Conus humerosus (Pilsbry, 1921)

Some specimens in the lot of proteus have fewer spots, as noted by Gabb. In the one figured there are 6 spiral rows of spots on narrower continuous bands. In another there seem to be 7 such spotted bands, but the color is nearly obliterated. Both of these shells are very broad-shouldered; otherwise they agree with C. proteus.

Length 65 (apical whorls lost), diam. 45 mm. (Type, no. 2548). Length 64, diam. 40.5 mm.

This cone agrees with C. williamgabbi Maury in general shape and dimensions, but the whorls of the spire are concave, without spiral threads, and there are no spirals in the lower part of the shell ⁽²⁾.

Coloration pattern

Two weakly interacting patterns possibly present. The primary (base) pattern might consist of a solid, undifferentiated ground pattern that extends over the entire shell. The secondary pattern consists of 5–7 spiral rows of heavily pigmented, square-shaped spots; these are usually visible in regular light. Interaction between the two patterns occurs when the spiral spots intersect the base pattern, resulting in unpigmented spaces between the spiral dots (these unpigmented spaces are the evidence that a solid ground pattern may be present). The two patterns differ in the color of emitted light. Sutural ramp with blotches⁽¹⁾.

Remarks

Among Dominican cone snail fossils, Conus humerosus can only be confused with C. spurius Gmelin, 1791. Additional work will be required to determine whether C. humerosus is truly a distinct species from C. spurius (as suggested here), or whether it is a variation of C. spurius (as suggested first by Pilsbry, who described it as a subspecies of C. proteus, a synonym of C. spurius). Given its close association with C. spurius, C. humerosus is also assigned here to the subgenus Spuriconus⁽¹⁾.

Conus humerosus is tentatively treated here as a species distinct from C. spurius; while the two species are consistent in most discrete aspects of shell morphology, their coloration patterns consistently differ, including in sympatry (both species occur at TU station 1354). In particular, C. humerosus has 5–7 spiral rows of square-shaped spots separated by regions lacking pigmentation. Furthermore, C. humerosus may have two patterns of shell pigmentation, whereas C. spurius only has one.

As recently documented by Kohn, modern C. spurius show a great deal of variation in their pigmentation pattern. The bold, spirally-arranged axial streaks documented here in Dominican fossil C. spurius are not known from the modern fauna, though modern individuals do sometimes show blotches that have coalesced to form axial streaks. On the other hand, some modern specimens also show spiral rows of square-shaped spots that are more similar to the pattern documented here for C. humerosus than for C. spurius (importantly, though, C. humerosus has fewer such rows of spots)⁽¹⁾.