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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, 42,5 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 Conus emersoni in the Galapagos Islands should put to rest speculation that this species is a synonym ol either Conus australis (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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