Lyncina carneola, Marshall Islands

Lyncina carneola (Linnaeus, 1758)
Carnelian cowry, 20-48mm

Lyncina carneola might occupy the widest range of Marshall Islands habitats. They can be found commonly under rocks from the intertidal reef on down as least to 45m and deeper in the lagoon and on the seaward slope. Within the lagoon, they can be found under rocks along shallow interisland reefs on both leeward and windward shores. Dead empty shells are abundant in oceanside surge channels and common on deep lagoon shipwrecks. In shell color and pattern, this species is almost identical to two other cowries, Lyncina leviathan and L. propinqua. We have to admit we still have trouble telling them apart, and feel that some of the characters that have been used to differentiate them are not consistent. DNA analysis (Meyer (2003)) has apparently confirmed that these three species are indeed different, but since that is not a tool available to most of us underwater photographers, we have to make do with less distinctive and sometimes variable features of the shell and animal. The shells of Lyncina carneola and L. propinqua are smaller and smoother along the margins than L. leviathan, which tends to have an irregularly bumpy outer edge. Lyncina carneola and L. propinqua are said to usually have a diffuse bluish-white band between the dorsal orange and brownish marginal coloration; this is clearly visible in the first and several other photos below, less obvious in some others. Lyncina leviathan is supposed to always lack this bluish-white band. Lyncina carneola and L. propinqua are externally differentiated mostly by the shape of the shell: L. carneola has more smoothly rounded lateral sides, giving the overall shell a more elongate oval outline when viewed from above, while L. propinqua is a bit wider with slightly more angular sides, making it appear less elongate from above. Anatomically, there are consistent and distinct differences in the radulae of L. carneola and L. leviathan. The mantle papillae have been reported to be quite different as well, although there is often confusing variation in the papillae of both L. carneola and L. propinqua. Usually the papillae in those two species are somewhat flattened paddles with serrations or small branches near the top, but some times the papillae approach those of L. leviathan, which are more tree-like with numeous branches, sometimes described as shaped like a "shaving brush." We have included numerous photos of L. carneola below to show the variation in mantle papillae. Lyncina carneola is known from most of the Indo-Pacific.

Here is a close view of some of the larger papillae from the specimen above. Would these be considered flat with fingerlike branches near the top? Maybe.

The specimens above and below clearly have the bluish-white band (less clear in the photo below) separating the dorsal from the marginal coloration. However, the papillae of the photo above look like some more problematic photos below.

This slightly fuzzy shot, taken in the Solomon Islands, illustrates papillae that seem to me to more closely match the description of Lyncina carneola, which Burgess (1985) says are round at the base with "flat blunt branches that closely resemble the flattened human hand with the fingers spread on the same plane." It also matches the color photo on page 80 of Burgess (1985). Or would these be better considered square flattened sails with serrated tops, as described for L. propinqua? Compare this with the following two photos.

The next three shots illustrate a specimen we considered Lyncina carneola due to its small size and lack of bumps along the lateral shell margins. However, its papillae are distinctly branched up near the top, much more like Lyncina leviathan's "shaving brush-like dendritic papillae" of Lorenz & Hubert (2000). Of course, this could have been a small L. leviathan with no lateral bumps, but its papillae seem to us at least similar to the obvious L. carneola in the first photo on this page. We think this group of cowries has a fair bit more work that needs to be done on it. In particular, we would be interested in seeing the results of DNA analysis on particular specimens from this area whose living anatomical features have also been clearly photographed for comparison.