3217
Author
Raines, Bret
Author
Huber, Markus
text
Zootaxa
2012
2012-02-29
3217
1
106
journal article
11755334
Moerella laperousea
sp. nov.
Figures 39 A–F
Type Material.
Holotype
: LACM 3169, 1 articulated specimen,
10.5 mm
.
Paratypes
1–4: LACM 3170, 4 single valves from the type locality.
Paratypes
5–6: LACM 3171, 2 articulated specimens,
4.5 mm
from Tahai,
30–50 m
.
Paratypes
7–12: LACM 3172, 1 articulated specimen and 5 single valves, up to
12.5 mm
from Tahai,
50–100 m
.
Paratypes
13–18: Coll. MHU, 1 articulated specimen and 5 single valves from Tahai,
50–100 m
.
Type
Locality.
Dredged
at
50–150 m
in sand,
La Perouse Bay
,
Easter Island
,
27°04’26” S
,
109°16’50” W
.
Description.
A finely commarginally sculptured, radially orange-red colored
Moerella
with the characteristic short and strong anterior lateral tooth in the RV and an opisthogyrate position of the umbones. Shell moderately small, not exceeding
13 mm
, elongate-ovate, posteriorly with a weak flexure and obscurely rostrate; rather thin; white with 5–6 broad orange-red radial streaks, emanating from the umbones; internal posteriorly and in the nymphal area rose red in some, otherwise white; no lunule; umbones very low, small, opisthogyrate, situated at the posterior third of the valve. Prodissoconch round, moderately elevated, P1 somewhat pitted, ca. 118 µm length by 93 µm height, P2 with faint to weak commarginal lines, ca. 228 µm length by 185 µm height. Adult valves compressed. Sculpture of dense, regular, commarginal threads. Hinge line rather thin, in RV with a strong, bifid posterior and a weak anterior cardinal, a short, strong anterior lateral and a nymphal posterior lateral. LV with a single strong bifid cardinal, laterals thin and vanishing. Pallial sinus very deep, ventrally surpassing anterior adductor scar, confluent; both muscle scars are comparatively large. External ligament rather short and strong, resting on a nymph, yellowish-brown. Margins smooth.
TABLE 11.
Selected measurements from the type material.
|
M. laperousea
sp. nov.
|
Length (mm) |
Height (mm) |
P1 (L x H) (µm) |
P2 (L x H) (µm) |
| Holotype |
10.5 |
5.7 |
not visible |
not visible |
| Paratype 1 |
6.2 |
3.3 |
130 x 100 |
225 x 190 |
| Paratype 4 |
9.1 |
4.8 |
125 x 90 |
230 x 185 |
| Paratype 7 |
6 |
3.2 |
100 x 90 |
230 x 180 |
FIGURE 39. A–F
,
Moerella laperousea
sp. nov.
;
A
, Exterior LV, 5 mm in length;
B
, Exterior RV, 4.8 mm in length, SEM;
C
, Interior RV, 4.4 mm in length, SEM;
D
, Interior LV, 4.7 mm in length, SEM;
E–F
, Close-up of the prodissoconch, RV, SEM, arrows indicating boundaries;
G–I
,
Pristipagia radians
(Deshayes, 1855)
;
G
, Interior LV, 13 mm in length;
H
, Exterior of same valve;
I
, Interior RV of same specimen.
Comparative diagnosis.
With regard to placement of this new species, the commarginal sculpture and lateral dentition exclude
Loxoglypta
Dall, Bartsch & Rehder, 1938
, and the finer sculpture and lateral dentition exclude
Nitidotellina
Scarlato, 1965
, as well. The hinge with a pronounced anterior lateral in the RV, vanishing laterals in the LV and the deep, confluent pallial sinus, together with shape, size and sculpture match the European
type
species of
Moerella
quite well. This assessment was shared by A. Langleit, (pers. comm., 2010). None of the illustrated
Moerella
species
from
Australia
,
New Zealand
or
Japan
are particularly close.
Remarks.
There is nothing similar known from the Hawaiian Islands.
Distribution.
Moerella laperousea
is commonly found from
30–200 m
in fine sand, at various Easter Island locations, notably off the western coastline near Tahai—
E1
.
Etymology.
The name reflects the
type
locality.