Conus (Profundiconus) emersoni (Hanna, 1963)
Description:
Sides of spire straight with nine whorls showing;
nuclear whorl smooth, next seven strongly but finely beaded; angle of last
whorl sharp and beads becoming weaker toward the aperture. Very weak spiral
threads on the deeply curved shoulder as in many Turridae. Body whorl slightly
concave, with the tip slightly recurved. Shallow spiral grooves cover the body
whorl, weak at the shoulder and becoming progressively deeper downward. Color markings,
reddish brown on a light clay colored background; the markings are crowded in
three spiral bands, one at the shoulder and two farther down on the body whorl;
the bands are made up of lines and spots, irregular in space and direction.
Elsewhere on the body whorl the markings are dots and dashes on the ridges
between the spiral grooves. The spire has large irregular blotches of reddish
brown.
Length, 43.0 mm.; diameter, 18.5 mm.
Holotype: No. 92200 (American Museum of Natural
History), paratype No. 12405 (Calif. Acad. Sci. Geol. Type Coll.) from off Los
Frailes Cape San Lucas, Baja California in 300 fathoms.
The species is named for Dr. William K. Emerson. It
was collected by one of the expeditions of the Scripps Institution of
Oceanography, along with other mollusks, some living and some perhaps from a
submarine deposit containing fossils. The holotype is a dead shell and appears
to be faded. It obviously belongs to the group of species sometimes referred to
Asprella Schaufuss, 1869, and is reminiscent of Eocene species with
beaded spires.
Dr. Emerson examined the fragment of a shell which
Dall (1910, p. 226) questionably identified as Conus sieboldii Reeve and
which was collected in 300 fathoms off Hood Island, Galapagos group. Available
illustrations of that species indicate that it has stronger spiral lines, and,
as shown by Kira (1959, p. 99, pi. 38, fig. 4) is nearly without color. In
coloration and strength of spirals, the Cape San Lucas shell is closer to Conus
australis Holten of the "south seas" and Japan (Kira, 1959, p.
99, pi. 38, fig. 6) than any other species which has been noted. If a series of
specimens were available it is possible that C. emersoni is sufficiently
variable to be referred to C. australis.
With only the holotype and a rather poorly preserved
younger shell, however, it seems best to separate them at the present time. A
Japanese fossil species, Conus comatosa Pilsbry (1904, p. 550) (originally
named C. dormitor Pilsbry, 1904, p. 6) is also very close to the Cape San
Lucas shell. It is from the Pliocene ("probably") of Kikai, Osumi and
has no color as figured by Shuto (1961, p. 140, pi. 8, figs. 9, 10).
Spiral sculpture is much stronger on this fossil than
on either C. australis or C. emersoni.
The rediscovery of Conns emersoni in the Galapagos Islands should put to rest speculation that this
species is a synonym ol either Conus anstralis
(suggested by Hanna, 1963) or C. orbignyi (suggested by
Walls, 1979). Each of these Indo-Pacific species is unlike C. emersoni
in having persistent sulci on the body whorl along with persistent cords on the spire
whorl tops. (Conus emersoni differs in having the sulci strong only anteriorly and
in having fine spiral striae on the whorl tops. Radular differences are that the radular tooth of C. orbignyi has three anterior barbs (Kilburn, 1973:
fig. 6), whereas that of C. emersoni has but two (2).
The scarcity of
C. emersoni may be due to the great depth at which it occurs and the
paucity of sampling at depths below 300 m. It is possible that the specimens
from the Galapagos Islands are specifically or subspecifically distinct. They differ
in color pattern (that of the holotype being more intricate) and in spire
profile (that of the holotype appearing to be more acute). However, such
intraspecific differences in color pattern are not uncommon in Conus (2).
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Conus emersoni
Holotype No. 92200 (American Museum of Natural History) from off Cape San Lucas, Baja California. Length 42.5 mm., diameter 18.1 mm. |
Conus dormitor (Pilsbry,
1904)
Conus comatosa (Pilsbry, 1904) figured by Shuto (1961, p. 140, pi. 8,
figs. 9, 10) Pliocene ? |
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Figures 1-7. Conus emersoni (Hanna, 1963) (2)
Figures 1-3.
Type material dredged off Los Fralies, Baja California, depth 549
1
Holotype, AMNH 105211 length 43 mm, faded, dead-collected
specimen, lacking periostracum.
2, 3. Paratype,
CAS 12405, length 49.0 mm, subfossil specimen (surface gray), showing naticid
bore hole.
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Figures 4-7. Newly reported
specimens dredged off Isla Santa Maria (Floreana), Galapagos Islands,
Ecuador, depth 310 m.
4. AMNH 248261, length 46.2
mm, dead-collected specimen.
5. LACM 146906a, length
33.3 mm, live-collected specimen with periostracum intact. This specimen was
used for opercular and radular illustration.
6, 7. LAC;M 146906b, length
34 mm, dead-collected specimen with periostracum removed to show color pattern.
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Bibliografia Consultata
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(1) -
Occasional papers of the California Academy of Sciences – n.35 - 1963
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(2) - John
K. Tucker (1993) “The Rediscovery, Morphology, and Identity of Conus
emersoni Hanna, 1963”
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