed shells. All five specimens of
Sin.
garciai
available show highly congruent features with very little intraspecific variability. The same applies to 68 lots of
Sin.
confusa
inspected ranging from
Bermuda
to
Venezuela
.
Sinezona columbiana
is a synonym of
Sin.
confusa
, showing all features of that species, which also distinguish it from
Sin.
garciai
: overall more elevated shell, more narrow umbilicus, and a protoconch with fewer and broader axials as well as an apertural varix.